The Effects of High Intensity Interval Training and the Dietary Approaches to Stop Hypertension in Patients with Heart Failure with Preserved Ejection Fraction 45 views

Heart failure effects >6 million adults in the United States and is associated with high economic burden and ~75% 5-year mortality rate. Within this, patients with heart failure with preserved ejection fraction (HFpEF) have limited treatment options shown to improved outcomes. Exercise has been shown to improve cardiorespiratory fitness (VO2peak) but has had limited impact on cardiac and vascular outcomes. High intensity interval training (HIIT) has been shown to induce quicker adaptations to exercise than moderate intensity in small scale trials. The DASH diet has been shown to improve arterial stiffness and diastolic function in HFpEF. Arterial stiffness increases in HFpEF with exercise and can lead to a blunted cardiac reserve, possibly reducing VO2peak. The combination of exercise and DASH diet may lead to greater improvements in VO2peak than exercise alone through its effect on the vascular system. We thus sought to examine the effect that four weeks of HIIT, DASH diet, or the combination of the two on VO2peak, cardiac function, and vascular function. Following enrollment, patients came in for baseline testing after an overnight fast. During their baseline testing they underwent a maximal exercise test, echocardiogram, pulse wave analysis and velocity, flow mediated dilation, completed questionnaires and underwent a blood draw. Patients were than randomized into three groups: HIIT, DASH or HIIT+DASH. Those randomized into the HIIT intervention came in for 12 supervised exercise sessions over 4 weeks (12 total sessions). HIIT workouts utilized the 4x4 protocol at 90-95% of peak heart rate separated by 3 minutes of active recovery at 50% peak heart rate. Patients in the DASH group had all meals provided to them for the duration of the intervention. Meal plans were designed in consultation with a registered dietician and food was prepared by chefs in the hospital kitchen at UVA. Macronutrient composition for the diet was: 55-60% carbohydrates, 15-20% protein, 15-25% fat. The diet also included 35-40 grams of fiber a day. Patients randomized to the combination group participated in both the exercise intervention and had meals provided to them. Oneway ANOVAs or Kruskal-Wallis tests were used to assess for between group differences of the deltas for each outcome of interest (calculated as post minus pre) due to the small sample size and underpowered nature of the current study. There were no significant between group differences for change in VO2peak (p >0.05). However, a medium to large effect size was found due to non-significant increases in both exercise groups but no change in the DASH group. While not significant, patients in the HIIT group lost on average 1.1 kg compared to the 2.5-3 kg weight loss observed in the two diet groups. In addition, there were no significant differences seen for any marker for systolic or diastolic function. There were large effect sizes observed for LAVI, lateral and average E/e’ and lateral e’ in favor of the exercise groups. No significant reductions were seen for blood pressure or flow mediated dilation however a trend was found was pulse wave velocity (p = 0.093). No significant differences were found for glucose or changes in lipid panel outcomes. However, a time effect appeared to be present in which all groups saw improvements. Lastly, there was no significant difference found for health-related quality of life as measured by the MLHFQ. In conclusion we did not find any significant differences between our groups for the primary outcome of VO2peak. There was a medium to large effect size seen and both exercise groups did see an improvement in VO2peak, however there was no additive effect of diet to the exercise intervention. In addition, no significant changes were seen in any measure of cardiac or vascular function. The primary limitation of the current study is that we were severely underpowered due to not reaching patient accrual targets based on our sample size calculations. Due to the underpowered nature of the current analysis, strong conclusions cannot be made about the effectiveness of HIIT, DASH or the combination of the two in patients with HFpEF.

PHD (Doctor of Philosophy)

Heart Failure; Exercise; Diet; HFpEF

English

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2025-07-31