Comparison of Coronary Computed Tomography Angiography, Fractional Flow Reserve, and Perfusion Imaging for Ischemia Diagnosis

Background: Fractional flow reserve (FFR) computation from coronary computed tomography angiography (CTA) datasets (FFR) has emerged as a promising noninvasive test to assess hemodynamic severity of coronary artery disease (CAD), but has not yet been compared with traditional functional imaging.

Objectives: The purpose of this study was to evaluate the diagnostic performance of FFR and compare it with coronary CTA, single-photon emission computed tomography (SPECT), and positron emission tomography (PET) for ischemia diagnosis.

Methods: This subanalysis involved 208 prospectively included patients with suspected stable CAD, who underwent 256-slice coronary CTA, 99mTc-tetrofosmin SPECT, [O]HO PET, and routine 3-vessel invasive FFR measurements. FFR values were retrospectively derived from the coronary CTA images. Images from each modality were interpreted by core laboratories, and their diagnostic performances were compared using invasively measured FFR ≤0.80 as the reference standard.

Results: In total, 505 of 612 (83%) vessels could be evaluated with FFR. FFR showed a diagnostic accuracy, sensitivity, and specificity of 87%, 90%, and 86% on a per-vessel basis and 78%, 96%, and 63% on a per-patient basis, respectively. Area under the receiver-operating characteristic curve (AUC) for identification of ischemia-causing lesions was significantly greater for FFR (0.94 and 0.92) in comparison with coronary CTA (0.83 and 0.81; p < 0.01 for both) and SPECT (0.70 and 0.75; p < 0.01 for both), on a per-vessel and -patient level, respectively. FFR also outperformed PET on a per-vessel basis (AUC 0.87; p < 0.01), but not on a per-patient basis (AUC 0.91; p = 0.56). In the intention-to-diagnose analysis, PET showed the highest per-patient and -vessel AUC followed by FFR (0.86 vs. 0.83; p = 0.157; and 0.90 vs. 0.79; p = 0.005, respectively).

Conclusions: In this study, FFR showed higher diagnostic performance than standard coronary CTA, SPECT, and PET for vessel-specific ischemia, provided coronary CTA images were evaluable by FFR, whereas PET had a favorable performance in per-patient and intention-to-diagnose analysis. Still, in patients in whom 3-vessel FFR could be analyzed, FFR holds clinical potential to provide anatomic and hemodynamic significance of coronary lesions.