Impact of mild renal impairment on early postoperative mortality after open cardiac surgery.

Preoperative severe renal impairment is included in the risk scores to predict outcome after open cardiac surgery. The purpose of this study was to assess the impact of preoperative mild renal impairment on the early postoperative mortality after open heart surgery. Data of all cases of open cardiac surgery performed from January 2005 to June 2006 were collected. Cases with preoperative creatinine clearance below 60 mL/min were excluded from the study. Data were retrospectively analyzed to find the impact of renal impairment on short-term outcome. Of the 500 cases studied, 47 had preoperative creatinine clearance between 89-60 mL/min. The overall mortality in the study cases was 6.8%. The mortality was 28.7% in those who developed postoperative ARF, 33.3% in those who required dialysis and 40.8% in those with preoperative mild renal impairment. Binary logistic regression analysis showed that female gender (P = 0.01), preoperative mild renal impairment (P = 0.007) as well as occurrence of multi organ failure (P < 0.001) were the only independent variables determining the early postoperative mortality after cardiac surgeries. Among them, preoperative mild renal impairment was the most significant and the best predictor for early postoperative mortality after cardiac surgery. Our study suggests that renal impairment remains a strong predictor of early mortality even after adjustment for several confounders.