Abstract 12: Skeletal Muscle Density, Not Size, is Beneficially Associated With Incident Coronary Heart Events: The Multi-Ethnic Study of Atherosclerosis

Abstract

Introduction: Fat infiltration into muscle reduces muscle density and increases the risk for metabolic dysfunction, mobility disability and mortality. We assessed abdominal muscle density and muscle area in relation to incident coronary heart disease (CHD) events. Methods: Adults (mean age 64.6 ± 9.6) from the Multi-Ethnic Study of Atherosclerosis body composition ancillary study had computed tomography (CT)-derived measures of muscle density, muscle area and visceral fat at the L2-L4 spinal column levels between 2002-05 and were followed for incident events. Using sex-stratified Cox proportional hazards regression, associations of muscle density and muscle area (in the same model) with CHD events were assessed using restricted cubic splines with adjustment for confounders including visceral adiposity and BMI. Results: After 10.3±2.9 years of follow up, 924 males had 70 CHD (7.6%) events and 945 females had 44 CHD (4.7%) events. Muscle density was higher in males (44.5±4.9 HU) than females (40.1±5.2 HU), as was muscle area (116.7±23.9 vs. 80.4±23.9 cm 2 , respectively). Among males, and in mutually adjusted models, each incremental SD of muscle density was inversely associated with CHD (HR=0.67; 95%CI=0.49-0.92), while each SD of muscle area was associated with higher risk of CHD (HR=1.75; 95%CI=1.34-2.28; Figure). Overall patterns were similar but less strong among females for density (HR=0.79; 95%CI=0.50-1.22) and area (HR=1.17; 95%CI=0.79-1.73). Conclusions: Greater muscle density is associated with lower CHD risk, while greater muscle size is associated with increased CHD risk. These associations were independent of traditional CHD risk factors and measures of visceral and total body adiposity. Quantity and quality of skeletal muscle may represent distinct aspects of aging and physical functioning that are important in heart health.