Assessing Computational Fractional Flow Reserve From Optical Coherence Tomography in Patients With Intermediate Coronary Stenosis in the Left Anterior Descending Artery

Abstract

Background-Intravascular optical coherence tomography (OCT) imaging provides limited information on the functional assessment of coronary stenosis. We evaluated a new approach to OCT image-based computation modeling, which can be used to estimate the fractional flow reserve (FFR) 14 The objective of this study was to present a new approach for estimating invasive FFR using OCT lumen contour-based 3D coronary models (FFR OCT ) and CFD algorithms. In addition, the clinical usefulness of FFR OCT was evaluated with pressure wire-based FFR in patients with ambiguous intermediate diameter stenosis in the left anterior descending artery. MethodsA total of 100 consecutive patients who underwent both OCT and FFR evaluation of intermediate stenosis in the left anterior descending artery between November 2013 and January 2015 were retrospectively enrolled. Eight patients were excluded because of poor reconstruction of the 3D OCT images. A total of 92 patients were finally included in the analysis. The inclusion criteria included (1) clinical presentation of angina, (2) intermediate diameter stenosis (40%-70%) in de novo lesions proximal to the mid-portion of the left anterior descending artery, and (3) visual angiographic lesions of <20 mm in length. The exclusion criteria included: (1) clinical presentation of acute myocardial infarction, (2) previous history of myocardial infarction, (3) presence of regional wall motion abnormality in the territory of the left anterior descending artery, (4) significant stenosis (≥50% diameter stenosis) distal to the target lesion, (5) angiographic thrombus, and (6) contraindication to adenosine. This study was approved by the institutional review board at our institution. Written informed consent was obtained from all patients.An off-line quantitative coronary angiographic system (CAAS system; Pie Medical Instruments, Maastricht, Netherlands) was used to perform QCA analysis in an independent core laboratory (Cardiovascular Research Center, Seoul, Korea). Using the guiding catheter for magnification calibration, the reference vessel diameter and minimum luminal diameter (MLD) were measured from diastolic frames in a single, matched view showing the smallest MLD ( Figure 1A). OCT Imaging and Reconstruction of 3D Coronary Artery GeometryTarget lesion imaging was performed using a frequency-domain OCT system (C7-XR OCT imaging system; LightLab Imaging, Inc./ St. Jude Medical, St. Paul, MN). The OCT cross-sectional images were generated at a rotational speed of 100 frames/s. The fiber probe was withdrawn at 20 mm/s within the stationary imaging sheath. All OCT images were analyzed at the core laboratory (Cardiovascular Research Center) by analysts who were blinded to patient and procedural information. The minimal luminal area (MLA) was identified at the segment with the smallest lumen area by OCT analysis. Area stenosis was calculated as follows: [(mean reference lumen area−minimum lumen area)÷mean reference lumen area] ×100. The reference lumen area was the region within the same segme...

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