Head to head comparison of quantitative flow ratio using 4-French and 6-French catheters versus fractional flow reserve.

OBJECTIVES: To validate QFR using 4-F diagnostic catheters compared to using 6-F guiding catheters, with conventional guidewire-based FFR as the reference standard, using independent core laboratory analysis. BACKGROUND: Quantitative Flow Ratio (QFR) allows Fractional Flow Reserve (FFR) calculation based on the coronary angiogram, using 5- or 6-French (F) catheters. However, the use of 4-F diagnostic catheters to perform coronary angiography is currently routine in some centers. METHODS: We included all consecutive patients with stable coronary artery disease and indicated for physiological assessment. QFR was performed using a 4-F diagnostic catheter, then QFR was performed using a 6-F guiding catheter while conventional FFR was measured using a pressure guidewire. Angiograms were sent to two separate core laboratories. RESULTS: One hundred lesions in 67 consecutive patients with QFR performed using 4-F and 6-F catheters, and with conventional FFR, were included. Pearson's correlation coefficient was for QFR 4-F vs. FFR 0.91 [0.87-0.94], for QFR 6-F vs. FFR 0.90 [0.86-0.94], and for QFR 4-F vs. QFR 6-F 0.93 [0.90-0.95]. Receiver-operator characteristic curves (ROC) comparing the ability to predict an FFR value above or below 0.80 with QFR 4-F and 6-F were generated. The area under the ROC curve (AUC) vs. FFR was 0.972 [0.95-0.99] for QFR 4-F and 0.970 [0.94-0.99] for QFR 6-F. CONCLUSIONS: Our study demonstrated the feasibility of performing QFR analysis from angiograms obtained by 4-F catheters, and showed a good correlation with QFR performed using 6-F catheters as well as with conventional FFR performed using a pressure guidewire.

Quantitative Flow Ratio Analysis by Paramedical Compared With Medical Users.

OBJECTIVES: We aimed to validate whether quantitative flow ratio (QFR) analysis could be performed by both medical and paramedical certified users. Therefore, we compared QFR values with conventional guidewire-based fractional flow reserve (FFR) as the reference using core laboratory analysis. QFR allows FFR calculation based on the coronary angiogram. QFR analysis requires certified users with dedicated training and skills. However, the ability of medical and paramedical users to correctly analyze QFR remains unknown. METHODS: In a prospective, single-center study, we included all consecutive patients with stable coronary artery disease and indicated physiological assessment. QFR was performed and analyzed by 1 medical and 2 paramedical QFR users who were unaware of conventional pressure-guidewire FFR measurements. RESULTS: We included 67 consecutive patients and 100 lesions for assessment with QFR and FFR. Pearson's correlation coefficient of QFR performed by paramedical users compared with medical users was 0.89 (range, 0.83-0.92). A Bland-Altman analysis showed no significant bias (-0.0008). Receiver-operator characteristic curves were generated to compare the ability to predict an FFR value above or below 0.80 with QFR performed by paramedical vs medical users. When comparing FFR with QFR performed by paramedical and medical users, the values for area under the curve were 0.964 and 0.970, respectively. Intraclass correlation was 0.884. CONCLUSION: Our study showed a noticeable correlation between QFR analysis performed by QFR-certified paramedical and medical users, as compared with FFR. These data suggest that QFR analysis could be performed by certified paramedicals in order to reduce physician workload without impacting the quality of the obtained results.