Researchers from the Oslo University Hospital in Norway explore the association between exercise duration and exercise intensity and adverse outcome in patients with arrhythmogenic cardiomyopathy.

The study published in JACC: Clinical Electrophysiology suggests that high-intensity exercise is an independent marker for ventricular arrhythmia in arrhythmogenic cardiomyopathy.

Previous studies suggest that vigorous exercise aggravates and accelerates arrhythmogenic cardiomyopathy, but there are no data assessing the harmful effects of exercise intensity and duration in these patients.

So Øyvind H. Lie, M.D., from Oslo University Hospital in Norway, and colleagues recorded exercise habits at the time of diagnosis by standardized interviews in consecutive arrhythmogenic cardiomyopathy patients.

Exercise >6 metabolic equivalents was defined as high intensity; exercise duration above the median was categorized as long. Data were included for 173 arrhythmogenic cardiomyopathy patients.

The researchers found that the median weekly exercise duration was 2.5 hours and about half (52%) of patients reported high-intensity exercise.

Ventricular arrhythmia occurred in 48% of patients and was more prevalent in those with high- versus low-intensity exercise (74 versus 20%) and for long- versus short-duration exercise (65 versus 31%).

High-intensity exercise was an independent marker for ventricular arrhythmia, even after adjustment for the interaction with long-duration exercise (odds ratio, 3.8); long-duration exercise was not.

"High-intensity exercise was a strong and independent marker of life-threatening ventricular arrhythmia in arrhythmogenic cardiomyopathy patients, independent of exercise duration. Arrhythmogenic cardiomyopathy patients could be advised to restrict their exercise intensity," the authors write.