Moderate Exercise Still Standard vs High-intensity Routine in Chronic HF
Twelve weeks of high intensity interval training (HIIT) is no better than moderate exercise for changing left ventricular remodeling and improving aerobic capacity in patients with chronic heart failure and reduced ejection fraction (HFrEF), according to a study published online on December 6, 2016 in Circulation.1
The study, called the SMARTEX Heart Failure study, is the first randomized controlled multicenter trial to evaluate HIIT in patients with HFrEF.
“Given that HIIT was not superior to MCT [moderate continuous training] in reversing remodeling or improving secondary endpoints, and considering that adherence to the prescribed exercise intensity based on heart rate may be difficult to achieve, even when supervised and performed in centers experienced in cardiac rehabilitation, MCT remains the standard exercise modality for patients with chronic heart failure,” wrote first author Øyvind Ellingsen, MD, PhD, of Norwegian University of Science and Technology (Trondheim, Norway), and colleagues with the SMARTEX Heart Failure Study Group.
The European Society of Cardiology recommends exercise training in heart failure patients. However, because no agreement exists about what type of exercise is best, an individualized approach is generally advised.2
Moderate continuous exercise has most support for its efficacy and safety in chronic heart failure, though evidence comes mainly from the HF-ACTION study. Results from that study showed that patients with HFrEF who were randomized to moderate continuous exercise had modest reductions in mortality and hospitalization.3
Recently, however, one small study suggested that HIIT may be better than moderate continuous exercise for reversing cardiac remodeling and increasing aerobic capacity in HFrEF.4 That has raised questions about whether HIIT should be part of standard care for heart failure patients.
The SMARTEX Heart Failure study was designed to address this question in a larger group of patients. The study took place in nine European centers between June 2009 and July 2014. It included patients with HFrEF and symptomatic, stable heart failure. Participants were randomized to 12 weeks of HIIT, moderate continuous exercise, or regular exercise at home.
► HIIT and moderate continuous exercise groups: 3 supervised training sessions/wk on treadmill or bicycle.
-- HIIT: exercised at targeted maximal heart rate of 90-95% for 38 minutes total, in four minute intervals separated by a three minute active recovery period.
-- Moderate continuous: exercised for 47 minutes total and trained to 60-70% of maximal heart rate.
► Regular exercise group: exercised at home, attended a moderate exercise session every three weeks; trained to 50-70% of maximal heart rate.
After twelve weeks, researchers encouraged participants to continue exercising on their own.
Researchers did clinical assessments at baseline, after training sessions, and at 52 week follow-up.
The primary endpoint was change in left ventricular end diastolic diameter from baseline to 12 weeks. The analysis included 215 participants.