Prospective comparison of integrated on-site CT-fractional flow reserve and static CT perfusion with coronary CT angiography for detection of flow-limiting coronary stenosis.

OBJECTIVES To compare the diagnostic power of separately integrating on-site computed tomography (CT)-derived fractional flow reserve (CT-FFR) and static CT stress myocardial perfusion (CTP) with coronary computed tomography angiography (CCTA) in detecting patients with flow-limiting CAD. The flow-limiting stenosis was defined as obstructive (≥ 50%) stenosis by invasive coronary angiography (ICA) with a corresponding perfusion deficit on stress single photon emission computed tomography (SPECT/MPI). METHODS Forty-eight patients (74 vessels) were enrolled who underwent research-indicated combined CTA-CTP (320-row CT scanner, temporal resolution 137 ms) and SPECT/MPI prior to conventional coronary angiography. CT-FFR was computed on-site using resting CCTA data with dedicated workstation-based software. All five imaging modalities were analyzed in blinded independent core laboratories. Logistic regression and the integrated discrimination improvement (IDI) index were used to evaluate incremental differences in CT-FFR or CTP compared with CCTA alone. RESULTS The prevalence of obstructive CAD defined by combined ICA-SPECT/MPI was 40%. Per-vessel sensitivity and specificity were 95 and 42% for CCTA, 76 and 89% for CCTA + CTP, and 81 and 96% for CCTA + CT-FFR, respectively. The diagnostic performance of CCTA (AUC = 0.82) was improved by combining it with CT-FFR (AUC = 0.92, p = 0.01; IDI = 0.27, p < 0.001) or CTP (AUC = 0.90, p = 0.02; IDI = 0.18, p = 0.003). CONCLUSION On-site CT-FFR combined with CCTA provides an incremental diagnostic improvement over CCTA alone in identifying patients with flow-limiting CAD defined by ICA + SPECT/MPI, with a comparable diagnostic accuracy for integrated CTP and CCTA. KEY POINTS • Both on-site CT-FFR and CTP perform well with high diagnostic accuracy in the detection of flow-limiting stenosis. • Comparable diagnostic accuracy between CCTA + CT-FFR and CCTA + CTP is demonstrated to detect flow-limiting stenosis. • Integrated CT-FFR and CCTA derived from a single widened CCTA data acquisition can accurately and conveniently evaluate both coronary anatomy and physiology in the future management of patients with suspected CAD, without the need for additional vasodilator administration and contrast and radiation exposure.