Heart failure
Meta-Analysis of Aerobic Interval Training on Exercise Capacity and Systolic Function in Patients With Heart Failure and Reduced Ejection Fractions

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It is unknown if vigorous to maximal aerobic interval training (INT) is more effective than traditionally prescribed moderate-intensity continuous aerobic training (MCT) for improving peak oxygen uptake (Vo2) and the left ventricular ejection fraction (LVEF) in patients with heart failure with reduced ejection fraction. MEDLINE, PubMed, Scopus, and the Web of Science were searched using the following keywords: “heart failure,” high-intensity interval exercise,” “high-intensity interval training,” “aerobic interval training,” and “high-intensity aerobic interval training.” Seven randomized trials were identified comparing the effects of INT and MCT on peak Vo2, 5 of which measured the LVEF at rest. The trials included clinically stable patients with heart failure with reduced ejection fraction with impaired left ventricular systolic function (mean LVEF 32%) who were relatively young (mean age 61 years) and predominantly men (82%). Weighted mean differences were calculated using a random-effects model. INT led to significantly higher increases in peak Vo2 compared with MCT (INT vs MCT, weighted mean difference 2.14 ml O2/kg/min, 95% confidence interval 0.66 to 3.63). Comparison of the effects of INT and MCT on the LVEF at rest was inconclusive (INT vs MCT, weighted mean difference 3.29%, 95% confidence interval −0.7% to 7.28%). In conclusion, in clinically stable patients with heart failure with reduced ejection fraction, INT is more effective than MCT for improving peak Vo2 but not the LVEF at rest.

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Methods

We searched MEDLINE (1948 to 2012), PubMed, Scopus (1960 to 2012), and the Web of Science (no limit to years published) using the following keywords: “heart failure,” high-intensity interval exercise,” “high-intensity interval training,” “aerobic interval training,” and “high-intensity aerobic interval training.” We also hand-searched the reference lists of all identified studies and previous reviews. The primary and secondary end points were peak Vo2 and the LVEF at rest, respectively. Two

Results

After initial review of 88 citations and 5 additional citations identified from manual searches (Figure 1), 7 unique randomized trials were identified comparing the effects of INT with those of MCT on peak Vo2 in patients with HFREF,5, 6, 7, 8, 9, 10, 11 5 of which measured the LVEF at rest5, 6, 8, 9, 11 (Table 1). Reasons for exclusion are reported in Figure 1. The trials included clinically stable patients with HFREF with impaired LV systolic function (mean LVEF 32%) who were relatively young

Discussion

Our findings indicate that in clinically stable patients with HFREF, INT is more effective than MCT for improving peak Vo2. The biologic mechanisms through which INT results in higher changes in peak Vo2 may be due to intensity-dependent improvements in exercise cardiovascular and skeletal muscle function.3, 8, 9, 11, 12 Tomczak et al,3 using cardiac magnetic resonance imaging, recently found that an acute bout of INT was associated with a significant increase in the LVEF and a concomitant

Disclosures

The authors have no conflicts of interest to disclose.

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