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Quantitative flow ratio and instantaneous wave-free ratio for the assessment of the functional severity of intermediate coronary artery stenosis

Emori, Hiroki; Kubo, Takashi; Kameyama, Takeyoshi; Ino, Yasushi; Matsuo, Yoshiki; Kitabata, Hironori; Terada, Kosei; Katayama, Yosuke; Taruya, Akira; Shimamura, Kunihiro; Shiono, Yasutsugu; Tanaka, Atsushi; Hozumi, Takeshi; Akasaka, Takashi

doi: 10.1097/MCA.0000000000000650
Coronary Physiology

Objective Quantitative flow ratio (QFR) is a novel physiological index of the severity of coronary stenosis. The aim of the present study was to investigate the relationship between QFR and the instantaneous wave-free ratio (iFR).

Patients and methods We analyzed contrast-flow QFR, iFR, and fractional flow reserve (FFR) in 100 coronary arteries with intermediate stenosis.

Results There was a high correlation (r=0.71, P<0.001) and a good agreement (mean difference: −0.09±0.11) between QFR and iFR. Both QFR and iFR were correlated significantly with FFR (r=0.89, P<0.001 and r=0.76, P<0.001, respectively). The mean absolute difference between FFR and QFR was significantly smaller than that between FFR and iFR (−0.01±0.07 vs. −0.08±0.09, P<0.001). The diagnostic accuracy of QFR less than or equal to 0.80 for predicting FFR less than or equal to 0.80 was numerically higher than that of iFR less than or equal to 0.89 for predicting FFR less than or equal to 0.80 [QFR: 94% (95% confidence interval: 85–97%) vs. iFR: 74% (95% confidence interval: 65–81%)].

Conclusion QFR was correlated highly with iFR as well as FFR. Like FFR and iFR, QFR might be reliable for assessing the physiological severity of coronary stenosis in the angiographic intermediate lesions.

Department of Cardiovascular Medicine, Wakayama Medical University, Wakayama, Japan

Correspondence to Takashi Kubo, MD, PhD, Department of Cardiovascular Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan Tel: +81 734 410 621; fax: +81 734 460 631; e-mail: takakubo@wakayama-med.ac.jp

Received April 5, 2018

Received in revised form May 23, 2018

Accepted May 24, 2018

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