The Impact of COVID‐19 Infection and Vaccination on Myocarditis Incidence: A Comparative Analysis of Pre‐, Peri‐, and Post‐Pandemic Eras

ABSTRACT Background The coronavirus disease 2019 (COVID‐19) pandemic introduced a surge in cardiovascular complications, with myocarditis emerging as a concern due to both direct viral effects and rare vaccine‐associated events. Aims This analysis examines the incidence and outcomes of myocarditis in patients across a large healthcare system in the Washington, DC Metropolitan Area, focusing on periods before, during, and after the COVID‐19 pandemic. Methods A retrospective cohort study was conducted using electronic health records from the MedStar Health System (2017−2024). Myocarditis cases were identified using ICD‐10 codes, with cases stratified by pre‐ (2017−2019), peri‐ (2020−2022), and post‐COVID‐19 (2023−2024) pandemic periods, as well as by association with COVID‐19 infection and/or vaccination. The overall incidence and inpatient mortality of myocarditis were compared over these eras. Results This study included 778 myocarditis patients admitted between January 2017 and December 2024, categorized into pre‐COVID‐19 ( n = 207), peri‐COVID‐19 ( n = 370), and post‐COVID‐19 ( n = 201) periods. Total myocarditis incidence surged during the peri‐pandemic period, peaking in 2022, and declined in 2023‐2024. In the post‐pandemic period, total myocarditis remained elevated and higher than in the pre‐pandemic era. During the pandemic and post‐pandemic periods, myocarditis patients were older, included a higher proportion of African American individuals, and had a greater burden of cardiometabolic comorbidities, compared to pre‐pandemic myocarditis hospitalizations. Conclusion This study demonstrates a marked increase in myocarditis cases during the COVID‐19 pandemic, driven initially by a surge in COVID‐19‐related myocarditis. Notably, total myocarditis cases remained elevated in the post‐pandemic period compared to pre‐pandemic levels. These findings, particularly the increased post‐pandemic myocarditis patients, warrant further investigation into underlying risk factors and long‐term outcomes.