Prognostic value of combined fractional flow reserve and pressure-bounded coronary flow reserve: outcomes in FFR and Pb-CFR assessment.

BACKGROUND: Coronary flow reserve (CFR) has an emerging role to predict outcome in patients with and without flow-limiting stenoses. However, the role of its surrogate pressure bounded-CFR (Pb-CFR) is controversial. We investigated the usefulness of combined use of fractional flow reserve (FFR) and Pb-CFR to predict outcomes. METHODS: This is a sub-study of the PROPHET-FFR Trial, including patients with chronic coronary syndrome and functionally tested coronary lesions. Patients were divided into four groups based on positive or negative FFR (cut-off 0.80) and preserved (lower boundary ≥2) or reduced (upper boundary <2) Pb-CFR: Group1 FFR≤0.80/ Pb-CFR <2; Group 2 FFR≤0.80/Pb-CFR≥2; Group 3 FFR >0.80/Pb-CFR<2; Group 4 FFR>0.80/Pb-CFR≥2. Lesions with positive FFR were treated with PCI. Primary endpoint was the rate of major adverse cardiac events (MACEs), defined as a composite of death from any cause, myocardial infarction, target vessel revascularization, unplanned cardiac hospitalization at 36-months. RESULTS: A total of 609 patients and 816 lesions were available for the analysis. At Kaplan-Meier analysis MACEs rate was significantly different between groups (36.7% Group 1, 27.4% Group 2, 19.2% Group 3, 22.6% Group 4, P=0.019) and more prevalent in groups with FFR≤0.80 irrespective of Pb-CFR. In case of discrepancy, no difference in MACEs were observed between groups stratified by Pb-CFR. FFR≤0.80 was associated with an increased MACEs rate (30.2% vs. 21.5%, P<0.01) while Pb-CFR<2 was not (24.5% vs. 24.2% Pb-CFR≥2 P=0.67). CONCLUSIONS: FFR confirms its ability to predict outcomes in patients with intermediate coronary stenoses. Pb-CFR does not add any relevant prognostic information.

Safety and effectiveness of post percutaneous coronary intervention physiological assessment: Retrospective data from the post-revascularization optimization and physiological evaluation of intermediate lesions using fractional flow reserve registry.

Background: While the importance of invasive physiological assessment (IPA) to choose coronary lesions to be treated is ascertained, its role after PCI is less established. We evaluated feasibility and efficacy of Physiology-guided PCI in the everyday practice in a retrospective registry performed in a single high-volume and "physiology-believer" center. Materials and methods: The PROPHET-FFR study (NCT05056662) patients undergoing an IPA in 2015-2020 were retrospectively enrolled in three groups: Control group comprising patients for whom PCI was deferred based on a IPA; Angiography-Guided PCI group comprising patients undergoing PCI based on an IPA but without a post-PCI IPA; Physiology-guided PCI group comprising patients undergoing PCI based on an IPA and an IPA after PCI, followed by a physiology-guided optimization, if indicated. Optimal result was defined by an FFR value ≥ 0.90. Results: A total of 1,322 patients with 1,591 lesions were available for the analysis. 893 patients (67.5%) in Control Group, 249 patients (18.8%) in Angiography-guided PCI Group and 180 patients (13.6%) in Physiology-guided PCI group. In 89 patients a suboptimal functional result was achieved that was optimized in 22 cases leading to a "Final FFR" value of 0.90 ± 0.04 in Angiography-Guided PCI group. Procedural time, costs, and rate of complications were similar. At follow up the rate of MACEs for the Physiology-guided PCI group was similar to the Control Group (7.2% vs. 8.2%, p = 0.765) and significantly lower than the Angiography-guided PCI Group (14.9%, p < 0.001), mainly driven by a reduction in TVRs. Conclusion: "Physiology-guided PCI" is a feasible strategy with a favorable impact on mid-term prognosis. Prospective studies using a standardized IPA are warrant to confirm these data.

Adenosine-Free Indexes vs. Fractional Flow Reserve for Functional Assessment of Coronary Stenoses: Systematic Review and Meta-Analysis.

BACKGROUND: Adenosine-free indexes (AFIs), including resting Pd/Pa, instantaneous wave-free ratio (iFR) and contrast-FFR (cFFR), have been proposed to circumvent the use of vasodilators, in order to simplify the functional evaluation of coronary stenoses. Aims of this study were to analyze the correlation between AFIs and Fractional Flow Reserve (FFR) and to compare their diagnostic accuracy when FFR is used as reference. METHODS: We conducted a systematic review and meta-analysis of observational studies in which AFIs were compared to FFR. We produced paired forest plots to show the variation of the sensitivity and specificity estimates. We used a hierarchical summary ROC model (HSROC) to summarize the sensitivity and specificity of AFIs in detecting the concordance with FFR assessment. RESULTS: Eighteen studies were included in this meta-analysis. Overall, 4424, 4822 and 2021 coronary lesions in 4410, 4472 and 1898 patients, respectively, were evaluated by Pd/Pa, iFR and cFFR, respectively. The overall Pearson's correlations were 0.81 (95%CI 0.78-0.83), 0.80 (95%CI 0.78-0.81) and 0.92 (95%CI 0.90-0.94) for Pd/Pa, iFR and cFFR, respectively. cFFR showed a significantly higher correlation with FFR compared to Pd/Pa and iFR (p < 0.0001). The area under the HSROC estimating the discriminating accuracy of cFFR was 0.95 (95%CI 0.94-0.96) and it was significantly higher compared to Pd/Pa (0.86, 95%CI 0.80-0.93) and iFR (0.89, 95%CI 0.84-0.94) (p < 0.0001). CONCLUSIONS: AFIs show a good correlation with the gold standard FFR. Among AFIs, cFFR shows the highest correlation with FFR and the best diagnostic accuracy.

Angiographic assessment of myocardial perfusion in Tako-Tsubo syndrome.

OBJECTIVES: To angiographically assess myocardial perfusion in patients with Tako-Tsubo syndrome (TTS) in comparison with control individuals and patients with ST-elevation myocardial infarction (STEMI). BACKGROUND: Coronary microvascular dysfunction has been proposed as the pathophysiological mechanism underlying TTS. METHODS: We retrospectively selected consecutive TTS patients showing typical left ventricular (LV) apical dysfunction admitted to our Department in the period 2007-2011 (n=25). We also enrolled an age and gender-matched control group showing normal coronary arteries (CTR, n=25), patients with STEMI undergoing primary percutaneous intervention with myocardial reperfusion (SR, n=25) or microvascular obstruction (SMVO, n=25). TIMI flow, TIMI frame count (TFC) and both qualitative and quantitative myocardial blush grade in LV apex were assessed. Specifically, myocardial perfusion was quantitatively evaluated using 'Quantitative Blush Evaluator' (QuBE), an open source software previously validated in the setting of STEMI. RESULTS: In TTS, TIMI flow on the LAD was significantly lower and TFC significantly higher compared to CTR and SR (p=0.008 for both), while it did not significantly differ compared to SMVO (p=0.06). In TTS, MBG was significantly lower than that in CTR and SR (p=0.001 for both), while it was significantly higher than that in SMVO (p<0.001). In TTS, QuBE score was significantly lower than that in CTR and SR (p=0.001 for both) and higher than in SMVO (p=0.02). CONCLUSIONS: Our data indicate that myocardial perfusion assessed during angiography is more impaired in patients with TTS than in patients with STEMI exhibiting myocardial reperfusion, while it is less impaired than in patients with STEMI exhibiting MVO.

Maximal hyperemia in the assessment of fractional flow reserve: intracoronary adenosine versus intracoronary sodium nitroprusside versus intravenous adenosine: the NASCI (Nitroprussiato versus Adenosina nelle Stenosi Coronariche Intermedie) study.

OBJECTIVES: This study sought to compare increasing doses of intracoronary (i.c.) adenosine or i.c. sodium nitroprusside versus intravenous (i.v.) adenosine for fractional flow reserve (FFR) assessment. BACKGROUND: Maximal hyperemia is the critical prerequisite for FFR assessment. Despite i.v. adenosine currently representing the recommended approach, i.c. administration of adenosine or other coronary vasodilators constitutes a valuable alternative in everyday practice. However, it is surprisingly unclear which i.c. strategy allows the achievement of FFR values comparable to i.v. adenosine. METHODS: Fifty intermediate coronary stenoses (n = 45) undergoing FFR measurement were prospectively and consecutively enrolled. Hyperemia was sequentially induced by incremental boli of i.c. adenosine (ADN) (60 µg ADN60, 300 µg ADN300, 600 µg ADN600), by i.c. sodium nitroprusside (NTP) (0.6 µg/kg bolus) and by i.v. adenosine infusion (IVADN) (140 µg/kg/min). FFR values, symptoms, and development of atrioventricular block were recorded. RESULTS: Incremental doses of i.c. adenosine and NTP were well tolerated and associated with fewer symptoms than IVADN. Intracoronary adenosine doses (0.881 ± 0.067, 0.871 ± 0.068, and 0.868 ± 0.070 with ADN60, ADN300, and ADN600, respectively) and NTP (0.892 ± 0.072) induced a significant decrease of FFR compared with baseline levels (p < 0.001). Notably, ADN600 only was associated with FFR values similar to IVADN (0.867 ± 0.072, p = 0.28). Among the 10 patients with FFR values ≤0.80 with IVADN, 5 were correctly identified also by ADN60, 6 by ADN300, 7 by ADN600, and 6 by NTP. CONCLUSIONS: Intracoronary adenosine, at doses higher than currently suggested, allows obtaining FFR values similar to i.v. adenosine. Intravenous adenosine, which remains the gold standard, might thus be reserved for those lesions with equivocal FFR values after high (up to 600 µg) i.c. adenosine doses.