Aortic valve replacement: Determinants of operative mortality

Abstract

Contradictory results have been reported regarding risk factors for aortic valve replacement (AVR). This study was designed to investigate determinants of operative mortality for AVR with emphasis on concomitant coronary artery bypass grafting (CABG) and old age. Between January 1986 and June 1992, 371 patients with a mean age of 61.99 ± 0.76 years underwent AVR, There were 256 men (69.0%) and 115 women (31.0%). Twentysix patients (7.0%) were 80 years old or older, and 97 (26.1%) were between 70 and 80 years old. Of these patients, 210 (56.6%) had isolated AVR, 142 (38.3%) had concomitant CABG, and 31 (8.4%) had concomitant mitral valve operations. Twenty patients (5.4%) underwent emergency operation. There were 33 operative deaths (8.9%). Univariate analysis and stepwise multiple logistic regression analysis were used to determine the risk factors for operative mortality. In the univariate analysis, 13 preoperative variables (sex, age, history of congestive heart failure, myocardial infarction, arrhythmia, functional class, class I / II versus III / IV , four variables related to aortic valve pathology, ejection fraction, left ventricular function) and 20 perioperative variables (emergency operation, individual surgeon, myocardial protection by type and route of cardioplegia, type of prosthesis, size of prosthesis, mean size by survival, small versus large size, concomitant procedure, concomitant CABG (versus others or AVR alone), concomitant mitral valve operation (versus others or AVR alone), concomitant CABG and MV operation, aortic cross-clamp time, cardiopulmonary bypass time, use and time of insertion of intraaortic balloon pump, low cardiac output, postoperative complications) were examined. Among these variables, sex, age, history of congestive heart failure, history of myocardial infarction, ejection fraction, left ventricular function, emergency operation, type of prosthesis, size of prosthesis, small versus large size, concomitant procedure, concomitant CABG or mitral valve operation (versus others or AVR alone), cross-clamp time, cardiopulmonary bypass time, insertion of intraaortic balloon pump, low cardiac output, and postoperative complications were significantly associated with higher mortality ( p < 0.05). Significant preoperative and intraoperative variables were entered into the logistic regression analysis. Bypass time was the strongest variable ( p = 0.0001) and age, the second strongest ( p = 0.0002). Aortic crossclamp time, concomitant mitral valve operation, and aortic insufficiency were also independent variables ( p < 0.05). We conclude that age of 60 years or more, long bypass time, and long aortic cross-clamp time are the major risk factors for operative mortality in patients undergoing AVR. Concomitant CABG is not an independent risk factor.