MUNICH, Germany—A noninvasive strategy that integrates computed tomography (CT) angiography with CT myocardial perfusion imaging shows strong diagnostic accuracy in identifying patients who have flow-limiting coronary artery disease (CAD) and need revascularization. The findings were presented August 28, 2012, at the European Society of Cardiology Congress by João AC Lima, MD, of Johns Hopkins Hospital (Baltimore, MD).

For the prospective CORE320 (Combined Coronary Atherosclerosis and Myocardial Perfusion Evaluation using 320 Detector Row Computed Tomography) study, investigators assessed the diagnostic accuracy of combined 320-row CT angiography (Aquilion One; Toshiba Medical Systems; Nasu, Japan) and myocardial CT perfusion imaging in 381 patients with suspected or known CAD at 16 hospitals in 8 countries. Blinded coronary image analysis and myocardial perfusion analysis were performed at separate core labs.

Among the cohort, 26% had previous MI and 29% prior PCI. The prevalence of obstructive CAD defined by combined invasive angiography and SPECT myocardial perfusion imaging was 38%, while the prevalence defined by invasive angiography alone was 59%.

CT Perfusion Adds Value

The incremental value of CT angiography plus CT perfusion for detecting functionally significant lesions was demonstrated by an area under the receiver operating characteristic (ROC) curve of 0.87 (95% CI 0.83-0.91) when the reference standard was 50% or greater obstruction on invasive angiography together with a flow-limiting defect, compared with 0.81 (95% CI 0.77-0.86) for CT angiography alone (P < 0.001). Concomitant use of CT angiography and CT perfusion showed similar diagnostic power when patients with known CAD were excluded.

In addition, the combination of CT angiography and CT perfusion proved comparable to the pairing of invasive angiography and single photon computed tomography (SPECT) myocardial perfusion imaging for predicting which vessels need for revascularization at 30 days (area under the ROC curve 0.79 [95% CI 0.76-0.83] and 0.81 [95% CI 0.78-0.84], respectively; P = 0.35)

Diagnostic Duo Promising, But Clinical Role Unsettled

Commenting on the presentation, Gerald Maurer, MD, of the Medical University of Vienna (Vienna, Austria), said the study “convincingly shows the ability of combined CT angiography and CT perfusion to provide both anatomic and functional information in CAD.

But, he cautioned, the procedure is not applicable to the entire CAD patient population since there are a number of contraindications. In general, more experience is needed to define the future role of this test in clinical practice, he observed. And in many patients—especially those with a high pretest likelihood of disease—proceeding directly to invasive angiography based on clinical information, with or without a nonimaging stress test, will likely continue to be the most appropriate course. Another issue that needs to be addressed, Dr. Maurer said, is the role of invasive FFR at the time of angiography compared with prior CT perfusion imaging.

Dr. Maurer noted that although stress CT perfusion, which uses adenosine, is performed in the same imaging session as CT angiography, it is a separate study and requires additional radiation as well as contrast material. Another consideration, he noted, is that 320-row scanners are not widely available, and different scanners may yield different results. And finally, cost-effectiveness will have to be carefully assessed.

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