Relationship between low relative muscle mass and coronary artery calcification in healthy adults

Objective - Sarcopenia or low muscle mass is related to cardiovascular risk factors; however, the association between low muscle mass and subclinical atherosclerosis has been largely unexplored. We investigated whether muscle mass is related to coronary artery calcification (CAC) in a large sample of middle-aged asymptomatic adults. Approach and Results - We performed a cross-sectional study of 31 108 asymptomatic adults without cancer, diabetes mellitus, or known cardiovascular disease who underwent a health checkup examination including cardiac tomography estimation of CAC scores between 2012 and 2013. Skeletal muscle mass index (SMI) [SMI (%)=total skeletal muscle mass (kg)/body weight (kg)×100] was estimated using a bioelectrical impedance analyzer. We assessed the relationship between SMI and CAC scores using both multivariate-adjusted Tobit models and multinomial logistic regression models. Of the 31 108 subjects, 3374 subjects (10.9%) had a CAC score 1 to 100, and 628 subjects (2.0%) had a CAC score >100. SMI was inversely associated with CAC score ratios. Specifically, in a multivariable-adjusted model adjusting for potential confounders, CAC score ratios (95% confidence intervals) of SMI for quartiles 1, 2, and 3 compared with quartile 4 were 2.27 (1.70-3.05), 1.46 (1.15-1.85), and 1.24 (0.98-1.55), respectively (P for trend <0.001). Adjusting for insulin resistance reduced the magnitude of the associations, but they remained statistically significant. Conclusions - Relative muscle mass was negatively associated with the prevalence of coronary calcification, supporting low muscle mass as an independent risk factor of coronary heart disease.