Clinical presentation, imaging features and long-term outcomes of acute myocarditis: a tertiary-centre experience

Background

Myocarditis is an inflammatory cardiac disease with a broad clinical spectrum, ranging from mild, self-limited presentations to acute heart failure, life-threatening arrhythmias, and cardiogenic shock. Accurate characterization of clinical presentation, imaging features, and long-term outcomes is essential to optimize diagnostic strategies and patient management.

Purpose

To provide a comprehensive overview of clinical characteristics, diagnostic imaging findings, therapeutic strategies, and long-term outcomes in patients hospitalized with myocarditis.

Methods

We performed a retrospective observational study including consecutive patients admitted with myocarditis between January 2016 and November 2025 at a tertiary hospital. Data were extracted from electronic medical records. Continuous variables are reported as median (IQR) and categorical variables as percentages.

Results

A total of 138 patients were included; 81.2% were male, with a median age of 28 years (IQR 22–38). Chest pain was the most frequent presenting symptom (92.8%). Acute heart failure occurred in 3.6% of patients, of whom 60% were in NYHA functional class IV. At presentation, 51.4% of patients showed ST-segment elevation on ECG, which was diffuse in 47.9% of cases, while 39.1% had a normal ECG. Viral aetiology was identified in 66.7% of cases, most commonly following prior gastroenteritis (30.9%), and 59.4% had concomitant pericarditis. Median troponin was 6,803 (IQR 1,653–14,325) and median C-reactive protein was 62 mg/L (IQR 21–121).

Cardiac magnetic resonance (CMR) was performed in 88.4% of patients at a median of 4 days after admission (IQR 2–6), showing myocardial oedema in 71.3% and late gadolinium enhancement (LGE) in 86.1%, with a median of 3 involved segments. Median left ventricular ejection fraction was 58% (IQR 55–61), and median right ventricular ejection fraction was 60% (IQR 54–64). At discharge, 57.2% of patients were treated with non-steroidal anti-inflammatory drugs in combination with colchicine, and 2.9% received systemic corticosteroids. Median length of hospital stay was 5 days (IQR 3–6).

Over a median observation period of 37 months (IQR 19–51), CMR was repeated in 39.1% of patients, showing persistent myocardial oedema in 3.7% and persistent LGE in 72.2%, with a median of 2 involved segments. Cardiovascular readmission occurred in 13.8% of patients, with myocarditis recurrence in 5.9%. One patient (1.4%) underwent heart transplantation. Mortality was 1.4%, exclusively from non-cardiac causes.

Conclusion

In this cohort, myocarditis predominantly affected young male patients and was commonly associated with viral triggers and ST-segment elevation at presentation. Overall outcomes were favourable, with low rates of recurrence and mortality during long-term follow-up.