Association Between Abdominal Fat and Mortality in Patients Undergoing Cardiovascular Surgery

Background Obesity is associated with reduced postoperative mortality among patients undergoing cardiovascular surgery. However, body mass index cannot differentiate abdominal fat composition. This study evaluated the relationships between total abdominal, subcutaneous, and visceral fat composition and postoperative mortality in East Asian patients undergoing cardiovascular surgery. Methods Adult patients who underwent cardiovascular surgery between October 2004 and December 2016 were retrospectively included. Total, subcutaneous, and visceral fat areas were measured from cross-sectional computed tomography images. The relationships between each fat composition and mortality were evaluated. Results In all, 3661 patients were analyzed, and overall mortality was 19.9% (729 died) during the 4.6-year median follow-up period. The risks of all-cause and cardiac-cause mortality decreased as subcutaneous fat composition increased (adjusted hazard ratio 0.997; 95% confidence interval, 0.994 to 1.000; and adjusted hazard ratio 0.994; 95% confidence interval, 0.989 to 0.999; P = .02 and P = .01, respectively). No association was detected between the total and visceral fat area and mortality. Conclusions Reduced abdominal subcutaneous fat, but not the total or visceral fat composition, was associated with higher all-cause and cardiac-cause mortality after cardiovascular surgery in East Asian patients, consisting mainly of normal weight or overweight patients.