1352192 - Impact of Obesity on Left Ventricular Structure and Function in the Absence of Cardiovascular Disease in a Community Dwelling Cohort

Obesity is associated with excess burden of cardiovascular disease (CVD) as well as adverse alterations in left ventricular (LV) mass (LVM) and concentricity. LVM is commonly indexed (LVMi) to account for body size, but it is unclear what is the “optimal” measure of body size for indexation. We investigated the combined effect of severity of obesity and indexation method on LVMi and concentricity, as well as myocardial contraction fraction (MCF, a novel measure of LV systolic function) as assessed by cardiovascular magnetic resonance (CMR) imaging in a community dwelling cohort free of clinical CVD.

Methods: Framingham Offspring study participants free of myocardial infarction, heart failure, or CMR wall-motion abnormality who underwent bSSFP CMR at 1.5T were included. They were stratified by sex and body mass index (BMI) category (normal weight =18.5 to 24.9; overweight =25.0 to 29.9; grade 1 obese=30-34.9; grade 2+ obese ≥35 kg/m²). LVM was measured from contiguous short-axis images, then indexed to height (HT, m), body surface area (BSA, m²), and weight (WT, kg). We calculated MCF as LV stroke volume divided by LV myocardial volume. The ratio of LVM/LVEDV (end-diastolic volume) was used as a measure of LV concentricity.

Results: Data were available from 1334 Offspring (mean 65±9 y , 62% women) The Table shows LVMi, LV concentricity (LVM/LVEDV), and MCF stratified by BMI. LVMi by WT declined with increasing BMI in both men and women. Conversely, indexation to HT demonstrated an increasing LVMi with higher BMI. However, BSA-indexation remained consistent across BMI categories in both men and women. MCF decreased with increase in BMI from normal weight to obese. Concentricity increased with increasing BMI in both sexes.

Conclusion:

The association of LVMi with BMI varies by indexation method. Among CVD-free members of a community-dwelling cohort, in both sexes, indexation to BSA yielded values of LVMi that were consistent across categories of increasing BMI, whereas LVMi by HT increased, and LVMi by WT decreased, with greater BMI. Concentricity increased with increasing categories of BMI, while MCF decreased. These adverse alterations of MCF and concentricity may provide additional insight into obesity-related LV remodeling over LVMi alone. These data lay the groundwork for future outcomes analyses, in this population and in larger prospective cohorts, regarding the predictive utility of various methods of LVM indexation.