Clinical Impact of Sarcopenia Screening on Long-Term Mortality in Patients Undergoing Coronary Bypass Grafting

Background: Sarcopenia is an aging-related condition characterized by loss of skeletal muscle mass and is an indicator of subclinical atherosclerosis. The relationship between reduced muscle mass and long-term clinical outcomes in patients with advanced coronary artery disease who have undergone coronary artery bypass grafting (CABG) is not fully understood. This study is sought to evaluate the prognostic implications of sarcopenia screening in patients undergoing CABG. Methods: A total of 2810 patients who underwent CABG were analysed and classified according to presence of reduced muscle mass. The skeletal muscle index (SMI) was calculated as L3 muscle area (cm²)/height (m)² on computed tomography. Reduced SMI was defined as SMI ≤ 45 cm²/m² in male and ≤ 38 cm²/m² in female. The primary outcome was all-cause mortality, and survival analysis was performed using the Kaplan–Meier method and compared with the log-rank test. Results: The median follow-up was 8.7 years, and 924 patients (32.9%) had reduced SMI. Patients with reduced SMI were older (67.7 ± 8.8 vs. 62.2 ± 9.8 years; p < 0.001) and less frequently male (69.8% vs. 81.1%; p < 0.001). SMI was significantly associated with risk of death on a restricted cubic spline curve (HR = 1.04 per-1 decrease; 95% CI 1.03–1.05; p < 0.001). Patients with reduced SMI had a higher incidence of long-term mortality than those with preserved SMI (survival rate 41.4% vs. 62.8%; HR_adj = 1.18, 95% CI 1.03–1.36, p = 0.020). Subgroup analysis showed that the prognostic implication of reduced SMI on long-term survival was more evident in male (HR_adj = 2.01, 95% CI 1.72–2.35) than female (HR_adj = 1.28, 95% CI 0.98–1.68) (interaction p = 0.006). Conclusions: Reduced muscle mass, defined by SMI on computed tomography, was associated with long-term mortality after CABG. These results provide contemporary data to allow the evaluation of physical frailty in patients with advanced coronary artery disease before surgery. Trial Registration: Long-Term Outcomes and Prognostic Factors in Patients Undergoing CABG or PCI: NCT03870815.