Silent myocardial ischemia and infarction in diabetics with peripheral vascular disease: assessment by dipyridamole thallium-201 scintigraphy. We investigated the incidence of silent myocardial ischemia and infarction as assessed by dipyridamole thallium scintigraphy in 30 diabetic patients with peripheral vascular disease and without clinical suspicion of coronary artery disease. Seventeen patients (57%) had thallium abnormalities, with reversible thallium defects compatible with ischemia in 14 patients (47%) and evidence of prior, clinically silent myocardial infarction in 11 patients (37%). Thallium abnormalities were most frequent in patients with concomitant hypertension and cigarette smoking (p = 0.001). These results suggest that unsuspected coronary artery disease is common in this particular group of patients with diabetes mellitus. 