Increased incidence of silent ischemia after acute myocardial infarction

Objective.-To determine the incidence of angina pectoris during induced myocardial ischemia in patients who have had thrombolytic therapy for acute myocardial infarction in comparison with patients with angina pectoris. Design.-During percutaneous transluminal coronary angioplasty, both study groups had coronary artery occlusion by the balloon dilatation catheter for 5 minutes. Setting.-A tertiary, cardiology referral center. Patients.-Twenty-five patients with angina pectoris who were undergoing angioplasty were compared with 30 patients having angioplasty 2 days after thrombolytic therapy for acute myocardial infarction. Outcomes.-Development of angina pectoris during balloon occlusion of the coronary artery was the primary end point; the ischemic response and muscle viability were assessed using both surface and intracoronary electrocardiograms and pulmonary artery wedge pressure. Results.-During balloon occlusion 16 (64%) of 25 patients in the angina pectoris group developed angina. In contrast, nine (30%) of 30 patients in the thrombolysis group had angina pectoris during balloon occlusion of the infarct artery (P<.01). The electrocardiographic response to ischemia and changes in pulmonary wedge pressure were similar in the two study groups. Conclusion.-After thrombolytic therapy for myocardial infarction, silent ischemia may be the rule rather than the exception.