The prevalence and the clinical characteristics of silent myocardial ischemia detected by stress thallium scintigraphy]

The prevalence of silent myocardial ischemia was retrospectively assessed in a group of 100 consecutive patients with angiographically proved coronary artery disease, and diagnostic ECG, by symptom-limited exercise thallium-201 scintigraphy. Twenty-four patients had no evidence of ischemia despite adequate exercise level. So among 76 patients with exercise induced ischemia, only 33 patients (43%) stopped exercise due to anginal pain (symptomatic ischemia: Group 3). And 43 patients with asymptomatic ischemia composed of 23 patients (30%) with ECG change (Group 2B) and 20 patients (26%) without ECG change (Group 2A). Patients background including the history of old myocardial infarction and diabetes mellitus, were similar among Group 2A, 2B, and Group 3. And our major observation was that the extent and severity of quantified SPECT perfusion defects was nearly identical between 3 groups Thus in this study group, there was a rather high prevalence rate of silent ischemia (57%) by exercise thallium-201 criteria. Patients with silent ischemia, associated with positive and negative exercise ECG findings, and those with exercise angina had similar background and comparable amount of jeopardized myocardium.