CMR predictors of favourable outcome in myocarditis: a single-centre experience

Abstract

Abstract Background Cardiovascular magnetic resonance (CMR) has emerged as the most accurate, non-invasive method to support diagnosis of clinically suspected myocarditis and has proved to risk-stratify patients with both ischemic and non-ischemic cardiomyopathies. Purpose We aimed to assess the diagnostic and prognostic role of CMR at diagnosis in patients with clinically suspected or endomyocardial biopsy (EMB) proven myocarditis. Methods We enrolled consecutive single-centre patients with EMB-proven or clinically suspected myocarditis (defined in keeping with the World Health Organization and the European Society of Cardiology (ESC) criteria) undergoing CMR at diagnosis. Extent of late gadolinium enhancement (LGE) was quantified with the full width at half maximum method. Pre-specified outcome was defined as NYHA class > I and echocardiographic left ventricular ejection fraction (LVEF) < 50% at follow-up. Results We included 207 patients (74% male, median age 36 years; 25% EMB-proven). CMR showed the highest diagnostic sensitivity in myocarditis patients with infarct-like presentation. Myocardial oedema was found in 63% of patients and LGE in 93%, with a more diffuse distribution in EMB-proven myocarditis. Right ventricular LGE was more prevalent among EMB-proven myocarditis (8% vs 0, p<0.001) and in patients with arrhythmic presentation (12% vs 1% in patients with infarct-like or heart failure presentation, p=0.001). Outcome was met in 17 patients at any follow-up time point, more commonly in patients with larger biventricular volumes (end-diastolic left HR 1.02, right HR 1.04, p<0.001), CMR-based diagnosis of dilated cardiomyopathy (HR 40.7, p<0.001) and ischemic LGE (HR 56.4, p=0.005), while higher biventricular function (LVEF HR 0.89, p<0.001) and greater LGE extent (HR 0.73, p=0.033) at diagnosis had a protective effect. Conclusions Higher biventricular function and greater LGE extent on CMR at diagnosis predict more favourable outcome in myocarditis; LGE at diagnosis may represent oedema rather than fibrosis.