title: Validation of the "smart" minimum FFR Algorithm in an unselected all comer population of patients with intermediate coronary stenoses.
abstract: Using data from a commercial pressure wire system (St. Jude Medical) we previously developed an automated "smart" algorithm to determine a reproducible value for minimum FFR (smFFR) and confirmed that it correlated very closely with measurements made off-line by experienced coronary physiology core laboratories. In this study we used the same "smart" minimum algorithm to analyze data derived from a different, commercial pressure wire system (Philips Volcano) and compared the values obtained to both operator-defined steady state FFR and the online automated minimum FFR reported by the pressure wire analyser. For this analysis, we used the data collected during the VERIFY 2 study (Hennigan et al. in Circ Cardiovasc Interv, doi: 10.1161/CIRCINTERVENTIONS.116.004016 ) in which we measured FFR in 257 intermediate coronary stenoses (mean DS 48%) in 197 patients. Maximal hyperaemia was induced using intravenous adenosine (140 mcg/kg/min). We recorded both the online minimum FFR generated by the analyser and the operator-reported steady state FFR. Subsequently, the raw pressure tracings were coded, anonymised and 256/257 were subjected to further off-line analysis using the smart minimum FFR (smFFR) algorithm. The operator-defined steady state FFR correlated well with smFFR: r = 0.988 (p < 0.001), average bias 0.008 (SD 0.014), 95% limits of agreement -0.020 to 0.036. The online automated minimum FFR also correlated well with the smFFR: r = 0.998 (p < 0.001), average bias 0.004 (SD 0.006), 95% limits of agreement -0.016 to 0.008. Finally, the online automated minimum FFR correlated well the operator-reported steady state FFR: r = 0.988 (p < 0.001), average bias 0.012 (SD 0.014), 95% limits of agreement -0.039 to 0.015. In 95% of lesions studied (244/256), the operator reported steady-state FFR, smFFR, and online automated minimum FFR agreed with each other to within 0.04, which is within the previously reported test/retest limits of agreement of FFR reported by an experienced core lab. Disagreements >0.05 among methods were rare but in these cases the two automated algorithms almost always agreed with each other rather than with the operator-reported value. Within the VERIFY 2 dataset, experienced operators reported a similar FFR value to both an online automated minimum (Philips Volcano) and off-line "smart" minimum computer algorithm. Thus, treatment decisions and clinical studies using either method will produce nearly identical results.
authors.affiliation: University of Glasgow, Glasgow, Scotland, UK. barryhennigan@physicians.ie.|Golden Jubilee National Hospital, Clydebank, Glasgow, Scotland, UK. barryhennigan@physicians.ie.
authors.forename: Barry
authors.identifier: http://orcid.org/0000-0002-3325-5718
authors.initials: B
authors.lastname: Hennigan
authors.affiliation: The Weatherhead PET Imaging Center, Houston, TX, USA.
authors.forename: Nils
authors.initials: N
authors.lastname: Johnson
authors.affiliation: Golden Jubilee National Hospital, Clydebank, Glasgow, Scotland, UK.
authors.forename: John
authors.initials: J
authors.lastname: McClure
authors.affiliation: University of Glasgow, Glasgow, Scotland, UK.|Golden Jubilee National Hospital, Clydebank, Glasgow, Scotland, UK.
authors.forename: David
authors.initials: D
authors.lastname: Corcoran
authors.affiliation: Golden Jubilee National Hospital, Clydebank, Glasgow, Scotland, UK.
authors.forename: Stuart
authors.initials: S
authors.lastname: Watkins
authors.affiliation: University of Glasgow, Glasgow, Scotland, UK.|Golden Jubilee National Hospital, Clydebank, Glasgow, Scotland, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Berry
authors.affiliation: University of Glasgow, Glasgow, Scotland, UK.|Golden Jubilee National Hospital, Clydebank, Glasgow, Scotland, UK.
authors.forename: Keith G
authors.initials: KG
authors.lastname: Oldroyd
mesh_terms: D000465:Algorithms; D001331:Automation; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization / Q000295:instrumentation / Q000379:methods*; D062906:Cardiac Catheters; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D003331:Coronary Vessels / Q000503:physiopathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D009204:Myocardial Revascularization; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012815:Signal Processing, Computer-Assisted; D012986:Software Validation; D014160:Transducers, Pressure
keywords: Coronary revascularisation; Fractional flow reserve; Percutaneous coronary intervention; Revascularisation