COVID-19 Associated Myocarditis Clinical Outcomes among Hospitalized Patients in the United States: A Propensity Matched Analysis of National Inpatient Sample

Coronavirus-19 (COVID-19), preliminarily a respiratory virus, can affect multiple organs, including the heart. Myocarditis is a well-known complication among COVID-19 infections, with limited large-scale studies evaluating outcomes associated with COVID-19-related Myocarditis. We used the National Inpatient Sample (NIS) database to compare COVID-19 patients with and without Myocarditis. A total of 1,659,040 patients were included in the study: COVID-19 with Myocarditis (n = 6,455, 0.4%) and COVID-19 without Myocarditis (n = 1,652,585, 99.6%). The primary outcome was in-hospital mortality. Secondary outcomes included mechanical ventilation, vasopressor use, sudden cardiac arrest, cardiogenic shock, acute kidney injury requiring hemodialysis, length of stay, health care utilization costs, and disposition. We conducted a secondary analysis with propensity matching to confirm results obtained by traditional multivariate analysis. COVID-19 patients with Myocarditis had significantly higher in-hospital mortality compared to COVID-19 patients without Myocarditis (30.5% vs. 13.1%, adjusted OR: 3 [95% CI 2.1-4.2], p < 0.001). This cohort also had significantly increased cardiogenic shock, acute kidney injury requiring hemodialysis, sudden cardiac death, required more mechanical ventilation and vasopressor support and higher hospitalization cost. Vaccination and more research for treatment strategies will be critical for reducing worse outcomes in patients with COVID-19-related Myocarditis.