MYOCARDITIS is increasingly diagnosed in the COVID-19 era, but it’s at least partly due to increased awareness of the condition and advances in detecting milder cases, experts say.

Speaking with InSight+, Associate Professor Andrew MacIsaac, Director of Cardiology at St Vincent’s Hospital in Melbourne, stressed that myocarditis remained a “rare and mostly mild condition”.

His team has seen several cases of SARS-CoV-2-related myocarditis since 2020 and one definitive case of myocarditis related to the Comirnaty (Pfizer) vaccine.

“We have had to admit some people with myocarditis, but we haven’t had anyone with long term complications from having it,” Associate Professor MacIsaac said.

Awareness of the condition has grown as a result of its association with COVID-19 and mRNA COVID-19 vaccines, so that cardiologists are seeing increasing numbers of suspected cases, he said.

“The vast majority of people who are referred to cardiologists with suspected myocarditis don’t have myocarditis,” he said. “There is a lot of anxiety in the community and brief chest pains are very common when people are anxious.”

Many of today’s cases were mild and would not have been diagnosed a decade ago, Associate Professor MacIsaac said.

“When doctors used to think of myocarditis, they thought of a very serious condition where someone might be febrile with a viral illness, chest pain, and have acute heart failure,” he said. “However, it’s becoming recognised that myocarditis is a spectrum.”

Cardiac magnetic resonance imaging (MRI) had proved a breakthrough in diagnosing the condition, he said, enabling cases that might previously have been described as “atypical chest pain”, “no diagnosis made” or sometimes “suspected myocardial infarction” to be definitively diagnosed.

Professor MacIsaac urged GPs to be guided by the severity of a patient’s symptoms when considering suspected cases of myocarditis.

“If a GP is concerned because their patient has chest pain and they suspect it might be myocarditis they should do an [electrocardiogram (ECG)] to make sure its normal,” he said. “Then check the troponin and arrange an echocardiogram, and if the troponin or the echocardiogram are abnormal, specialist advice is required.”

In a case study published in the MJA, a patient with COVID-19 mRNA vaccine (Comirnaty)-induced myocarditis was treated with ibuprofen, pantoprazole and bisoprolol, with complete resolution of symptoms within 24 hours.

The 20-year-old man had developed chest pain 48 hours after administration of his second dose of the Comirnaty vaccine, and also had fevers and diaphoresis. His first dose had been uncomplicated.

He had sinus tachycardia with global ST elevation and elevated troponin. No abnormality was detected with echocardiogram, but cardiac MRI showed epicardial late gadolinium enhancement over the mid and apical lateral segments, consistent with myocarditis.

The authors from the Royal Melbourne Hospital said the case was consistent with a recent case series of 61 patients with COVID-19 vaccination-related myocarditis, in which 90% had symptom resolution, with a median hospitalisation duration of 4.6 days.

“COVID-19 mRNA vaccine-related myocarditis is an extremely rare and mild complication, and is much less frequent than myocarditis secondary to SARS-CoV-2 infection,” they wrote, adding:

“Management in the primary care or outpatient setting is appropriate if presentation is mild and if ECG, troponin and inflammatory markers can be reviewed within 12 hours.”

The authors stressed that the benefit–risk assessment for COVID-19 mRNA vaccination was still overwhelmingly favourable for all age and sex groups, including males aged 12–29 years, who were at highest risk of vaccine-related myocarditis.

The Australian Technical Advisory Group on Immunisation (ATAGI) notes that COVID-19 is estimated to cause myocarditis at a rate of 11.0 events per 100 000 persons, whereas the Comirnaty (Pfizer) vaccine has been estimated to cause myocarditis at an overall rate of 2.7 events per 100 000 persons.

By 23 January 2022, 431 likely myocarditis cases and 774 likely pericarditis cases related to the Comirnaty vaccine had been reported to the Therapeutic Goods Administration, out of 31.6 million doses given. A further 46 likely myocarditis and 57 likely pericarditis cases linked to Spikevax (Moderna) were also reported, out of 2.7 million doses. For both vaccines, the data include several cases among adolescents.

The Royal Australian College of General Practitioners spokesperson, Professor Mark Morgan of Queensland’s Bond University, said a GP’s decision to refer a patient with suspected myocarditis or pericarditis took into account not only clinical factors but also psycho-social ones and the capacity of general practice to manage the situation safely and promptly.

“GPs can conduct and interpret ECGs, request and interpret the results of blood tests and make clinical assessments and try to make sense of undifferentiated symptoms such as chest wall pain, heart pain and combinations of the two,” he said.

“However, the management of a patient may change depending on whether the patient has support available to them at home and can get back to us for regular reviews, or if they are presenting on a Saturday afternoon when a deputising service is about to take over.”

The federal government introduced a Medicare Benefits Schedule item in January 2022 for cardiac MRI to assist in diagnosing myocarditis that may occur following COVID-19 vaccination with an mRNA vaccine. Only consultant physicians can order the test under the temporary item, and only after inconclusive results from echocardiogram, troponin and chest x-ray. The item is timed to coincide with the COVID-19 vaccine and booster vaccine rollout and will expire in June. The schedule fee is $855.20.

Professor MacIsaac applauded the decision to fund the test, and said it should be made a permanent item and broadened to test for other heart conditions.

Associate Professor David Prior, deputy director of cardiology at St Vincent’s hospital in Melbourne, also welcomed the funding, but said it was “a little bit weird” given the federal government in 2016 rejected a submission by the Cardiac Society of Australia and New Zealand to expand funding for cardiac MRI.

“If the government thinks it is sensible to fund cardiac MRI for myocarditis related to the vaccine, then it doesn’t make sense not to fund it in an ongoing way for suspected myocarditis unrelated to COVID-19 vaccination and other cardiac diseases which have much worse outcomes,” he said.

Ironically, St Vincent’s hospital was not using the new item number to fund cardiac MRI, he said.

“Because there are almost no item numbers for cardiac MRI funded through Medicare, much of the cardiac MRI in Australia is done through teaching hospitals that have an interest in it and often self-fund it, and they tend to be done therefore on cardiac MRI machines that are not licensed for Medicare,” he said.

“So, if you’re going to do MRI scans for COVID- vaccine-related myocarditis, it would necessitate 6you moving to a different machine – the one you usually do hips and knees and backs on.

“We’ve made the decision to just keep using our usual machine, which is our best one, even though we don’t get money for it,” he added.

Associate Professor Prior agreed that cardiac MRI was now picking up mild cases that in the past wouldn’t have been detected.

“Are we now picking up cases where it doesn’t matter? I don’t think we know the answer to that yet,” he said. “What we do know is that with cardiac MRI, you can see things which you can’t see any other way, sometimes providing the definitive diagnosis that changes the whole treatment paradigm.”

He gave a typical example of a symptomatic patient who had elevated troponin but a normal angiogram.

“With cardiac MRI, a common thing we find under those circumstances is myocarditis, but sometimes you discover they have had [a myocardial infarction] and the abnormality was not seen on the angiogram,” he said. “So, from the cardiac MRI, we know whether to treat with medications to prevent further myocardial infarction or to look at appropriate therapy for myocarditis.”

Associate Professor Prior said mild cases of myocarditis could be treated with pain relief and observation, while cases with abnormal heart function might require antihypertensives. Cases should not exercise competitively for 6 months, and only after cardiac testing, he added.

Australian guidelines on myocarditis and pericarditis after mRNA COVID-19 vaccines are available here.

Separate guidelines for assessment of possible vaccine-induced pericarditis or myocarditis in children and adolescents presenting to the ED are available here.

8 thoughts on “COVID-related myocarditis: what you need to know

  1. Anonymous says:

    My husband had Moderna vaccination on the 1 Feb 2022 arrive to emergency department on the 16th February 2022 with Heart failure symptoms being Shortness of breath pain and pressure in his chest too abdomen area swollen ankles and calves he waited for 10 hours to be seen was given a covid test came back negative did a few tests fluid was found on his lungs had another test found a cyst on his pancreas was given antibiotics then sent home on the 18th February still short of breath and swollen legs the only medication he was given was for his pancreas, then started to deteriorate from there went back to the emergency department 21st February 2022 he was given another covid test then isolated in a covid ward for two days which came back negative on the 23rd February he was put into a general ward finally given medicine for fluid then taken for a echocardiogram then found his heart at 11% has now been diagnosed with severe IDC?

  2. Anonymous says:

    Myocarditis/pericarditis is a bit like viral meningitis in this sense – when one sustains a viraemia or autoimmune inflammatory crisis, the entire body can be affected.

    What matters in these cases is not just the tissue diagnosis, but the prognosis and potential/need for treatment.

    When a person has marked influenza, for example, with severe headache, it’s possible that the virus seeds into the CSF. If they are also tachycardic, it’s possible that there is a mild myocarditis and even troponin leak.

    These diagnoses would only be made if we did lumbar punctures and myocardial MRI on every patient with potential symptoms – but what would be gained? Just more expense and increased anxiety for little gain in a stable patient with a self-limiting condition.

  3. Brett Forge says:

    “Patients after post covid-19 vaccination presenting with chest pain will best be referred to ER for necessary blood tests, ECG and imaging to be able to exclude or confirm cardiac including myocarditis or non cardiac cause and advise appropriately.”
    That statement ignores the fact that relying on troponin and ECGs is far too insensitive and adding echo also would clearly miss numerous cases of mild myocarditis. MRI is not a practical solution in all these cases.
    Advising appropriately would require some evidence as to the safety of repeating vaccination in someone who has developed severe pleuritic chest pain 2 days after vaccination. I haven’t seen any evidence that would enable us to make that decision.

  4. Dr Ratnakar Bhattacharyya says:

    Any patient presenting with chest pain regardless of Covid-19 vaccination needs to be carefully assessed because chest pain can be due to non cardaic cause and often it will be difficult to exclde cardiac cause clnically. Patients after post covid-19 vacciation preseting with chest pain will best be referred to ER for necessary blood tests, ECG and imaging to be able to exclude or confirm cardiac including myocrditis or non cardaic cause and advise appropriately.

  5. Brett Forge says:

    Totally agree with Randall that the overall prevalence is much higher than that reported by the narrow diagnostic criteria currently used. I would like to know the advice for pts that have had an episode of vaccine related myocarditis or far more commonly post vaccine chest pains. The problem tends to be higher with second injections. Should these pts be referred for a third vaccine? I haven’t seen any data on outcomes of pts with severe chest pains with another vaccination.

  6. Anonymous says:

    I suggest that data from Uk, USA some European countries and Israel on the incidence of post-vaccination with Pfizer ans Moderna be reviewed and analysed to better assess this problem of Myocarditis/Pericarditis in the under 20 age group before giving such assurances when so little has nothing has been published about the development of these messenger RNA vaccines and Pfizer wants to keep their data hidden for years which is being challenged in the courts in USA. Lack of transparency is a major problem and risks a distrust in the community.
    Just for the record I am Pro-vaccination and have had my Moderna booster jab.
    Since the Omicron escapes these vaccines we need another new Vaccine for this variant and future variants

  7. Anonymous says:

    Any experience of Covid 19 infection related myocarditis/pericarditis? All the article seems to be about the less common post vaccination cases.

  8. Randal says:

    An excellent summary that I and surely many others have been waiting for. In my regional hospital, which has secondments to two others, our rural generalists have seen an unusually high incidence of post-mRNA-vaccination prolonged chest pain — with duration from a week to months, and characteristics that do not suggest anxiety. None of these patients have had any positive test results (TNI, ECG, CXR, and in some instances, echo), which has led us to believe that while some cases may be psychogenic, there is surely an auto-immune inflammatory process at work, and indeed as common sense (er, from first principles) would dictate, lying on a continuum.

    As a result (along with several other reasons that one could summarize as a healthy cynicism over current public health processes/mandates/etc), we have not been reporting these cases. Between the mildness and the factors preventing reporting, we’d bet that the overrall prevalence of cardiac inflammation is several orders of magnitude higher than that for the diagnosed myocarditis lying towards the other end of the spectrum.

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