Prognosis of Myocarditis Developing After mRNA COVID-19 Vaccination Compared With Viral Myocarditis

J Am Coll Cardiol. 2022 Dec 13;80(24):2255-2265. doi: 10.1016/j.jacc.2022.09.049.

Abstract

Background: Association between messenger RNA (mRNA) COVID-19 vaccines and myocarditis has aroused public concern over vaccine safety.

Objectives: The goal of this study was to compare the prognosis of this condition with viral infection-related myocarditis over 180 days.

Methods: A territory-wide electronic public health care database in Hong Kong linked with population-based vaccination records was used to conduct a retrospective cohort study. Since the roll-out of BNT162b2 (Pfizer-BioNTech), patients aged ≥12 years hospitalized with myocarditis within 28 days after BNT162b2 vaccination were compared against viral infection-related myocarditis recorded before the pandemic (2000-2019), over a 180-day follow-up period (starting from diagnosis of myocarditis). All-cause mortality, heart failure, dilated cardiomyopathy, heart transplant, and postdischarge health care utilization were examined with Cox proportional hazards models.

Results: A total of 866 patients were included for analysis. Over the follow-up period, 1 death (1.0%) of 104 patients with postvaccination myocarditis and 84 deaths (11.0%) of 762 patients with viral infection-related myocarditis were identified. One case (1.0%) of dilated cardiomyopathy and 2 cases (1.9%) of heart failure were identified in the postvaccination group, compared with 28 (3.7%) and 93 (12.2%) in the viral infection-related myocarditis group, respectively. Adjusted analysis showed that the postvaccination myocarditis group had a 92% lower mortality risk (adjusted HR: 0.08; 95% CI: 0.01-0.57). No significant differences in other prognostic outcomes were seen.

Conclusions: This study found a significantly lower rate of mortality among individuals with myocarditis after mRNA vaccination compared with those with viral infection-related myocarditis. Prognosis of this iatrogenic condition may be less severe than naturally acquired viral infection-related myocarditis.

Keywords: SARS-CoV-2; adverse events of special interest; immunization; myopericarditis; perimyocarditis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aftercare
  • BNT162 Vaccine
  • COVID-19 Vaccines / adverse effects
  • COVID-19* / epidemiology
  • COVID-19* / prevention & control
  • Cardiomyopathy, Dilated*
  • Heart Failure*
  • Humans
  • Myocarditis* / epidemiology
  • Myocarditis* / etiology
  • Patient Discharge
  • RNA, Messenger
  • Retrospective Studies
  • Virus Diseases*

Substances

  • COVID-19 Vaccines
  • RNA, Messenger
  • BNT162 Vaccine