Patients with hypertrophic cardiomyopathy (HCM) can benefit from regular moderate–intensity exercise without worsening disease or increasing risk of arrhythmic events, according to results of the RESET–HCM trial.

“Moderate intensity aerobic training improves exercise capacity in patients with HCM without causing harm,” Dr. Sara Saberi, of the Frankel Cardiovascular Center, University of Michigan, Ann Arbor, told Reuters Health by email. “We also saw an improvement in quality of life. A simple walking program (4–7 days a week, for at least 20 minutes) is all it seems to take.”

“I think we should be encouraging patients to make light–moderate intensity exercise a part of their routine so that they can reap all the benefits that have been proven by many others as well (decreased incidence of obesity, hypertension, diabetes, coronary artery disease, and importantly, mortality),” Dr. Saberi added.

The study was published online March 17 in JAMA to coincide with presentation at the American College of Cardiology annual meeting in Washington, DC.

Formulating exercise advice for patients with HCM is “challenging” due to concern about trigging arrhythmias and the clinical benefit of exercise has not been established in this patient population, the authors note in their article.

The RESET–HCM trialists randomly assigned 136 patients with HCM to 16 weeks of moderate–intensity, unsupervised aerobic training after consultation with an exercise physiologist or usual activity. The patients had a mean age of 50 and 42% were women. A total of 113 patients completed the study (57 of 67 in the exercise group and 56 of 69 in the control group).

At 16 weeks, there was a small but statistically significant increase in exercise capacity (mean peak oxygen consumption, the primary end point) in the exercise group compared to the control group (+1.35 mL/kg/min versus +0.08 mL/kg/min), the researchers report.

“Decreased oxygen consumption has been associated with adverse outcomes in HCM and this simple intervention has now been shown to improve oxygen consumption,” Dr. Saberi commented.

There were no cases of sustained ventricular arrhythmia, sudden cardiac arrest, appropriate defibrillator shock, or death in either group.

Limitations of the study include the absence of blinding, small sample size and short length of follow up.

“Future studies will need to address other levels of exercise, sports participation, and the clinical implications of our findings,” Dr. Saberi said. The long–term safety of exercise in these patients also needs to be studied.

In a JAMA editorial, Dr. Anjali Owens of the University of Pennsylvania Perelman School of Medicine in Philadelphia notes that the exercise prescription investigated in this trial is simple, practical, and easily implemented in clinical practice.

“The improvement in peak VO2 supports efficacy in improving fitness,” he adds, “but the between–group improvement of 1.27 mL/kg/min is small and of debatable clinical importance in a cohort of mostly asymptomatic patients (New York Heart Association functional class I). However, this result could be an underestimate of the true effect, owing to patient attrition in both study groups and the short study duration of 4 months.”

“Defining a safe level of exercise for patients with hypertrophic cardiomyopathy is still a work in progress. The findings of this clinical trial, although preliminary, represent an important beginning in using data from randomized clinical trials to guide exercise recommendations for patients with hypertrophic cardiomyopathy,” Dr. Owens concludes.