Risk Factors of Coronary Artery Bypass Grafting According to Ventricular Function

Lee, Hyeon Jae; Hyun, Sung Ryul; Lim, Jung Chul; Park, Chul Hyun; Park, Kook Yang; Kim, Ju E; Lim, Chang Young

Abstract

Patients with coronary artery disease and depressed ventricular function have better long- term benefits after coronary artery bypass grafting compared with medical therapy. But operative mortality remains high. This study was designed to identify the risk factors for coronary artery bypass grafting according to ventricular function. The records of 103 patients who underwent coronary artery bypass grafting from July 1994 to June 1996 were analysed. The patients were divided into two groups based on preoperative ejection fraction: Low EF group(Ejection fraction < 40%, n=24) and Normal EF group(Ejection fraction >or= 40%, n=79). The indication of operation was significantly different between the two groups (p=0.00003). Postinfarction angina was frequent in Low EF group but unstable angina was frequent in Normal EF group. The frequency of cardiomegaly(p=0.0012), serum creatinine abnormality(p=0.0473) and preoperative use of IABP(Intra Aortic Balloon Pump, p=0.0095) were higher in Low EF group. The left internal thoracic artery was used less frequently in Low EF group(p=0.00416). The operative mortality was 8.3% in Low EF group and 5.1% in Normal EF group, but without statistical difference(p=0.5492). In Normal EF group, age (p=0.041) was identified as a significant risk factor for operative mortality. In Low EF group, age(p=0.018), preopertive use of IABP(p=0.0036), hypercholesterolemia(p=0.0007), and emergency of operation(p=0.0037) were identified as significant risk factors. Postoperative morbidity was 50% in Low EF group and 33% in Normal EF group, but without statistical significance(p=0.1007). These results suggest that in patients with coronary artery disease and depressed ventricular function, more aggresive coronary artery bypass grafting is needed to improve the symptom and long-term benefit. Risk factor