Association (or Lack Thereof) of Body Roundness Index (BRI) with Left and Right Ventricular Ejection Function: The Framingham Heart Study

Background: 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 left ventricular (LV) and right ventricular (RV) ejection fraction (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. LVEF and RVEF were measured from contiguous-stack bSSFP cine images obtained in the LV-shortaxis orientation. LV concentricity was assessed as LV mass divided by LV end-diastolic volume (LVM/EDV). We used sex-specific linear regression analysis to test for trends across BRI tertiles for LVEF, RVEF, and LVM/EDV.

Results: Of the total 1764 participants (Age: 69±9yrs; 53% Women), 775 (57% women) met REF criteria. The proportion of participants meeting REF criteria decreased with greater BRI for each sex. Within each tertile mean LVEF and mean RVEF were greater among women versus men (Table), but LVM/EDV was greater in men than women. LVEF increased significantly with greater BRI tertile among both men and women, but there were not similar trends with RVEF. LVM/EDV increased with greater BRI in both sexes.

Conclusion: LVEF increased with greater tertile of BRI among both men and women. The increase in LVEF 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 obesity, as characterized by body roundness index, and LV systolic function is related to incident adverse CVD events, particularly heart failure with preserved EF, remains to be investigated.

Table 1