Prognostic relevance of demographic factors in cardiac magnetic resonance-proven acute myocarditis: A cohort study.

AIM

Acute myocarditis (AM) is a heterogeneous condition with variable estimates of survival. Contemporary criteria for the diagnosis of clinically suspected AM enable non-invasive assessment, resulting in greater sensitivity and more representative cohorts. We aimed to describe the demographic characteristics and long-term outcomes of patients with AM diagnosed using non-invasive criteria.

METHODS AND RESULTS

A total of 199 patients with cardiac magnetic resonance (CMR)-confirmed AM were included. The majority ( = 130, 65%) were male, and the average age was 39 ± 16 years. Half of the patients were White ( = 99, 52%), with the remainder from Black and Minority Ethnic (BAME) groups. The most common clinical presentation was chest pain ( = 156, 78%), with smaller numbers presenting with breathlessness ( = 25, 13%) and arrhythmias ( = 18, 9%). Patients admitted with breathlessness were sicker and more often required inotropes, steroids, and renal replacement therapy ( < 0.001, < 0.001, and = 0.01, respectively). Over a median follow-up of 53 (IQR 34-76) months, 11 patients (6%) experienced an adverse outcome, defined as a composite of all-cause mortality, resuscitated cardiac arrest, and appropriate implantable cardioverter defibrillator (ICD) therapy. Patients in the arrhythmia group had a worse prognosis, with a nearly sevenfold risk of adverse events [hazard ratio (HR) 6.97; 95% confidence interval (CI) 1.87-26.00, = 0.004]. Sex and ethnicity were not significantly associated with the outcome.

CONCLUSION

AM is highly heterogeneous with an overall favourable prognosis. Three-quarters of patients with AM present with chest pain, which is associated with a benign prognosis. AM presenting with life-threatening arrhythmias is associated with a higher risk of adverse events.