Effect of preoperative mild renal dysfunction on mortality and morbidity following valve cardiac surgery

The objective of this study was to investigate the effect of preoperative mild renal dysfunction (RD) not requiring dialysis on mortality and morbidity after valve cardiac surgery (VCS). We studied 681 consecutive patients (2002-2006) who underwent valve cardiac surgery with or without coronary artery bypass graft (CABG). Preoperative RD was calculated with the abbreviated Modification of Diet in Renal Disease formula and was defined as a glomerular filtration rate <60 ml/min/1.73 m(2). Logistic regression analysis was used to assess the effect of preoperative renal dysfunction on operative and adverse outcomes. Two hundred and seven patients (30%) had preoperative mild RD. Patients with preoperative RD were older, had a higher rate of preoperative anaemia (43% vs. 25%, P<0.001) and more comorbidities. Patients with preoperative RD had worse outcomes with more reoperation (6.8% vs. 2.3%, P<0.001). Preoperative RD was significantly and independently associated with more red blood cell transfusions and longer hospital stay (median 9 vs. 8 days, P<0.001). Mortality was similar in both groups (3.4% vs. 2.3%, P=0.43). Preoperative mild renal dysfunction in patients undergoing cardiac valve surgery is an independent marker of postoperative morbidity.