BACKGROUND: Sarcopenic obesity is a health condition involving a combination of excess adipose tissue and loss of muscle mass. Although sarcopenic obesity is known to contribute to the morbidity and mortality of chronic diseases, limited data are available in patients with cardiovascular disease. The present study was performed to examine whether sarcopenic obesity determined by preoperative computed tomography (CT) is a useful predictor of postoperative mortality in patients undergoing cardiovascular surgery. METHODS: We reviewed the findings in 664 consecutive cardiovascular surgery patients (mean age, 65.8±12.7 years; male, 66.6%) who underwent preoperative CT including the level of the third lumbar vertebra for clinical purposes. Psoas muscle attenuation (MA) and visceral adipose tissue (VAT) were measured as metrics of sarcopenia and obesity, respectively. Sarcopenia was defined as low MA (below median), while obesity was defined as high VAT (≥103cm2 for males and ≥69cm2 for females). The endpoint was all-cause mortality and secondary outcomes were muscle function. RESULTS: After adjusting for age and sex, sarcopenic obesity showed significant associations with lower grip strength and quadriceps strength, slower gait speed, and shorter 6-min walking distance compared to the normal group (p<0.05). On multivariate Cox regression analysis, sarcopenic obesity was associated with increased risk of mortality after adjusting for EuroSCORE (hazard ratio, 3.04; 95% confidence interval, 1.25-7.40). CONCLUSIONS: Sarcopenic obesity is associated with poor muscle function and all-cause mortality in patients undergoing cardiovascular surgery.