Long-term prognostic performance of cardiac magnetic resonance imaging markers versus complicated clinical presentation after an acute myocarditis

Background: Identifying markers associated with adverse events after acute myocarditis (AM) is relevant to plan follow-up. We assessed the prognostic performance of previously described cardiac magnetic resonance imaging (CMRI) markers and their combination: septal late gadolinium enhancement (LGE) localization and left ventricular ejection fraction (LVEF) < 50 % on baseline CMRI versus complicated clinical presentation (CCP: the presence of sustained ventricular tachycardia, or LVEF<50 % on the first echocardiogram or fulminant presentation).

Methods: We retrospectively assessed 248 AM patients (median age of 34 years, 87.1 % male) from 6 hospitals with onset of cardiac symptoms<30 days, increased troponin, and CMRI/histology consistent with myocarditis to identify those at risk of major cardiac events (cardiac death, heart transplantation, aborted sudden cardiac death, sustained ventricular tachycardia, or heart failure hospitalization).

Results: Thirteen patients (5.2 %) experienced at least one major cardiac event after a median follow-up of 4.7 years with a significant hazard ratio of 35.8 for CCP vs. 9.2 for septal LGE vs. 12.4 for LVEF<50 % on baseline CMRI (p = 0.001). CCP had the best c-index to identify patients with events: 0.836 vs. 0.786 for septal LGE and 0.762 for LVEF<50 %, while the combination of CCP plus LVEF<50 % or septal LGE has the highest c-index of 0.866. All 3 markers had high negative predictive value (NPV) of ≥0.98.

Conclusions: Major cardiac events after an AM are relatively low, and CCP, septal LGE, and LVEF<50 % are significantly associated with events. These markers have especially high NPV to identify patients without events after an AM. These observations can help clinicians to monitor the patients after an AM.