CMR for Identifying the Substrate of Ventricular Arrhythmia in Patients with Q1 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.
Q6 METHODS A single-center prospective study was conducted in consecutive patients with significant VA, categorized as
>1,000 but <10,000 ventricular ectopic beats [VEB]s/24 h; $10,000 VEBs/24 h; nonsustained ventricular tachycardia,
sustained ventricular tachycardia (SVT), 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 ¼ 91) was the more frequent disease, followed by arrhythmogenic cardiomyopathy (n ¼ 55),
dilated cardiomyopathy (n ¼ 39), ischemic heart disease (n ¼ 22), hypertrophic cardiomyopathy (n ¼ 13), congenital
cardiac disease (n ¼ 10), left ventricle noncompaction (n ¼ 5), and pericarditis (n ¼ 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 SVT
(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 SVT were the strongest predictors of positive CMR imaging
results.