Outcome after acute myocardial infarction in patients with prior coronary artery bypass surgery

Abstract

Little is known concerning the influence of remote prior coronary artery bypass grafting (CABG) on the outcome of patients with acute myocardial infarction (AMI). Therefore, this study evaluated 2,494 patients with AMI of whom 219 (8.8%) had a history of CABG a mean of 7.1 ± 3.7 years before the index AMI. Compared with all other patients, those with a history of CABG had an increased prevalence of a history of prior AMI (153 [70%] vs 547 [24%]), congestive heart failure (48 [22%] vs 236 [10%]), and angina pectoris (165 [75%] vs 787 [35%]), all p < 0.001. There was no difference in age, but patients with prior CABG were more often men (192 [88%] vs 1,702 [75%], p < 0.001). During the hospitalization for AMI, patients with prior CABG had more recurrent ischemic pain (100 [46%] vs 732 [32%, p < 0.001]), and more frequently developed non-Q-wave AMI (72 [33%] vs 514 [23%], p < 0.01). In-hospital mortality did not differ among patients with or without prior CABG (15 [7%] vs 195 [9%]). At hospital discharge, more patients with prior CABG had complex ventricular ectopic activity on 24-hour ambulatory electrocardiographic monitoring (48 of 74 [65%] vs 327 of 797 [41%], p < 0.0001), and radionuclide ejection fraction <0.45 (53 of 99 [54%] vs 430 of 1,024 [42%], p < 0.01). Among patients undergoing coronary angiography during the first 2 months, multivessel coronary artery disease was more prevalent among patients with prior CABG (78 of 107 [73%] vs 508 of 959 [53%], p < 0.0l). Among patients with prior CABG, 25 of 133 (19%) had all grafts occluded, whereas 40 of 133 (30%) had only minor narrowing in any graft. The proportion with totally occluded grafts increased from 7 of 61 (11%) in patients who underwent operation <7 years before their AMI to 17 of 71 (24%) in patients with prior CABG ≥7 years before the index AMI (p < 0.10). One-year cardiac mortality after hospital discharge was significantly higher in patients with prior CABG (28 of 175 [16%] vs 152 of 1,827 [8%], p < 0.01). On multivariate analysis, prior CABG was of borderline (p < 0.054) independent importance to 1-year cardiac mortality. Thus, patients with prior CABG constitute a group at high risk for death after hospital discharge for AMI. This fact exists principally because of increased severity of underlying coronary artery disease and reduced left ventricular ejection fraction.