Perioperative myocardial ischemic injury in high-risk vascular surgery patients: Incidence and clinical significance in a prospective clinical trial

Objective: The purpose of this study was to assess prospectively the incidence, health care resource utilization, and economic burden associated with perioperative myocardial ischemic injury (PMII) in high-risk patients undergoing noncardiac vascular surgery. Methods: Two hundred thirty-six patients consented to participate in a pharmacoeconomic substudy as part of a randomized, multicenter clinical trial. Patients were assessed for myocardial ischemic injury by using clinical, biochemical, and electrocardiographic criteria. PMII was defined as fatal or nonfatal myocardial infarction, new or worsened congestive heart failure, or new arrhythmias. Resource utilization parameters were compared for patients with and without PMII. Patients underwent the following index procedures: open abdominal aortic aneurysm repair (n = 44), bypass for aortoiliac disease (n = 29), bypass for femoropopliteal disease (n = 62), bypass for femorotibial disease (n = 71), extra-anatomic bypass (n = 23), and miscellaneous (n = 7). Patients undergoing carotid endarterectomy or only endovascular interventions were excluded. The incremental cost of PMII was estimated by applying the average costs (adjusted to 2004 US dollars) of the hospital ward ($700.00/d) or intensive care unit ($2500.00/d) to the length of stay differences for patients with and without PMII. Results: The overall mortality was 3.4% (8/236), and 7 of 8 deaths were related to PMII. PMII occurred in 42 (17.8%) of 236 patients: 22 myocardial infarctions, 11 congestive heart failures, and 12 new arrhythmias (3 patients had 2 PMII events). There was no evidence of differences in the incidence of PMII among the various index procedures. PMII was associated with a dramatic increase in resource utilization. The mean length of stay was 16.8 and 10.0 days for patients with and without PMII, respectively (P < .001). Intensive care unit care was required by 35 (83.3%) of 42 patients with and 121 (62.4%) of 194 patients without PMII (P < .009). The mean intensive care unit length of stay was 6.6 and 3.7 days for patients with and without PMII, respectively (P < .009). Ten (23.8%) of 42 patients with and 20 (10.3%) of 194 patients without PMII returned to the emergency department for care after discharge (P < .02). Conclusions: In modern vascular surgery practice, PMII remains common despite the availability of β-blockers and other preventative strategies. PMII is associated with dramatic increases in resource utilization and cost. The increase in resource utilization associated with PMII resulted in an estimated incremental cost per patient of $9980.00. If 250,000 high-risk open vascular operations are performed annually in the United States, the economic burden of PMII in these procedures alone approximates $444 million. Strategies to decrease PMII incidence and severity should be evaluated in large-scale prospective trials.