Coronary interventions - Mini focus on Coronary Physiology

Reproducibility of quantitative flow ratio: the QREP study

EuroIntervention 2022;17:1252-1259. DOI: 10.4244/EIJ-D-21-00425

Jelmer Westra
Jelmer Westra1, MD; Martin Sejr-Hansen1, BSc; Lukasz Koltowski2, MD; Hernán Mejía-Rentería3, MD; Shengxian Tu4, PhD; Janusz Kochman2, MD; Yimin Zhang4, MSc; Tommy Liu5, MD; Gianluca Campo6, MD; Jakob Hjort1, MPH; Lone Juul Hune Mogensen1, MStat; Andrea Erriquez6, MD; Birgitte Krogsgaard Andersen1, MD; Ashkan Eftekhari1, MD, PhD; Javier Escaned3, MD, PhD; Evald Høj Christiansen1, MD, PhD; Niels Ramsing Holm1, MD
1. Department of Cardiology, Aarhus University Hospital, Skejby, Denmark; 2. Department of Cardiology, Medical University of Warsaw, Warsaw, Poland; 3. Department of Cardiology, Hospital Clinico San Carlos, Madrid, Spain; 4. School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China; 5. Department of Cardiology, Hagaziekenhuis, The Hague, the Netherlands; 6. Cardiology Unit, Azienda Ospedaliera Universitaria di Ferrara, Ferrara, Italy and Maria Cecilia Hospital, GVM Care & Research, Cotignola (RA), Italy

Background: Quantitative flow ratio (QFR) is a tool for physiological lesion assessment based on invasive coronary angiography.

Aims: We aimed to assess the reproducibility of QFR computed from the same angiograms as assessed by multiple observers from different, international sites.

Methods: We included 50 patients previously enrolled in dedicated QFR studies. QFR was computed twice, one month apart by five blinded observers. The main analysis was the coefficient of variation (CV) as a measure of intra- and inter-observer reproducibility. Key secondary analysis was the identification of clinical and procedural characteristics predicting reproducibility.

Results: The intra-observer CV ranged from 2.3% (1.5-2.8) to 10.2% (6.6-12.0) among the observers. The inter-observer CV was 9.4% (8.0-10.5). The QFR observer, low angiographic quality, and low fractional flow reserve (FFR) were independent predictors of a large absolute difference between repeated QFR measurements defined as a difference larger than the median difference (>0.03).

Conclusions: The inter- and intra-observer reproducibility for QFR computed from the same angiograms ranged from high to poor among multiple observers from different sites with an average agreement of 0.01±0.08 for repeated measurements. The reproducibility was dependent on the observer, angiographic quality and the coronary artery stenosis severity as assessed by FFR.

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