Objective: Low muscle mass was known to be associated with cardiovascular diseases. However, only few studies investigated the association between muscle quality and subclinical coronary atherosclerosis. Thus, we evaluated whether muscle quality measured by abdominal computed tomography is associated with the risk of coronary artery calcification. Approach and Results: We conducted a cross-sectional study on 4068 subjects without cardiovascular disease who underwent abdominal and coronary computed tomography between 2012 and 2013 during health examinations. The cross-sectional area of the skeletal muscle was measured at the L3 level (total abdominal muscle area) and segmented into normal attenuation muscle area, low attenuation muscle area, and intramuscular adipose tissue. We calculated the normal attenuation muscle area/total abdominal muscle area index, of which a higher value reflected a higher proportion of good quality muscle (normal attenuation muscle area) and a lower proportion of myosteatosis (low attenuation muscle area and intramuscular adipose tissue). In women, as the normal attenuation muscle area/total abdominal muscle area quartiles increased, the odds ratios (95% CIs) for significant coronary artery calcification (>100) consistently decreased (0.44 [0.24-0.80], 0.39 [0.19-0.81], 0.34 [0.12-0.98]; P=0.003) after adjusting for cardiovascular risk factors including visceral fat area and insulin resistance. In men, the odds ratios in the Q2 group were significantly lower than those in the Q1, but the association was attenuated in Q3-4 after adjustment.
Conclusions: A higher proportion of good quality muscle was strongly associated with a lower prevalence of significant coronary artery calcification after adjustment, especially in women. Poor skeletal muscle quality may be an important risk factor for subclinical coronary atherosclerosis.
Keywords: adipose tissue; muscles; risk factors; vascular calcification.