Patients with heart failure with reduced ejection fraction (HFrEF) with an ischemic etiology have significantly lower baseline exercise capacity compared with those with a nonischemic etiology, according to the results of a study published in the American Heart Journal Plus: Cardiology Research and Practice.
A predefined analysis within the randomized, controlled Study of Myocardial Recovery after Exercise Training in Heart Failure (SMARTEX-HF; ClinicalTrials.gov Identifier: NCT00917046) was conducted. The investigators sought to explore the effect of moderate- or high-intensity exercise on left ventricular end-diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF), and maximal exercise capacity (peak VO2) in patients with ischemic cardiomyopathy (ICM) and nonischemic cardiomyopathy (NICM).
SMARTEX-HF consecutively enrolled a total of 231 patients with HFrEF (LVEF ≤35%; New York Heart Association [NYHA] II-III) in a 12-week supervised exercise program. All participants were stratified according to their HFrEF etiology (ICM vs NICM) and were randomly assigned in a 1:1:1 ratio to 1 of the following supervised exercise programs 3 times per week: moderate continuous training at 60% to 70% of peak heart rate (HR); high-intensity interval training at 90% to 95% of peak HR; or recommendation of regular exercise, based on guidelines. LVEDD, LVEF, and peak VO2 were evaluated at baseline, after 12 weeks, and after 52 weeks in the participants.
Of the participants enrolled in the exercise intervention program, 215 completed the 12-week intervention program and were assessed in the subanalysis. Of these individuals, 59% were ICM patients and 41% were NICM patients.
Results of the study showed that exercise target attainment was similar in the NICM and ICM cohorts. In the moderate continuous training group, 92% of NICM patients and 72% of ICM patients trained at a higher intensity compared with the target protocol (P =.10). In the high-intensity interval training group, 61% of NICM individuals and 43% of ICM individuals trained at a lower intensity than the protocol target (P =.16).
Additionally, those in the ICM group compared with those in the NICM group had significantly lower peak VO2 values at baseline and after 12 weeks (P <.0005), without any differences between the time points (P =.11) or the various training groups (P =.15). The etiology of a participant’s HFrEF did not affect changes in LVEDD or LVEF (P =.30 and P =.12. respectively), even after adjusting for sex, age, and smoking status (P =.54 and P =.12, respectively). After 52 weeks, 202 patients remained in the study and received evaluation, and similar findings were reported.
Some key limitations of the study include that by dividing the primary group, the study sample size for each group is reduced, thus limiting generalizability. Further, the number of participants enrolled is too low to determine clinical adverse effects, which are especially important when using high-intensity interval training in patients with HFrEF.
“Etiology of HFrEF did not influence the effects of moderate or high intensity exercise on cardiac dimensions, systolic function or exercise capacity,” the study authors wrote.
Halle M, Prescott E, Van Craenenbroeck EM, et al; SMARTEX-HF Study Group. Moderate continuous or high intensity interval exercise in heart failure with reduced ejection fraction: differences between ischemic and non-ischemic etiology. Am Heart J Plus: Card Res Pract. 2022;22:100202. doi:10.1016/j.ahjo.2022.100202