Postoperative renal dysfunction and preoperative left ventricular dysfunction predispose patients to increased long-term mortality after coronary artery bypass graft surgery

Abstract

Background. Both preoperative left ventricular dysfunction and postoperative renal function deterioration are associated with increased long-term mortality after cardiac surgery. The influence of preoperative left ventricular dysfunction on postoperative renal dysfunction and long-term mortality is not defined. Methods. We collected data from 641 consecutive patients undergoing coronary bypass surgery with cardiopulmonary bypass in 1991 at our institution. Prospective follow-up was through to July 2004. Results. In-hospital mortality was 2.7 (17 of 641). During follow-up, 248 (40) patients discharged alive died (5 and 10 yr survival 90 and 70, respectively). On univariate analysis, preoperative left ventricular dysfunction (ejection fraction <50) and an increase in serum creatinine ≥25 in the first postoperative week were associated with long-term mortality. The associated mortality risk was additive in predominantly non-overlapping patients groups: the hazard ratio (HR) for renal function deterioration only was 1.41 [95 confidence interval (CI) 0.95-2.32, P=0.083; n=64] and for left ventricular dysfunction only 1.71 (95 CI 1.26-2.95, P=0.0026; n=73). In patients in whom both were present, HR was 3.23 (95 CI 2.52-20.28, P<0.0001; n=20). Although postoperative renal dysfunction was associated with left ventricular dysfunction (P=0.008), both left ventricular dysfunction and postoperative renal function deterioration were independently associated with long-term mortality on multivariate analysis, as were age and the use of venous conduits. Conclusions. Both postoperative renal function deterioration and preoperative left ventricular dysfunction independently identify largely non-overlapping groups of patients with increased long-term mortality after coronary bypass surgery. In the group of patients with both factors present, the mortality risks appear additive.