Cardiac Events in Patients with Silent Myocardial Ischemia

The clinical implications of silent myocardial ischemic (SMI) episodes in patients with coronary artery disease were assessed in 253 patients whose angina symptoms were resolved by antianginal drugs. This population included 93 patients without a history of myocardial infarction (angina group) and 160 patients with myocardial infarction (infarction group). These patients were further divided into 2 subgroups according to whether or not SMI was detected by Holter monitoring immediately before discharge. The incidence of cardiac events was 19% for the angina group and 18% for the infarction group. The incidence of cardiac events did not differ between the 2 groups, but the cardiac event profile did. Briefly, 14 angina patients experiencing cardiac events needed coronary revascularization for worsening symptoms, while 18 myocardial infarction patients experiencing cardiac events had another infarction. In both angina and myocardial infarction patients, the cumulative rates of cardiac events were significantly higher in the subgroups with SMI (p<0.01 in either group). The significant prognostic factors as determined in the Cox regression model were multivessel disease, asynergy score, and SMI on Holter monitoring for angina patients, and SMI on Holter monitoring and multivessel disease for myocardial infarction patients. In conclusion, the cardiac event rate is significantly elevated in the subgroups with SMI, regardless of whether the patient had previous myocardial infarction; patients with SMI carry a poor prognosis, especially when they have a history of myocardial infarction.