Predictors of Left Ventricular Scar Using Cardiac Magnetic Resonance in Athletes With Apparently Idiopathic Ventricular Arrhythmias

BACKGROUND: In athletes with ventricular arrhythmias (VA) and otherwise unremarkable clinical findings, cardiac magnetic resonance (CMR) may reveal concealed pathological substrates. The aim of this multicenter study was to evaluate which VA characteristics predicted CMR abnormalities. METHODS AND RESULTS: We enrolled 251 consecutive competitive athletes (74% males, median age 25 [17‐39] years) who underwent CMR for evaluation of VA. We included athletes with >100 premature ventricular beats/24 h or ≥1 repetitive VA (couplets, triplets, or nonsustained ventricular tachycardia) on 12‐lead 24‐hour ambulatory ECG monitoring and negative family history, ECG, and echocardiogram. Features of VA that were evaluated included number, morphology, repetitivity, and response to exercise testing. Left‐ventricular late gadolinium‐enhancement was documented by CMR in 28 (11%) athletes, mostly (n=25) with a subepicardial/midmyocardial stria pattern. On 24‐hour ECG monitoring, premature ventricular beats with multiple morphologies or with right‐bundle‐branch‐block and intermediate/superior axis configuration were documented in 25 (89%) athletes with versus 58 (26%) without late gadolinium‐enhancement (P<0.001). More than 3300 premature ventricular beats were recorded in 4 (14%) athletes with versus 117 (53%) without positive CMR (P<0.001). At exercise testing, nonsustained ventricular tachycardia occurred at peak of exercise in 8 (29%) athletes with late gadolinium‐enhancement (polymorphic in 6/8, 75%) versus 17 athletes (8%) without late gadolinium‐enhancement (P=0.002), (P<0.0001). At multivariable analysis, all 3 parameters independently correlated with CMR abnormalities. CONCLUSIONS: In athletes with apparently idiopathic VA, simple characteristics such as number and morphology of premature ventricular beats on 12‐lead 24‐hour ambulatory ECG monitoring and response to exercise testing predicted the presence of concealed myocardial abnormalities on CMR. These findings may help cost‐effective CMR prescription.