Diagnostic concordance and discordance between angiography-based quantitative flow ratio and fractional flow reserve derived from computed tomography in complex coronary artery disease

Background: Both quantitative flow ratio (QFR) and fractional flow reserve derived from computed tomography (FFRCT) have shown significant correlations with invasive wire-based fractional flow reserve. However, the correlation between QFR and FFRCT is not fully investigated in patients with complex coronary artery disease (CAD). The aim of this study is to investigate the correlation and agreement between QFR and FFRCT in patients with de novo three-vessel disease and/or left main CAD. Methods: This is a post-hoc sub-analysis of the international, multicenter, and randomized SYNTAX III REVOLUTION trial, in which both invasive coronary angiography and coronary computed tomography angiography were prospectively obtained prior to the heart team discussion. QFR was performed in an independent core laboratory and compared with FFRCT analyzed by HeartFlow (TM). The correlation and agreement between QFR and FFRCT were assessed per vessel. Furthermore, independent factors of diagnostic discordance between QFR and FFRCT were evaluated. Results: Out of 223 patients, 40 patients were excluded from this analysis due to the unavailability of FFRCT and/or QFR, and a total of 469 vessels (183 patients) were analyzed. There was a strong correlation between QFR and FFRCT (R = 0.759; p < 0.001), and the Bland-Altman analysis demonstrated a mean difference of -0.005 and a standard deviation of 0.116. An independent predictor of diagnostic concordance between QFR and FFRCT was the lesion location in right coronary artery (RCA) (odds ratio 0.395; 95% confidence interval 0.174-0.894; P = 0.026). Conclusion: In patients with complex CAD, QFR and FFRCT were strongly correlated. The location of the lesion in RCA was associated with the highest diagnostic concordance between QFR and FFRCT.