Agreement of Angiography-Derived and Wire-Based Fractional Flow Reserves in Percutaneous Coronary Intervention

Clinical Value of Computational Angiography-derived Fractional Flow Reserve in Stable Coronary Artery Disease

The utilization of FFR remains low. Our study evaluated the per-vessel prognostic value of computational pressure-flow dynamics-derived FFR (caFFR) among patients with stable coronary artery disease. A total of 3329 vessels from 1308 patients were included and analysed. They were stratified into ischaemic (caFFR ≤ 0.8) and non-ischaemic (caFFR > 0.8) cohorts, and the associations between PCI and outcomes were evaluated. The third cohort comprised all included vessels, and the associations between treatment adherent-to-caFFR (PCI in vessels with caFFR ≤ 0.8 and no PCI in vessels with caFFR > 0.8) and outcomes were evaluated. The primary outcome was VOCE, defined as a composite of vessel-related cardiovascular mortality, non-fatal myocardial infarction, and repeat revascularization. PCI was associated with a lower 3-year risk of VOCE in the ischaemic cohort (HR, 0.44; 95% CI, 0.26-0.74; P = 0.002) but not in the non-ischaemic cohort. The risk of VOCE was lower in the adherent-to-caFFR group (n = 2649) (HR, 0.69; 95% CI, 0.48-0.98; P = 0.039). A novel index that uses coronary angiography images to estimate FFR may have substantial clinical value in guiding management among patients with stable coronary artery disease.

Complete revascularization based on angiography derived fractional flow reserve versus incomplete revascularization in patients with ST-segment elevation myocardial infarction

BACKGROUND

Nearly half of ST-segment elevation myocardial infarction (STEMI) patients present with significant multivessel coronary artery disease, they are at high risk of subsequent adverse events. Whether complete revascularization guided by coronary angiography-derived fractional flow reserve (caFFR) further reduces such events risk is not fully investigated.

METHODS

In this study, 367 consecutive STEMI patients who underwent successful primary percutaneous coronary intervention (PCI) were enrolled. caFFR of all three coronary vessels were measured, including 367 culprit vessels and 703 non-culprit vessels. Complete revascularization was defined as post-PCI caFFR > 0.8 of all three coronary vessels. The primary endpoint was major adverse cardiovascular events (MACE, a composite of cardiovascular death, non-fatal recurrent myocardial infarction, ischemia-driven revascularization and non-fatal stroke/transient ischemic attacks) during follow-up.

RESULTS

At a median follow-up of 3.8 years, MACE had occurred in 39 patients of the 220 (17.7%) in the complete revascularization group as compared with 49 patients of the 131 (37.4%) in the incomplete revascularization group (hazard ratio [HR] 1.9; 95% confidence interval [CI] 1.2-3.0; p = 0.005). The incomplete revascularization in culprit vessels evaluated by caFFR showed the highest risk for MACE occurrence.

CONCLUSIONS

In STEMI patients with multivessel coronary artery disease, incomplete revascularization based on caFFR might contribute to identifying patients at high-risk.

Accuracy and Reproducibility of Coronary Angiography-Derived Fractional Flow Reserve in the Assessment of Coronary Lesion Severity

Purpose

Coronary angiography-derived fractional flow reserve (caFFR) is a novel computational flow dynamics (CFD)-derived assessment of coronary vessel flow with good diagnostic performance. Herein, we performed a retrospective study to evaluate the reproducibility of caFFR findings between observers and investigate the diagnostic performance of caFFR for coronary stenosis defined as FFR ≤0.80, especially in the grey zone (0.75≤caFFR ≤0.80).

Patients and Methods

A total of 150 patients (167 coronary vessels) underwent caFFR (with FlashAngio used for calculation of flow variables) and subsequent invasive fractional flow reserve (FFR) measurements. Outcomes, including reproducibility, were compared for vessels in and outside the grey zone.

Results

The correlation of caFFR findings was good between the two laboratories (r = 0.723, p<0.001). The AUC of ROC were both high for caFFR-CoreLab1 and caFFR-CoreLab2 (0.975 and 0.883). The diagnostic accuracy, sensitivity, specificity, and negative and positive predictive values were not significantly different between the two laboratories (p>0.05). caFFR had a strong correlation with measures to FFR (r=0.911, p<0.001). There was no systematic difference between caFFR and FFR on Bland-Altman analysis in and outside the grey zone. There was no difference in diagnostic accuracy between the grey and non-grey zones in the prediction of FFR ≤0.80 (p=0.09).

Conclusion

The inter-observer reproducibility for caFFR was high, and the diagnostic accuracy of caFFR was good compared to that of FFR.

Current status and future perspectives of fractional flow reserve derived from invasive coronary angiography

Assessment of the functional significance of coronary artery stenosis using invasive measurement of fractional flow reserve (FFR) or non-hyperemic indices has been shown to be safe and effective in making clinical decisions on whether to perform percutaneous coronary intervention (PCI). Despite strong evidence from clinical trials, utilization of these techniques is still relatively low worldwide. This may be to some extent attributed to factors that are inherent to invasive measurements like prolongation of the procedure, side effects of drugs that induce hyperemia, additional steps that the operator should perform, the possibility to damage the vessel with the wire, and additional costs. During the last few years, there was a growing interest in the non-invasive assessment of coronary artery lesions, which may provide interventionalist with important physiological information regarding lesion severity and overcome some of the limitations. Several dedicated software solutions are available on the market that could provide an estimation of FFR using 3D reconstruction of the interrogated vessel derived from two separated angiographic projections taken during diagnostic coronary angiography. Furthermore, some of them use data about aortic pressure and frame count to more accurately calculate pressure drop (and FFR). The ideal non-invasive system should be integrated into the workflow of the cath lab and performed online (during the diagnostic procedure), thereby not prolonging procedural time significantly, and giving the operator additional information like vessel size, lesion length, and possible post-PCI FFR value. Following the development of these technologies, they were all evaluated in clinical trials where good correlation and agreement with invasive FFR (considered the gold standard) were demonstrated. Currently, only one trial (FAVOR III China) with clinical outcomes was completed and demonstrated that QFR-guided PCI may provide better results at 1-year follow-up as compared to the angiography-guided approach. We are awaiting the results of a few other trials with clinical outcomes that test the performance of these indices in guiding PCI against either FFR or angiography-based approach, in various clinical settings. Herein we will present an overview of the currently available data, a critical review of the major clinical trials, and further directions of development for the five most widely available non-invasive indices: QFR, vFFR, FFRangio, caFFR, and AccuFFRangio.

The prognostic value and economic benefits of coronary angiography-derived fractional flow reserve-guided strategy in patients with coronary artery disease

Objective

This study aims to investigate the prognostic value and economic benefit of coronary angiography-derived fractional flow reserve (caFFR) guided percutaneous coronary intervention (PCI) in patients with coronary artery disease.

Methods

All patients with coronary artery disease (CAD) who underwent coronary angiography in our center between April 2021 and November 2021 were retrospectively enrolled and divided into the caFFR guidance group (n = 160) and angiography guidance group (n = 211). A threshold of caFFR≤0.8 was used for revascularization. Otherwise, delayed PCI was preferred. The patients were prospectively followed up by telephone or outpatient service at six months for major adverse cardiovascular events (MACE) of all-cause death, myocardial infarction or target vessel revascularization, stent thrombosis, and stroke. All in-hospital expenses were recorded, including initial hospitalization and re-hospitalization related to MACE.

Results

There was no significant difference in the baseline characteristics between the two groups. There were 2 (1.2%) patients in the caFFR guidance group and 5 (2.4%) patients in the angiography guidance group with MACE events during the following six months. Compared with angiography guidance, caFFR guidance reduced the revascularization rate (63.7% vs. 84.4%, p = 0.000), the average length of stents implanted (0.52 ± 0.88 vs. 1.1 ± 1.4, P < 0.001). The cost of consumables in the caFFR guidance group was significantly lower than that in the angiography guidance group (33257 ± 19595 CNY vs. 38341 ± 16485 CNY, P < 0.05).

Conclusion

Compared with coronary angiography guidance, caFFR guidance is of great significance in reducing revascularization and cost, which has significant health and economic benefits.

Diagnostic accuracy of CT-derived and angiogram-derived fractional flow reserve

AIMS

Although accumulating evidence demonstrated that virtual fractional flow reserve (FFR) based on coronary computed tomography angiography (CCTA) (CT-FFR) or invasive coronary angiogram (ICA) (CA-FFR) are promising alternatives to wire based FFR, which method has better diagnostic accuracy was still unclear. In our study, we aim to directly compare the diagnostic performance of CT-FFR and CA-FFR.

METHODS

During the period of September 2019 to December 2020, patients with at least one 30%-90% coronary artery stenosis were enrolled and received invasive FFR. Then, virtual FFR values were calculated based on both CCTA and ICA, and then compared with the invasive FFR value.

RESULTS

Invasive FFR measurements were successfully performed in 114 vessels of 96 patients. Both CT-FFR and CA-FFR showed good correlation with wire-based FFR, with r values of 0.84 and 0.71 respectively. In paired t-test, the deviation of CT-FFR and CA-FFR was not significantly different (t = -1.9083, p = 0.05889). In Bland-Altman analysis, the coefficients of variation were 8.4% and 13.2% for CT-FFR and CA-FFR respectively. In ROC curve analysis, the per-vessel diagnostic accuracy of CT-FFR and CA-FFR was 94.7% and 92.1% respectively. The area under the curve of CT-FFR was slightly higher than that of CA-FFR (0.986 and 0.916 respectively, the difference between areas = 0.070, 95% CI 0.003-0.137, p = 0.0227).

CONCLUSION

Both CT-FFR and CA-FFR had good diagnostic concordance with wire-based FFR. In ROC Curve analysis, CT-FFR demonstrated slightly higher diagnostic accuracy than CA-FFR.

CLINICAL TRIAL REGISTRATION

URL: https://www.chictr.org.cn/showproj.aspx?proj=44719. Unique Identifier: ChiCTR1900026971.