Abstract 11640: Increased Fitness Modifies the Obesity Paradox by Body Composition Even in Individuals With Low Cardio-Respiratory Fitness

Abstract

Introduction: An association of obesity and increased survival has been shown in stable coronary heart disease (CHD) patients, especially in individuals with low cardiorespiratory fitness (CRF). We aimed to examine the impact of fitness improvement on this paradoxical relationship. Hypothesis: Increasing fitness after cardiac rehabilitation will change the nature of the obesity paradox by body composition even in a population with low baseline cardiorespiratory fitness. Methods: 588 subjects with stable CHD referred for cardiac rehabilitation with CRF (<17 cc/kg/min peak oxygen consumption [VO2]) where stratified based on their degree of improvement in CRF. Mortality from the cohort was analyzed with respect to body mass index (BMI), body fat (BF), and lean mass index (LMI). Results: In all subjects, higher BMI, BF, and LMI were associated with significant protective effects after adjusting for age, gender, left ventricular ejection fraction, and baseline VO2 (HR 0.5 p = 0.01; HR = 0.60 p = 0.006; HR 0.20 p < 0.001, respectively). In a subgroup that comprised the top 50 th percentile of VO2 improvement, obesity by BMI and BF was no longer associated with improved survival (HR 0.75 p = 0.4 for BMI and HR 0.83 p = 0.6 for BF, Figure 1), but increased lean mass continued to be protective (HR 0.2 p < 0.001). Conclusions: Persons with low baseline CRF who have significant improvement in absolute VO2 continue to have survival benefits from increased LMI but not from increased BF and BMI. The obesity paradox by BF may be limited to those individuals with low CRF that fail to improve after CR.