Impact of simple equation for estimating appendicular skeletal muscle mass in patients with stable coronary artery disease undergoing percutaneous coronary intervention()

BACKGROUND: Sarcopenia, which is evaluated based on appendicular skeletal muscle mass (ASM) using dual-energy X-ray absorptiometry and bioelectrical impedance analysis, is a prognostic predictor for adverse outcomes in patients with coronary artery disease (CAD). However, a simple equation for estimating ASM is yet to be validated in clinical practice. METHODS: We enrolled 2211 patients with CAD who underwent percutaneous coronary intervention at our hospital between 2010 and 2017. The mean age was 68 years and 81.5 % were men. Patients were divided into 2 groups based on each ASM index (ASMI): low; male < 7.3 and female < 5.0 and high; male ≥ 7.3 and female ≥ 5.0. ASM was calculated using the following equation: 0.193 × bodyweight + 0.107 × height − 4.157 × gender − 0.037 × age − 2.631. Primary endpoints were major adverse cardiac events (MACE, which includes cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization for heart failure), and all-cause mortality. RESULTS: During the median follow-up period of 4.8 years, cumulative incidence of events were significantly higher in the low ASMI group. Cox proportional hazards model revealed that the low ASMI group had a significantly higher risk of primary endpoints than the high ASMI group (all-cause mortality; hazard ratio (HR): 2.13, 95 % confidence interval [CI]: 1.40–3.22, p < 0.001 and 4-point MACE; HR: 1.72, 95 % CI: 1.12–2.62, p = 0.01). Similar trends were observed after stratification by age of 65 years. CONCLUSION: Low ASMI, evaluated using the aforementioned equation, is an independent predictor of MACE and all-cause mortality in patients with CAD.