Silent myocardial ischemia monitoring predicts late as well as perioperative cardiac events in patients undergoing vascular surgery

Abstract

In a previous study we have shown that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at significantly increased risk for perioperative myocardial infarction. In the present study a group of 385 patients undergoing peripheral vascular surgery was studied long-term as well as short-term to determine whether perioperative monitoring for silent ischemia can identify those patients who are at significantly increased risk of late cardiac death or late cardiac complications as well as those patients at increased risk of perioperative myocardial infarction. All patients were monitored before, during, and after operation and were divided into two groups on the basis of results of monitoring: patients whose total duration of silent ischemia as a percentage of the total duration of perioperative monitoring was 1% or greater (group I, n = 120) and those for whom this value was less than 1% (group II, n = 265). Among patients in group I 13.3% (16 of 120) suffered a perioperative myocardial infarction in contrast to only 1.1% (3 of 265) patients in group II (p < 0.001). Multivariate logistic regression analysis of preoperative and perioperative characteristics showed that the presence of a total perioperative percent time ischemic 1% or greater and age were the only significant predictors of perioperative myocardial infarction. Actuarial freedom at 24 months after operation for group I compared with group II was, respectively, 89.1% versus 98.4% for late myocardial infarction (p < 0.001), 89.5% versus 99.2% for late cardiac death (p < 0.001), and 58.7% versus 69.4% for late cardiac death or late cardiac complication (angina, myocardial infarction, cardiac evaluation, or cardiac revascularization) (p < 0.02). Cox proportional hazards analysis showed that only the occurrence of a total perioperative percent time ischemic 1% or greater and age were significant independent predictors of early or late myocardial infarction and early or late cardiac death as combined end points. These results show that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at increased risk for late cardiac death or complication as well as perioperative myocardial infarction.