Effects of Asymptomatic Ischemia

Background. Ischemia on ambulatory electrocardiographic monitoring has been shown to adversely affect short-term prognoses in patients with unstable angina, after myocardial infarction, and with chronic stable angina. Methods and Results. In this long-term study, we followed 138 patients (mean age, 59±9 years) with chronic stable angina and positive exercise tests for cardiac events (e.g., death, myocardial infarction, percutaneous transluminal coronary angioplasty, or coronary artery bypass graft surgery). In 105 patients, ambulatory electrocardiographic monitoring was performed after all antianginal medication was withheld for 48 hours. In 26 patients, the diagnostic tests were repeated while on their usual medication. In addition to the 105 patients, 33 patients had their monitoring performed only while on their usual medication. During 37±17 months of follow-up, there were nine deaths, nine myocardial infarctions, and 35 revascularization procedures. In patients monitored off medication, Cox survival analysis showed that the occurrence of ischemia on electrocardiographic monitoring was the most significant predictor of death and myocardial infarction in the subsequent 2 years (p=0.02) and of all adverse events for 5 years (p=0.009). Patients who were monitored on medication and did not have ischemia (n=18) appeared to have more adverse events than patients who had no ischemia while being monitored off medication (n =43). Conclusions. Asymptomatic ischemia on ambulatory electrocardiographic monitoring in patients with stable angina predicts death and myocardial infarction for 2 years and all adverse events for 5 years. Monitoring performed while on medication may show no ischemia; however, this may not indicate low risk of future coronary events. (Circulation 1991;83:1598-1604)