Sex differences in myocarditis hospitalizations: Rates, outcomes, and hospital characteristics in the National Readmission Database.

Inflammation of the myocardium, or myocarditis, presents with varied severity, from mild to life-threatening such as cardiogenic shock or ventricular tachycardia storm. Existing data on sex-related differences in its presentation and outcomes are scarce. Using the Nationwide Readmission Database (2016-2019), we identified myocarditis hospitalizations and stratified them according to sex to either males or females. Multivariable regression analyses were used to determine the association between sex and myocarditis outcomes. The primary outcome was in-hospital mortality, and the secondary outcomes included sudden cardiac death (SCD), cardiogenic shock (CS), use of mechanical circulatory support (MCS), and 90-day readmissions. We found a total of 12,997 myocarditis hospitalizations, among which 4,884 (37.6 %) were females. Compared to males, females were older (51 ± 15.6 years vs. 41.9 ± 14.8 in males) and more likely to have connective tissue disease, obesity, and a history of coronary artery disease. No differences were noted between the two groups with regards to in-hospital mortality (adjusted odds ratio [aOR] 1.20; confidence interval [CI] 0.93-1.53; P = 0.16), SCD (aOR:1.18; CI 0.84-1.64; P = 0.34), CS (aOR: 1.01; CI 0.85-1.20;P = 0.87), or use of MCS (aOR: 1.07; CI:0.86-1.34; P = 0.56). In terms of interventional procedures, females had lower rates of coronary angiography (aOR: 0.78; CI 0.70-0.88; P < 0.01), however, similar rates of right heart catheterization (aOR 0.93; CI:0.79-1.09; P = 0.36) and myocardial biopsy (aOR: 1.16; CI:0.83-1.62; P = 0.38) compared to males. Additionally, females had a higher risk of 90-day all-cause readmission (aOR: 1.25; CI: 1.16-1.56; P < 0.01) and myocarditis readmission (aOR:1.58; CI 1.02-2.44; P = 0.04). Specific predictors of readmission included essential hypertension, congestive heart failure, malignancy, and peripheral vascular disease. In conclusion, females admitted with myocarditis tend to have similar in-hospital outcomes with males; however, they are at higher risk of readmission within 90 days from hospitalization. Further studies are needed to identify those at higher risk of readmission.