Covid-associated myocarditis and in-hospital mortality: a national inpatient analysis of predictors and outcomes

Background/Introduction Myocarditis associated with coronavirus disease 2019 (COVID-19) has been linked to adverse cardiovascular outcomes; however, contemporary national data evaluating its independent association with in-hospital mortality and critical care utilisation remain limited. Purpose To assess in-hospital mortality and identify independent predictors of death among patients hospitalised with COVID-associated myocarditis compared with non-COVID myocarditis. Methods We conducted a retrospective cohort study using a nationally representative inpatient database from 2021. Adult hospitalisations with myocarditis were identified and stratified by COVID status. The primary outcome was in-hospital mortality. Secondary outcomes included cardiogenic shock, mechanical ventilation, extracorporeal membrane oxygenation (ECMO), and arrhythmia. Multivariable logistic regression was performed adjusting for age, sex, cardiogenic shock, mechanical ventilation, ECMO, and arrhythmia. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were reported. Results Among 2,200 myocarditis admissions, 850 were COVID-associated. In-hospital mortality was significantly higher in COVID-associated myocarditis compared with non-COVID myocarditis (24.5% versus 3.7%). After multivariable adjustment, COVID-associated myocarditis remained independently associated with mortality (aOR 4.13, 95% CI 2.80–6.17). Mechanical ventilation demonstrated the strongest association with death (aOR 26.99, 95% CI 18.32–40.4), followed by ECMO (aOR 2.29, 95% CI 1.06–4.84). Increasing age was independently associated with mortality (aOR 1.04 per year, 95% CI 1.03–1.05). Conclusion(s) COVID-associated myocarditis is associated with substantially higher in-hospital mortality compared with non-COVID myocarditis, independent of critical illness markers. Mechanical ventilation and ECMO strongly correlate with mortality, reflecting a severe disease phenotype. These findings highlight the importance of early risk stratification and aggressive supportive management in this high-risk population.