-Original-

Prognostic Factors Affecting Clinical Outcomes after Coronary Artery Bypass Surgery: Analysis of Patients with Chronic Kidney Disease after 5.9 Years of Follow-Up

Kouan Orii^1,2, Masafumi Hioki^1,2, Yoshio Iedokoro^1,2 and Kazuo Shimizu^1,3

¹Department of Biological Regulation and Regenerative Surgery, Graduate School of Medicine, Nippon Medical School
²Department of Cardiovascular Surgery, Nippon Medical School Musashi Kosugi Hospital
³Department of Surgery, Nippon Medical School

Background: Coronary artery bypass grafting (CABG) is a highly successful treatment for prolonging the lives of selected patients; however, preoperative and postoperative renal dysfunction has been an important predictor of adverse cardiovascular events. Concerns have recently grown regarding chronic kidney disease (CKD), which is an independent risk factor for cardiovascular diseases. In the present study we examined the significance of renal function on the basis of the estimated glomerular filtration rate (eGFR) and analyzed other factors as predictors of long-term clinical outcomes after CABG.
Methods: The subjects were 195 patients who underwent CABG from July 1996 through September 2008 at our hospital. Patients who received preoperative dialysis or who died during hospitalization or both were excluded. The patients were divided into 2 groups based on eGFR at the time of discharge (eGFR ≥60 mL/min/1.73 m²: non-CKD group; or eGFR <60 mL/min/1.73 m²: CKD group), and long-term outcomes were compared between the groups. The effects of other risk factors on long-term morbidity and mortality were also examined.
Results: The mean age of patients was 64.6 ± 9.3 years, and the mean duration of follow-up was 69.5 ± 44.5 months. There were no significant differences in either deaths from all causes or cardiovascular deaths between the CKD group and the non-CKD group. Multivariate analysis using the Cox proportional hazards model revealed that age (hazard ratio, 1.044; p=0.001) was a predictor of all-cause death and that age (hazard ratio, 1.154; p<0.001), diabetes mellitus (hazard ratio, 3.122; p=0.046), unstable angina (hazard ratio, 5.012; p=0.003), and proteinuria (hazard ratio, 7.982; p<0.001) were predictors of cardiovascular death.
Conclusions: Our study demonstrates that age, diabetes mellitus, unstable angina, and proteinuria are factors that affect long-term prognosis after CABG, whereas eGFR <60 mL/min/1.73 m² is not a predictive risk factor for either all-cause death or cardiovascular death. Although the predictive value of eGFR <60 mL/min/1.73 m² is generally accepted, analysis of our own data with receiver operating characteristic curves shows that eGFR <50 mL/min/1.73 m² is a more sensitive predictor of long-term outcome.

J Nippon Med Sch 2011; 78: 156-165

Keywords
coronary artery bypass grafting, chronic kidney disease, estimated glomerular filtration rate, cardiovascular mortality, proteinuria

Correspondence to
Kouan Orii, Department of Cardiovascular Surgery, Nippon Medical School Musashi Kosugi Hospital, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
nms-orii@nms.ac.jp

Received, June 25, 2010
Accepted, December 20, 2010