The Association Between Body Mass Index And Functional Status In Minority Patients With Heart Failure With Preserved Ejection Fraction: The SCAN-MP Study

Introduction Obesity is thought to be play a pathogenic role in the development of heart failure with preserved ejection fraction (HFpEF) due to the physiologic impairments associated with excess fat mass. While obesity has been associated with poor functional status and quality of life in HFpEF, the relative contributions of excess adiposity or decreased muscle mass associated with HF are unclear. We sought to determine the association of body mass index (BMI) with measurements of functional status and quality of life in HFpEF in patients with and without obesity. Methods Patients with HFpEF from the Screening for Cardiac Amyloidosis Using Nuclear Imaging for Minority Populations (SCAN-MP) study but without transthyretin cardiac amyloidosis were included. Patients were classified by obesity status using a BMI cutoff of 30 kg/m2. We examined differences in 6-minute walk test (6MWT) distance, Short Physical Performance Battery (SPPB) score, and Kansas City Cardiomyopathy (KCCQ) overall summary score by obesity status. Results 332 minority patients (79% black) with HFpEF were included in the analysis. The majority of the cohort was obese (61%) with a median BMI of 31.8 kg/m2 (interquartile range 27.5-37.5 kg/m2). Compared to those without obesity (BMI < 30 kg/m2), obese patients were younger, majority female (55%), with a greater incidence of diabetes and atrial fibrillation. Patients with obesity demonstrated worse functional status overall with lower 6MWT distance (241 vs. 304 meters, p<0.001) and SPPB score (4.4 vs. 8.2 points, p=0.002) as well as worse quality of life as determined by the KCCQ overall summary score (61 vs. 69 points, p<0.001) (Table). Notably, when examined separately by obesity status, higher BMI was associated with worse functional capacity in obese patients but not in patients without obesity. BMI was a significant independent predictor of shorter 6MWT, worse SPPB score, and worse KCCQ overall summary score among those patients with obesity and was an independent predictor of shorter 6MWT controlling for age, sex, and NYHA class (p<0.001). Notably, increasing BMI was not associated with any functional status or quality of life measure among those without obesity. In this cohort, time to survival and/or first heart failure hospitalization did not differ by obesity status (log rank p=0.28). Conclusion Obesity as determined by BMI is associated with poor functional capacity in a cohort of minority patients with HFpEF. Notably, relationships between BMI and functional capacity differ between those with and without obesity which may be explained by differences in body composition such as excess fat mass versus decreased muscle mass.