Abstract 16443: Discordant Effects of Lean Mass and Body Fat on Survival in Obesity

Abstract

Background_In several cardiac diseases and in the elderly population, an inverse relationship between obesity, as determined by body mass index (BMI) , and subsequent prognosis has been demonstrated (the “obesity paradox”). However, some have postulated that it is the lean mass (LMI) component that is beneficial, and that body fat (BF) is, in fact, detrimental.

Patients and Methods_We retrospectively assessed 26228 patients, classified as obese by BMI with a preserved left ventricular ejection fraction (LVEF; ≥50%). We calculated BF as determined by the Jackson Pollock equation and LMI as (1-BF) x BMI kg/m². The population was divided based on age and gender adjusted BF classification and a gender adjusted LMI classification. The population was analyzed by total mortality over average 3.1-year follow-up by National Death Index.

Results_ In proportional hazard analysis, after adjusting for age, gender, relative wall thickness, LVEF and left ventricular mass index, higher BMI was associated with higher mortality (1.03 CI 1.02-1.03). Higher BF category (HR 1.20; CI 1.07-1.36) was associated with higher mortality, but higher lean mass category remained protective (HR 0.72; CI 0.65-0.82) (Figure 1).

Conclusions_In patients with preserved LVEF at high BMIs, BF is detrimental, but LMI seems to remain independently protective, even after adjusting for confounding variables. Weight loss programs in obesity need to emphasize reducing BF while maintaining lean mass.

Figure 1 - Multivariate model showing event rates based on lean mass group after adjusting for age, gender, relative wall thickness, LVEF, BF and left ventricular mass index.