Strength-Based Exercise Is Not Associated With Ventricular Arrhythmia in Arrhythmogenic Cardiomyopathy-Towards Safer Exercise Options.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is a genetic heart disorder characterized by fibrofatty replacement of ventricular myocardium, sustained ventricular arrhythmia (VA), and elevated risk of sudden death. Current guidelines restrict high-intensity aerobic exercise and competitive sports in individuals with ACM or at risk due to pathogenic/likely-pathogenic (P/LP) gene variants; however, the impact of strength-based exercise is poorly understood. OBJECTIVES: This study sought to evaluate the risk of VA in individuals with ACM and/or P/LP ACM gene variants exposed to strength-based exercise. METHODS: Participants were from the Johns Hopkins ARVC Registry. Exercise exposure was assessed via telephone from age 10 through follow-up. Participants were stratified into 4 groups: dual athlete, endurance athlete, strength athlete, and sedentary. Kaplan-Meier curves visualized the impact of endurance vs strength exercise on VA risk. Cox proportional hazards regression tested independent associations between strength exercise and VA. RESULTS: 355 individuals were enrolled, with median age 34 years; 55% were dual athletes, 26% sedentary, 12% endurance athletes, and 7% strength athletes. Overall lifetime risk of VA was higher with increased aerobic exercise (dual + endurance) than without (strength + sedentary). There was no difference between dual vs endurance athletes, nor strength athletes vs sedentary. A multivariable Cox regression showed no association of VA with strength training, whereas risk of endurance exercise was significant. CONCLUSIONS: Our study found no association between strength exercise and risk of sustained VA. These findings support individualized risk stratification and shared decision-making in ACM care and show the need for additional studies to guide recommendations.