Background: Fractional flow reserve (FFR) is the gold standard for identifying ischemia-causing coronary artery stenosis and improves clinical decision-making for revascularization in patients coronary artery disease. Computational fluid dynamics applied to coronary CT angiograms (CCTA) permits non-invasive calculation of FFR (FFR_CT) (Figure), but the diagnostic performance of FFR_CT as compared to invasive measured FFR is unknown.
Methods: We conducted a prospective multicenter study to determine the diagnostic performance of FFR_CT on 159 vessels in 103 patients. Independent core laboratories determined FFR_CT and stenosis severity by CCTA. Ischemia was defined by an FFR_CT and FFR���0.80, and anatomically obstructive stenosis was defined with stenosis ���50%. Diagnostic performance of lesion-specific ischemia was determined for FFR_CT and CCTA stenosis relative to an invasive FFR reference standard.
Results: 56% of patients had ���1 vessel with FFR���0.80. On a per-vessel basis, for the diagnosis of lesion-specific ischemia, accuracy, sensitivity, specificity, positive and negative predictive values for FFR_CT were 84.3%, 87.9%, 82.2%, 73.9%, 92.2%, respectively; and for CCTA stenosis were 58.5%, 91.4%, 39.6%, 46.5%, 88.9%, respectively. The area under the receiver operator characteristics curve was 0.90 for FFR_CT and 0.75 for CCTA stenosis (p=0.001), with no added discriminatory value of CCTA stenosis to FFR_CT (p=0.50). FFR_CT and FFR were well correlated (r=0.717, p<0.001) with a slight underestimation by FFR_CT (0.022짹0.116, p=0.016). Similar relationships were observed for diagnostic performance and discrimination for per-patient analyses.
Conclusions: Non-invasive FFR computed from CCTA images is a novel method with high diagnostic performance for the detection and exclusion of coronary lesions that cause ischemia