Guidelines for the management of atrial fibrillation released

Guidelines for the management of atrial fibrillation (AF) have been released by the European Society of Cardiology (ESC).

The 2016 Atrial Fibrillation Guidelines, created around state-of-the-art research and evidence, were released earlier this week at the ESC Congress in Rome.

AF remains one of the major causes of stroke, heart failure, sudden death and cardiovascular morbidity in the world, with emerging evidence offering innovative approaches to its diagnosis and management.

The guidelines list recommendations for diagnosis, general management, stroke prevention, rate control and rhythm control of AF.

Catheter ablation, which has now become a common treatment for recurrent AF, is also discussed as a possible treatment within the guidelines. In general, it should be used as second-line treatment after failure of or intolerance to antiarrhythmic drug therapy. In such patients, when performed in experienced centres by adequately trained teams, catheter ablation is more effective than antiarrhythmic drug therapy.

Other guideline recommendations for the management of AF include:

Opportunistic screening for AF is recommended by pulse taking or ECG rhythm strip in patients over the age of 65
The proposal of lifestyle changes to all suitable AF patients to make their management more effective
The use of the CHA₂DS₂-VAS_c score to predict stroke risk, and initiation of oral anticoagulation when score is 2 or more for males, or 2 or more for females
The avoidance of combinations of oral anticoagulants and platelet inhibitors in AF patients without another indication for platelet inhibition
The selection of antiarrhythmic drugs based on the presence of co-morbidities, cardiovascular risk, potential for proarrhythmia, extracardiac toxic effects, patient preference and symptoms, and consideration of catheter or surgical ablation when antiarrhythmic drugs fail
Moderate regular physical activity is recommended to prevent AF, while athletes should be counselled that long-lasting, more intense sports participation can promote AF

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[Perspectives] Shengshou Hu: leader of cardiac surgery and health reform in China

“Wise man finds pleasure in streams”, says an old Chinese saying. Being at one with water has always been part of Chinese cardiac surgeon Shengshou Hu’s life, from the wide waters of the Yangtze river to the swimming pool close to his professional home today in Beijing, where he is President of Fuwai Hospital, affiliated with the Chinese Academy of Medical Sciences. “As a young man, swimming across the Yangtze river with its strong currents seemed a good metaphor for life, and even today I find swimming a good time for reflection and relaxation, especially after surgery”, he says.

Cardiac machines linked to infection

Health departments around the country are contacting open heart surgery patients who may have been exposed to a rare infection that can be found in some heater-cooler units used in surgery.

According to international reports the design and manufacture of some heart bypass heater-cooler units made by Sorin have made them susceptible to harbouring the rare bacterium mycobacterium chimaera.

M. chimaera infections in cardiac surgery patients overseas have been linked to the heater-cooler units made by medical equipment manufacturer Sorin. It is thought that the units were contaminated during their manufacture.

It’s a common bacterium that occurs naturally in the environment and only causes rare infection. The infections tend to be slow to develop (it can take from several months to over a year for an infection to develop) and often affect people with compromised immune systems.

There has been one reported possible patient infection following an open cardiac surgery in 2015.

According to a statement by the Therapeutic Goods Association: “These infections have been associated with the use of heater-cooler devices which are used within the operating theatre to control the temperature of blood diverted to cardio-pulmonary bypass machines. Heater-cooler devices contain water tanks that provide temperature-controlled water for the operation of the device. This water does not come in contact with the patient.”

The TGA says it’s monitoring the situation and has updated its advice for health facilities regarding how to manage devices that test positive for mycobacterium chimaera.

In NSW, the hospitals that have used the potentially contaminated machines are Prince of Wales, St George, Sydney Children’s Hospital and The Children’s Hospital at Westmead.

All machines have been cleaned or replaced and the risk to patients is low.

Related: Cheap way to cut infection risk

“The risk of infections to an individual patient is very small, but it’s important that we’ve alerted clinicians to the risk and put systems in place to reduce the risk further,” infectious disease specialist Dr Kate Clezy, from the NSW Clinical Excellence Commission, said in a statement.

In Victoria, Fairfax media reports that the bacterium has been detected in heater-cooler units at The Alfred, Austin and Cabrini hospitals in Melbourne.

“All the units were decommissioned and replaced once the test results were known,” a department spokesman said.

It’s believed doctors are checking patient records to see whether anyone has been harmed by the bacterium.

According to director of infectious diseases and microbiology at the Austin Hospital Professor Lindsay Grayson, there is about a 1 in 10 000 chance of the bacterium causing an infection.

“If you think about this, the chances of having a car accident are one in 4000, so it is very rare.”

He said the infection could be cured with surgery and use of specific antibiotics.

According to NSW Health, the signs of possible M. chimaera infection include:
fatigue
difficulty breathing
persistent cough or cough with blood
fever
night sweats
redness, heat, or pus at the surgical site
muscle pain
joint pain
abdominal pain
weight loss
nausea
vomiting

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Progress in the care of familial hypercholesterolaemia: 2016

Familial hypercholesterolaemia (FH) is the most common autosomal dominant condition.1 FH reduces the catabolism of low-density lipoprotein cholesterol (LDL-c) and increases rates of premature atherosclerotic cardiovascular disease (CVD). This review focuses on recent advances in the management of FH, and the implications for both primary and secondary care, noting that the majority of individuals with FH remain undiagnosed.2

FH was previously considered to have a prevalence of one in 500 in the general community, including in Australia.3 Recent evidence, however, suggests the prevalence is between one in 200 and one in 350, which equates to over 30 million people estimated to have FH worldwide.4,5 These prevalence figures relate to the general population, and while FH is present in all ethnic groups, communities with gene founder effects and high rates of consanguinity, such as the Afrikaans, Christian Lebanese and Québécois populations, have a higher prevalence of the condition.

Further, the prevalence of homozygous or compound heterozygous FH has been demonstrated to be at least three times more common than previously reported, with a prevalence of about one in 300 000 people in the Netherlands.4 The detection and management of individuals with homozygous FH has been described in a consensus report from the European Atherosclerosis Society.6 Homozygous FH is a very severe disorder, with untreated people often developing severe atherosclerotic CVD before 20 years of age. Such individuals often have LDL-c concentrations > 13 mmol/L and severe cutaneous and tendon xanthomata. While diet and statins are the mainstays of therapy, early intervention (before 8 years of age) with LDL apheresis or novel lipid-lowering medication, such as proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors or microsomal triglyceride transfer protein inhibitors, is indicated. Patients with suspected homozygous FH should be referred to a specialist centre.6

Several recent international guidelines on the care of FH have been published.3,7–10 These have focused on early detection and treatment of individuals with FH. However, there is still no international consensus on the diagnostic criteria for FH, or on the utility of genetic testing. The Dutch Lipid Clinic Network criteria (DLCNC) are preferred for diagnosing FH in index cases in Australia (Box 1).2 The International FH Foundation guidance acknowledges geographical differences in care, and recognises the need for countries to individualise service delivery. CVD risk in FH is dependent on classic CVD risk factors. However, FH is appropriately excluded from general absolute CVD algorithms, since these underestimate the absolute risk in FH.

FH guidelines provide therapeutic goals, which vary depending on the specific absolute CVD risk for patients with FH. In adults, the general LDL-c goal is a least a 50% reduction in pre-therapy LDL-c levels, followed by a target of LDL-c < 2.5 mmol/L, or < 1.8 mmol/L in individuals with CVD or other major CVD risk factors; these international targets update those of previously published Australian FH recommendations.2,3,10 Currently only about 20% of individuals with FH attain an LDL-c level < 2.5 mmol/L.11

Detecting FH in children

The European Atherosclerosis Society published a guideline focusing on paediatric aspects of the diagnosis and treatment of children with FH in 2015.8 This guideline outlined the benefit of early treatment of children with FH using statins. There is a significant difference in the carotid intima medial thickness (a measure of subclinical atherosclerosis) in children with FH and their unaffected siblings by 7 years of age, with implications for the value of early treatment. Lifestyle modifications and statins from 8 years of age can reduce the progression of atherosclerosis to the same rate as unaffected siblings over a 10-year period.8 Early treatment of children improves CVD-free survival by 30 years of age (100%) compared with their untreated parents (93%; P = 0.002).8 While further long term data on statin use in children are required, there are 10-year follow up data for children who were initiated on pravastatin between the ages of 8 and 18 years, which demonstrate that statin therapy is safe and effective.12 Hence, the balance of risk and benefit suggests that use of statins in children with FH is safe and efficacious, at least in the short to intermediate term, with all recommendations appropriately requiring that potential toxicity and adverse events be closely monitored.

Childhood is the optimal period for detecting FH, as LDL-c concentration is a better discriminator between affected and unaffected individuals in this age group. After excluding secondary causes and optimising lifestyle and repeating fasting LDL-c on two occasions, a child is considered likely to have FH if they have:

an LDL-c level ≥ 5.0 mmol/L;
a family history of premature CVD and an LDL-c level ≥ 4.0 mmol/L; or
a first-degree relative with genetically confirmed FH and an LDL-c level ≥ 3.5 mmol/L.

Universal screening for FH in children has been demonstrated to be effective in Slovenia, but experience is limited elsewhere.13 The therapeutic targets for children are less aggressive than for adults: a reduction in LDL-c of over 50% in children aged 8–10 years and an LDL-c level < 3.5 mmol/L from the age of 10 years.8

Cascade screening

Recent reports from Western Australia confirm that cascade screening is efficacious and cost-effective.11,14 The genetic cascade screening and risk notification process followed in Western Australia is shown in Box 2.11 Cascade screening involves testing close relatives of individuals diagnosed with FH. The autosomal dominant inheritance suggests 50% of first-degree relatives would be expected to have FH. Two new cases of FH were found by cascade screening for each index case in WA.11 These individuals were younger and had less atherosclerotic CVD than index cases. Interestingly, about 50% were already on lipid-lowering therapy, but they were not treated to the recommended goals and further lipid reductions were achieved overall. Over 90% of patients were satisfied with the cascade screening process and care provided by this service .11 However, for individuals who have not had genetic testing performed, or for individuals with clinical FH in whom a mutation has not been identified, cascade screening should also be undertaken using LDL-c alone.

Although we have recently shown that genetic testing is cost-effective in the cascade screening setting ($4155 per life year saved),14 only a few centres in Australia have this facility and testing is currently not Medicare rebatable. However, combining increased awareness of the benefits of identifying people with FH with the reducing analytical costs may increase the use of genetic testing. This in turn could guide advocacy and lobbying Medicare to support genetic testing for FH.

Detecting FH in the community

A novel approach that utilises the community laboratory to augment the detection of FH has recently been tested in Australia. The community laboratory is well placed to perform opportunistic screening, since they perform large numbers of lipid profiles, the majority (> 90%) of which are requested by general practitioners.15 Clinical biochemists can append an interpretive comment to the lipid profile reports of individuals at high risk of FH based on their LDL-c results. These interpretive comments on high risk individuals (LDL-c ≥ 6.5 mmol/L) led to a significant additional reduction in LDL-c and increased referral to a specialist clinic.16 A phone call from the clinical biochemist to the requesting GP improved both the referral rate of high risk (LDL-c ≥ 6.5 mmol/L) individuals to a lipid specialist and the subsequent confirmation of phenotypic FH in 70% of those referred, with genetic testing identifying a mutation in 30% of individuals.17 There is a list of specialists with an interest in lipids on the Australian Atherosclerosis Society website (http://www.athero.org.au/fh/health-professionals/fh-specialists).

In Australia, GPs consider they are the best placed health professionals to detect and treat individuals with FH in the community.18 A large primary care FH detection program in a rural community demonstrated that using pathology and GP practice databases was the most successful method to systematically detect people with FH in the community.19 However, a survey of GPs uncovered some key knowledge deficits in the prevalence, inheritance and clinical features of FH, which would need to be addressed before GPs can effectively detect and treat individuals with FH in the community.18 A primary care-centred FH model of care for Australia has recently been proposed to assist GPs with FH detection and management, but this requires validation.20 The model of care includes an algorithm that is initiated when an individual is found to have an LDL-c level ≥ 5.0 mmol/L, which could be highlighted as at risk of FH by either a laboratory or the GP practice software.20,21 The doctor is then directed to calculate the likelihood of FH using the DLCNC. Patients found to have probable or definite FH are assessed for clinical complexity and considered for cascade testing. See the Appendix at mja.com.au for the algorithm and definition of complexity categories. FH-possible patients should be treated according to general cardiovascular disease prevention guidelines.

Molecular aspects

There have also been advances in molecular aspects of FH. A recent community-based study in the United States confirmed that among patients with hypercholesterolaemia, the presence of a mutation was independently predictive of CVD, underscoring the value of genetic testing.22 The mutation spectrum of FH was described in an Australian population and was found to be similar to that in Europe and the United Kingdom.23 Mutation detection yields in Australia are comparable with the international literature; for example, 70% of individuals identified with clinically definite FH (DLCNC score > 8) had an identifiable mutation, whereas only 30% of those with clinically probable FH had a mutation.23

Polygenic hypercholesterolaemia (multiple genetic variants that each cause a small increase in LDL-c but collectively have a major effect in elevating LDL-c levels) is one explanation for not identifying an FH mutation. An LDL-c gene score has been described to differentiate individuals with FH (lower score) from those with polygenic hypercholesterolaemia (higher score), but this requires validation.24 About 30% of individuals with clinical FH are likely to have polygenic hypercholesterolaemia, and cascade screening their family members may not be justified.25

A further possible explanation for failure to detect a mutation causative of FH in an individual with clinically definite FH may lie in the limitations of current analytical methods such as restricting analysis to panels of known mutations. Further, FH is genetically heterogeneous and there may be unknown alleles and loci that cause FH. Next generation sequencing is capable of sequencing the whole genome or targeted exomes rapidly at a relatively low cost, and may improve mutation detection and identify novel genes causing FH, but further experience with its precise value in a clinical setting is required. Whole exome sequencing was able to identify a mutation causing FH in 20% of a cohort of “mutation negative” but clinically definite FH patients.25 However, when applied to patients with hypercholesterolaemia in a primary care setting, pathogenic mutations were only detected in 2% of individuals, with uncertain or non-pathogenic variants detected in a further 1.4%.26

Cardiovascular risk assessment

Absolute CVD risk assessment, employing risk factor counting, should be performed as atherosclerotic CVD risk is variable in FH.10,27 This involves appraisal of classic CVD risk factors including, age, sex, hypertension, diabetes, chronic kidney disease and smoking. The prevalence of classic CVD risk factors among Western Australians with recently identified FH was 13% for hypertension, 3% for diabetes and 16% for smokers, all of which were amenable to clinical intervention.11

Other non-classic CVD risk factors are also important for individuals with FH, especially chronic kidney disease and elevated levels of lipoprotein(a).28 Lipoprotein(a) is a circulating lipoprotein consisting of an LDL particle with a covalently linked apolipoprotein A. Its plasma concentration is genetically determined and it is a causal risk factor for CVD in both the general population and FH patients.29,30 Lipoprotein(a) concentrations are not affected by diet or lowered by statins.31

Management and new therapies

The past 2 years have also seen the development of new treatments for FH, but lifestyle modifications and statins remain the cornerstones of therapy for FH. Ezetimibe has been demonstrated to reduce coronary events against a background of simvastatin in non-FH patients with established CVD.32 PCSK9 inhibitors have recently been approved to treat individuals with FH or atherosclerotic CVD not meeting current LDL-c targets in Europe and America. PCSK9 is a hepatic convertase that controls the degradation and hence the lifespan of the LDL receptor. PSCK9 is secreted by the hepatocyte and binds to the LDL receptor on the surface of the hepatocyte. The LDL receptor–PCSK9–LDL-c complex is then internalised via clathrin-dependent endocytosis, but the PSCK9 directs the LDL receptor towards lysosomal degradation instead of recycling it back to the hepatocyte surface.33 A recent meta-analysis of early PCSK9 inhibition trials involving over 10 000 patients demonstrated a 50% reduction in LDL-c, a 25% reduction in lipoprotein(a), and significant reductions in all-cause and cardiovascular mortality.34

The PCSK9 inhibitors alirocumab and evolocumab were approved by the European Medicines Agency in 2016 for homozygous and heterozygous FH and non-FH individuals unable to reach LDL-c targets, and for individuals with hypercholesterolemia who are statin intolerant. In the US, the Food and Drug Administration has approved alirocumab for heterozygous FH and individuals with atherosclerotic CVD who require additional reduction of LDL-c levels. Evolocumab and alirocumab have recently been approved by the Therapeutic Goods Administration in Australia for people with FH. Adverse events are generally similar to placebo, but reported side effects include influenza-like reaction, nasopharyngitis, myalgia and raised creatine kinase levels, and there have been reports of neurocognitive side effects (confusion, perception, memory and attention disturbances).34 The cost of these agents is likely to be the major limitation to their clinical use. The indications and use of lipoprotein apheresis and other novel therapies, including lomitapide, a microsomal triglyceride transfer protein inhibitor, and mipomersen (an antisense oligonucleotide that targets apolipoprotein B), have been recently reviewed.35

Despite the advances reviewed, the implementation and optimisation of models of care for FH remain a major challenge for preventive medicine. Areas of future research should focus on better approaches for detecting FH in the young and on enhancing the integration of care between GPs and specialists. The value of genetic testing and imaging of pre-clinical atherosclerosis in stratifying risk and personalising therapy merits particular attention. Further, with families now living in a global community, more efficient methods of communication and data sharing are required. This may be enabled by international Web-based registries.36 Care for people with FH needs to be incorporated into health policy and planning in all countries.10

Conclusion

There have been significant advances in the care of individuals with FH over the past 3 years. An integrated model of care has been proposed for primary care in Australia. Progress has also been made in the treatment of FH with the emergence of PCSK9 inhibitors capable of allowing more patients already on statins to attain therapeutic LDL-c targets and hence redressing the residual risk of atherosclerotic CVD. Future research is required in the areas of models of care, population science and epidemiology, basic science (including genetics), clinical trials, and patient-centric studies.37 Finally, the onus rests on all health care professionals to improve the care of families with FH, in order to save lives, relieve suffering and reduce health care expenditure.

Box 1 –
Dutch Lipid Clinic Network Criteria score for the diagnosis of familial hypercholesterolaemia (FH)2

Criteria

Score

Family history

First-degree relative with known premature coronary and/or vascular disease (men aged < 55 years, women aged < 60 years); or

First-degree relative with known LDL-c > 95th percentile for age and sex

First-degree relative with tendon xanthomas and/or arcus cornealis; or

Children aged < 18 years with LDL-c > 95th percentile for age and sex

Clinical history

Patient with premature coronary artery disease (ages as above)

Patient with premature cerebral or peripheral vascular disease (ages as above)

Physical examination

Tendon xanthomata

Arcus cornealis at age < 45 years

LDL-c

≥ 8.5 mmol/L

6.5–8.4 mmol/L

5.0–6.4 mmol/L

4.0–4.9 mmol/L

DNA analysis: functional mutation in the LDL receptor, apolipoprotein B or PCSK9 gene

Stratification

Definite FH

> 8

Probable FH

6–8

Possible FH

3–5

Unlikely FH

< 3

LDL-c = low-density lipoprotein cholesterol. PCSK9 = proprotein convertase subtilisin/kexin type 9.

Box 2 –
Protocol for genetic cascade screening in Western Australia*

* Family cascade screening process performed according to national guidelines2 after obtaining written consent from the index case.11 This was undertaken by a trained nurse who contacted the family members and obtained verbal consent to contact further family members, after providing counselling and offering specialist review as indicated.

[Editorial] Atrial fibrillation and stroke: unrecognised and undertreated

When did you or your primary care physician last palpate your wrist to check for a regular heart rate? This simple action, followed by an electrocardiogram if the heart rate is irregular, might be crucial in preventing death and disability from ischaemic stroke, heart failure, or myocardial infarction. In this week’s issue, we publish a clinical Series of three papers on atrial fibrillation ahead of the annual European Society of Cardiology (ESC) meeting held in Rome, Italy, Aug 27–31. Atrial fibrillation is estimated to affect 33 million people worldwide.

Remote Australians more likely to be hospitalised with heart-related issues

Patients from very remote Australia are nearly twice as likely to need a hospital for a heart-related event.

The Heart Foundation has released heart-related hospital admissions data maps, revealing huge gaps between city dwellers and those living in remote Australia.

Heart Foundation National Chief Executive Officer Adjunct Professor John Kelly said the maps bring together a national picture of hospital admission rates for the first time.

“Those regions that rate in the top hotspot areas are regions where a large proportion of residents are of significant disadvantage. This disadvantage includes a person’s access to education, employment, housing, transport, affordable healthy food and social support,” he said.

“This contrasts to areas with the lowest rates – particularly the northern suburbs of Sydney, where there is little disadvantage of the community.

“There is a five-fold difference of hospital admissions between Northern Territory Outback and the region with the lowest admission rates North Sydney & Hornsby, which highlights the association between remoteness, disadvantage and our heart health.”

The heart maps reinforce the knowledge that heart admissions are correlated with obesity, smoking and physical activity.

However Professor Kelly points out that the differences are not because people from disadvantaged areas make unhealthy choices.

“They are the result of a combination of social, economic and physical conditions, like a person’s access to education, employment, housing, transport, affordable healthy food, and social support,” he explained.

“These conditions shape matters such as people’s eating habits, participation in physical activity and their likelihood to see a doctor.

He said governments and health services need to work together to provide access and opportunities for people in more remote locations.

“Prevention programs work, simple early detection and heart health checks by doctors can help early identification of the risk factors and reduce hospital admissions.

“Health is a basic human right. It should not matter who you are, how much you earn or where you live,” he said.

Top 5 Regions for Heart-Related Hospital Admissions

Top 5 Regions with the lowest heart-related hospital admission rates

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Pitting and non-pitting oedema

The distinction is essential to determine aetiology and treatment

Oedema can be divided into two types: pitting and non-pitting. These types are relatively easy to distinguish clinically and the distinction is essential to determine aetiology and treatment.

Oedema is the swelling of soft tissue due to fluid accumulation. Pitting is demonstrated when pressure is applied to the oedematous area and an indentation remains in the soft tissue after the pressure is removed (Box 1 and Box 2). Moreover, mild pitting oedema is best identified by applying pressure over an area of bony prominence. Non-pitting oedema refers to the lack of persistent indentation in the oedematous soft tissue when pressure is removed.1

In addition to the differentiation of pitting and non-pitting oedema, the pattern of distribution is reflective of the underlying aetiology. With pitting oedema, there may be bilateral dependent oedema of the lower limbs, generalised oedema or localised oedema. Non-pitting oedema generally affects an isolated area, such as a limb. There are two ways of describing the severity of pitting oedema. Most commonly, in the setting of peripheral oedema, severity is graded by its proximal extent, so that oedema located above the knee is more severe than oedema presenting below the knee. The alternative approach is based on depth and duration of pitting after the release of pressure (Box 3).2

A number of factors3 can be considered to be major contributors to the development of oedema:

increased intravascular hydrostatic pressure;
reduced intravascular oncotic pressure;
increased blood vessel wall permeability;
obstructed fluid clearance in the lymphatic system; and
increased tissue oncotic pressure.

The underlying pathophysiology for oedema explains the reason for pitting and non-pitting. Oedema is the accumulation of fluid in the interstitium. In normal circumstances, there is a balance between fluid leaking from capillaries and drainage by the lymphatics.3 In the setting of increased intravascular hydrostatic pressure, reduced oncotic pressure or where there is increased vessel wall permeability, fluid leaks out of vessels into the interstitial space. When external pressure is applied, extracellular fluid is displaced with increased drainage through the lymphatic system, creating an indentation that is visible in the skin and is described as pitting. When pressure is removed, the fluid slowly returns and the indentation disappears (see the video at mja.com.au). Lymphoedema, which is the most common form of non-pitting oedema, occurs when fluid accumulates in the interstitial space as a result of a reduction in lymphatic drainage. The application of pressure does not result in an indentation as there is an inability to drain fluid through the damaged lymphatic system.4 An uncommon form of non-pitting oedema, myxoedema, can occur as a result of accumulation of hydrophilic molecules in the subcutaneous tissue.5

The differentiation between pitting and non-pitting oedema, in addition to the pattern of distribution, reflects different pathophysiology and may therefore be helpful in identifying the underlying aetiology. Pitting peripheral lower limb oedema resulting from raised hydrostatic pressure can occur in congestive cardiac failure, venous insufficiency and as a result of the use of a calcium channel blocker. Generalised oedema may be seen in kidney disease, where reduced intravascular oncotic pressure occurs through protein loss or where increased vascular volume occurs through sodium and fluid retention. Localised pitting oedema is likely related to a local inflammatory process resulting in increased vessel wall permeability. Non-pitting oedema of an isolated area is consistent with failure of lymphatic drainage, which may rarely have a primary (hypoplastic) aetiology or, more commonly, a secondary (obstructive) aetiology. Secondary causes include external compression from a tumour, involvement of lymph nodes in metastatic disease, and lymph vessel damage following radiotherapy or following lymph node resection. Myxoedema is associated with thyroid disease.5

The underlying aetiology will guide treatment options. In the setting of congestive cardiac failure, treatment would generally include fluid restriction and diuretics (including spironolactone). Compression bandaging and leg elevation are useful for oedema related to venous insufficiency. In the setting of oedema related to inflammation, a general approach would include applying ice and elevation in addition to treating the underlying cause of the inflammatory process. Lymphoedema may be detected using a perometer and managed with compression garments and manual lymph drainage. Myxoedema may resolve with treatment of the underlying thyroid condition.

Box 1 –
Pressure applied to an oedematous area to demonstrate pitting

Box 2 –
Indentation remaining in soft tissue after pressure to an oedematus area is removed

Box 3 –
Alternative approach for grading the severity of pitting oedema based on depth and duration of pitting after release of pressure

Severity

Description

Grade 1+

A pit of up to 2 mm that disappears immediately

Grade 2+

A pit of 2–4 mm that disappears in 10–15 seconds

Grade 3+

A pit of 4–6 mm that may last more than 1 minute

Grade 4+

A deep pit greater than 6 mm that may last as long as 2–5 minutes

Adapted from Guelph General Hospital Congestive Heart Failure Pathway.2

How health technology helps promote cardiovascular health outcomes

Health technology in the hands of cardiac patients — helpful, hindrance, or hesitate to say?

Cardiovascular disease (CVD) is a leading cause of death and hospital admissions in Australia.1 Almost a third of patients will have a recurrence such as myocardial infarction (MI), stroke, heart failure and death within 5 years.2 Reductions of at least 80% in these events can be achieved through secondary prevention behaviours, including taking cardioprotective medications as prescribed, ceasing smoking, increasing physical activity and consuming a healthy diet.3 The most comprehensive and proven of strategies to support secondary prevention is cardiac rehabilitation. This is an evidence-based, cost-effective method to reduce CVD deaths, assist recovery and promote secondary prevention through reduction of cardiovascular risk factors.

The strength of secondary prevention success in cardiac rehabilitation ultimately depends on patients’ awareness, willingness and capacity to make lifestyle changes and to engage in the required behaviours. Patients must have a strong commitment to their health to sustain secondary prevention behaviours for the rest of their lives, often without direct evidence of benefit, as CVD is asymptomatic in the majority of cases.3 However, cardiac rehabilitation is widely underutilised, with less than a third of eligible patients attending the sessions and dropout rates estimated at 25%. In the absence of support, many patients struggle with sustaining the requisite behaviours.

Medications are a prime example of this struggle. Less than two-thirds of patients are reported to persist with all prescribed medications by 1 year following MI.4 The reasons given for discontinuation are largely self-determined, emphasising the importance of the patients’ understanding and engagement.5 Similar issues are present for most secondary prevention behaviours. At 6 months after MI, 27% of patients smoked, 26% consumed an unhealthy diet and 59% did not exercise enough.3 The key reasons identified for patients’ struggles are a lack of awareness that treatments must be long term to achieve effective prevention, and forgetting to follow recommendations.5 Patient education is necessary, but specialised support is often required for sustained behaviour change. Technology, particularly mobile technology, offers a solution for support for long term behaviour change and may also augment existing secondary prevention programs, such as cardiac rehabilitation.

Adoption of mobile technologies, such as mobile phones, smart phones and tablets that provide internet access, has been widespread in Australia.6 Rapid growth in popularity and technological advances have also occurred in wearable devices for tracking behaviours, such as fitness activities, that connect with mobile phones. These technologies and related applications can efficiently enable long term support for patients and provide memory prompts for behaviours. However, there has been such rapid evolution of technologies that we ask: are health technologies helpful, a hindrance, or should we hesitate to say?

Are health technologies helpful?

The evidence indicates that well designed and often simple technologies can improve patient outcomes in multiple cardiovascular risk factors.7 The most consistent evidence of benefit from health technologies is for coronary heart disease compared with other cardiovascular diseases.8 Simple short-message service (SMS) interventions delivered regularly can improve awareness and prompt actions, which may otherwise be forgotten. Text messages double the odds of adhering to medications and the Australian TEXT ME program has improved cardiovascular disease risk factor profiles.9 Emerging evidence indicates that many more risk factors may also be addressed through text messages and mobile phone apps, and potentially decrease dropout from cardiac rehabilitation.8,10 In addition, wearable activity trackers provide reliable information on steps and time spent in moderate to vigorous physical activity, which can be monitored, used for goal-setting and shared with treating doctors.11

There may be a temptation to assume that health technology is not applicable to cardiac patients because of their older age and lack of experience; however, such patients may be more ready and willing to use health technology than previously suspected. At least two-thirds of cardiac patients (67%) use the internet and at least half (50%) use mobile technologies for health, with higher rates of acceptance of health technology in cardiac rehabilitation participants (74%).12

Are health technologies a hindrance?

Several key issues hinder uptake and complicate recommendations for patient-facing technology in regular clinical practice. There is a proliferation of publicly available health technologies suitable for cardiac patients, particularly mobile phone apps, alongside a paucity of research-based evidence to support selection.7 Quality too is generally low, and popularity is a poor indicator. For instance, an evaluation of patient engagement, quality and safety of 1046 health care-related, patient-facing apps for chronic disease found that only 43% (iOS, Apple) and 27% (Android, Google) were actually likely to be useful.13 A recent review of mobile phone interventions for secondary prevention of cardiovascular disease did not identify any intervention that resulted in a negative impact, but six of the 28 interventions reviewed had no benefit.8 Owing to the poor quality of the studies included, it is difficult to distinguish the features that independently predict success; however, the use of text messaging, telemonitoring and interaction may have been important. In a similar way, popular weight loss apps do not incorporate successful behaviour change techniques and many have inaccurate content. The motivation of app developers must be carefully considered given the rise of pro-smoking apps disguised as educational games. At best, patients may experience no benefits from using health technology, and at worst, patients may question and disregard credible advice given by health professionals. Patients have few sources of advice for selection and use of health technologies, as physicians, like patients, have varying capacity and interest in using them. Previous experience, education, confidence and interaction with early adopters to understand how to interface with the health app and with the patient using the app are all required for success.14 Patients who are older, have little or no prior experience with technology and who have lower levels of education are less likely to be interested and have lower expectations of success or benefit from using technology for their health.12 The same could be argued for health professionals. This is important because, for health technologies that do prove useful, positive staff attitudes may offset the lower levels of expertise or interest present in older people and in those with lower education.

Should we hesitate to say?

The rapid advances in health technology, the mass of publicly available apps and programs, and the inability of research to keep pace are major factors affecting our ability to definitively determine whether health technologies are a help or a hindrance. These factors make it difficult to identify the technologies that are evidence-based and free from unintended negative consequences.15 However, there are a few shortcuts. For instance, there is no single repository for patient-based health technologies for cardiovascular secondary prevention, nor is there an accrediting or regulatory system for quality or effectiveness. There has been some attempt to catalogue apps, but the process is slow and apps are often modified by the time of publication. Regulation of health technologies, such as mobile phone apps, is poorly developed. A balance is needed between two polar possibilities: government regulation, as used for implanted medical devices, which is rigorous but slow and expensive; and self-regulation by technology companies through checklist certification, which is dependent on the company ethics.16 App stores such as those of Apple and Google currently vet apps sold in their stores, but the emphasis is on security, not on the quality or credibility of the app.17 Ultimately consumers must decide. One shortcut to ensuring credible content is to only use or recommend health technologies and health apps developed by reliable institutions, such as the Heart Foundations of Australia, Britain and Canada. However, the gains in credibility and time-saving from using this shortcut occur at a trade-off in diversity, innovation and personalisation for patients.

A principles-based approach may be more appropriate and feasible to discriminate the features of technology that encourage consumer uptake and promote appropriate behaviour change effectively. These principles have been highlighted for apps for the secondary prevention of CVD in a recent review12 and are relevant to most health technologies. Key elements to consider include simplicity, credibility of content, behaviour change components, real-time tracking, reward system, personalisation, social features and attention to privacy of data collected. A positive, but discerning attitude to patient-facing health technology is required, much the same as with any new health treatments, to maximise patient outcomes and ensure equitable access. Regular screening to identify effective health technology has become a necessary component of health professional life, equivalent to keeping up to date with effective medications and techniques. Evidence-based practice was introduced to medical curricula to help ensure the most effective treatment for an individual patient. Likewise, it is now time to introduce screening and selection systems for health technologies into health professional education.

In summary, the evidence suggests that mobile technologies will improve access to and participation in secondary prevention activities, but careful consideration is needed to ensure that the most effective and acceptable technologies are incorporated into patient care.

“Congenital heart health”: how psychological care can make a difference

An integrated approach incorporating both physical and mental health is critical to “congenital heart health”

Congenital heart disease (CHD) affects more than 2400 Australian babies each year. It is the most common cause of admission to paediatric intensive care in the neonatal period,1 a leading cause of infant death2 and one of the leading causes of disease-related disability in children under 5 years of age.3 In Australia and around the world, the landscape of CHD care is rapidly evolving. With advances in medicine, survival has markedly improved over the past two decades4 and the best estimates suggest that the total population, from newborns through to adults living with CHD, now represents well over 65 000 Australians.5 These gains in survival are a triumph, but paradoxically, they bring new challenges. Earlier diagnosis, more complex treatment choices, longer survivorship and a need for transition from paediatric to adult cardiac services lead us into new territory. Embedded in each of these challenges are a range of psychological complexities, foremost of which is how to best support the wellbeing of people with CHD across a lifetime. “Congenital heart health” requires an integrated, life course approach — with equal emphasis on the physical and the psychological — beginning before birth, through infancy to adulthood. This article presents the evidence for such an approach, highlighting the areas where evidence is lacking and calling for national standards of mental health care in CHD.

Beginning before birth: the mental health of expectant parents

Fetal diagnosis of CHD has changed clinical care. Half of all babies who need heart surgery in the first year of life are now diagnosed while in the womb.6 A major advantage of fetal diagnosis is that potentially unstable newborns can be delivered close to specialised paediatric cardiac services, reducing morbidity and improving survival.7,8 Fetal diagnosis also facilitates early family counselling regarding the nature of the baby’s heart abnormality and expected prognosis. But when a parent hears words such as “your baby has tetralogy of Fallot” their world stops. Fetal diagnosis of any abnormality, major or minor, precipitates an emotional crisis for expectant parents. Threats to the health of the fetus have long been recognised as an important risk factor for psychological disturbance during pregnancy, which in turn indicates a high risk of ongoing psychiatric disorders postpartum. Research has shown that one in three mothers and fathers of infants with complex CHD report symptoms that meet clinical criteria for depression, and about 50% of parents report severe stress reactions consistent with a need for clinical care up to 1 year after their baby’s diagnosis.9 These rates far exceed documented rates of perinatal depression and anxiety in the general community10 and as health care providers, we often markedly underestimate the severity and potential consequences of these symptoms.

There is now overwhelming evidence that depression and anxiety in the perinatal period (from conception to the end of the first postnatal year) can have devastating consequences, not only for the person experiencing it, but also for his or her children and family. Parents with high distress report poorer physical health,11 greater parenting burden,12 higher health service use13 and more suicidal ideation14 compared with parents of sick children with lower distress. At least 14 independent prospective studies have demonstrated a link between maternal antenatal stress and child neurocognitive, behavioural and emotional outcomes.15 Acknowledging these findings is not to blame parents — not in any way, not at all. But to not talk about this, to not address the significant emotional toll of CHD, is to not provide optimal care.

Early life experiences can have profound consequences

Diagnosis of a life-threatening illness during a child’s formative years can have far-reaching effects that ripple through the family and across a lifetime. Infants with complex CHD experience a range of uncommon and painful events, such as separation from their mother at birth, urgent transfer to specialised intensive care, frequent invasive medical procedures, feeding difficulties and withdrawal from narcotic pain relief. These early life experiences can have profound consequences for the developing child, shaping brain development, the body’s immune system and responses to stress. Studies of individuals exposed to high levels of stress early in life consistently show that the experience of early adversity is associated with disrupted child–parent attachment and with alterations in the developmental trajectories of networks in the brain associated with emotion and cognition.16

From a neurodevelopmental perspective, children with CHD experience greater difficulties compared with their healthy peers. The risk and severity of neurodevelopmental impairment increases with greater CHD complexity, the presence of a genetic disorder or syndrome, and greater psychological stress. During infancy, the most pronounced difficulties occur in motor functioning. By early childhood, studies show that children with complex CHD have an increased risk of neurodevelopmental impairment, characterised by difficulties in fine and gross motor skills, speech and language, attention, executive functioning, emotion regulation and behaviour.17 Emotionally, 15–25% of parents report significant internalising (eg, anxiety, depression, somatisation) or externalising (eg, aggression) difficulties in their child.18 Few studies have used validated clinical assessments, but those studies that have included a clinical assessment report psychiatric illness in more than 20% of adolescents and young adults with CHD. There is also a diagnostic rate of attention deficit and hyperactivity disorder up to four times higher than in the general population.18

Navigating the transitions of adolescence

Young people must not only navigate the typical transitions of adolescence and early adulthood, they also face the challenges that come with developing a sense of identity and autonomy in the context of CHD while, at the same time, breaking the bonds formed with their paediatric team and transitioning to adult cardiovascular care. Clinicians lose their “clinical hold” on so many patients during this process, with an alarmingly high proportion of adults with CHD (24–61%) not receiving the recommended cardiac care.5,19,20 This can have catastrophic health consequences,5 yet our understanding of the factors that influence transition is wanting. In 2013, the Cardiac Society of Australia and New Zealand published a statement outlining best practices in managing the transition from paediatric to adult CHD care.21 This statement recognises the role that psychological factors play in shaping young people’s capacity to manage their heart health care, in addition to clinical, familial and practical factors.

Living with CHD into adulthood

Our understanding of the psychology of adult CHD lags decades behind our knowledge of children’s experiences. While neurodevelopmental clinics have been established at several paediatric cardiac centres across Australia, little attention is paid to neurocognitive health in adult CHD care. Without effective intervention, hardships encountered during infancy and childhood can persist for years after diagnosis and treatment. It is also possible for difficulties to emerge for the first time in adulthood, with heart failure, atrial fibrillation, cardiac surgery and recurrent strokes increasing vulnerability to neurocognitive impairment in adults with CHD. A meta-analysis of 22 survey-based studies of emotional functioning in adolescents and adults with CHD found no differences from the norm;22 however, studies using clinical interviews have found that one in three adults with CHD report symptoms of anxiety or depression warranting intervention.23 The vast majority of these adults go untreated.

An integrated psychology service dedicated to CHD

In 2010, we established an integrated clinical psychology service dedicated to CHD. Located across the Sydney Children’s Hospitals Network, we provide a statewide mental health service for children and young people with all forms of heart disease and their families (Box). Evidence-based, psychologically informed care and a variety of interventions can prevent or relieve psychological morbidity.24 National (beyondblue, 2011) and international (International Marcé Society, 2013) authorities now recognise and endorse psychosocial assessment for depression and anxiety in the perinatal period as part of routine clinical care. Integrating psychosocial assessment within existing health services has been shown to improve treatment uptake, as well as mental health and parenting outcomes, up to at least 18 months postpartum.24 Indeed, integrating psychosocial assessment within a clinical setting with which families are already engaged is a key factor distinguishing successful and unsuccessful early mental health interventions. Providing tailored skills-based training and support to staff also has the potential to overcome a range of patient (eg, stigma, cost), provider (eg, limited awareness, low confidence), and health system (eg, cost, under-prioritisation) factors that can prevent access to care. Moreover, there are costs to not offering mental health care. In neonatal intensive care, for example, targeted interventions significantly reduce maternal depression and anxiety, increase positive parent–infant interactions, and reduce health service costs by reducing the length of stay at the neonatal intensive care unit and total hospital admission.25

A call for national standards of mental health care in CHD

While there may be deep sadness associated with many aspects of CHD, there may also be deep hope and, for many, good health. Early intervention can make a profound difference for families and influence a lifetime of outcomes for a child. To transition CHD to “congenital heart health”, equal emphasis must be placed on both physical and mental health so that the successes in physical care are not undermined by the absence of adequate emotional care. Across the CHD continuum, there are still huge gaps in access to mental health services. To start to address these gaps, we call for the formation of a multidisciplinary working group to develop national standards of mental health care in CHD. We also advocate strongly for more Australian research across the discovery-to-translation pipeline such that, from early life in the womb through to adulthood, we can better understand — and prevent or assuage — the difficulties that our patients and their families experience.

Box –
Integrated model of psychological care dedicated to congenital heart disease and based at the Heart Centre for Children

National Institute for Health and Care Excellence. Antenatal and postnatal mental health: clinical management and service guidance. NICE clinical guidelines, no. 192 (updated edition). London: NICE, 2014.

The clinical utility of new cardiac imaging modalities in Australasian clinical practice

Cardiac imaging is a rapidly evolving field, with improvements in the diagnostic capabilities of non-invasive cardiac assessment. In this article, we seek to introduce family physicians to the two main emerging technologies in cardiac imaging: computed tomography coronary angiography (CTCA) to evaluate chest symptoms consistent with ischaemia and exclude coronary artery disease; and cardiovascular magnetic resonance (CMR) imaging for evaluating cardiac morphology, function and presence of scar. These modalities are now in routine clinical practice for cardiologists in Australia and New Zealand. We provide a practical summary of the indications, clinical utility and limitations of these modern techniques to help familiarise clinicians with the use of these modalities in day-to-day practice. The clinical vignettes presented are cases that may be encountered in clinical practice. We searched the PubMed database to identify original papers and review articles from 2008 to 2016, as well as specialist society publications and guidelines (Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, Cardiac Society of Australia and New Zealand, and Australian and New Zealand Working Group for Cardiovascular Magnetic Resonance), to formulate an evidence-based overview of new cardiac imaging techniques, as applied to clinical practice.

Part 1: Computed tomography coronary angiography for clinicians

CTCA is a non-invasive coronary angiogram, using electrocardiogram (ECG)-gated CT. The accuracy of CTCA has been well established in three large multicentre studies, with a negative predictive value approaching 100%, making it an excellent “rule out” test.1 This means that a normal CTCA showing no coronary plaque or stenosis accurately correlates to absence of disease on invasive angiography. Prognostic data have shown that a negative CTCA has very low event rate (< 1%), whereas increasing levels of disease seen on CTCA are associated with increasing risk of myocardial infarction and death over 5 years for both men and women.2

CTCA has been formally tested in randomised trials of chest pain in the emergency department, showing more rapid discharge and decreased health care costs, including in the Australian health system.3,4

The radiation dose for CTCA has decreased dramatically in recent years, with current generation scanners able to image the entire heart and coronary arteries for 2–3 mSv (equivalent to annual background radiation), and < 1 mSv in appropriate patients (similar to a mammogram). Thus, CTCA is gaining traction in clinical practice to rule out coronary artery disease (CAD) in a variety of clinical situations.

The primary use for CTCA is to exclude significant coronary artery stenosis in patients with symptoms consistent with coronary ischaemia due to potential stenotic CAD (harnessing the near 100% negative predictive value of CTCA). Application of the test in this manner is appropriate for patients with chest pain syndromes, with angina equivalent symptoms (eg, dyspnoea), to exclude graft stenosis in symptomatic patients after coronary artery bypass surgery, and also for patients with ongoing symptoms despite negative results from functional tests such as nuclear or echocardiography stress tests (as functional tests may return false-negative results). The Society of Cardiovascular Computed Tomography has published Appropriate Use Criteria,5 and the Cardiac Society of Australia and New Zealand has produced guidelines on non-invasive coronary imaging (Box 1).6

Clinical vignette 1: A 55-year-old woman presents to her general practitioner with dyspnoea on exertion, and risk factors of obesity and hypertension. A nuclear single-photon emission computed tomography myocardial perfusion scan is reported as positive for “mild apical ischaemia”. Computed tomography coronary angiography (CTCA) is performed to exclude significant coronary artery disease, demonstrating no significant stenosis in the major epicardial coronaries (left anterior descending, left circumflex or right coronary artery), but mild diffuse coronary atherosclerosis is present (with a calcium score of 370 Agatston units). She is commenced on medical therapy of aspirin and a statin, and is reassured that she does not have a stenosis requiring stent or bypass surgery, and that her chest symptoms are not due to coronary artery disease.

CTCA showing “clean” coronary arteries with no plaque or stenosis.

In Australia, Medicare reimbursement is available via specialist referral for three indications:

chest symptoms consistent with coronary ischaemia in low to intermediate risk patients;
evaluation of suspected coronary anomaly or fistula; or;
exclusion of CAD before heart transplant or valve surgery (non-coronary cardiac surgery).

Medicare-reimbursed indications do not cover asymptomatic patients with a strong family history of coronary artery disease (in which case, a coronary calcium score may suffice).7 When used appropriately, CTCA reduces the need for invasive coronary angiography, which is about five times more expensive, as a consequence of the reduced need for hospital admissions and different Medicare Benefits Schedule charges. Data suggest that use of CTCA is cost-effective and reduces downstream testing.8

Importantly, CTCA is not appropriate in patients with typical angina (defined as “constricting discomfort in the chest, which is precipitated by physical exertion, and relieved by rest or GTN”9) who have a high pre-test probability of obstructive disease and should proceed directly to invasive coronary angiography.

Evaluation after coronary artery stenting is limited to large diameter stents (> 3 mm) in proximal arteries and, in general, functional testing remains the clinical standard for reassessment of patients with known CAD.5 Conversely, assessment of graft patency following coronary artery bypass surgery can be well assessed by CTCA, without the risks of stroke or graft dissection from invasive engagement of the grafts during catheter angiography.5

The main weakness of CTCA is its modest positive predictive value, which varies from 60% to 90% depending on the prevalence of disease and the study. In clinical practice, this generally means that although coronary disease seen on CTCA is real, the percentage of stenosis generally appears more severe on CTCA compared with invasive coronary angiography. On the other hand, CTCA can visualise eccentric coronary plaques with positive vessel wall remodelling, which may be missed on invasive angiography (which only images the coronary lumen, and not the vessel wall itself).

An important factor in CTCA is heart rate control, which remains essential for good quality CTCA imaging. Ideal heart rates are in the 50–60 beats per minute range for optimal imaging, requiring pre-medication with β-blockers and/or ivabradine. Heart rate control is proportional to radiation dose, therefore low dose studies require a slow and steady heart rate. This improves the diagnostic accuracy of CTCA, but negative chronotropic medications may not be suitable for all patient groups, and atrial fibrillation remains a challenge. Newer high resolution and dual source scanners are able to image at higher heart rates, with algorithms to reconstruct cardiac motion, and are becoming more widely available.

Clinical vignette 2: A 38-year-old man presents to an emergency department with atypical central chest pain. Serial troponins are negative, and a 12-lead electrocardiogram shows non-specific T wave changes. He has ongoing pain, is not deemed suitable for an “accelerated diagnostic protocol” pathway, and early computed tomography coronary angiography (CTCA) is performed after 100 mg oral metoprolol with 10 mg ivabradine, to achieve a heart rate of 59 beats per minute, allowing a low dose (< 1 mSv) scan. CTCA shows a normal left coronary system, but an anomalous right coronary artery origin arising from the contralateral cusp, with an interarterial course and a slit-like origin.6 This is a potentially life-threatening anomaly due to potential compression between the aorta and pulmonary artery resulting in sudden death;10 however, this may not have been diagnosed on functional testing (eg, single-photon emission computed tomography). Cardiac CT is the reference test for the assessment of coronary anomalies and coronary fistulae.6

CTCA axial view showing the RCA origin adjacent to the left main sinus and with an interarterial course between the aorta and pulmonary artery (arrow). Ao = aorta. Cx = circumflex. LA = left atrium. LAD = left anterior descending artery. LCC = left coronary cusp. LMCA = left main coronary artery. NCC = non-coronary cusp. PA = pulmonary artery. RCA = right coronary artery. RCC = right coronary cusp.

Recent data from the PROMISE trial in 10 000 patients showed equivalence of a CTCA versus functional testing strategy in symptomatic patients, but with a reduced rate of “normal” invasive angiograms and decreased downstream testing in the CTCA group.11 Further, the SCOT-HEART trial recently demonstrated that adding CTCA to standard care reduced the need for additional stress testing, and was associated with a 38% reduction in fatal and non-fatal myocardial infarction.12

Future directions for CTCA

Rapid technological advancement in both CT hardware and post-processing reconstruction software algorithms are leading to further improvements in spatial and temporal resolution while minimising radiation exposure. CTCA has the ability to detect high risk vulnerable plaques,6,13 and statin therapy may help alter the natural history of atherosclerosis as imaged by CTCA.13 New developments enable functional assessment of a lesion on CTCA, allowing assessment of lesion-specific ischaemia at the same time as evaluating coronary anatomy. Adenosine stress perfusion cardiac CT allows functional assessment of myocardial perfusion in a similar manner to nuclear single-photon emission computed tomography (SPECT), and can be performed at the same time as CTCA with minimal additional radiation.14 Fractional flow reserve can be derived from static CTCA datasets, using computational fluid dynamics, and has been compared favourably with invasive haemodynamic assessment of fractional flow reserve during invasive coronary angiography.15 Overall, CTCA is a very useful tool to non-invasively assess the coronary arteries, with prognostic data now available to support its routine use in clinical practice.

Part 2: Cardiovascular magnetic resonance imaging for clinicians

CMR is a specialised form of magnetic resonance imaging (MRI), which employs specific MRI techniques with ECG gating to capture high resolution images of the heart and cardiac motion, in any imaging plane, without radiation.16 CMR is like a “super-echocardiogram” to assess heart function, but has the additional ability to quantitate vascular flow, myocardial oedema, cardiac perfusion, viability, and the presence of infiltrate or scar using gadolinium-based contrast agents. CMR improves diagnosis and risk stratification, predicts prognosis, and guides treatment decisions in many cardiac disorders.

Left and right ventricular function

Accurate quantitation of left and right ventricular function are essential to making decisions in clinical medicine, from commencement of drug therapy to implantation of costly devices such as automatic defibrillators. CMR is the gold standard for measurements of left ventricular mass, volume and ejection fraction and assessing the presence of regional wall motion abnormalities,17,18 and it is more reproducible than echocardiography.19

CMR offers particular advantages for conditions affecting the right ventricle, which is particularly difficult to assess using echocardiography. Assessment of right ventricular volume and wall motion by CMR are assigned as major criteria in the diagnosis of arrythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), a genetic condition resulting in arrhythmias and sudden death.20 Right ventricular function is important in patients in pulmonary hypertension and with adult congenital heart disease,21 for which CMR is critical to decision making (eg, timing of surgery, replacement of cardiac valves). In patients with dilated right hearts, CMR is useful to detect the underlying causes, which may not be apparent on echocardiography (such as partial anomalous pulmonary venous drainage, or ARVD/C).

Viability and scar imaging

CMR can be used to confirm the diagnosis of myocardial infarction and assess viability before stenting or coronary artery bypass surgery, using gadolinium contrast agents to image scar tissue.

Clinical vignette 3: A 74-year-old man with a late-presentation ST-elevation myocardial infarction is shown to have an occluded left anterior descending artery during coronary angiography. Echocardiography shows an ejection fraction of 40%. Cardiovascular magnetic resonance (CMR) demonstrates that the anterior wall is akinetic, with full thickness infarction and no residual viable myocardium. Based on this information, he does not undergo stenting or coronary artery bypass graft surgery and is treated medically with heart failure therapy.

CMR imaging: two-chamber view showing a dilated left ventricle with akinetic anterior wall (A), and post-contrast imaging showing full thickness infarction of the entire anterior wall with no residual viable myocardium (B, arrows).

Infiltrative disorders traditionally requiring cardiac biopsy

CMR is a useful tool to diagnose infiltrative disorders which have traditionally required invasive cardiac biopsy, such as cardiac sarcoidosis, cardiac amyloidosis, and detection of fibrosis in hypertrophic cardiomyopathy.22–25 The EuroCMR registry of over 27 000 patients showed that using CMR improves diagnosis and changes clinical management in patients with cardiac conditions.26 Common indications and contraindications for CMR are shown in Box 2.27

Clinical vignette 4: A 26-year-old woman with palpitations has an echocardiogram showing a dilated right heart but with intact atrial and ventricular septum; the cause for right heart dilation was unclear. CMR showed a right ventricular volume index of 143 mL/m² (moderate to severely dilated), and confirmed a diagnosis of partial anomalous pulmonary venous drainage of the right veins to the superior vena cava (significant intracardiac shunt: Qp:Qs, 2:1). She underwent minimally invasive cardiac surgical repair, with normalisation of right heart size at follow-up.

Myocardial fibrosis and iron overload

CMR is a “non-invasive microscope” of the heart, with techniques such as quantitative T1 mapping allowing non-invasive measurement of fibrosis and extracellular volume fraction.28 Cardiac iron overload occurs in haemochromatosis and thalassaemia, and is a significant cause of morbidity and mortality in these conditions.29 In the past, cardiac biopsy was the only means to assess myocardial iron overload. However, using iron-sensitive T2* imaging, CMR has been validated to quantitatively and non-invasively measure myocardial iron stores. Australian guidelines exist for using CMR to assess for iron overload, with T2* values of > 20 ms being normal, < 10–20 ms indicating moderate iron overload, and values of < 10 ms indicating severe iron overload warranting consideration for chelation therapy.29

Ventricular thrombus

CMR is the gold standard test for detection of ventricular thrombus after myocardial infarction and is superior to echocardiography, including microsphere contrast echocardiography (Box 3).30

Valvular dysfunction

Quantitation of valvular regurgitation is more reproducible by CMR than by echocardiography,31 and is particularly useful in assessing aortic and pulmonary regurgitation, which are difficult to quantitate echocardiographically. CMR has been allocated a Class I indication for use in patients with moderate or severe valve disorders and suboptimal or equivocal echocardiographic evaluation (Class I, Level of evidence B).31,32 CMR is validated for the direct planimetric assessment of aortic stenosis, which can be performed using steady-state free precession cine imaging without requiring contrast (this may be useful for patients with renal impairment, such as those being assessed for transcatheter aortic valve implantation).33 CMR is also superior to echocardiography for the assessment of mitral regurgitation after percutaneous mitral valve repair.34 In clinical practice, CMR is useful when a valve lesion is of indeterminate or equivocal severity by echocardiography, when quality echocardiographic images are suboptimal (eg, due to limited acoustic windows), or when the “downstream effect” of a lesion needs further quantitation, such as left ventricular dilation in severe but asymptomatic valve regurgitation.

Stress perfusion CMR

Stress perfusion testing can be performed with CMR and has superior spatial resolution to nuclear SPECT imaging without the exposure to radiation. A large, prospective comparative efficacy trial recently demonstrated that stress perfusion CMR was superior to SPECT for the diagnosis of myocardial ischaemia.35 CMR can also provide information on viability (scar) and the coronary arteries in the same non-invasive test, making it a “one-stop shop” that is increasingly being adopted in Europe and the United Kingdom for stress imaging in cardiology practice.26

Limitations of CMR

The main limitation of CMR is availability, with the technique mainly confined to reference expert centres owing to its complexity and the degree of training required to perform and report CMR. Guidelines exist from the Society of Cardiovascular Magnetic Resonance on the performance and reporting of CMR, and specific Australian and New Zealand guidelines are currently being formulated. The second major limitation is the lack of specific Medicare reimbursement for CMR. At present, two applications are before the Medical Services Advisory Committee (MSAC): one for stress perfusion/viability imaging and one for assessment of cardiomyopathies in patients with abnormal baseline echocardiography (MSAC application 1393: http://www.msac.gov.au/internet/msac/publishing.nsf/Content/1393-public).

While CMR provides superior diagnostic information than echocardiography in virtually all cardiac disorders, it is more resource intensive, time consuming and currently less available than echocardiography. CMR should be targeted for patients in whom echocardiography is inconclusive or non-diagnostic, or in specific circumstances where CMR is more appropriate than echocardiography (such as complex congenital heart disease, or the use of stress perfusion when it is clinically appropriate to assess ventricular function, viability and ischaemia in a single test).

Relative contraindications are present in patients with arrhythmias that affect ECG gating, claustrophobia, implantable devices, and severe renal impairment (if contrast imaging is required). Most modern pacemaker systems are MRI conditional at a field strength of 1.5 T, but are not compatible with 3 T systems.

Conclusions

Cardiac imaging is a rapidly evolving field, with improvements in the diagnostic capabilities of non-invasive cardiac assessment. CTCA is useful to exclude coronary artery disease non-invasively. CMR is useful to accurately quantitate left ventricular and right ventricular function and investigate cardiomyopathies, or patients with congenital heart disease. CTCA and CMR and are becoming routine clinical practice for cardiologists in Australia and New Zealand, with increasing use in both hospital and outpatient settings. General practitioners and general physicians should be familiar with the basic indications, clinical utility and limitations of these modern techniques to assist in their appropriate use and interpretation in day-to-day practice.

Box 1 –
Appropriate indications for computed tomography coronary angiography endorsed by the Cardiac Society of Australia and New Zealand6

Chest pain with low to intermediate pre-test probability of coronary artery disease (CAD)
Chest pain with uninterpretable or equivocal stress test or imaging results
Normal stress test results but continued or worsening symptoms
Suspected coronary or great vessel anomalies
Evaluation of coronary artery bypass grafts (with symptoms)
Exclude coronary artery disease in new onset left bundle branch block or heart failure

Box 2 –
Common indications and contraindications for cardiovascular magnetic resonance imaging25

Common indications

Myocardial viability (ischaemic cardiomyopathies)
Accurate assessment of left ventricular ejection fraction; eg, before device implantation (implantable cardioverter defibrillator and cardiac resynchronisation therapy)
Detection of interventricular thrombus
Interstitial fibrosis (dilated and infiltrative cardiomyopathies)
Congenital heart disease
Cardiac mass
Right ventricular quantification
Evaluation for arrythmogenic right ventricular dysplasia/cardiomyopathy
Post cardiac transplantation surveillance
Constrictive pericarditis
Quantification of valvular dysfunction
Aortic and vascular measurement
Iron overload quantification (T2*)

Contraindications

Absolute
- Non-magnetic resonance compatible implantable devices
- Severe claustrophobia
Relative
- Magnetic resonance imaging conditional pacemakers (only 1.5 T field strength)
- Arrythmias that affect electrocardiogram gating (atrial fibrillation and ectopy)
- Severe renal impairment (risk of nephrogenic systemic fibrosis)

Box 3 –
Early post-contrast cardiovascular magnetic resonance image showing multiple thrombi in the mid-anterior wall and left ventricular apex (arrows)

Note: on microsphere contrast echocardiography, only the apical thrombus was seen; the thrombi adherent to the mid-anterior wall were not observed.