Risk factors for intermediate-term survival after coronary artery bypass grafting

Background. Risk factors for short-term mortality after coronary artery bypass grafting are well established, but little is known about risk factors for intermediate-term mortality. Methods. We analyzed the outcomes of 11,815 patients undergoing coronary artery bypass grafting in one of the 43 cardiac surgery programs of the Department of Veteran Affairs. Risk factors for intermediate- and short-term mortality were determined using Cox proportional hazards regression models. Effects of risk factors during these two periods were explicitly compared. Results. We found important differences in mortality risk-factor sets between the intermediate- and short-term periods after coronary artery bypass grafting. The majority of predictors of intermediate-term mortality were noncardiac-related variables, whereas the majority of predictors of short-term mortality were cardiac-related variables. Impaired functional status, chronic obstructive pulmonary disease, and renal dysfunction had greater effects in the intermediate-term period. Previous heart operation, angina class III or IV, previous myocardial infarction, and preoperative use of an intraaortic balloon pump had greater effects in the short-term period. Conclusions. The risk factors for intermediate-term mortality identified in this study can augment preoperative risk assessment and counseling of patients. Clinicians should be aware of the importance of noncardiac-related variables as predictors of mortality in the intermediate-term period after coronary artery bypass grafting.