Diagnostic value and prognostic implications of early cardiac magnetic resonance in survivors of out-of-hospital cardiac arrest

Background: In patients who survived out-of-hospital cardiac arrest (OHCA), it is crucial to establish the underlying cause and its potential reversibility. Objective: The purpose of this study was to assess the incremental diagnostic and prognostic role of early cardiac magnetic resonance (CMR) in survivors of OHCA. Methods: Among 139 consecutive OHCA patients, the study enrolled 44 patients (median age 43 years; 84% male) who underwent coronary angiography and CMR ≤7 days after admission. The CMR protocol included T2-weighted sequences for myocardial edema and late gadolinium enhancement (LGE) sequences for myocardial fibrosis. Results: Coronary angiography identified obstructive coronary artery disease in 18 of 44 patients in whom CMR confirmed the diagnosis of ischemic heart disease by demonstrating subendocardial or transmural LGE. The presence of myocardial edema allowed differentiation between acute myocardial ischemia (n = 12) and postinfarction myocardial scar (n = 6). Among the remaining 26 patients without obstructive coronary artery disease, CMR in 19 (73%) showed dilated cardiomyopathy in 5, myocarditis in 4, mitral valve prolapse associated with LGE in 3, ischemic scar in 2, idiopathic nonischemic scar in 2, arrhythmogenic cardiomyopathy in 1, hypertrophic cardiomyopathy in 1, and takotsubo cardiomyopathy in 1. In this subgroup of 26 patients, 6 (23%) had myocardial edema. During mean follow-up of 36 ± 17 months, all 18 patients with myocardial edema had an uneventful outcome, whereas 9 of 26 (35%) without myocardial edema experienced sudden arrhythmic death (n = 1), appropriate defibrillator interventions (n = 5), and nonarrhythmic death (n = 3; P =.006). Conclusion: In survivors of OHCA, early CMR with a comprehensive tissue characterization protocol provided additional diagnostic and prognostic value. The identification of myocardial edema was associated with a favorable long-term outcome.