Three-dimensional modeling and numerical analysis of fractional flow reserve in human coronary arteries

Introduction: Noninvasive fractional flow reserve (FFR) computed from CT (FFR_CT) is a novel method for determining the physiologic significance of coronary artery disease (CAD). Several clinical trials have been conducted, but its diagnostic performance varied among different trials.

Aim: To determine the cut-off value of FFR_CT and its correlation with the gold standard used to diagnose CAD in clinical practice.

Material and methods: Forty patients with single vessel disease were included in our study. Computed tomography scan and coronary angiography with FFR were conducted for these patients. Three-dimensional geometric reconstruction and numerical analysis based on the computed tomographic angiogram (CTA) of coronary arteries were applied to obtain the values of FFR_CT. The correlation between FFR_CT and the gold standard used in clinical practice was tested.

Results: For FFR_CT, the best cut-off value was 0.76, with the sensitivity, specificity, positive predictive value and negative predictive values of 84.6%, 92.9%, 88% and 73.3%, respectively. The area under the receiver-operator characteristics curve was 0.945 (p < 0.0001). There was a good correlation of FFR_CT values with FFR values (r = 0.94, p < 0.0001), with a slight overestimation of FFR_CT as compared with measured FFR (mean difference 0.01 ±0.11, p < 0.05). For inter-observer agreement, the mean κ value was 0.69 (0.61 to 0.78) and for intra-observer agreement the mean κ value was 0.61 (0.50 to 0.72).

Conclusions: FFR_CT derived from CT of the coronary artery is a reliable non-invasive way providing reliable functional information of coronary artery stenosis.