Utilisation and Prognostic Value of Cardiac Magnetic Resonance Imaging in Myocarditis

Abstract

Aim: To explore the cardiac magnetic resonance imaging (CMR) features of myocarditis and its prognostic implications in New Zealand. Method: Retrospective study of all patients >15 years of age admitted with suspected myocarditis who had a CMR at Waitemata District Health Board (WDHB) between 2007-2016. Results: Of the 178 patients admitted during this period with myocarditis, 94 (53%) had a CMR. The median number of days from admission to CMR was 9.5 (IQR 4-51). 22 patients had a reduced left ventricular ejection fraction (LVEF) <50%, which was associated with presence of dyspnoea on presentation (38% vs 17%, p = 0.03) and an absence of chest pain (46% vs 16%, p = 0.003). Late gadolinium enhancement (LGE) was found in 71 patients (76%), but its presence was not associated with major adverse cardiac events (MACE) (p = ns). Of those who had LGE, 55% was mid-myocardial and 34% was epicardial. When indexed for body surface area (BSA), 41% and 24% of patients had an increased left ventricular end systolic volume (LVESV) and end diastolic volume (LVEDV) respectively. LVEF<50% on CMR was associated with MACE (HR 3.7, 95% CI 1.2-11.4, p = 0.03), while increased BSA indexed LVESV tended towards significance for MACE (HR 3.2, 95% CI 0.96-10.5, p = 0.06). Conclusion: Reduced LVEF<50% and dilated LV volumes appear to be more significant than tissue enhancement patterns in predicting MACE in patients with myocarditis. Larger studies are warranted to investigate whether CMR findings can be combined with clinical factors to risk stratify myocarditis patients.