Adverse Plaque Characteristics Relate More Strongly With Hyperemic Fractional Flow Reserve and Instantaneous Wave-Free Ratio Than With Resting Instantaneous Wave-Free Ratio

JACC Cardiovasc Imaging. 2020 Mar;13(3):746-756. doi: 10.1016/j.jcmg.2019.06.013. Epub 2019 Aug 14.

Abstract

Objectives: The current substudy of the PACIFIC (Prospective Comparison of Cardiac PET/CT, SPECT/CT Perfusion Imaging and CT Coronary Angiography With Invasive Coronary Angiography) trial explores the impact of computed tomography (CT)-derived unfavorable plaque features on both hyperemic and non-hyperemic flow indices.

Background: Next to lesion severity, plaque vulnerability as assessed using coronary CT angiography affects fractional flow reserve (FFR), which is associated with imminent acute coronary syndromes. Instantaneous wave-free ratio (iFR) has recently emerged as an alternative for FFR to interrogate coronary lesions for ischemia. It is, however, unknown whether vasodilator-free assessment with iFR is associated with plaque stability similarly as FFR.

Methods: Of 120 patients (62% men, age 58.3 ± 8.6 years) with suspected coronary artery disease, 257 vessels were prospectively evaluated. Each patient underwent 256-slice coronary CT angiography to assess stenosis severity and plaque features (positive remodeling [PR], low attenuation plaque [LAP], spotty calcification [SC], and napkin ring sign [NRS]), as well as intracoronary pressure measurements (FFR, iFR, Pd/Pa, and pressure ratio during adenosine within the wave-free period [iFRa]). CT-derived plaque characteristics were related to these invasive pressure measurements.

Results: Atherosclerotic plaques were present in 170 (66%) coronary arteries. On a per-vessel basis, luminal stenosis severity was significantly associated with impaired FFR, iFR, Pd/Pa, and iFRa. Multivariable analysis revealed that FFR and iFR were independently related to ≥70% stenosis (-0.10, p < 0.001 and -0.09, p = 0.003, respectively) and plaque volume (-0.02, p = 0.020 and -0.02, p = 0.030, respectively). Additionally, PR and SC were also independent predictors of an impaired FFR (-0.10, p < 0.001 and -0.07, p = 0.021, respectively), but adverse plaque characteristics were not independently related to the vasodilator-free iFR.

Conclusions: CT-derived vulnerable plaque characteristics are independently associated with hyperemic flow indices as assessed with FFR and iFRa, but not with non-hyperemic indices such as iFR and Pd/Pa. These findings suggest that the effects of hyperemia on pressure-derived indices might depend not only on hemodynamic stenosis severity but also on plaque characteristics.

Keywords: adverse plaque characteristics; coronary artery disease; coronary computed tomography angiography; fractional flow reserve; instantaneous wave-free ratio.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study

MeSH terms

  • Adenosine / administration & dosage*
  • Aged
  • Computed Tomography Angiography*
  • Coronary Angiography*
  • Coronary Artery Disease / diagnostic imaging*
  • Coronary Artery Disease / physiopathology
  • Coronary Stenosis / diagnostic imaging*
  • Coronary Stenosis / physiopathology
  • Female
  • Fractional Flow Reserve, Myocardial*
  • Hemodynamics
  • Humans
  • Hyperemia / physiopathology*
  • Male
  • Middle Aged
  • Multidetector Computed Tomography*
  • Plaque, Atherosclerotic*
  • Predictive Value of Tests
  • Prospective Studies
  • Severity of Illness Index
  • Vasodilator Agents / administration & dosage*

Substances

  • Vasodilator Agents
  • Adenosine