Determinants of hospital mortality after coronary artery bypass grafting.

Abstract

OBJECTIVES: To examine causes of death and to find predictors of hospital mortality after elective coronary artery bypass graft (CABG) surgery. DESIGN: Case-control study. SETTING: Tertiary teaching hospital. METHODS: We prospectively collected various preoperative, operative, and immediate postoperative variables in a cohort of patients undergoing elective CABG surgery. RESULTS: Of the 2,014 consecutive patients (mean [+/- SD] age of 61.3+/-6.7 years old) undergoing elective CABG over a 2-year period, 27 patients (1.3%) died during their hospitalization. The main causes of death (either isolated or in combination) were cardiogenic shock (n = 13), brain death or stroke (n = 7), septic shock (n = 4), ARDS (n = 2), and pulmonary embolism (n = 1). A univariate statistical analysis revealed factors that significantly correlate with outcome: patient age, preoperative left ventricular ejection fraction, bypass time, aortic cross-clamp time, number of blood units transfused, number of inotropic agents administered in the operating room during the first postoperative day (POD), history of arterial hypertension, intra-aortic balloon pump usage, and perioperative development of shock. A logistic regression analysis showed that the combination of the number of inotropes and the number of blood units administered in the operating room during POD 1 was the most important determinant of outcome, with an overall positive predictive value of 91.7%. CONCLUSIONS: We conclude that the analysis of simple variables enhances our ability to accurately predict hospital mortality in patients undergoing elective CABG surgery. The number of inotropic agents and blood transfusions administered during the immediate postoperative period is the most important independent predictor of hospital mortality.