The prevalence and prognosis of unrecognized myocardial infarction and silent myocardial ischemia in patients undergoing major vascular surgery

OBJECTIVE: The aim of this study is to determine the prevalence and prognosis of unrecognized myocardial infarction (MI) and silent myocardial ischemia in vascular surgery patients.

METHODS: In a cohort of 1092 patients undergoing preoperative dobutamine stress echocardiography and noncardiac vascular surgery, unrecognized MI was determined by rest wall motion abnormalities in the absence of a history of MI. Silent myocardial ischemia was determined by stress-induced wall motion abnormalities in the absence of angina pectoris. Beta blockers and statins were noted at baseline. During follow-up (mean: 6+/-4 years), all-cause mortality and major cardiac events (cardiac death or nonfatal MI) were noted.

RESULTS: The prevalence of unrecognized MI and silent myocardial ischemia was 23 and 28%, respectively. Both diabetes and heart failure were important predictors of unrecognized MI and silent myocardial ischemia. During follow-up, all-cause mortality occurred in 45% and major cardiac events in 23% of patients. In multivariate analysis, unrecognized MI and silent myocardial ischemia were significantly associated with increased risk of mortality [hazard ratio (HR), 1.86; 95% confidence interval (CI), 1.53-2.25 and HR, 1.74; 95% CI, 1.46-2.06, respectively] and major cardiac events (HR, 2.15; 95% CI, 1.59-2.92 and HR, 1.86; 95% CI, 1.43-2.41, respectively). In patients with unrecognized MI, beta-blockers and statins were significantly associated with improved survival. Statins improved survival in patients with silent myocardial ischemia.

CONCLUSIONS: In patients undergoing major vascular surgery, unrecognized MI and silent myocardial ischemia are highly prevalent (23 and 28%) and associated with increased long-term mortality and major cardiac events.