Association Between Mitral Valve Disease and Myocarditis in COVID-19 Hospitalizations: A National Inpatient Sample Analysis

Background: Myocarditis has emerged as a complication of COVID-19 infection. However, its relationship to pre-existing cardiac conditions, such as mitral valve disease (MVD), still needs to be elucidated. This study aimed to assess the development of myocarditis in COVID-19 patients and to determine whether the presence of MVD was an associated factor.

Methods: A retrospective cohort study utilizing the 2021 National Inpatient Sample database examined adult hospitalizations for COVID-19, categorizing patients into four groups based on COVID-19 and MVD status. Statistical analysis included survey weights for national estimates, including Rao-Scott X2 tests for categorical variables and linear regression for continuous variables. Two models using logistic regression were created to assess the relationship between COVID-19, myocarditis, and MVD. Model 1 adjusts for individual comorbidities, while Model 2 uses the Elixhauser comorbidity score for overall comorbidity assessment.

Results: Out of approximately 1 million hospitalizations, 600,873 weighted hospitalizations were included. Patients with concomitant COVID-19 and MVD demonstrated greater comorbidity burden. In model 1, MVD was not significantly associated with myocarditis (OR 1.97, 95% CI 0.82-4.76; p = 0.13). In Model 2, MVD was independently associated with increased odds of myocarditis (OR 3.14, 95% CI 1.36-7.27; p=0.008). Higher Elixhauser scores increased myocarditis risk, whereas older age and female sex had lower odds.

Conclusions: This study suggests a potential association between MVD and myocarditis among hospitalized COVID-19 patients after adjustment for overall comorbidity burden. Findings are limited by reliance on ICD-10 coding and the low incidence of myocarditis, which may affect statistical stability.

Keywords: COVID-19, SARS-CoV-2, myocarditis, mitral valve disease, cardiovascular risks