The combination of CT angiography (CTA) and CT myocardial perfusion (CTP) accurately identified patients with flow-limiting coronary artery disease (CAD) defined by 50 percent stenosis or greater using invasive tests, according to a study published online Nov. 19 in European Heart Journal.

“The purpose of this study was to test the hypothesis that a combined, noninvasive CTA/CTP strategy could reliably identify or exclude flow limiting coronary stenoses in patients with suspected CAD using the composite reference standard of ICA [invasive coronary angiography] plus SPECT/MPI,” wrote the authors, co-led by Carlos E. Rochitte, MD, of the University of Sao Paulo Medical School in Brazil, and Richard T. George, MD, of Johns Hopkins Hospital in Baltimore.

The Coronary Artery Evaluation using 320-row Multidetector Computed Tomography Angiography and Myocardial Perfusion (CORE320) study evaluated the accuracy of a 320-row CT scanner in identifying flow-limiting CAD. Investigators enrolled 381 patients between 45 and 85 years old with CAD who were referred for ICA in eight countries. They performed a combination of CTA and CTP along with SPECT/MPI before standard coronary angiography.

Using ICA-SPECT/MPI resulted in an obstructive CAD prevalence of 38 percent compared with 59 percent using ICA alone.

The area under the curve (AUC) of CTA-CTP for detecting or excluding flow limiting CAD was 0.87. In patients with no heart attack history, the AUC was 0.90 and in patients with no CAD history, the AUC for CTA-CTP was 0.93. In patients with both a CTA stenosis of 50 percent or greater and a CTP perfusion deficit, the sensitivity value was 80 percent, the specificity value was 74 percent, the positive predictive value was 65 percent and the negative predictive value was 86 percent.

The findings are relevant to patients with chest pain but no heart attack, co-author Joao A.C. Lima, MD, of Johns Hopkins Hospital explained. These patients are often sent for more invasive testing which, in about 30 percent of cases, reveals either minor disease or no blockage at all.

“Many patients are sent for an angioplasty when they may not need it,” George said in a press release. “Our ultimate goal is to have more certainty about which patients having chest pain – without evidence of a heart attack – need an invasive procedure to open an arterial blockage.”