Modeling Fractional Flow Reserve: Developing an Estimate of a Better Mousetrap.

Abstract

See Article by Kang et al The longstanding, traditional construct of stable coronary artery disease in which patient symptoms and catheterization-defined stenosis severity drive treatment decisions is slowly evolving. The importance of prerevascularization physiological lesion assessment, whether by noninvasive imaging or by fractional flow reserve (FFR), is increasingly appreciated. The latter has been shown in randomized clinical trials to identify patients with superior outcomes with revascularization compared with medical therapy and to reduce stent use and cost.1–3 FFR has a IIa guideline indication in multisociety percutaneous intervention guidelines.4 Despite this, the actual use of FFR in the setting of diagnostic catheterization or percutaneous coronary intervention remains low.5,6 The factors that may explain this relative underuse include time, cost, and practicality of routine deployment. To improve the utilization of physiological stenosis assessment, methods to reliably estimate FFR from resting data (based on modeling measured FFR) have been examined. Several prior studies of varying size have addressed this question,7–11 finding different combinations of clinical, angiographic, and plaque characteristics to be associated with FFR and, in some, presenting simplified scores for use. In the current study, Kang et al12 examined the question of the impact of lesion geometry on the physiology associated with a coronary stenosis. To this end, the authors utilized data from the prospective Interventional Cardiology Research In-cooperation Society Fractional Flow Reserve and Intravascular Ultrasound registry. The study cohort consisted of 1552 non–left main coronary lesions in 1236 patients in whom simultaneous angiography, intravascular ultrasound, and FFR were assessed. Exclusion criteria included left main disease, TIMI (Thrombolysis In Myocardial Infarction) flow <3, bypass …