Open Heart (Jun 2020)

Functional classification discordance in intermediate coronary stenoses between fractional flow reserve and angiography-based quantitative flow ratio

  • Yoshinori Kanno,
  • Masahiro Hoshino,
  • Rikuta Hamaya,
  • Tomoyo Sugiyama,
  • Yoshihisa Kanaji,
  • Eisuke Usui,
  • Masao Yamaguchi,
  • Masahiro Hada,
  • Hiroaki Ohya,
  • Yohei Sumino,
  • Hidenori Hirano,
  • Haruhito Yuki,
  • Tomoki Horie,
  • Tadashi Murai,
  • Tetsumin Lee,
  • Taishi Yonetsu,
  • Tsunekazu Kakuta

DOI
https://doi.org/10.1136/openhrt-2019-001179
Journal volume & issue
Vol. 7, no. 1

Abstract

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BackgroundMeasurement of the contrast-flow quantitative flow ratio (cQFR) is a novel method for rapid computational estimation of fractional flow reserve (FFR). Discordance between FFR and cQFR has not been completely characterised.MethodsWe performed a post-hoc analysis of 504 vessels with angiographically intermediate stenosis in 504 patients who underwent measurement of FFR, coronary flow reserve (CFR), the index of microcirculatory resistance (IMR) and Duke jeopardy score.ResultsIn total, 396 (78.6%) and 108 (21.4%) lesions showed concordant and discordant FFR and cQFR functional classifications, respectively. Among lesions with a reduced FFR (FFR+), those with a preserved cQFR (cQFR−) showed significantly lower IMR, shorter mean transit time (Tmn), shorter lesion length (all, p<0.01) and similar CFR and Duke jeopardy scores compared with lesions showing a reduced cQFR (cQFR+). Furthermore, lesions with FFR+ and cQFR− had significantly lower IMR and shorter Tmn compared with lesions showing a preserved FFR (FFR−) and cQFR+. Of note, in cQFR+ lesions, higher IMR lesions were associated with decreased diagnostic accuracy (high-IMR; 63.0% and low-IMR; 75.8%, p<0.01). In contrast, in cQFR− lesions, lower IMR lesions was associated with decreased diagnostic accuracy (high-IMR group; 96.8% and low-IMR group; 80.0%, p<0.01). Notably, in total, 31 territories (6.2%; ‘jump out’ group) had an FFR above the upper limit of the grey zone (>0.80) and a cQFR below the lower limit (≤0.75). In contrast, five territories (1.0%; ‘jump in’ group) exhibited opposite results (FFR of ≤0.75 and cQFR of >0.80). The ‘jump out’ territories showed significantly higher IMR values than ‘jump in’ territories (p<0.01).ConclusionsFFR− with cQFR+ is associated with increased microvascular resistance, and FFR+ with cQFR− showed preservation of microvascular function with high coronary flow. Microvascular function affected diagnostic performance of cQFR in relation to functional stenosis significance.