Prognostic significance of silent myocardial ischemia in variant angina pectoris

The present study investigates the prognostic significance of silent myocardial ischemia in variant angina. Forty-eight-hour Holter monitoring and coronary angiography were performed in 54 patients with transient ST elevation and no history of myocardial infarction admitted to the coronary care unit for worsening of symptoms. Coronary artery spasm was documented in most of these patients. Over the subsequent month, 20 patients (group 1) had a major coronary event (2 died, 6 had nonfatal myocardial infarction and 12 had urgent coronary revascularization), and the remaining 34 patients (group 2) had a good clinical outcome. From 2,578 hours of recording, 547 ischemic episodes were identified of which only 9% were associated with angina. The mean daily number of ST elevation in group 1 was similar to that in group 2 (4.8 ± 5.1 vs 4.1 ± 4.6; p = not significant). Conversely, the mean daily duration of such ischemic episodes was consistently greater in group 1 than in 2 (79 ± 36 vs 37 ± 25 minutes; p < 0.005). The occurrence of ≥ 1 long-lasting (≥10 minutes) episode of ST elevation was observed in 18 of 20 patients in group 1 (sensitivity 90%), but only in 4 of 34 in group 2 (specificity 88%). Significant coronary atherosclerosis (>50% stenoses) was found at angiography in 18 of 20 patients in group 1, and in 18 of 34 in group 2. Furthermore, morphologic analysis of coronary angiograms revealed the presence of a complex coronary stenosis (overhanging edges, irregular borders or intracoronary thrombus) in 16 of 20 patients in group 1, but only in 4 of 34 in group 2 (p < 0.0005). It is concluded that silent myocardial ischemia is an important predictor of unfavorable short-term clinical outcome due to high-risk (complex morphology) coronary stenoses in variant angina. Patients with coronary artery spasm but without plaque disruption have a benign prognosis. © 1991.