Isolated Nonischemic Left Ventricular Scar in Asymptomatic Athletes: Clinical Characteristics, Genetic Background, and Follow-Up

Background: Isolated nonischemic left ventricular scar (NILVS), identified by cardiac magnetic resonance, is an increasing finding in athletes and may be the substrate for life-threatening arrhythmias. Clinical significance in asymptomatic athletes is yet to be investigated. Objectives: This study sought to describe the clinico-genetic profile and follow-up of asymptomatic athletes diagnosed with NILVS through preparticipation screening. Methods: We evaluated 40 athletes (90% males, 44 [range:33-52] years) including 9 elites, with isolated NILVS involving at least 2 segments, no previous major arrhythmic events, with available genetic testing and >1 year of follow-up. Data regarding electrocardiography, echocardiography, 24-hour Holter, exercise testing, and genetic analysis were collected. Follow-up assessed therapy, sport participation, and outcome. Results: Electrocardiogram abnormalities were present in 48%, and all showed premature ventricular beats at exercise testing, mostly with right bundle branch/superior axis morphology. Left ventricular ejection fraction was normal or mildly reduced. Genetic testing or family screening was positive in 9 (23%). Athletes without familial/genetic background were older and declared higher cumulative years of sports activity. Over a median follow-up time of 23 months, 84% continued noncompetitive sport, mostly (73%) on beta-blocker therapy. Two major arrhythmic events occurred (resuscitated cardiac arrest and sustained ventricular tachycardia), both in athletes with a positive family history for NILVS, but negative genetic testing, and both during noncompetitive exercise. Conclusions: NILVS in asymptomatic athletes may carry arrhythmic risk even in the absence of previous symptoms or left ventricular dysfunction. Athletes with NILVS and no gene mutations/family history are older and with a higher past exercise volume.