Exercise thallium scans: patterns of use and impact on management of patients with known or suspected coronary artery disease.

Physicians' ordering patterns and subjective assessments of the management impact of 345 exercise thallium studies at a tertiary care hospital were evaluated. Exercise thallium tests were ordered to obtain functional information (60%), to detect myocardial ischemia (29%), for routine follow-up (6%) and for screening for coronary artery disease (CAD) (5%). Exercise thallium testing was ordered instead of exercise electrocardiography alone because of an interest in assessing the size of an ischemic or infarcted area (37%), a belief that the exercise electrocardiogram was likely to be nondiagnostic (35%) or that exercise thallium was a better test (23%). In 20% of cases physicians said that thallium imaging results were helpful or pivotal in major management decisions, such as those regarding catheterization or surgery. In most cases, no further tests were ordered and antianginal therapy or activity prescription was changed after exercise thallium testing. Exercise thallium images also helped to stratify patients into low and high probability of CAD categories better than exercise electrocardiographic results alone did. Our data suggest that physicians are using exercise thallium testing to obtain functional information more often than simply to detect CAD and that physicians consider the test to be of considerable value.