Aims: A novel method for computation of fractional flow reserve (FFR) from optical coherence tomography (OCT) was developed recently. This study aimed to evaluate the diagnostic accuracy of a new OCTbased FFR (OFR) computational approach, using wire-based FFR as the reference standard.Methods and results: Patients who underwent both OCT and FFR prior to intervention were analysed.The lumen of the interrogated vessel and the ostia of the side branches were automatically delineated and used to compute OFR. Bifurcation fractal laws were applied to correct the change in reference lumen size due to the step-down phenomenon. OFR was compared with FFR, both using a cut-off value of 0.80 to define ischaemia. Computational analysis was performed in 125 vessels from 118 patients. Average FFR was 0.80±0.09. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for OFR to identify FFR ≤0.80 was 90% (95% CI: 84-95), 87% (95% CI: 77-94), 92% (95% CI: 82-97), 92% (95% CI: 82-97), and 88% (95% CI: 77-95), respectively. The AUC was higher for OFR than minimal lumen area (0.93 [95% CI: 0.87-0.97] versus 0.80 [95% CI: 0.72-0.86], p=0.002). Average OFR analysis time was 55±23 seconds for each OCT pullback. Intra-and inter-observer variability in OFR analysis was 0.00±0.02 and 0.00±0.03, respectively. FFR fractional flow reserve IVUS intravascular ultrasound MLA minimal lumen area OCT optical coherence tomography OFR optical coherence tomography-based fractional flow reserve QFR quantitative flow ratio
Percutaneous coronary intervention (PCI) guided by coronary physiology provides symptomatic benefit and improves patient outcomes. Nevertheless, over one-fourth of patients still experience recurrent angina or major adverse cardiac events following the index procedure. Coronary angiography, the current workhorse for evaluating PCI efficacy, has limited ability to identify suboptimal PCI results. Accumulating evidence supports the usefulness of immediate post-procedural functional assessment. This review discusses the incidence and possible mechanisms behind a suboptimal physiology immediately after PCI. Furthermore, we summarize the current evidence base supporting the usefulness of immediate post-PCI functional assessment for evaluating PCI effectiveness, guiding PCI optimization, and predicting clinical outcomes. Multiple observational studies and post hoc analyses of datasets from randomized trials demonstrated that higher post-PCI functional results are associated with better clinical outcomes as well as a reduced rate of residual angina and repeat revascularization. As such, post-PCI functional assessment is anticipated to impact patient management, secondary prevention, and resource utilization. Pre-PCI physiological guidance has been shown to improve clinical outcomes and reduce health care costs. Whether similar benefits can be achieved using post-PCI physiological assessment requires evaluation in randomized clinical outcome trials.
Background: Evaluating prospectively the feasibility, accuracy and reproducibility of optical flow ratio (OFR), a novel method of computational physiology based on optical coherence tomography (OCT). Methods and results: Sixty consecutive patients (76 vessels) underwent prospectively OCT, angio graphybased quantitative flow ratio (QFR) and fractional flow ratio (FFR). OFR was computed offline in a central corelab by analysts blinded to FFR. OFR was feasible in 98.7% of the lesions and showed excellent agreement with FFR (ICCa = 0.83, r = 0.83, slope = 0.80, intercept = 0.17, kappa = 0.84). The area under curve to predict an FFR ≤ 0.80 was 0.95, higher than for QFR (0.91, p = 0.115) and for minimal lumen area (0.64, p < 0.001). Diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio were 93%, 92%,
Cyclic biomechanical stress at the lumen-intima interface plays a crucial role in the rupture of coronary plaque. We performed a comprehensive assessment of a novel angiography-based method for four-dimensional (4D) dynamic assessment of superficial wall stress (SWS) and deformation with a total of 32 analyses in virtual stenosis models with equal lumen dimensions and 16 analyses in human coronary arteries in vivo. The in silico model analyses demonstrated that the SWS, derived by the proposed global displacement method without knowledge of plaque components or blood pressure, was comparable with the result calculated by traditional finite element method. Cardiac contraction-induced vessel deformation increased SWS. Softer plaque and positive arterial remodeling, associated with a greater plaque burden, showed more variation in mean lumen diameter within the cardiac cycle and resulted in higher SWS. In vivo patient analyses confirmed the accuracy of computed superficial wall deformation. The centerlines predicted by our method at random selected time instant matched well with the actual one in angiograms by Procrustes analysis (scaling: 0.995 ± 0.018; dissimilarity: 0.007 ± 0.014). Over 50% of the maximum SWS occurred at proximal plaque shoulders. This novel 4D approach could be successfully to predict superficial wall deformation of coronary artery in vivo. The dynamic SWS might be more realistic to evaluate the risk of plaque rupture.
Background: Computational fractional flow reserve (FFR) was recently developed to expand the use of physiology-guided percutaneous coronary intervention (PCI). Nevertheless, current methods do not account for plaque composition. It remains unknown whether the numerical precision of computational FFR is impacted by the plaque composition in the interrogated vessels.Methods: This study is an observational, retrospective, cross-sectional study. Patients who underwent both optical coherence tomography (OCT) and FFR prior to intervention between August 2011 and October 2018 at Wakayama Medical University Hospital were included. All frames from OCT pullbacks were analyzed using a deep learning algorithm to obtain coronary plaque morphology including thin-cap fibroatheroma (TCFA), lipidic plaque volume (LPV), fibrous plaque volume (FPV), and calcific plaque volume (CPV). The interrogated vessels were stratified into three subgroups: the overestimation group with the numerical difference between the optical flow ratio (OFR) and FFR >0.05, the reference group with the difference ≥−0.05 and ≤0.05, and the underestimation group with the difference <−0.05.
Results:In total 230 vessels with intermediate coronary artery stenosis from 193 patients were analyzed.The mean FFR was 0.82±0.10. Among them, 21, 179, and 30 vessels were in the overestimation, the reference, and the underestimation group, respectively. TCFA was higher in the underestimation group (60%) compared with reference (36.3%) and overestimation group (19%). Besides, it was not associated with numerical difference between OFR and FFR (NDOF) after multilevel linear regression. LPV was associated with NDOF as OFR underestimated FFR with −0.028 [95% confidence interval (CI): −0.047, −0.009] for every 100 mm 3 increase in LPV.Conclusions: High lipid burden underestimates FFR when OFR is used to assess the hemodynamic importance of intermediate coronary artery stenosis. TCFA, FPV, and CPV were not independent predictors of NDOF.
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