Several studies show that patients, especially those with low to intermediate pretest probability of coronary artery disease (CAD) and normal stress single-photon emission computed tomography (SPECT) perfusion imaging, have an annual event rate of death or nonfatal myocardial infarction of <1%/year.(1-3) It is unlikely that coronary interventions can improve survival in this cohort of patients. In 1 study the utilization rate of coronary angiography and coronary revascularization was directly related to the use of stress imaging (more imaging studies resulted in more coronary angiography and coronary revascularization).(4) In other studies, however, the rate of coronary angiography was deemed appropriate based on SPECT results: very low rate in patients with normal or near-normal images, intermediate rate in patients with intermediate abnormality, and high rate in patients with severe abnormality.(5,6) This study examined the downstream utilization rate in 2 cohorts of patients with intermediate pretest probability of CAD. In 1 group, coronary angiography was used as an initial screening test and in the second group stress SPECT perfusion imaging was the initial screening test and coronary angiography was subsequently performed if deemed necessary. Medicare reimbursements were used to calculate the cost savings.

This study compared qualitative assessment of exercise thallium imaging to quantitative assessment in predicting outcome in 713 patients with 78% prevalence of coronary artery disease by coronary angiography; during a mean follow-up of 52 months, there were 106 hard cardiac events (death or nonfatal myocardial infarction). The qualitative method provided important prognostic information; however, unlike the quantitative technique, less patients were assigned to either the low- or high-risk group and proportionally more patients into the intermediate-risk group, which may limit the clinical usefulness of the technique.