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Vigorous Exercise in Congenital Long-QT Syndrome
Quick Takes
- Long-QT syndrome (LQTS)-triggered cardiac events were low in both those exercising vigorously and those exercising nonvigorously, and there was no statistical difference in event rate.
- Of note, confidence intervals were wide, and noninferiority was not demonstrated.
- These data may inform individualized shared decision-making conversations between patients and physicians on vigorous exercise participation in the context of overall expert assessment and management of LQTS.
Study Questions:
Is engagement in vigorous exercise, including competitive sports, associated with increased risk for life-threatening ventricular arrhythmias in individuals with known and treated congenital long-QT syndrome (LQTS)?
Methods:
The investigators conducted the National Institutes of Health–funded LIVE-LQTS study (Lifestyle and Exercise in Genetic Cardiovascular Conditions), which prospectively enrolled individuals 8-60 years of age with phenotypic or genotypic LQTS from 37 sites in five countries from May 2015 to February 2019. Participants (or parents) answered physical activity and clinical events surveys every 6 months for 3 years with follow-up completed in February 2022. Vigorous exercise was defined as ≥6 metabolic equivalents for >60 hours per year. A blinded Clinical Events Committee adjudicated the composite endpoint of sudden death, sudden cardiac arrest, ventricular arrhythmia treated by an implantable cardioverter-defibrillator (ICD), and likely arrhythmic syncope. A National Death Index search ascertained vital status for those with incomplete follow-up. A noninferiority hypothesis (boundary of 1.5) between vigorous exercisers and others was tested with multivariable Cox regression analysis.
Results:
Among the 1,413 participants (13% <18 years of age, 35% 18-25 years of age, 67% female, 25% with ICDs, 90% genotype positive, and 49% with LQT1), 91% were treated with beta-blockers, left cardiac sympathetic denervation, or ICD; 52% participated in vigorous exercise (55% competitively). Thirty-seven individuals experienced the composite endpoint (including one sudden cardiac arrest and one sudden death in the nonvigorous group, one sudden cardiac arrest in the vigorous group) with overall event rates at 3 years of 2.6% in the vigorous and 2.7% in the nonvigorous exercise groups. The unadjusted hazard ratio for experience of events for the vigorous group compared with the nonvigorous group was 0.97 (90% confidence interval [CI], 0.57-1.67), with an adjusted hazard ratio of 1.17 (90% CI, 0.67-2.04). The upper 95% one-sided confidence level extended beyond the 1.5 boundary. Neither vigorous nor nonvigorous exercise was found to be superior in any group or subgroup.
Conclusions:
The authors report that among individuals diagnosed with phenotypic or genotypic LQTS who were risk assessed and treated in experienced centers, LQTS-associated cardiac event rates were low and similar between those exercising vigorously and those not exercising vigorously.
Perspective:
This study reports that LQTS-triggered cardiac events were low in both those exercising vigorously and those exercising nonvigorously, and there was no statistical difference in the event rate. Of note, CIs were wide, and noninferiority was not demonstrated. These data may inform individualized shared decision-making conversations between patients and physicians on vigorous exercise participation in the context of overall expert assessment and management of LQTS.
Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Diabetes and Cardiometabolic Disease, Prevention, Genetic Arrhythmic Conditions, SCD/Ventricular Arrhythmias, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Prevention, Exercise
Keywords: Exercise, Long QT Syndrome
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