Abnormal thallium-201 scans in patients with chest pain and angiographically normal coronary arteries.

We reviewed the exercise thallium-201 (TI-201) scans and clinical data of 41 patients with chest pain and normal coronary arteries to identify clinical factors associated with "false-positive" studies. Exercise TI-201 studies were performed before angiography and often precipitated referral. Sex, beta-blocker therapy, anginal pattern, and results of exercise electrocardiography were evaluated and compared with TI-201 imaging. A negative TI-201 study was the most common finding (p less than 0.005). Of the 41 patients, 11 (27%) had abnormal exercise TI-201 scans. No clinical factor was significantly associated with a false-positive TI-201 scans. Of the 11 patients with abnormal scans, 9 had greater than or equal to 1 cardiac abnormality: right bundle branch block in 2, mitral valve prolapse in 3, paroxysmal atrial fibrillation in 2, abnormal left ventricular diastolic pressure in 3, and left bundle branch block in 1. Thus, (1) when results of exercise TI-201 imaging are used to refer patients for angiography, "false-positive" TI-201 studies are common; (2) sex, beta blockade, anginal pattern, and results of exercise electrocardiogram are not useful predictors of a false-positive TI-201 study; and (3) patients with chest pain, normal coronary arteries, and abnormal TI-201 scans frequently have other cardiac abnormalities.