Abstract Body (Do not enter title and authors here): Introduction:
Myocarditis is more commonly reported among young males and may be complicated by cardiogenic shock. Animal models and clinical studies demonstrate that myocardial fibrosis after myocarditis disproportionately impacts males. There is limited contemporary data on sex-specific clinical outcomes among patients with myocarditis complicated by cardiogenic shock.

Methods:
This retrospective cohort study used an EHR-based data platform from large academic medical centers across the United States (TriNetX, Inc.) to identify patients diagnosed with cardiogenic shock secondary to myocarditis between January 2012 and January 2024. Baseline demographics, clinical characteristics, medication use, and outcomes were defined using standardized ICD codes. The primary study outcome was all-cause mortality at 6 months. Secondary outcomes included cardiac arrest, acute kidney injury (AKI), atrial fibrillation, and ventricular tachycardia/fibrillation (VT/VF). The study population was stratified based on sex. Propensity score matching (1:1), incorporating demographic factors, comorbidities, and medication usage, was employed to compare the risk of primary and secondary outcomes between groups.

Results:
We identified 3,048 individuals (1,857 males, 60.9%) with myocarditis complicated by cardiogenic shock. After propensity-score matching, there were 1,072 individuals in each group (Table). Females had a higher risk of all-cause mortality (HR: 1.27, 95%CI: 1.06-1.52), but a lower risk of AKI (HR: 0.83, 95% CI: 0.74-0.92) and VT/VF (HR: 0.74, 95%CI: 0.60-0.92). The risks of atrial fibrillation (HR: 0.88, 95% CI: 0.70-1.09) and cardiac arrest (HR: 1.04, 95% CI: 0.85-1.27) were similar between the two groups.

Conclusion:
Significant sex-based differences in clinical outcomes exist among patients with myocarditis complicated by cardiogenic shock. Further studies are warranted to investigate the pathophysiological basis of the higher risk of all-cause mortality, and lower risk of AKI and ventricular arrhythmias among females with myocarditis complicated by cardiogenic shock compared with males.