Epidemiology, clinical characteristic and prognosis of acute myocarditis from a high volume cardiology center

Myocarditis and pericarditis are inflammatory diseases characterized by a heterogeneous clinical course ranging from mild to life-threatening presentations. Their estimated prevalence is 4.2–8.7 cases per 100,000 people per year, with higher frequency among males aged 30–40 years.

In this observational study, we included all adult patients (≥18 years) with cardiac magnetic resonance (CMR)-confirmed myocarditis admitted to the Cardiology Department between March 2017 and July 2025. The primary aim was to evaluate in-hospital management and follow-up according to the 2020 ANMCO/SIC protocol and the 2025 ESC Guidelines for the Management of Myocarditis and Pericarditis.

Seventy patients were enrolled, 87.1% male and 12.9% female, with a mean age of 34 years. The predominant presentation was infarct-like chest pain (97.1%). The initial suspicion was myocarditis or myopericarditis in 68.6% of patients. Based on clinical risk, 38 underwent CMR as the first imaging exam, 6 coronary CT angiography, and 4 invasive coronary angiography, all with normal findings. In 27.1% of cases, the first suspicion was acute coronary syndrome, including 8 non-STEMI presentations and 11 STEMI presentations, with angiography showing no significant coronary disease. One patient initially suspected of cardiomyopathy underwent CMR and endomyocardial biopsy.

Patients were stratified into three risk classes considering symptoms, arrhythmias, left ventricular ejection fraction (LVEF), and extent of late gadolinium enhancement (LGE) on CMR. Most were intermediate-risk (84.3%), 14.3% low-risk, and only one high-risk with fulminant myocarditis. On admission, 41.4% had ST-segment elevation, 2.9% depression, and 22.9% T-wave inversion. Echocardiography revealed LVEF <55% in 18.6%. CMR detected LGE in 98.6%, with ≥2 segments in 72.9% and anteroseptal localization in 17.1%. At discharge, 60 patients were diagnosed with myocarditis and 10 with myopericarditis.

At six-month follow-up, 2.9% still had LVEF <50%. LGE persisted in 90%, involving >2 segments in 60% and the anteroseptal region in 8.6%. Follow-up Holter-ECG and stress testing were normal in all but one patient. Echocardiographic and CMR reassessment demonstrated improvement in LVEF and reduction in LGE extension and localization.

Major adverse cardiac events assessed at one- and three-year follow-up included death, heart transplantation, left ventricular assist device implantation, post-biopsy arrhythmia, recurrent myocarditis, and transplant listing. One recurrence was observed at one year and five at three years. Genetic testing was performed in two recurrent cases, with one positive result.

In conclusion, in patients with myocarditis referred to a non-transplant center, low- and intermediate-risk profiles predominated. Follow-up confirmed a favorable prognosis, supporting the real-world applicability of the 2025 ESC recommendations.Figure 1  Figure 2