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Reproducibility of quantitative flow ratio: the QREP study.

Jelmer Westra1, Martin Sejr-Hansen1, Lukasz Koltowski2

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Eurointervention : Journal of Europcr in Collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology
|July 5, 2021
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Summary

Quantitative flow ratio (QFR) reproducibility varied among international observers. Factors like observer experience, image quality, and lesion severity (FFR) impacted QFR measurement consistency.

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Area of Science:

  • Cardiovascular Imaging
  • Interventional Cardiology
  • Medical Device Technology

Background:

  • Quantitative flow ratio (QFR) is an invasive tool for assessing coronary artery physiology.
  • Accurate physiological assessment is crucial for guiding revascularization decisions.

Purpose of the Study:

  • To evaluate the reproducibility of QFR measurements.
  • To assess inter- and intra-observer variability in QFR analysis across different international sites.

Main Methods:

  • Fifty patients from prior QFR studies were included.
  • QFR was calculated twice, one month apart, by five blinded observers.
  • Reproducibility was measured using coefficient of variation (CV); predictors of variability were analyzed.

Main Results:

  • Intra-observer CV ranged from 2.3% to 10.2%; inter-observer CV was 9.4%.
  • Observer, low angiographic quality, and low fractional flow reserve (FFR) predicted larger QFR differences.
  • Average agreement for repeated measurements was 0.01±0.08.

Conclusions:

  • QFR reproducibility is variable among international observers and dependent on multiple factors.
  • Observer, image quality, and stenosis severity (FFR) influence QFR measurement consistency.
  • Further standardization may be needed to optimize QFR application in clinical practice.