Prevalence and clinical outcomes of myocarditis and pericarditis in 718,365 COVID-19 patients.

Buckley, Benjamin J R; Harrison, Stephanie L; Fazio-Eynullayeva, Elnara; Underhill, Paula; Lane, Deirdre A; Lip, Gregory Y H

BACKGROUND COVID-19 has a wide spectrum of cardiovascular sequelae including myocarditis and pericarditis; however, the prevalence and clinical impact is unclear. We investigated the prevalence of new-onset myocarditis/pericarditis and associated adverse cardiovascular events in patients with COVID-19. METHODS AND RESULTS A retrospective cohort study was conducted using electronic medical records from a global federated health research network. Patients were included based on a diagnosis of COVID-19 and new-onset myocarditis or pericarditis. Patients with COVID-19 and myocarditis/pericarditis were 1:1 propensity score matched for age, sex, race and co-morbidities to patients with COVID-19 but without myocarditis/pericarditis. The outcomes of interest were 6-month all-cause mortality, hospitalisation, cardiac arrest, incident heart failure, incident atrial fibrillation, and acute myocardial infarction, comparing patients with and without myocarditis/pericarditis. Of 718,365 patients with COVID-19, 35,820 (5.0%) developed new onset myocarditis and 10,706 (1.5%) developed new onset pericarditis. Six-month all-cause mortality was 3.9% (n=702) in patients with myocarditis and 2.9% (n=523) in matched controls (P<0.0001), odds ratio 1.36 (95% confidence interval (CI): 1.21-1.53). Six-month all-cause mortality was 15.5% (n=816) for pericarditis and 6.7% (n=356) in matched controls (P<0.0001), odds ratio 2.55 (95% CI: 2.24-2.91). Receiving critical care was associated with significantly higher odds of mortality for patients with myocarditis and pericarditis. Patients with pericarditis seemed to associate with more new-onset cardiovascular sequelae than those with myocarditis. This finding was consistent when looking at pre-COVID-19 data with pneumonia patients. CONCLUSIONS Patients with COVID-19 who present with myocarditis/pericarditis associate with increased odds of major adverse events and new-onset cardiovascular sequelae.