Clinical Research
Coronary Artery Disease
Multicenter Core Laboratory Comparison of the Instantaneous Wave-Free Ratio and Resting Pd/Pa With Fractional Flow Reserve: The RESOLVE Study

https://doi.org/10.1016/j.jacc.2013.09.060Get rights and content
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Objectives

This study sought to examine the diagnostic accuracy of the instantaneous wave-free ratio (iFR) and resting distal coronary artery pressure/aortic pressure (Pd/Pa) with respect to hyperemic fractional flow reserve (FFR) in a core laboratory–based multicenter collaborative study.

Background

FFR is an index of the severity of coronary stenosis that has been clinically validated in 3 prospective randomized trials. iFR and Pd/Pa are nonhyperemic pressure-derived indices of the severity of stenosis with discordant reports regarding their accuracy with respect to FFR.

Methods

iFR, resting Pd/Pa, and FFR were measured in 1,768 patients from 15 clinical sites. An independent physiology core laboratory performed blinded off-line analysis of all raw data. The primary objectives were to determine specific iFR and Pd/Pa thresholds with ≥90% accuracy in predicting ischemic versus nonischemic FFR (on the basis of an FFR cut point of 0.80) and the proportion of patients falling beyond those thresholds.

Results

Of 1,974 submitted lesions, 381 (19.3%) were excluded because of suboptimal acquisition, leaving 1,593 for final analysis. On receiver-operating characteristic analysis, the optimal iFR cut point for FFR ≤0.80 was 0.90 (C statistic: 0.81 [95% confidence interval: 0.79 to 0.83]; overall accuracy: 80.4%) and for Pd/Pa was 0.92 (C statistic: 0.82 [95% confidence interval: 0.80 to 0.84]; overall accuracy: 81.5%), with no significant difference between these resting measures. iFR and Pd/Pa had ≥90% accuracy to predict a positive or negative FFR in 64.9% (62.6% to 67.3%) and 48.3% (45.6% to 50.5%) of lesions, respectively.

Conclusions

This comprehensive core laboratory analysis comparing iFR and Pd/Pa with FFR demonstrated an overall accuracy of ∼80% for both nonhyperemic indices, which can be improved to ≥90% in a subset of lesions. Clinical outcome studies are required to determine whether the use of iFR or Pd/Pa might obviate the need for hyperemia in selected patients.

Key Words

coronary physiology
fractional flow reserve
myocardial ischemia

Abbreviations and Acronyms

CI
confidence interval
ECG
electrocardiographic
FFR
fractional flow reserve (hyperemic by definition)
iFR
instantaneous wave-free ratio (nonhyperemic)
LAD
left anterior descending
NPV
negative predictive value
Pd/Pa
distal coronary artery pressure/aortic pressure (nonhyperemic)
PPV
positive predictive value
ROC
receiver-operating characteristic

Cited by (0)

Dr. Jeremias has served as a consultant and member of the Speakers' Bureau for Volcano Corp. Dr. Berry has served as a consultant for and received a research grant from St. Jude Medical. Dr. De Bruyne has received institutional consulting fees from St. Jude Medical. Dr. Davies has received study support from and served as a consultant with licensed intellectual property for Volcano Corp. Dr. Escaned has served as a member of the Speakers' Bureau for St. Jude Medical and Volcano Corp. Dr. Fearon has received research support from St. Jude Medical. Dr. Gould holds a nonfinancial, mutual nondisclosure agreement with Volcano Corp. and is a 510(k) applicant for cfrQuant, a software package for quantifying absolute flow using cardiac PET; all royalties will go to a University of Texas scholarship fund and the University of Texas has a commercial, nonexclusive agreement with Positron Corporation to distribute and market cfrQuant in exchange for royalties; however, Dr. Gould retains the ability to distribute cost-free versions to selected collaborators for research. Dr. Johnson holds a nonfinancial, mutual nondisclosure agreement with Volcano Corp. Dr. Koo has received honorarium and a research grant from St. Jude Medical. Dr. Oldroyd has served as a member of the Speaker's Bureau for St. Jude Medical and Volcano Corp. Dr. Piek has served as a consultant for MAB Abbott Vascular and Miracor. Dr. Pijls has served as a consultant for St. Jude Medical; received institutional research grants from St. Jude Medical; and served as an advisory board member for Heart Flow. Dr. Mintz has served as a consultant and received grant support from Volcano Corp. Dr. Stone has served as a consultant for Volcano Corp., InfraReDx, and Boston Scientific. This study was an investigator-sponsored study by the Cardiovascular Research Foundation and was supported by funding from Volcano Corp. (San Diego, California). The funding source was uninvolved with the design of the protocol and the analysis and interpretation of the study results. All other authors have reported that they have no relationships relevant to the content of this paper to disclose.