Harmful Effects of Exercise Intensity and Exercise Duration in Patients With Arrhythmogenic Cardiomyopathy

OBJECTIVES: The goal of this study was to explore the association between exercise duration versus exercise intensity and adverse outcome in patients with arrhythmogenic cardiomyopathy (AC). BACKGROUND: Vigorous exercise aggravates and accelerates AC, but there are no data assessing the harmful effects of exercise intensity and duration in these patients. METHODS: Exercise habits at time of diagnosis were recorded by standardized interviews in consecutive AC patients. Exercise >6 metabolic equivalents was defined as high intensity, and exercise duration was categorized as long if above median. Life-threatening ventricular arrhythmia (VA) was defined as aborted cardiac arrest, documented sustained ventricular tachycardia, ventricular fibrillation, or appropriate implantable cardioverter-defibrillator therapy. RESULTS: We included 173 AC patients (53% probands; 44% female; 41 ± 16 years of age). Median weekly exercise duration was 2.5 h (interquartile range: 2.0 to 5.5 h), and 91 patients (52%) reported high-intensity exercise. VA had occurred in 83 patients (48%) and was more prevalent in patients with high-intensity exercise than low-intensity exercise (74% vs. 20%, p < 0.001), and more prevalent in long-duration than short-duration exercise (65% vs. 31%, p < 0.001). High-intensity exercise was a strong and independent marker of VA, even when adjusted for the interaction with long-duration exercise (odds ratio: 3.8; 95% confidence interval: 1.3 to 11.0, p < 0.001), whereas long-duration exercise was not. CONCLUSIONS: High-intensity exercise was a strong and independent marker of life-threatening VA in AC patients, independent of exercise duration. AC patients could be advised to restrict their exercise intensity.