Genotype status and arrhythmic risk in sport participants with hypertrophic cardiomyopathy.

AIMS: The impact of genotype on arrhythmic risk in sports-active hypertrophic cardiomyopathy (HCM) patients remains unclear. We compared outcomes between genotype-positive (G+) and genotype-negative (G-) athletes with HCM. METHODS AND RESULTS: In this retrospective study, HCM patients actively engaged in sports underwent standardized baseline evaluation and follow-up. The primary endpoint included sudden cardiac death (SCD)/sudden cardiac arrest, appropriate implantable cardioverter-defibrillator (ICD) therapy, sustained ventricular tachycardia/non-sustained ventricular tachycardia (NSVT). Secondary outcomes included a composite of ventricular arrhythmias, atrial fibrillation, ischaemic stroke, and heart-failure hospitalization. Fifty-nine patients [age 40 years (23.2-50.0)] were followed for 6.3 years (3.0-12.6). Twenty-nine participants (49.2%) carried a likely pathogenic or pathogenic variant, most commonly MYBPC3 (44.8%), MYH7 (24.1%), and TNNT2 (17.2%). At inclusion, median sport practice was 6.0 (3.0-10.0) hours per week, with 67.8% of competitors. At last follow-up, 88.1% remained active in sports. The ESC 5-year SCD risk score was slightly higher in G+ compared with G- patients [1.87% (1.47-3.67) vs. 1.54% (1.24-2.20), P = 0.048], but most of the participants were classified as low risk. Ventricular arrhythmias occurred in 20.7% of G+ and 23.3% of G- patients (P = 0.807), with similar event-free survival (P = 0.685). Most ventricular arrhythmias were isolated NSVT (84.6%). Hard ventricular arrhythmic events were limited to two ICD-terminated ventricular fibrillations in G+ patients, one at rest and one during low-intensity exercise. The incidence of the composite secondary cardiovascular outcome was comparable between groups (31.0% vs. 33.3%, P = 0.850). CONCLUSION: In this exploratory cohort of sports-active HCM patients, ventricular arrhythmic and cardiovascular event rates were similar between G+ and G- participants during follow-up.