CMR for Identifying the Substrate of Ventricular Arrhythmia in Patients With Normal Echocardiography

Objectives: This study sought to determine whether cardiac magnetic resonance (CMR) may identify structural heart disease (SHD) in patients with ventricular arrhythmia who had echocardiography ruled out pathological findings. Background: Approximately one-half of sudden cardiac deaths are attributable to malignant VA. Echocardiography is commonly used to identify SHD that is the most frequent substrate of VA. Methods: A single-center prospective study was conducted in consecutive patients with significant VA, categorized as >1,000 but <10,000 ventricular ectopic beats [VEBs]/24 h; ≥10,000 VEBs/24 h; nonsustained ventricular tachycardia, sustained ventricular tachycardia, or a history of resuscitated cardiac arrest, and no pathological findings at echocardiography, requiring a clinically indicated CMR. Primary endpoint was CMR detection of SHD. Secondary endpoints were a composite of CMR detection of SHD and abnormal findings not specific for a definite SHD diagnosis. Results: A total of 946 patients were enrolled (mean 41 ± 16 years of age; 64% men). CMR studies were used to diagnose SHD in 241 patients (25.5%) and abnormal findings not specific for a definite SHD diagnosis in 187 patients (19.7%). Myocarditis (n = 91) was the more frequent disease, followed by arrhythmogenic cardiomyopathy (n = 55), dilated cardiomyopathy (n = 39), ischemic heart disease (n = 22), hypertrophic cardiomyopathy (n = 13), congenital cardiac disease (n = 10), left ventricle noncompaction (n = 5), and pericarditis (n = 5). The strongest univariate and multivariate predictors of SHD on CMR images were chest pain (odds ratios [OR]: 2.52 and 2.38, respectively) and sustained ventricular tachycardia (ORs: 2.67 and 2.23, respectively). Conclusions: SHD was able to be identified on CMR imaging in a sizable number of patients with significant VA and completely normal echocardiography. Chest pain and sustained ventricular tachycardia were the strongest predictors of positive CMR imaging results.