Accuracy of coronary computed tomography angiography-derived quantitative flow ratio for onsite assessment of coronary lesions.

Background: Coronary computed tomography angiography (CCTA)-derived Murray law-based quantitative flow ratio (CT-μFR) is a novel non-invasive method for fast computation of fractional flow reserve (FFR) from CCTA images, yet its diagnostic performance remains to be prospectively validated.

Aims: We aimed to evaluate the diagnostic performance of onsite CT-μFR in patients with coronary artery disease.

Methods: This prospective, single-centre trial enrolled patients with ≥1 lesion with 30-90% diameter stenosis on CCTA and planned invasive coronary angiography (ICA) within 30 days. CT-μFR, ICA-derived μFR and FFR were evaluated separately in a blinded fashion. The primary endpoint was the diagnostic accuracy of CT-μFR in identifying patients with haemodynamically significant coronary stenosis defined by the invasive standard: FFR ≤0.80, or μFR ≤0.80 when FFR was not available.

Results: Between December 2020 and August 2023, 260 patients were consecutively enrolled. Paired comparison between CT-μFR and the invasive standard was obtained in 706 vessels from 260 patients. The patient-level accuracy of CT-μFR was 89.6% (95% confidence interval [CI]: 85.9-93.4%), which was significantly higher than the prespecified target of 72.0% (p<0.001). Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios for CT-μFR were 93.1%, 86.1%, 87.1%, 92.5%, 6.7, and 0.1, respectively. Out of the 231 vessels investigated by FFR, the accuracy of CT-μFR in vessels without extensive calcification was non-inferior to that of μFR (90.6% vs 88.9%; difference=1.8% [95% CI: -2.8 to 5.5%]; p for non-inferiority<0.001).

Conclusions: The study met its prespecified primary endpoint of the diagnostic accuracy of CT-μFR in identifying patients with haemodynamically significant coronary stenosis. CT-μFR was non-inferior to ICA-derived μFR in vessels without extensive calcification. (ClinicalTrials.gov: NCT04665817).