Analysis of risk factors for myocardial infarction and cardiac mortality after major vascular surgery

Background: Patients undergoing vascular surgical procedures are at high ri sk for perioperative myocardial infarction (PMI). This study was undertaken to identify predictors of PMI and in-hospital death in major vascular surg ical patients. Methods: From the Vascular Surgery Registry (6,948 operations from January 1989 through June 1997) the authors identified 107 patients in whom PMI dev eloped during the same hospital stay. Case-control patients (patients witho ut PMI) were matched at a 1x:x1 ratio with index cases according to the typ e of surgery, gender, patient age, and year of surgery, The authors analyze d data regarding preoperative cardiac disease and surgical and anesthetic f actors to study association with PMI and cardiac death. Results: By using univariable analysis the authors identified the following predictors of PMI: valvular disease (P = 0.007), previous congestive heart failure (P = 0.04), emergency surgery (P = 0.02), general anesthesia (P = 0.03), preoperative history of coronary artery disease (P = 0.001), preoper ative treatment with beta-blockers (P = 0.003), lower preoperative (P = 0.0 3) and postoperative (P = 0.002) hemoglobin concentrations, increased bleed ing rate (as assessed from increased cell salvage; P = 0.025), and lower ej ection fraction (P = 0.02). Of the 107 patients with PMI, 20.6% died of car diac cause during the same hospital stay. The following factors increased t he odds ratios for cardiac death: age (P = 0.001), recent congestive heart failure (P = 0.01), type of surgery (P = 0.04), emergency surgery (P = 0.02 ), lower intraoperative diastolic blood pressure (P = 0.001), new intraoper ative ST-T changes (P = 0.01), and increased intraoperative use of blood (P = 0.005). Patients who underwent coronary artery bypass grafting, even mor e than 12 months before index surgery, had a 79% reduction in risk of death if they had PMI (P = 0.01). Multivariable analysis revealed preoperative d efinitive diagnosis of coronary artery disease (P = 0.001) and significant valvular disease (P = 0.03) were associated with increased risk of PMI. Con gestive heart failure less than 1 yr before index vascular surgery (P = 0.0 002) and increased intraoperative use of blood (P = 0.007) were associated with cardiac death. The history of coronary artery bypass grafting reduced the risk of cardiac death (P = 0.04) in patients with PMI. Conclusions: The in-hospital cardiac mortality rate is high for patients wh o undergo vascular surgery and experience clinically significant PMI. Stres s of surgery (increased intraoperative bleeding and aortic, peripheral vasc ular, and emergency surgery), poor preoperative cardiac functional status ( congestive heart failure, lower ejection fraction, diagnosis of coronary ar tery disease), and preoperative history of coronary artery bypass grafting are the factors that determine perioperative cardiac morbidity and mortalit y rates.