HEART ON FIRE: Post-COVID Vaccine Myocarditis

by Torie Quinn, DO (’23)

The first patient I met during my pediatric cardiology elective was a previously healthy male teenager who had done everything right during the pandemic to keep himself and his family safe. And when it was his turn to do the next right thing and become vaccinated, he stepped up with the optimism, hope and excitement that everyone had advertised came with this next step. Except… plot twist! His heart lit on fire. 

He developed myocarditis and pericarditis four days after receiving his second dose of the Pfizer SARS-CoV-2 mRNA vaccine and required admission to the pediatric intensive care unit. He had a severe troponin leak > 10,000ng/L, significant chest pain and dyspnea, decreased left ventricular systolic function and coronary vasospasm. 

Myocarditis diagnosis

Endomyocardial biopsy is the gold standard for diagnosis but is invasive and has low sensitivity, so cardiac MR is increasingly used. If either of these are unavailable, the clinical criteria below are considered:

– Signs/symptoms of acute cardiac dysfunction (chest pain, SOB, palpitations, dyspnea on exertion)
Elevated troponin
MRI, EKG, or echo findings consistent with myocarditis

Pericarditis diagnostic criteria – need 2 of the following: 

Chest pain
– Pericardial friction rub by stethoscope
Abnormal EKG findings (new ST elevation or PR depression)
– Pericardial effusion on echo or MRI

* highlighted red are the criteria met by the above patient 

Multiple studies have confirmed an association between the Pfizer and Moderna mRNA SARS-CoV-2 vaccines and myocarditis. Recently, Marshall et al. Pediatrics. 2021 illustrated a case series of seven healthy males aged 14-19 who, just like the patient above, presented with chest pain within four days of their second dose of the Pfizer vaccine and were found to have ST elevations, significant troponin leak, cardiac dysfunction and positive cardiac MRI findings. 

While this is fascinating and ever-evolving science, it also highlights what I believe to be one of the most crucial skills in pediatrics – the ability to sift through the literature, look parents in the eyes, and counsel them on how to keep their children safe. It requires shared decision making, anticipatory guidance, and benefit-risk discussions. Because while we as medical professionals view a 12-in-one-million chance of developing myocarditis after receipt of a vaccine that can help curtail a pandemic as a significant benefit, parents will understandably focus on the risk of their child being one of those 12. 

In light of this, counseling families through COVID-vaccine hesitancy requires a consideration of factors at both the individual and population level. Specifically in terms of post-vaccine myocarditis, there are important discrepancies in risk when considering both sex and age, with most cases occurring after the second dose in males at a median age of 24 years old. For further individual considerations, the CDC has specific recommendations for patients who have had myocarditis or pericarditis previously, as well as for patients who may have developed it after the first dose of their COVID vaccine. 

At a population level, it is crucial to educate parents and patients about how higher levels of vaccination lead to less community transmission, which in turn decreases the risk of emerging variants. Adolescents in particular hold a pivotal role in reducing spread, with data from the CDC as of June 11, 2021 demonstrating that individuals 12-29 years old are responsible for at least 7.7 million COVID-19 cases since the start of the pandemic. Also poignant for parents and adolescents is the importance of the vaccine as it pertains to the safe reopening of schools, and highlighting the myriad of biopsychosocial benefits that accompany in-person learning. 

As we have all learned over the last year, these conversations are not one-and-done. This is not stagnant information, as science rarely is, and will require patience and persistence on the part of all medical providers to stay updated on the most recent data and recommendations. Especially for pediatricians in conversations with parents and adolescents, compassion and respect should be at the foundation of all discussions to support a positive and therapeutic partnership.


  1. Adler Y, et al.. 2015 ESC Guidelines for the diagnosis and management of pericardial diseases: The Task Force for the Diagnosis and Management of Pericardial Diseases of the European Society of Cardiology (ESC)Endorsed by: The European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2015 Nov 7;36(42):2921-2964. doi: 10.1093/eurheartj/ehv318. Epub 2015 Aug 29. PMID: 26320112; PMCID: PMC7539677.
  2. Baden LR et al. N Engl J Med 2021; DOI: 10.1056/NEJMoa2035389
  3. Marshall M, Ferguson ID, Lewis P, Jaggi P, Gagliardo C, Collins JS, Shaughnessya R, Carona R, Fuss C, Corbin KJE, Emuren L, Faherty E, Hall EK, Di Pentima C, Oster ME, Paintsil E, Siddiqui S, Timchak DM, Guzman-Cottrill JA. Symptomatic Acute Myocarditis in Seven Adolescents Following Pfizer-BioNTech COVID-19 Vaccination. Pediatrics. 2021 Jun 4:e2021052478. doi: 10.1542/peds.2021-052478. Epub ahead of print. PMID: 34088762.
  4. Possible Association Between COVID-19 Vaccine and Myocarditis: Clinical and CMR Findings. JACC Cardiovasc Imaging 2021;Jun 14
  5. Shimabukuro T. COVID-19 Vaccine safety updates. Advisory Committee on Immunization Practices (ACIP) meeting, June 2021. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-06/03-COVID-Shimabukuro-508.pdf (Accessed on June 25, 2021).
  6. Wallace M, Oliver S. COVID-19 mRNA vaccines in adolescents and young adults: Benefit-risk discussion. Advisory Committee on Immunization Practices (ACIP) meeting, June 2021. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-06/05-COVID-Wallace-508.pdf (Accessed on June 25, 2021).