The Association Between Quantitative Flow Ratio and Intravascular Imaging-defined Vulnerable Plaque Characteristics in Patients With Stable Angina and Non-ST-segment Elevation Acute Coronary Syndrome

Abstract

Background: This study aimed to examine whether quantitative flow ratio (QFR), an angiography-based computation of fractional flow reserve, was associated with intravascular imaging-defined vulnerable plaque features, such as thin cap fibroatheroma (TCFA) in patients with stable angina, and non-ST-segment elevation acute coronary syndrome.Methods: Patients undergoing optical coherence tomography (OCT) or intravascular ultrasound (IVUS) examinations were identified from two prospective studies and their interrogated vessels were assessed with QFR. Lesions in the OCT cohort were classified into tertiles: QFR-T1 (QFR ≤ 0.85), QFR-T2 (0.85 < QFR ≤ 0.93), and QFR-T3 (QFR > 0.93). Lesions in the IVUS cohort were classified dichotomously as low or high QFR groups.Results: This post-hoc analysis included 132 lesions (83 for OCT and 49 for IVUS) from 126 patients. The prevalence of OCT-TCFA was significantly higher in QFR-T1 (50%) than in QFR-T2 (14%) and QFR-T3 (19%) (p = 0.003 and 0.018, respectively). Overall significant differences were also observed among tertiles in maximum lipid arc, thinnest fibrous cap thickness, and minimal lumen area (p = 0.017, 0.040, and <0.001, respectively). Thrombus was more prevalent in QFR-T1 (39%) than in QFR-T2 (3%), and QFR-T3 (12%) (p = 0.001 and 0.020, respectively). In the multivariable analysis, QFR ≤ 0.80 remained as a significant determinant of OCT-TCFA regardless of the presence of NSTE-ACS and the level of low-density lipoprotein cholesterol (adjusted OR: 4.387, 95% CI 1.297–14.839, p = 0.017). The diagnostic accuracy of QFR was moderate in identifying lesions with OCT-TCFA (area under the curve: 0.72, 95% CI 0.58–0.86, p = 0.003). In the IVUS cohort, significant differences were found between two groups in minimal lumen area and plaque burden but not in the distribution of virtual histology (VH)-TCFA (p = 0.025, 0.036, and 1.000, respectively).Conclusions: Lower QFR was related to OCT-defined plaque vulnerability in angiographically mild-to-intermediate lesions. The QFR might be a useful tool for ruling out high-risk plaques without using any pressure wire or vasodilator.

Angiographic quantitative flow ratio in acute coronary syndrome: beyond a tool to define ischemia-causing stenosis—a literature review

“…Kanno et al (84) found that QFR severity was associated with a higher prevalence of OCT-defined thin-cap fibroatheroma (TCFA) in stable patients. Similar findings were reported by Dan et al (85) and Zuo et al (86), showing that lower QFR value was related to IVUS or OCT-defined vulnerable plaque features (i.e., minimal lumen area, plaque burden and TCFA) in both stable angina and NSTEMI patients. However, in a recent study of 87 patients with CCS, QFR was not associated with features of plaque vulnerability such as fibrous cap thickness, although significant correlations were found between QFR and OCT-derived intraluminal stenosis parameters (87).…”

Sex Differences in Murray Law‐Based Quantitative Flow Ratio Among Patients With Intermediate Coronary Lesions

“…Our previous study also supported this observation, reporting that high‐risk plaque characteristics such as thin‐cap fibroatheroma, lipid‐rich plaque, and thrombus, identified by optical coherence tomography, were negatively associated with 3‐dimensional QFR. 26 After controlling for patient characteristics, our study found a marginal association between sex and FFR values. These findings imply that other factors or confounders may be responsible for the observed difference in FFR values between men and women.…”

Impact of calcification on Murray law-based quantitative flow ratio for physiological assessment of intermediate coronary stenoses

“…The threshold was defined as FFR ≤ 0.80 to indicate functional ischemia [ 1 ]. The details of the procedure have been described in our previous reports [ 10 , 11 ].…”