Temporal Evolution of the iFR (Instantaneous Wave-Free Ratio) Employment Results Analysis

Keywords:
Myocardial Ischemia; Fractional Flow Reserve, Myocardial; Stents; Coronary Artery Disease; Percutaneous Coronary Intervention/methods

Dear Editor,

We read with interest the short editorial written by authors Chamié and Abzaid¹ regarding the paper “Evaluation of Myocardial Ischemia with iFR (instantaneous wave-free ratio) in the catheterization laboratory: a pilot study”.² The short editorial clearly translates to us the historical evolution reasoning that we must follow when interpreting coronary physiology studies in therapeutic decision-making. Although medicine is full of binary situations for resolution, such as the presence or absence of fever by the thermometer, it is very clear that different levels of values refer to different diagnoses, prognosis and treatments. With regard to coronary functional assessments, after an enormous amount of binary studies to demonstrate their validity, recent trials cited in the short editorial directed us to a phase where clinical decision-making power has an important weight once again,³ and the dissertation of this change in direction occurred brilliantly in the editorial. We did not neglect the clinical reasoning and other factors in our study, since the stent placement predictor was iFR < 0.87 in this group, despite the cutoff value established for iFR being 0.89, with a significant reduction in the use of stent.

It is worth mentioning that our study was conducted with data collected from 2014 to 2018, covering a long period in which the iFR did not have a still well-established binary cutoff value. Until the publication of Swedeheart and Define-Flair trials in 2017, the values of iFR > 0.86 and iFR < 0.93 were considered as gray zone, where the guidelines for the method indicated the use of fractional flow reserve (FFR).^4,5 In this time scenario, the placement of stents in patients with value of iFR ≤ 0.92 cannot be considered unnecessary as mentioned, due to the lack of literary data that definitively corroborated the 0.89 cutoff value, which only occurred after comparison between the FFR and iFR methods in the trials aforementioned.

I am grateful for the opportunity to clarify these points and corroborate that the editorial directs us and clarifies not only the need to increasingly use coronary physiology, but also how to use it today, contributing exquisitely in this area of interventional cardiology study.

Referências

• ¹
  Chamie D, Abzaid A. Avaliação Fisiológica Invasiva: Do Binário ao Contínuo. Arq Bras Cardiol. 2020; 114(2):265-7.
• ²
  Vieira HCA, Ferreira MCM, Nunes LC, Cardoso CJF, Nascimento EM, Oliveira GMM. Avaliação de Isquemia Miocárdica na Sala de Hemodinâmica com iFR Instantaneous Wave-Free Ratio: Estudo Piloto. Arq Bras Cardiol. 2020; 114(2):256-64.
• ³
  Al-Lamee R, Howard JP, Shun-Shin MJ, Thompson D, Dehbi HM, Sen S, et al. Fractional flow reserve and instantaneous wave-free ratio as predictors of the placebo-controlled response to percutaneous coronary intervention in stable single-vessel coronary artery disease: Physiology-stratified analysis of ORBITA. Circulation. 2018;138(17):1780–92.
• ⁴
  Davies JE, Sen S, Dehbi H-M, Al-Lamee R, Petraco R, Nijjer SS, et al. Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI. N Engl J Med. 2017;376(19):1824–34.
• ⁵
  Götberg M, Christiansen EH, Gudmundsdottir IJI, Sandhall L, Danielewicz M, Jakobsen L, et al. Instantaneous Wave-free Ratio versus Fractional Flow Reserve to Guide PCI. N Engl J Med. 2017;376(19):1813–23.

Publication Dates

• Publication in this collection
  23 Oct 2020
• Date of issue
  Oct 2020

History

• Received
  12 Mar 2020
• Reviewed
  30 Mar 2020
• Accepted
  30 Mar 2020