Usefulness of Exercise Thallium-201 Imaging in Evaluation of Low- and High-risk Groups in Coronary Artery Disease Patients with Disappearance of Anginal Episodes by Anti-anginal Drug Therapy.

Our objective was to clarify the management of patients with silent myocardial ischemia (SMI) and documented coronary artery disease. We evaluated 222 such patients who did not develop anginal pain during exercise thallium-201 imaging (ST-TL). They were divided into low- and high-risk groups based on results of left ventriculographic findings at rest, ST-TL, and coronary angiography. The incidence of cardiac events was 28/222 (13%) overall, being 9 of 110 (8%) in the low-risk patients, and 19 of 112 (17%) in the high-risk group. Kaplan-Meier survival analysis revealed a significant difference between the two groups (p = 0.020). Analysis of the survival of the high-risk group revealed significant differences between the patients with a negative and positive redistribution (p = 0.047), but such differences were not significant in the low-risk patients. Therefore, the classification of SMI patients into low- and high-risk categories was an appropriate strategy. ST-TL was useful for identifying patients with myocardial ischemia and selecting those to receive coronary revascularization and/or drug therapy.