Mild preoperative renal dysfunction as a predictor of long-term clinical outcome after coronary bypass surgery.

Background: Renal dysfunction is a prognostic marker in patients with cardiovascular disease. However, no long-term follow-up studies on the influence of mild renal dysfunction on mortality in patients undergoing coronary bypass grafting have been reported. Therefore, we aimed to identify the significance of preoperative (mild) renal dysfunction as a long-term predictor of clinical outcome after coronary bypass surgery.

Methods: In 358 patients who underwent isolated saphenous vein aorta-coronary artery bypass grafting, estimated glomerular filtration rates were calculated with the Cockroft-Gault equation (GFRc). Patients were categorized into 2 groups (group 1, GFRc >71.1 mL x min (-1) x 1.73 m (-2) ; group 2, GFRc <71.1 mL x min (-1) x 1.73 m (-2) ). Multivariate Cox proportional hazard analyses were performed to determine the independent prognostic value of GFRc.

Results: During a median follow-up of 18.2 years, 233 patients (65.1%) died. Patients who died had lower GFRc and were older. Multivariate analysis demonstrated that total mortality in patients with lower GFRc was significantly increased (lower GFRc group vs normal GFRc group: hazard ratio, 1.44; P = .019). Lower GFRc was also an independent predictor of cardiac mortality (hazard ratio, 1.51; P = .032). No significant differences were observed between groups in the occurrence of myocardial infarction and the need for reintervention.

Conclusions: Our study demonstrates that after long-term follow-up, preoperative mild renal dysfunction is an independent predictor of long-term (cardiac) mortality in patients who undergo coronary artery bypass grafting.