Coronary computed tomography angiography-derived quantitative flow ratio of stented coronary vessels: comparison with invasive fractional flow reserve.

BACKGROUND: Coronary computed tomography angiography (CCTA)-derived fractional flow reserve (FFR) is increasingly used for the assessment of chronic coronary syndrome (CCS). However, physiologic evaluation of stented vessels remains challenging. We aimed to evaluate the diagnostic performance of quantitative flow ratio derived from CCTA (CT-μFR) in stented vessels using invasive FFR as the reference standard. METHODS: We retrospectively investigated patients with CCS who underwent CCTA and coronary angiography with invasive FFR measurement for stented vessels within 3 months. CT-μFR and angiography-derived μFR were analyzed using dedicated computational software. Hemodynamically significant stenosis was defined as FFR, CT-μFR, or μFR ≤ 0.80. RESULTS: Paired FFR, CT-μFR, and μFR measurements were available in 57 vessels from 45 patients. Median FFR, CT-μFR, and μFR were 0.83 (interquartile range [IQR], 0.78-0.90), 0.80 (0.74-0.86), and 0.85 (0.79-0.90), respectively. Of the 57 vessels, 21 (36.8%) had FFR ≤ 0.80. CT-μFR showed good correlation with FFR (r = 0.804, p < 0.001) and acceptable agreement on Bland-Altman analysis (mean bias, 0.042; 95% limits of agreement, -0.083 to 0.167). Vessel-level diagnostic accuracy of CT-μFR for identifying invasive FFR-defined hemodynamically significant stenosis was 80.7% (95% CI, 68.1-90.0%), with high sensitivity and negative predictive value but more modest specificity and positive predictive value. ROC analysis showed that CT-μFR had discrimination comparable to μFR. CONCLUSIONS: CT-μFR showed promising diagnostic performance in evaluable stented coronary vessels. Its high sensitivity and negative predictive value suggest potential rule-out value, whereas rule-in capability remains limited.