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. (C) 2018 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.