Myocarditis Temporally Associated With COVID-19 Vaccination

The global coronavirus disease 2019 (COVID-19) pandemic brought significant mortality with more than 3 million deaths worldwide since January 2020.¹ Concerted efforts focused on the time-sensitive development of vaccines yielded 3 COVID-19 vaccines receiving provisional US Food and Drug Administration approval: Pfizer-BioNTech COVID-19 (BNT162b2; Pfizer, Inc; Philadelphia, PA), Moderna (mRNA-1273; ModernaTX, Inc; Cambridge, MA), and Janssen (Ad.26.COV2.S; Johnson and Johnson; New Brunswick, NJ).¹ All vaccines demonstrated excellent safety and clinical efficacy profiles in clinical trials. As of June 5, 2021, more than 170 million individuals in the United States and 894 million individuals worldwide had received at least 1 dose of a COVID-19 vaccine. Notwithstanding isolated rare serious adverse events, they have been well tolerated and associated with decreasing burden of disease in areas with high vaccination rates.²

Myopericarditis has been reported as a rare vaccination complication.³ We present a case series of 7 patients hospitalized for acute myocarditis-like illness after COVID-19 vaccination, from 2 US medical centers in Falls Church, VA, and Dallas, TX. All were men <40 years of age and of White or Hispanic race/ethnicity (Table). Only 1 patient reported previous history of COVID-19 infection. Six patients received an mRNA vaccine (Moderna or Pfizer/BioNTech), and 1 received the adenovirus vaccine (Johnson and Johnson). All patients presented 3 to 7 days after vaccination with acute onset chest pain and biochemical evidence of myocardial injury, by cTnI ([cardiac troponin I]; Abbott Diagnostics, Lake Forest, IL) (mean peak, 15.77 ng/mL; median peak, 12.01 ng/mL) or elevated high-sensitivity cTnI (Abbott Diagnostics) (peak, 7000 ng/L). All were hemodynamically stable and none had a pericardial friction rub or rash. ECG patterns varied from normal to ST segment elevation. Three patients underwent invasive coronary angiography, and none had evidence of obstructive coronary artery disease. Echocardiograms showed left ventricular ejection fraction ranging from 35% to 62%, with 5 of 7 having some degree of hypokinesis. Patients underwent cardiac magnetic resonance imaging between 3 and 37 days after vaccination, including multiplanar SSFP sequences, short axis T1 and T2 stacks, T1 mapping when available and multiplanar myocardial late gadolinium enhancement. Multifocal subepicardial late gadolinium enhancement was present in 7 of 7 patients and additional midmyocardial late gadolinium enhancement was 4 of 7 patients. There was corresponding myocardial edema in 3 of 7 patients. Two patients who underwent cardiac magnetic resonance imaging >7 days from presentation had no edema, with an additional patient’s T2 images limited by artifact. One patient underwent endomyocardial biopsy without pathological evidence of myocarditis. No patients reported palpitations, and there was no evidence of sustained arrhythmias. No patients had evidence of an active viral illness or autoimmune disease, and 6 of 7 had polymerase chain reaction testing for acute COVID-19 infection during hospitalization (all 6 were negative). Assessment of COVID-19 serology was obtained for 6 of 7 patients, with 4 of 6 showing presence of spike protein IgG antibodies.

Treatment varied and included β-blocker and anti-inflammatory medication. Hospital length of stay was 3±1 days, and all patients’ symptoms resolved by hospital discharge. All cases were reported to the Vaccine Adverse Event Reporting System and the Centers for Disease Control. Institutional review board approval was obtained for this report. The data that support the findings of this study are available from the corresponding author on reasonable request.

In 1990, the United States established the Vaccine Adverse Event Reporting System and from 1990 to 2018, myopericarditis comprised 0.1% of all adverse events reported.³ To date, while anecdotes of potential myocarditis from COVID-19 vaccines have been reported in the lay media⁴ and the US Centers for Disease Control and Prevention has acknowledged investigation of potential cases, to our knowledge there are no reported case series of myocarditis-like illness associated with COVID-19 vaccination in adults. Our series of 7 male COVID-19 vaccination recipients who presented with myocarditis-like illness supports a potential causal association with vaccination given the temporal relationship, clinical presentation, and cardiac magnetic resonance imaging findings. Although endomyocardial biopsy was negative in the single case in which it was performed, this may represent sampling bias, given the patchy nature of myocardial inflammation in myocarditis.⁵ Of the 2 patients without measurable spike protein IgG, both presented shortly after their first vaccine dose. This antibody response is not unexpected but may indicate an alternate vaccine-related immune mechanism or absence of causality with the vaccine.

Additional study is needed to confirm whether the rate of myocarditis-like illness is higher after vaccination than the background rate of myocarditis among similarly aged individuals in the population. Globally, myocarditis is diagnosed in approximately 10 to 20 individuals per 100 000 person-years.⁵ Moreover, careful immunophenotyping studies are needed to investigate potential mechanisms of vaccine-associated myocardial injury. Such studies could help determine populations at higher risk of this potential outcome and possible treatment strategies and should inform clinicians of the possibility of a myocarditis-like illness in patients with appropriate symptoms in the first few days after COVID-19 vaccination. Treatment considerations for myocarditis include anti-inflammatory medications and the addition of guideline-directed medical therapy if left ventricular ejection fraction is reduced,⁵ although no data specific to vaccine-associated myocarditis are available.

The clinical course of vaccine-associated myocarditis-like illness appears favorable, with resolution of symptoms in all patients. Given the potential morbidity of COVID-19 infection even in younger adults, the risk–benefit decision for vaccination remains highly favorable. Vaccine adverse event reporting remains of high importance and further studies are needed to elucidate the pathophysiological mechanism to potentially identify or prevent future occurrences.

Acknowledgments

The authors acknowledge the Dudley Family for their continued contributions and support of the Inova Dudley Family Center for Cardiovascular Innovation. The authors also acknowledge Kee Hyo Kang, Dr Lucy Nam, and Holly O’Donnell for their laboratory contributions and support of this project.

Footnotes