P853Guiding myocardial revascularization by computer assisted interpretation of FFR pullback curves: an agreement study with actual standard of care
Authors: Argacha J.-F , Decamp J , Mizukami T , Vandeloo B , Sonck J , Lochy S , Schoors D , Azzano A , Roosens B , Michiels V , Collet C , Cosyns B 
Published: October 2019

Abstract

Background
Guidelines recommend hemodynamic/functional assessment to guide treatment decision making in stable coronary artery disease. A Fractional flow reserve (FFR) motorized pullback allows a reproducible assessment of the distribution of pressure drop generated by coronary artery disease along the vessel and may provide more relevant hemodynamic information than a single distal FFR value.

Purpose
We aimed to assess the agreement between the revascularization strategy guided by coronary angiogram and a single distal FFR value interpretation (standard of care, SOC), and a treatment recommendation by a fully automated analysis of pullback FFR curves by an in-house developed computer-based algorithm (CBA).

Methods
Pullback FFR curves were recorded under continuous intra-venous adenosine in patients with intermediate coronary stenosis by using a motorized device working at a speed of 1 mm/s (Volcano R 100) set to grip a pressure wire. A proprietary algorithm (JD, Mathematica v.11) was applied to: 1) assess the distal FFR on the last 5 mm of the curves, 2) discriminate a stepwise from a progressive decrease of FFR, 3) propose a treatment strategy between optimal medical treatment (OMT), PCI (including the number, length(s) and position(s) of the stent) or CABG, 4) evaluate the post PCI expected change in FFR. A concordance analysis between effective and CBA recommended treatment was performed. Only curves with distal FFR ≤0.85 were included into the analysis. If post PCI FFR was recorded, CBA predicted and measured post PCI FFR were compared.

Results
50 vessels from 43 patients (75% LAD, 10% Cx, 15% RCA) with a distal FFR of 0.78±0.08 were assessed. A revascularization was performed in 29 vessels (24 PCI, 5 CABG). Post PCI FFR pullback was recorded in 11 vessels. Compared to SOC, a similar proportion of vessels was referred for revascularization by CBA (56 vs. 58% respectively, Chi2 0.041, p NS). Agreement between SOC and CBA, regarding the need of a revascularization, was observed in 76% of cases. Observed Cohen's Kappa coefficient for OMT, PCI or CABG revascularization strategy was 0.48 (CI 95%: 0.26–0.7). A mismatch between SOC and CBA strategy was observed in 30% (n=15) of vessels. A post hoc examination of FFR pullback curves showed that CBA decision might have been appropriate in 80% of these mismatches. Reclassification of treatment strategy by CBA was related to misinterpretation of one single FFR value (40%, n=6), incorrect detection of significant stepwise decrease in FFR (33%, n=5) and incorrect detection of progressive decrease in FFR (7%, n=1) by SOC approach. A mean bias of 0.01 (CI 95% −0.05–0.07) was observed between CBA predicted and measured post PCI FFR.

Conclusion
CBA recommended treatment differs from SOC treatment in almost 1/3 of vessels. CBA of FFR pullback curves offers new opportunity to guide myocardial revascularization stategy and warrants further prospective evaluation.