The role of a defined protocol for cardiac risk assessment in decreasing perioperative myocardial infarction in vascular surgery

Abstract

Major elective peripheral vascular surgery has historically carried a significant risk of perioperative myocardial infarction; this risk has been quantified further by its association with proved reduction in cardiac reserve/presence of coronary artery disease by stress testing or invasive monitoring. Recognition of this risk logically should lead to protocols that delineate coronary artery disease/cardiac reserve before surgery and correct for observed abnormalities during surgery. This study sought to show that a coherent algorithm of preoperative cardiac assessment combined with aggressive perioperative management could indeed reduce perioperative myocardial infarction rates. Six hundred thirty consecutive elective vascular operations were performed by the author during 6 years. All patients were entered into a prospective protocol for preoperative cardiac risk assessment, which then determined the choice of operation, type of anesthesia, and level of hemodynamic monitoring. Sixty-eight percent of the patients demonstrated clinical coronary artery disease, 15% had previously undergone coronary catheterization or surgery, and 9% had ejection fractions < 35%. All patients underwent baseline detailed cardiac histories, radionuclide cardioangiography, and electrocardiograms. Patients with significant historic coronary artery disease or ejection fraction <50% underwent stress thallium testing; patients with positive fixed or redistribution defects then underwent catheterization, constituting 7% of the series. Risk stratification by age and cardiac assessment then dictated the perioperative care. The overall perioperative myocardial infarction rate was 0.7% (5628), ranging from 0% for 156 aortic operations and 114 carotid endarterectomies to 0.6% for 159 femoropopliteal and 3.3% for 90 femorotibial revascularizations. All perioperative myocardial infarctions occurred with limb salvage infrapopliteal reconstruction in patients > 75 years of age or with ejection fraction <35%. Comparison with perioperative myocardial infarction rates from the recent literature suggests that our protocol is highly useful in reducing perioperative myocardial infarction rates for aortic and other inflow operations, of only moderate utility for screening outflow operations, and of little use for carotid endarterectomy.