- 作者：Nils P. Johnson ; MD ; MS? ; Richard L. Kirkeeide ; PhD? ; Kaleab N. Asrress ; MA ; BM ; BCh&dagger ; ; William F. Fearon ; MD&Dagger ; ; Timothy Lockie ; MB ; ChB ; PhD&dagger ; ; § ; ; Koen M.J. Marques ; MD ; PhD¡Î ; Stylianos A. Pyxaras ; MD¶ ; ; M. Cristina Rolandi ; MSc# ; Marcel van 't Veer ; MSc ; PhD?? ; &dagger ; &dagger ; ; Bernard De Bruyne ; MD ; PhD¶ ; ; Jan J. Piek ; MD ; PhD§ ; ; Nico H.J. Pijls ; MD ; PhD?? ; &dagger ; &dagger ; ; Simon Redwood ; MD&dagger ; ; Maria Siebes ; PhD# ; Jos A.E. Spaan ; PhD# ; K. Lance Gould ; MD? ; K.Lance.Gould@uth.tmc.edu
- 关键词：coronary physiology ; fractional flow reserve ; instantaneous wave-free ratio ; Monte Carlo simulation ; myocardial resistance ; vasodilation
- 刊名：Journal of the American College of Cardiology
- 出版年：2013
- 出版时间：2 April, 2013
- 年：2013
- 卷：61
- 期：13
- 页码：1428-1435
- 全文大小：1469 K
Objectives
This study sought to examine the clinical performance of and theoretical basis for the instantaneous wave-free ratio (iFR) approximation to the fractional flow reserve (FFR).Background
Recent work has proposed iFR as a vasodilation-free alternative to FFR for making mechanical revascularization decisions. Its fundamental basis is the assumption that diastolic resting myocardial resistance equals mean hyperemic resistance.
Methods
Pressure-only and combined pressure-flow clinical data from several centers were studied both empirically and by using pressure-flow physiology. A Monte Carlo simulation was performed by repeatedly selecting random parameters as if drawing from a cohort of hypothetical patients, using the reported ranges of these physiologic variables.
Results
We aggregated observations of 1,129 patients, including 120 with combined pressure-flow data. Separately, we performed 1,000 Monte Carlo simulations. Clinical data showed that iFR was +0.09 higher than FFR on average, with ¡À0.17 limits of agreement. Diastolic resting resistance was 2.5 ¡À 1.0 times higher than mean hyperemic resistance in patients. Without invoking wave mechanics, classic pressure-flow physiology explained clinical observations well, with a coefficient of determination of >0.9. Nearly identical scatter of iFR versus FFR was seen between simulation and patient observations, thereby supporting our model.
Conclusions
iFR provides both a biased estimate of FFR, on average, and an uncertain estimate of FFR in individual cases. Diastolic resting myocardial resistance does not equal mean hyperemic resistance, thereby contravening the most basic condition on which iFR depends. Fundamental relationships of coronary pressure and flow explain the iFR approximation without invoking wave mechanics.