Many Heart Scans Not Put to Good Use, Study Finds

January 26, 2012
Diagnostic Imaging Staff
Diagnostic Imaging Staff

SPECT, PET and CT angiography results were not leading to therapeutic changes in the patients receiving them.

The most accurate of radiologic scans is wasted if it doesn’t lead to appropriate care. A study published January 31 in the Journal of the American College of Cardiology found that patients at high risk of coronary artery disease gained only marginally from noninvasive imaging. Why? Because SPECT, PET and CT angiography results were not leading to therapeutic changes in the patients receiving them.

Using data from 1,703 patients in the Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in CAD (SPARC), lead author Marcelo Di Carli, MD, of Brigham & Women's Hospital in Boston, and colleagues assessed the rates of catheterization and medication changes 90 days after patients had undergone cardiac single-photon emission computed tomography (SPECT), positron emission tomography (PET), or 64-slice coronary computed tomography angiography (CT angiography). The patients had no documented history of coronary artery disease, but an intermediate to high likelihood of having heart disease.

At 90 days, 9.6 percent of patients underwent catheterization. But among patients with the most severe test result findings, 38 percent to 61 percent were not referred to catheterization, 20 percent to 30 percent were not receiving aspirin, 35 percent to 44 percent were not receiving a beta-blocker, and 20 percent to 25 percent were not receiving a lipid-lowering agent.

Compared with stress SPECT or PET, changes in aspirin and lipid-lowering agent use was greater after CT angiography, as was the 90-day catheterization referral rate for normal/nonobstructive and mildly abnormal test results.

Although cardiac catheterization and medical therapy increased in proportion to the degree of abnormality in imaging results, the relatively low frequency of catheterization and medication change in the wake of radiology exams suggests possible undertreatment of higher risk patients, the researchers said.

“A noninvasive procedure, the results of which have no impact on subsequent management, must be considered an inappropriate study; the current study suggests that a significant amount of inappropriate noninvasive procedures are currently performed,” Di Carli and colleagues added.