Dipyridamole-thallium stress testing: a local community hospital experience

Clinical data on the first 100 patients who underwent dipyridamole-thallium stress testing in our hospital were reviewed in order to re-evaluate safety guidelines and diagnostic utility in patients with coronary artery disease. Forty patients developed symptoms, including three major ones. One patient had significant bronchospasm, and two others developed significant hypotension with near syncope. The rest had nonspecific chest, shoulder, arm or throat pain, dyspnea, nausea, vomiting, and paresthesia. Most symptoms occurred within the first 10 minutes of dipyridamole infusion. Twenty-eight patients required treatment with intravenous (IV) aminophylline. Of the remaining 60 patients, 30 became hypotensive but remained asymptomatic. Fourteen of 20 patients who underwent coronary angiography had coronary disease. Thirteen were correctly identified by thallium imaging, and only one was identified by electrocardiogram (EKG). Six patients' angiographies showed no evidence of coronary disease. Five of these patients developed perfusion abnormalities during thallium scintigraphy. These results suggest that dipyridamole is a relatively safe drug for pharmacologic stress testing even though the incidence of side effects is relatively high. The high incidence of thallium perfusion abnormalities in patients without coronary disease probably reflects bias in patient selection for coronary angiography, resulting in a relatively small sample of catheterized patients. However, this requires further investigation.