Abstract Body (Do not enter title and authors here): Background: Evaluation of sarcopenia requires quantifying appendicular skeletal muscle mass and functional capacity, but resource constraints often limit feasibility. Alterations in muscle quality, especially intramuscular lipid infiltration (i.e., myosteatosis), and systemic metabolic derangements are associated with disability.
Hypothesis: Opportunistic CT imaging and plasma amino acid profiling could identify low physical function in patients with heart failure (HF).
Methods: We retrospectively examined 220 HF patients (74 ± 13 years old; 59% male) who underwent plasma amino acid profiling, abdominal CT imaging, and dual-energy X-ray absorptiometry (DXA) scan within two months. Myosteatosis was evaluated using single-slice CT imaging at the L3/4 level and quantified as mean muscle attenuation (MMA). Physical function was assessed by the short physical performance battery (SPPB), with low physical function defined as SPPB ≤9.
Results: CT-derived single-slice areas of skeletal muscle and adipose tissue were highly correlated with DXA-derived appendicular skeletal muscle mass and total fat mass. Logistic regression analyses revealed that higher age and lower MMA, but not skeletal muscle area, were significantly associated with low physical function independently of NT-proBNP. Subjects with MMA below the median value (32.0 HU for males and 23.7 HU for females) had higher odds of low physical function (adjusted OR 2.04, 95% CI 1.04-3.96). Ten amino acids and the Fischer ratio were significantly correlated with MMA levels. Multivariate regression analyses, adjusted for potential confounders including age, gender, and body mass index, demonstrated that serum albumin and Fischer ratio were independent determinants of MMA levels. When serum albumin and Fischer ratio were dichotomized by their median values (3.6 mg/dL and 3.23, respectively), the prevalence of low physical function was significantly higher in subjects with low albumin and low Fischer ratio, but not in those with low levels of only either parameter, compared to those with high albumin and high Fischer ratio (adjusted OR 2.36, 95% CI 1.02-5.49).
Conclusions: Myosteatosis assessed by single-slice abdominal CT imaging is an independent determinant of low physical function in HF patients. Combined with an assessment of serum albumin and Fischer ratio, these simple biomarkers could facilitate the early detection of patients at risk for developing frailty.