Quantitative Flow Ratio Is Related to Intraluminal Coronary Stenosis Parameters as Assessed with Optical Coherence Tomography

Abstract

Background: Quantitative flow ratio (QFR) is a novel method for assessing hemodynamic relevance of a coronary lesion based on angiographic projections without the need of a pressure wire. Various studies demonstrated that QFR consistently related to fractional flow reserve (FFR); however, it is still unclear to what extent QFR reflects intraluminal stenosis parameters. Given that optical coherence tomography (OCT) is currently the gold standard to assess intraluminal stenosis parameters, we investigated the relationship between OCT-derived lesion geometry and QFR. Methods: We determined QFR in 97 lesions from 87 patients who underwent coronary angiography and OCT due to stable angina. QFR was measured with proprietary software and compared with OCT-based assessment of intraluminal stenosis parameters as well as lesion morphology. Results: Mean QFR was 0.79 ± 0.10. QFR demonstrated a consistent association with FFR (r = 0.834, p < 0.001). Interestingly, QFR was associated with OCT-derived parameters such as minimal lumen area (MLA, r = 0.390, p = 0.015), percent area stenosis (r = 0.412, p < 0.001), minimal lumen diameter (MLD, r = 0.395, p < 0.001), and percent diameter stenosis (r = 0.400, p < 0.001). Both minimal luminal area (ROC = 0.734, optimal cut-off 1.75 mm2) and minimal luminal diameter (ROC = 0.714, optimal cut-off 1.59 mm) presented a good diagnostic accuracy in diagnosing hemodynamic relevance (QFR ≤ 0.80). There was no significant association between QFR and anatomic features of plaque vulnerability. Conclusion: OCT-derived intraluminal stenosis parameters are related to QFR values and predict hemodynamic lesion relevance. The data supports the validity of QFR as 3D-vessel reconstruction method to assess coronary physiology without the need of a pressure wire.

OCT-Derived Plaque Morphology and FFR-Determined Hemodynamic Relevance in Intermediate Coronary Stenoses

“…Our findings are consistent with some previous OCT studies in which minimum lumen area or percent area stenosis was associated with FFR, but not the plaque composition, such as the presence of thin cap fibroatheroma or the lipid angle [3,[8][9][10][21][22][23]. Similar observations were also reported in studies employing iFR or three-dimensional quantitative coronary angiography-derived FFR indices, such as quantitative flow ratio (qFR), which confirmed a significant association between the minimum lumen area and iFR or qFR, respectively [24][25][26].…”

Morphometric Assessment for Functional Evaluation of Coronary Stenosis with Optical Coherence Tomography and the Optical Flow Ratio in a Vessel with Single Stenosis

“…Doctors then formulate PCI strategies accordingly and select an appropriate balloon and stent [ 10 ]. Studies have explored the correlation between intracoronary imaging and coronary hemodynamics, but only a moderate diagnostic efficiency was found in identifying hemodynamically severe coronary stenoses for both OCT and IVUS [ 8 , 11 , 12 , 13 , 14 ]. Inclusion criteria were set regarding the vessel with stenosis severity but not the lesion size.…”

Functional Evaluation of Coronary Stenosis: is Quantitative Flow Ratio a Step Forward?

“…However, QFR did not correlate with plaque vulnerability, indicating that it could be used in conjunction with intravascular imaging. 35 Physiological assessment by QFR reduces ionizing radiation exposure compared to FFR and iFR. Increasing QFR usage reduced ionizing radiation exposure.…”