Detection and significance of intraoperative and postoperative myocardial ischemia in peripheral vascular surgery.

OBJECTIVE--To determine the incidence and significance of intraoperative and postoperative myocardial ischemia and their relationship to preoperative ischemia and postoperative cardiac events in patients undergoing peripheral arterial surgery. DESIGN--Prospective cohort trial. PATIENTS--One hundred fifteen patients undergoing elective vascular surgery who met predefined eligibility criteria and were thought to have acceptable cardiac risk as assessed by independent cardiologists. INTERVENTIONS--Ambulatory electrocardiographic monitoring preoperatively, intraoperatively, and up to 72 hours postoperatively. MEASUREMENTS--Preoperative clinical characteristics and laboratory data were collected. Predefined adverse cardiac events were identified by an investigator who was "blinded" to monitoring results. Monitor recordings were interpreted for ST-segment depression by investigators blinded to patient information. MAIN RESULTS--Intraoperative ischemia was present in 21 patients (18%), and postoperative ischemia was present in 35 (30%). There were 16 postoperative cardiac events. The relative risk of suffering a cardiac event was 2.7 in patients with intraoperative ischemia and was 16 in patients with postoperative ischemia. Preoperative ischemia closely correlated with intraoperative and postoperative ischemia. Preoperative and postoperative ischemia preceded cardiac events in 14 of 16 patients. CONCLUSIONS--Preoperative ischemia appears to identify high-risk patients, and subsequent perioperative monitoring detects silent ischemia that commonly precedes clinical events and that may be treatable with anti-ischemia therapy.