Exercise Training in Systolic Heart Failure Patients
Is high intensity interval training (HIIT) superior to moderate continuous training (MCT) in reversing cardiac remodeling and increasing aerobic capacity in systolic heart failure (HF) patients?
The study cohort was comprised of 261 patients with left ventricular ejection fraction (LVEF) <35% and New York Heart Association (NYHA) class II-III. These HF patients were randomly assigned 1:1:1 to a 12-week program of HIIT at 90-95% of maximal heart rate (HRmax), MCT at 60-70% of HRmax, or a recommendation of regular exercise (RRE). HIIT and MCT had three supervised sessions per week on treadmill or bicycle. HIIT performed four 4-minute intervals aiming at 90-95% of maximal heart rate (HRmax) separated by 3-minute active recovery periods of moderate intensity. HIIT sessions lasted 38 minutes including warm-up and cool-down at moderate intensity. MCT sessions aimed at 60-70% of HRmax and lasted 47 minutes. Patients randomized to RRE were advised to exercise at home according to current recommendations and attended a session of moderate intensity training at 50-70% of maximal heart rate every 3 weeks. Thereafter, these HF patients were encouraged to continue exercising on their own. Clinical assessments were performed at baseline, after the intervention, and at follow-up after 52 weeks. Primary endpoint was between-group comparison of change in left ventricular end-diastolic diameter (LVEDD) from baseline to 12 weeks. Key secondary endpoints were change in LVEF and peak VO2; the latter was also considered a measure of training effect.
After initial exclusions and withdrawals, 231 patients were included in HIIT, MCT, or RRE. Nine dropped out due to serious adverse events and seven withdrew or were lost to follow-up; 215 patients were assessed after 12 weeks and were included in the intention-to-treat analysis. Baseline characteristics were similar in all groups, although more RRE patients had a history of hypertension. The study investigators found that groups did not differ for age (median 60 years), gender (19% women), ischemic etiology (59%), or medication. Change in LVEDD from baseline to 12 weeks was not different between HIIT and MCT, p = 0.45; respective changes versus RRE were -2.8 mm (-5.2, -0.4; p = 0.02) in HIIT and -1.2 mm (-3.6, 1.2; p = 0.34) in MCT. They also found that there was no difference between HIIT and MCT in peak oxygen uptake, p = 0.70, but both were superior to RRE. However, none of these changes were maintained at follow-up after 52 weeks. There were no within-group or between-group differences in the quality-of-life measures at baseline, 12 weeks, or 52 weeks. Serious adverse events were not statistically different during supervised intervention or at follow-up at 52 weeks (HIIT 39%, MCT 25%, RRE 34%, p = 0.16). Training records showed that 51% of patients exercised below prescribed target during supervised HIIT and 80% above in MCT.
The study authors concluded that HIIT was not superior to MCT in changing LV remodeling or aerobic capacity, and its feasibility remains unresolved in HF patients.
As the authors point out, limitations of the study include possibly short duration of the study and the fact that target intensity was not achieved by a substantial number of participants of the study cohort. In the HF-ACTION study, exercise training resulted in nonsignificant reductions in the primary endpoint of all-cause mortality or hospitalization. Until we have more data, given these findings of the HF-ACTION study, patients with systolic HF should be encouraged to exercise regularly.
Clinical Topics: Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Prevention, Sports and Exercise Cardiology, Acute Heart Failure, Chronic Heart Failure, Exercise, Hypertension, Sports & Exercise and ECG & Stress Testing
Keywords: Bicycling, Exercise, Exercise Test, Exercise Tolerance, Heart Failure, Heart Failure, Systolic, Hypertension, Quality of Life, Stroke Volume
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