Is Cardiac CT Angiography a Proper Substitute for Conventional Procedures?

In a study by researchers the conclusion was that - Cardiac CT angiography misclassifies diagnosis of coronary stenosis in too many patients to replace conventional invasive imaging. The noninvasive technique had a diagnostic accuracy of 93% for coronary obstruction and identified patients who subsequently underwent revascularization at least as well as conventional angiography (area under the curve 0.84 versus 0.82, P=0.36), Joao A.C. Lima, M.D., of Johns Hopkins Hospital, and colleagues found in a prospective, international trial of symptomatic patients. CT angiography's positive predictive value of 91% and a negative predictive value of 83% didn't measure up, they reported in the November issue of the New England Journal of Medicine.

The 13% misclassification indicates that "multidetector CT angiography cannot be used as a simple replacement for conventional coronary angiography,".

Earlier studies on CT angiography have had widely varying results for determining coronary obstruction , likely because of limitations in selection of patients, small sample size, single-center study design, and CT technology .

This study compared 64-row, 0.5-mm multidetector CT angiography and conventional coronary angiography in 291 patients referred for conventional angiography because of suspected symptomatic coronary artery disease .

The participants underwent blinded calcium scoring and CT angiography before conventional coronary angiography and only those with calcium scores of 600 or less were included in the study.

Another area to examine is the fact that cardiac imaging leads to unnecessary procedures and the "equipment bombards patients with radiation many orders of magnitude greater that that of traditional radiographs ."

The findings could not answer questions of use in asymptomatic patients, the results should not be used to support screening for asymptomatic coronary artery disease