Sex differences in the clinical presentation and outcomes of acute myocarditis: insights from the PREMYO multicenter registry

Background/Introduction Acute myocarditis (AM) is defined as inflammation of the myocardium, characterized by a variable clinical presentation. The PREMYO cohort is the first Spanish multicentre registry to characterise patients with clinically suspected AM. Purpose The aim of our study was to analyse clinical differences and outcomes in patients with a confirmed diagnosis of AM according to sex. Methods This multicentre registry included 1.321 patients with clinically suspected AM between September 2023 and February 2026. A confirmed diagnosis was established by a national clinical committee, following the 2025 ESC Guidelines for the management of myocarditis and pericarditis criteria. Patients were classified in two groups according to sex. Baseline characteristics and a primary endpoint of major adverse cardiac events (heart failure, cardiogenic shock, mechanical circulatory support, pacemaker or cardioverter-defibrillator implantation and death) and ventricular complications (arrhythmias and dysfunction) during follow-up were recorded and compared between groups. Results Among 315 patients with a diagnosis of AM confirmed by the clinical committee,264 (83.8%) were male and 51 (16,2%) women. Women were older than men (53.22 vs 33.92 years), with a greater prevalence of hypertension, diabetes, previous cardiac disease,cancer and autoimmune disease (table 1).Dyspnoea at presentation (23.5% vs 9.8%; p = 0.010) was more frequent in women, whereas chest pain (91.7% vs 80.4%; p=0.022) and fever (44.5% vs 21.6%; p=0.004) were in men. Higher levels of troponin I and CRP were observed in men (5,442 vs 1,277 pg/mL; p=0.001) and (5.52 vs 2.30 mg/dL; p=0.009) respectively. Left ventricular ejection fraction (LVEF) and TAPSE were lower in women (43.09% vs 53.36%; p<0.001) and (18.04 mm vs 22.7 mm; p<0.001) respectively. Coronary angiography and endomyocardial biopsy were performed more frequently in women (49.3% vs 31.9%; p<0.001) and (12.7% vs 5.5%; p=0.012). The presence of late gadolinium enhancement on MRI was higher in men (93.9% vs 83.3%; p = 0.024). During hospitalization, women experienced a worse clinical course, with a higher prevalence of heart failure (19.6% vs 2.7%; p<0.001), ventricular arrhythmias (21.6% vs 3%; p< 0.001), ventricular dysfunction (19.6% vs 8.7%; p=0.041), need for inotropic support (9.8% vs 1.9%; p=0.001) and implantable cardioverter-defibrillator (5,9% vs 1,1%;p=0,022) or pacemaker implantation( 5,9% vs 0%; p=0,032). During follow-up, women exhibited higher rates of the primary endpoint (p<0.001, log-rank test), driven by increased mortality (8.2% vs 1.2%; p = 0.015) and persistent ventricular dysfunction (4.1% vs 0%; p=0.026)(Figure 1) Conclusions Clinical presentation of AM in women differed from men in our national cohort and, despite lower troponin levels, women had more frequently reduced LVEF and experienced worse clinical outcomes both during hospitalization and at follow-up.Table 1Figure 1