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Effect of Diet or Exercise on Peak Oxygen Consumption in Diastolic Heart Failure
Study Questions:
Does caloric restriction (diet) or aerobic exercise training (exercise) improve exercise capacity and quality of life (QOL) in obese older patients with diastolic heart failure (HF)?
Methods:
The study cohort was comprised of 100 older obese participants (mean age 67 years, mean body mass index 39.3 ± 5.6 kg/m2) with chronic stable diastolic HF. A total of 366 individuals were excluded by inclusion and exclusion criteria, 31 for other reasons, and 80 declined participation. The study design was a randomized, attention-controlled, 2 × 2 factorial trial. The intervention consisted of 20 weeks of diet, exercise, or both; attention control consisted of telephone calls every 2 weeks. The study investigators randomized 26 participants to exercise, 24 to diet, 25 to exercise + diet, and 25 to control. The main outcome measures were peak oxygen consumption (coprimary outcome) and QOL measured by the Minnesota Living With Heart Failure Questionnaire (coprimary outcome).
Results:
A total of 92 participants completed the trial. Exercise attendance was 84% (standard deviation [SD], 14%) and diet adherence was 99% (SD, 1%). Using main-effects analysis, the study investigators found that peak oxygen consumption increased significantly with both interventions: exercise, 1.2 ml/kg body mass/min (95% confidence interval [CI], 0.7-1.7; p < 0.001); diet, 1.3 ml/kg body mass/min (95% CI, 0.8-1.8; p < 0.001). The combination of exercise + diet was additive (complementary) for peak oxygen consumption (joint effect, +2.5 ml/kg/min, substantially greater than the accepted clinically meaningful increase of 1.0 ml/kg/min). The study investigators found no statistically significant change in Minnesota Living With Heart Failure total score with exercise and with diet (main effect: exercise, -1 unit [95% CI, -8 to 5], p = 0.70; diet, -6 units [95% CI, -12 to 1], p = 0.08). The change in peak oxygen consumption positively correlated with the change in percent lean body mass (r = 0.32; p = 0.003) and the change in thigh muscle: intermuscular fat ratio (r = 0.27; p = 0.02). There were no study-related serious adverse events. Body weight decreased by 7% (7 kg [SD, 1]) in the diet group, 3% (4 kg [SD, 1]) in the exercise group, 10% (11 kg [SD, 1] in the exercise + diet group, and 1% (1 kg [SD, 1]) in the control group.
Conclusions:
The authors concluded that in obese older patients with clinically stable diastolic HF, caloric restriction or aerobic exercise training increased exercise capacity, and the effects may be additive. However, neither intervention had a significant effect on QOL.
Perspective:
This is an important study because it suggests that both exercise and caloric restriction improve exercise capacity in obese diastolic HF patients. Larger studies are needed to determine whether indeed this translates into better outcomes since there are data regarding the ‘HF obesity paradox’ (some studies have suggested lower mortality in obese or overweight HF patients).
Keywords: Body Mass Index, Caloric Restriction, Diet, Exercise, Geriatrics, Heart Failure, Heart Failure, Diastolic, Obesity, Oxygen Consumption, Quality of Life, Secondary Prevention
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