RESUMO
BACKGROUND: The aim of this study was to evaluate the diagnostic performance of coronary CT angiography (CTA)-based quantitative flow ratio (QFR), namely CT-QFR, and compare it with invasive coronary angiography (ICA)-based Murray law QFR (µQFR), using fractional flow reserve (FFR) as the reference standard. METHODS: Patients who underwent coronary CTA, ICA and pressure wire-based FFR assessment within two months were retrospectively analyzed. CT-QFR and µQFR were computed in blinded fashion and compared with FFR, all applying the same cut-off value of ≤0.80 to identify hemodynamically significant stenosis. RESULTS: Paired comparison between CT-QFR and µQFR was performed in 191 vessels from 167 patients. Average FFR was 0.81 â± â0.10 and 42.4% vessels had an FFR ≤0.80. CT-QFR had a slightly lower correlation with FFR compared with µQFR, although statistically non-significant (r â= â0.87 versus 0.90, p â= â0.110). The vessel-level diagnostic performance of CT-QFR was slightly lower but without statistical significance than µQFR (AUC â= â0.94 versus 0.97, difference: -0.03 [95%CI: -0.00-0.06], p â= â0.095), and substantially higher than diameter stenosis by CTA (AUC difference: 0.17 [95%CI: -0.10-0.23], p â< â0.001). The patient-level diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio for CT-QFR to identify FFR value â≤ â0.80 was 88%, 90%, 86%, 86%, 91%, 6.59 and 0.12, respectively. The diagnostic accuracy of CT-QFR was 84% in extensively calcified lesions, while in vessels with no or less calcification, CT-QFR showed a comparable diagnostic accuracy with µQFR (91% versus 92%, p â= â0.595). Intra- and inter-observer variability in CT-QFR analysis was -0.00 â± â0.04 and 0.00 â± â0.04, respectively. CONCLUSIONS: Performance in diagnosis of hemodynamically significant coronary stenosis by CT-QFR was slightly lower but without statistical significance than µQFR, and substantially higher than CTA-derived diameter stenosis. Extensively calcified lesions reduced the diagnostic accuracy of CT-QFR.