Abstract Body: INTRODUCTION: Obesity, as assessed by body mass index (BMI), is associated with excess burden of cardiovascular disease, including heart failure, but BMI does not account for body shape or composition and may not be the optimal metric for obesity. In contrast to BMI, the novel body roundness index (BRI = 364.2 – 365.5*SQRT(1-(WC/(π*HT))²) incorporates both girth (waist circumference, WC) and height (HT). We sought to determine whether BRI is associated with differences in two measures of left ventricular (LV) systolic function: ejection fraction (EF), and myocardial contraction fraction (MCF), the dimensionless ratio of LV stroke volume to myocardial volume. MCF assesses the volume of blood ejected per unit volume of myocardium (LV mass) and is a metric complementary to EF.
METHODS. Participants from the Framingham Offspring cohort who underwent cardiac magnetic resonance (CMR) imaging were included in the study. Participants were divided into sex-specific tertiles of BRI, after which a referent group (REF) of Offspring free of prevalent cardiovascular disease (CVD), wall motion abnormalities on CMR, significant valve disease, or any history of hypertension was identified. We used sex-specific linear regression analysis to test for trends across BRI tertiles for LVEF and MCF. Finally, we considered the ratio of LV mass to end-diastolic volume as a measure of concentricity (CONC).
RESULTS: Of the total 1764 participants (Age: 69±9yrs; 53% Women), 775 (57% women) met REF criteria. Within each tertile mean LVEF and mean MCF were greater among women versus men (Table). MCF decreased with greater BRI for each sex. In contrast to MCF, LVEF increased significantly with greater BRI tertile among both men and women. CONC also increased across tertiles of BRI.
CONCLUSION: LVEF increased, while MCF decreased, with greater tertile of BRI. The decrease in MCF was concomitant with increasing concentricity. These results raise the possibility that the increase in LVEF with greater BRI is associated with geometric remodeling of the ventricle rather than intrinsically greater contractility. Whether this association between BRI-characterized obesity and LV systolic function is related to incident adverse CVD events, particularly heart failure with preserved EF, remains to be investigated.