Diagnostic performance of computed tomography-derived fractional flow reserve in patients with severe aortic stenosis

Abstract Background Computed tomography-derived fractional flow reserve (FFR-CT) is a clinical modality for assessing coronary artery disease; however, its use has not been validated in patients with severe aortic stenosis (AS). Purpose This study assessed the diagnostic performance of FFR-CT in patients with severe AS. Methods Retrospectively recruited patients with severe AS underwent standard-protocol invasive fractional flow reserve (FFR) and coronary CT angiography. The FFR-CT values were compared with the invasive FFR values (ischemia defined as invasive FFR ≦0.80). Results Among 46 patients (105 vessels), the mean age was 82.8 ± 5.9 years (37% male). Mean invasive FFR and FFR-CT values were 0.86 ± 0.11 and 0.83 ± 0.10, respectively. In a per-vessel analysis, there was a positive correlation between invasive FFR and FFR-CT values (Pearson correlation coefficient, R= 0.64; P<0.0001). In addition, the sensitivity, specificity, positive predictive, and negative predictive values were 100%, 86%, 43%, and 100% with 88% diagnostic accuracy, respectively. The Bland-Altman plot showed that the mean bias between invasive FFR and FFR-CT values was 0.031 (-0.146 to 0.209). The per vessels area under the receiver-operating characteristic curve analysis was 0.97 (95 % CI: 0.94-1.00, P<0.0001). Importantly, among another 58 patients who deferred invasive coronary angiography (ICA) because the FFR-CT value was negative (> 0.80), none experienced deterioration of condition during transcatheter aortic valve replacement (TAVR) or major adverse cardiac events (all-cause death, myocardial infarction, and unplanned hospitalization with urgent revascularization) within 30 days after TAVR. Conclusions FFR-CT values were significantly correlated with invasive FFR values and had a high negative predictive value in patients with severe AS. Patients with a negative FFR-CT value and deferred ICA had an excellent short-term prognosis after TAVR. FFR-CT is expected to serve as a gatekeeper for unnecessary ICA prior to TAVR.