Association Between Remnant Cholesterol and Muscle Mass and Quality: Insights from Muscle Quality Mapping and Abdominal Computed Tomography

Background/Objectives: Remnant cholesterol (remnant-C), derived from triglyceride-rich lipoproteins, is an important risk factor for cardiometabolic diseases. Given the metabolic link between dyslipidemia and skeletal muscle dysfunction, we aimed to evaluate the association between remnant-C and two key components of sarcopenia—low muscle mass and myosteatosis (ectopic fat deposition in skeletal muscle). Methods: This cross-sectional study included 11,570 patients who underwent abdominal computed tomography (CT) for health check-ups. Remnant-C was calculated as total cholesterol minus low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. We conducted multivariable logistic and linear analyses to assess the association between remnant-C and low muscle mass, defined as appendicular skeletal muscle mass divided by body mass index. Additional analysis examined the relationship between remnant-C and myosteatosis, defined using the NAMA (normal attenuation muscle area) divided by TAMA (total abdominal muscle area) index, a novel index derived from muscle quality mapping of abdominal CT scans. Results: Low muscle mass was observed in 244 males (3.9%) and 74 females (1.4%). Myosteatosis affected 950 males (15.0%) and 800 females (15.3%). There was an increasing prevalence of both low muscle mass and myosteatosis across remnant-C quartiles. The multivariate-adjusted odds ratios (ORs) for low muscle mass in the highest remnant-C quartile compared with the lowest quartile were 2.17 (95% confidence interval [CI] 1.45–3.26) for males and 1.37 (95% CI 0.68–2.76) for females. The corresponding ORs for myosteatosis were 1.37 (95% CI 1.11–1.69) for males and 1.24 (95% CI 0.96–1.59) for females. Conclusions: Elevated remnant-C level is associated with low muscle mass and myosteatosis, especially in male patients. Individuals with higher remnant-C levels may warrant comprehensive evaluation for skeletal muscle health.