The Official Journal of EuroPCR and the European Association of Percutaneous Coronary Interventions (EAPCI)

Reproducibility of Quantitative Flow Ratio: The QREP Study

DOI: 10.4244/EIJ-D-21-00425

1. Department of Cardiology, Aarhus University Hospital, Skejby, Denmark, 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

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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 interobserver reproducibility. Key secondary analysis was identification of clinical and procedural characteristics predicting reproducibility.

Results: The intraobserver CV ranged from 2.3% (1.5-2.8) to 10.2% (6.6-12.0) among the observers. The interobserver CV was 9.4% (8.0-10.5). The QFR observer, low angiographic quality, and low 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 with FFR.

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