P5275Cardiovascular magnetic resonance predictors of long term clinical outcome in myocarditis

Abstract Background The natural history of acute myocarditis (AM) remains partially unknown and predictors of outcome are still debated. The study objectives were to determine the potential value of cardiovascular magnetic resonance (CMR) parameters for the long-term Major Adverse Cardiac Events (MACE) prediction in patients presenting with suspected AM. In our centre we published in 2015 a first analysis of the CMR myocarditis registry which included patients presenting with suspected AM in routine practice, clinically followed-up for 18 months (median follow up). This first analysis, in disagreement with the published data, did not find CMR predictors of MACE except for the LVEF. Purpose As in myocarditis MACE could have a gradual evolution, to confirm our initial results, the aim of this study is to reinvestigate in the same population, the potential value of CMR parameters with a longer follow-UP (median 8.34 years, interquartile range: 7.7 to 9.16 years). Methods In a single-centre longitudinal prospective study, 203 routine consecutive patients with clinical suspicion of AM and initial CMR-based diagnosis of AM (typical Late Gadolinium Enhancement, LGE) were clinically followed up. Various CMR parameters were evaluated as potential predictors of outcome. The primary endpoint was defined as the occurrence of at least one of the combined MACE: cardiac death or aborted sudden cardiac death, cardiac transplantation, sustained documented ventricular tachycardia, heart failure, recurrence of acute myocarditis, and the need for hospitalization for cardiac causes. Results The vast majority of patients (70,44%; N=143) presented with chest pain, mild to moderate troponin elevation and ST-segment or T wave abnormalities. Various CMR parameters were evaluated on initial CMR performed 3±2 days after acute clinical presentation (LV functional parameters, presence/extent of edema on T2, presence/extent of Early Gadolinium Enhancement (EGA) and extent of late gadolinium enhancement lesions). Out of the 203 patients, 35 (17.2%) experienced at least one major cardiovascular event during follow-up. Among all CMR parameters, initial alteration of LVEF was confirmed a MACE independent predictor by multivariate analysis (HR: 1.03 per 10% decrease, 95% CI: 1.01 to 1.06, p=0.04). Furthermore, at longer FU analysis, absence of EGA predicted adverse clinical outcome (HR: 2.7, 95% CI: 1.12 to 6.27, p=0.02) suggesting a potential protecting role of inflammatory response. Conclusions In routine clinical practice, in patients without severe hemodynamic compromise and a CMR-based diagnosis of AM, various CMR parameters such as the presence, extent and myocardial localisation of late gadolinium-enhanced LV myocardial lesions, were not predictive of events at long term follow up. CMR predictor of adverse clinical outcome were an initial alteration of LVEF and the absence of EGA.