Preoperative silent myocardial ischemia. Has it prognostic significance?

We studied the prognostic significance of preoperative silent myocardial ischemia in patients undergoing coronary artery bypass grafting (CABG). Nonfatal and fatal perioperative myocardial infarction were regarded as prognostically important endpoints. Ninety-five patients (9 women) with stable-effort angina pectoris were studied during their hospital stay in the surgery ward before CABG. Silent ischemia was detected using Holter monitoring; all patients had Holter monitoring 76 +/- 9 h before surgery using Marguette Laser Holter and Cardiodata Prodigy systems. Two-channel electrocardiographic recordings were used which included CM5 and a modified inferior lead. Effort was taken to avoid leads with pathological Q waves and resting ST segment abnormalities. The mean duration of the monitoring was 27.9 +/- 11.3 h. Three patients (3.2%) had angina pectoris during these observations, 1 of them with significant ST depression. Silent ST depression was found in 12 patients (12.6%). Twelve patients (12.6%) had perioperative myocardial infarction. Perioperative myocardial infarction was more common in patients with silent ischemia: 4/12 vs. 8/83; chi 2 = 4.48955, p = 0.0341. Our results suggest that Holter monitoring identifies a group of patients with a higher probability of perioperative myocardial infarction. In the future, it may be possible to study different methods to prevent this surgical complication.