High-Intensity Exercise for Patients with Hypertrophic Cardiomyopathy – Safe and Effective?

By Benjamin Levine, M.D.

Professor of Internal Medicine
Director, Institute for Exercise and Environmental Medicine

Hypertrophic cardiomyopathy (HCM), is one of the most common genetic diseases, which may affect as many as 1 in 500 individuals. It causes abnormal thickening of the heart muscle, and patients may either be completely asymptomatic or suffer from life-threatening arrhythmias, heart failure, or even sudden cardiac death. UT Southwestern has one of only 39 centers in the United States recognized by the Hypertrophic Cardiomyopathy Association as being a specialized “Center of Excellence” in the management of HCM and two of our faculty – Drs. Mark Link and Jose Joglar – were on the committee that wrote the guidelines, published In November, for modern treatment of this challenging disease.

Part of the conventional wisdom about HCM is that it is particularly dangerous for those who have it to participate in high-intensity athletics because early reports identified HCM in nearly half of athletes who died suddenly during sports. However, recent data have challenged this paradigm. For example, some patients with HCM, almost all with an implanted defibrillator, chose to continue to play sports despite their doctor's proscription, and did quite well. More recently, in a large, multicenter study, HCM patients were able to participate in a moderate-intensity exercise program safely, though the gains in fitness were modest.

Now, at the recent AHA Scientific Sessions, my research group reported that patients with HCM may even be able to perform high-intensity exercise safely and gain additional fitness benefits. Led by postdoctoral fellow Dr. Katrin Dias, we enrolled 15 patients who started with exercising 3-4x/week at a moderate intensity for two months and then were randomized to continue moderate-intensity training or add 1-2 sessions of high-intensity interval training each week for an additional 3 months. Patients were monitored carefully with either their own defibrillators or implantable arrhythmia monitors, and all interval sessions were supervised. Preliminary results, reported at the meeting, showed that there were no serious exercise-related events in the patients performing high-intensity intervals, and the improvement in fitness was approximately 3 times greater compared to those performing moderate-intensity exercise, though the numbers who finished the study were too small for statistical analysis.

Overall, these results are encouraging and, if confirmed when the study is completed, pave the way for future trials examining exercise training strategies for select patients with HCM. Animal studies using genetic models of HCM have shown that starting exercise early on in life may actually be protective, which argues for additional studies of early life exercise, perhaps even among carriers of the gene who have not yet suffered the full consequences of the disease. However, I do caution that any patient with HCM should discuss their unique circumstance with their own physician before participating in an exercise program of any intensity.