Intake of unsaturated fatty acids (UFAs), which consist of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs), has recently been associated with favorable CRF, body composition, and cardiac diastolic function in patients with obesity and HFpEF (3). A high UFA diet also prevented weight gain and cardiac diastolic dysfunction (3) in a mouse model of Western diet-induced cardiac dysfunction (4), despite similar total caloric and total fats intake. However, the feasibility of a dietary intervention aimed at increasing daily UFA intake in a prospective trial is required in this population to test its potential efficacy in a large randomized controlled trial.

We hypothesized that a 12-week dietary intervention aimed at increasing UFA consumption was feasible in patients with obesity and HFpEF, and would result in increased consumption of UFAs at 12 weeks (primary endpoint), as assessed by both dietary recall and biomarkers. To test this hypothesis, we performed a proof-of-concept trial and enrolled 9 patients with obesity, symptomatic HFpEF (ie, dyspnea, fatigue), and reduced CRF (< 80% of predicted) measured with maximal cardiopulmonary exercise testing, in a single-arm dietary intervention. All study participants provided written consent (NCT03310099).