Rationale and design of the pullback pressure gradient (PPG) global registry.

INTRODUCTION: Diffuse disease has been identified as one of the main reasons leading to low post-PCI fractional flow reserve (FFR) and residual angina after PCI. Coronary pressure pullbacks allow for the evaluation of hemodynamic coronary artery disease (CAD) patterns. The pullback pressure gradient (PPG) is a novel metric that quantifies the distribution and magnitude of pressure losses along the coronary artery in a focal-to-diffuse continuum. AIM: The primary objective is to determine the predictive capacity of the PPG for post-PCI FFR. METHODS: This prospective, large-scale, controlled, investigator-initiated, multicenter study is enrolling patients with at least 1 lesion in a major epicardial vessel with a distal FFR ≤ 0.80 intended to be treated by PCI. The study will include 982 subjects. A standardized physiological assessment will be performed pre-PCI, including the online calculation of PPG from FFR pullbacks performed manually. PPG quantifies the CAD pattern by combining several parameters from the FFR pullback curve. Post-PCI physiology will be recorded using a standardized protocol with FFR pullbacks. We hypothesize that PPG will predict optimal PCI results (post-PCI FFR ≥ 0.88) with an area under the ROC curve (AUC) ≥ 0.80. Secondary objectives include patient-reported and clinical outcomes in patients with focal vs. diffuse CAD defined by the PPG. Clinical follow-up will be collected for up to 36 months, and an independent clinical event committee will adjudicate events. RESULTS: Recruitment is ongoing and is expected to be completed in the second half of 2023. CONCLUSION: This international, large-scale, prospective study with pre-specified powered hypotheses will determine the ability of the preprocedural PPG index to predict optimal revascularization assessed by post-PCI FFR. In addition, it will evaluate the impact of PPG on treatment decisions and the predictive performance of PPG for angina relief and clinical outcomes.

Clinical impact of FFR-guided PCI compared to angio-guided PCI from the France PCI registry.

OBJECTIVES: We sought to compare, in a national French registry (FrancePCI), the clinical impact of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) compared with angio-guided PCI at 1 year. BACKGROUND: FFR has become the invasive gold standard to quantify myocardial ischemia generated by a coronary stenosis in patients with chronic coronary syndrome, but in clinical practice it is still underutilised to guide PCI compared to angiography (angio). METHODS: We extracted from the FrancePCI database all chronic coronary syndrome patients treated with PCI for coronary stenosis <90% between 2014 and 2019. Our composite clinical endpoint was the rate of major adverse clinical events (MACE). RESULTS: Fourteen thousand three hundred eighty-four patients with 1-year clinical follow-up were included. Among them, 13,125 had angio-guided PCI (91%) and 1259 (9%) had FFR-guided PCI. We observed a significantly higher rate of MACE in the angio-guided group versus the FFR-guided group: 1478 (11.3%) versus 100 (7.9%) (p < 0.0001), respectively, with hazard ratio (HR) of 1.440, 95% confidence interval (CI) [1.211-1.713] (p = 0.0004). This result was driven by the higher occurrence of death in the angio-guided group versus the FFR-guided-group: 506 (3.9%) versus 17 (1.4%) (p < 0.0001), respectively, with HR of 2.845, 95% CI [2.099-3.856] (p < 0.0001). After adjustment for potential confounding factors, HRs were 1.287, 95% CI [1.028-1.613] (p = 0.028) for MACE and 2.527, 95% CI [1.452-4.399] (p = 0.001) for death. No significant differences between angio-guided PCI and FFR-guided PCI were observed for other clinical endpoints. CONCLUSIONS: FFR-guided PCI improves outcome at 1 year compared to angio-guided PCI with a reduction of 64% of death.

Head to head comparison of quantitative flow ratio using 4-French and 6-French catheters versus fractional flow reserve.

OBJECTIVES: To validate QFR using 4-F diagnostic catheters compared to using 6-F guiding catheters, with conventional guidewire-based FFR as the reference standard, using independent core laboratory analysis. BACKGROUND: Quantitative Flow Ratio (QFR) allows Fractional Flow Reserve (FFR) calculation based on the coronary angiogram, using 5- or 6-French (F) catheters. However, the use of 4-F diagnostic catheters to perform coronary angiography is currently routine in some centers. METHODS: We included all consecutive patients with stable coronary artery disease and indicated for physiological assessment. QFR was performed using a 4-F diagnostic catheter, then QFR was performed using a 6-F guiding catheter while conventional FFR was measured using a pressure guidewire. Angiograms were sent to two separate core laboratories. RESULTS: One hundred lesions in 67 consecutive patients with QFR performed using 4-F and 6-F catheters, and with conventional FFR, were included. Pearson's correlation coefficient was for QFR 4-F vs. FFR 0.91 [0.87-0.94], for QFR 6-F vs. FFR 0.90 [0.86-0.94], and for QFR 4-F vs. QFR 6-F 0.93 [0.90-0.95]. Receiver-operator characteristic curves (ROC) comparing the ability to predict an FFR value above or below 0.80 with QFR 4-F and 6-F were generated. The area under the ROC curve (AUC) vs. FFR was 0.972 [0.95-0.99] for QFR 4-F and 0.970 [0.94-0.99] for QFR 6-F. CONCLUSIONS: Our study demonstrated the feasibility of performing QFR analysis from angiograms obtained by 4-F catheters, and showed a good correlation with QFR performed using 6-F catheters as well as with conventional FFR performed using a pressure guidewire.

Accurate assessment of coronary blood flow by continuous thermodilution technique: Validation in a swine model.

OBJECTIVE: To assess the accuracy of coronary thermodilution measurements made with the RayFlow® infusion catheter. BACKGROUND: Measurements of absolute coronary blood flow (ABF) and absolute microvascular resistance (Rµ ) by continuous coronary thermodilution can be obtained in humans but their accuracy using a novel dedicated infusion catheter has not yet been validated. We compared ABF values obtained at different infusion rates to coronary blood flow (CBF) values obtained using flow probes, in swine. METHODS: Twelve domestic swine were instrumented with coronary flow probes placed around the left anterior descending and circumflex coronary arteries. ABF was assessed with the RayFlow® infusion catheter during continuous saline infusion at fixed rates of 5 (n = 14), 10 (n = 15), 15 (n = 19), and 20 (n = 12) ml/min. RESULTS: In the 60 measurements, ABF measured using thermodilution averaged 41 ± 17 ml/min (range from 17 to 90) and CBF values obtained with the coronary flow probes averaged 37 ± 18 ml/min (range from 8 to 87). The corresponding Rµ values were 1532 ± 791 (range from 323 to 5103) and 1903 ± 1162 (range from 287 to 6000) Woods units using thermodilution and coronary flow probe assessments, respectively. ABF and Rµ values measured using thermodilution were significantly correlated with the corresponding measurements obtained using coronary flow probes (R = 0.84 [0.73-0.95] and R = 0.80 [0.69-0.88], respectively). CONCLUSIONS: ABF and Rµ assessed by continuous saline infusion through a RayFlow® catheter closely correlate with measurements obtained with the gold standard coronary flow probes in a swine model.

Future culprit detection based on angiography-derived FFR.

OBJECTIVES: We sought to characterize the hemodynamic impact of mild coronary artery disease (CAD) using quantitative flow ratio (QFR, an angiography-derived fractional flow reserve [FFR]) in a population of patients with only non-significant CAD at baseline that subsequently experienced a myocardial infarction (MI). BACKGROUND: The discriminatory value of FFR in patients with mild CAD remains imperfect. METHODS: We retrospectively included patients who underwent invasive coronary angiography for an MI, in whom another angiogram had been performed within the previous 5 years. Three-dimensional quantitative coronary angiography, QFR, and lesion length analysis were conducted on lesions responsible for the MI (future culprit lesions, [FCL]) as well as on control lesions (non-culprit lesions, [NCL]). RESULTS: Eighty-three FCL and 117 NCL were analyzed in 83 patients: FCL were more severe (median % diameter of stenosis [DS] 39.1% [29.8; 45.7] vs. 29.8% [25.0; 37.2], p < .001), had lower QFR values (0.94 [0.86; 0.98] vs. 0.98 [0.96; 1.00], p < .001) and tended to be longer (15.2 mm [10.0; 27.3] vs. 12.7 mm [9.3; 22.4], p = .070) than NCL. In lesions with an interval < 2 years between baseline angiography and MI, the difference in QFR was more pronounced compared to the lesions with a longer interval (FCL: 0.92 [0.85; 0.97] vs. NCL: 0.98 [0.94; 1.00], p < .001 and FCL: 0.96 [0.88; 1.00] vs. NCL: 0.98 [0.96;1.00], p = .006 respectively) CONCLUSION: Mild coronary stenoses that are subsequently responsible for an MI (FCL) exhibit a higher DS and lower QFR years before the event. Furthermore, FCL with a lower QFR at baseline appear to lead earlier to MI.

Effects of the Interactive Web-Based Video "Mon Coeur, Mon BASIC" on Drug Adherence of Patients With Myocardial Infarction: Randomized Controlled Trial.

BACKGROUND: Secondary prevention strategies after acute coronary syndrome (ACS) presentation with the use of drug combinations are essential to reduce the recurrence of cardiovascular events. However, lack of drug adherence is known to be common in this population and to be related to treatment failure. To improve drug adherence, we developed the "Mon Coeur, Mon BASIC" video. This online video has been specifically designed to inform patients about their disease and their current medications. Interactivity has been used to increase patient attention, and the video can also be viewed on smartphones and tablets. OBJECTIVE: The objective of this study was to assess the long-term impact of an informative web-based video on drug adherence in patients admitted for an ACS. METHODS: This randomized study was conducted with consecutive patients admitted to University Hospital of Lausanne for ACS. We randomized patients to an intervention group, which had access to the web-based video and a short interview with the pharmacist, and a control group receiving usual care. The primary outcome was the difference in drug adherence, assessed with the Adherence to Refills and Medication Scale (ARMS; 9 multiple-choice questions, scores ranging from 12 for perfect adherence to 48 for lack of adherence), between groups at 1, 3, and 6 months. We assessed the difference in ARMS score between both groups with the Wilcoxon rank sum test. Secondary outcomes were differences in knowledge, readmissions, and emergency room visits between groups and patients' satisfaction with the video. RESULTS: Sixty patients were included at baseline. The median age of the participants was 59 years (IQR 49-69), and 85% (51/60) were male. At 1 month, 51 patients participated in the follow-up, 50 patients participated at 3 months, and 47 patients participated at 6 months. The mean ARMS scores at 1 and 6 months did not differ between the intervention and control groups (13.24 vs 13.15, 13.52 vs 13.68, respectively). At 3 months, this score was significantly lower in the intervention group than in the control group (12.54 vs 13.75; P=.03). We observed significant increases in knowledge from baseline to 1 and 3 months, but not to 6 months, in the intervention group. Readmissions and emergency room visits have been very rare, and the proportion was not different among groups. Patients in the intervention group were highly satisfied with the video. CONCLUSIONS: Despite a lower sample size than we expected to reach, we observed that the "Mon Coeur, Mon BASIC" web-based interactive video improved patients' knowledge and seemed to have an impact on drug adherence. These results are encouraging, and the video will be offered to all patients admitted to our hospital with ACS. TRIAL REGISTRATION: ClinicalTrials.gov NCT03949608; https://clinicaltrials.gov/ct2/show/NCT03949608.

Fractional flow reserve in clinical practice: from wire-based invasive measurement to image-based computation.

Fractional flow reserve (FFR) and instantaneous wave-free ratio are the present standard diagnostic methods for invasive assessment of the functional significance of epicardial coronary stenosis. Despite the overall trend towards more physiology-guided revascularization, there remains a gap between guideline recommendations and the clinical adoption of functional evaluation of stenosis severity. A number of image-based approaches have been proposed to compute FFR without the use of pressure wire and induced hyperaemia. In order to better understand these emerging technologies, we sought to highlight the principles, diagnostic performance, clinical applications, practical aspects, and current challenges of computational physiology in the catheterization laboratory. Computational FFR has the potential to expand and facilitate the use of physiology for diagnosis, procedural guidance, and evaluation of therapies, with anticipated impact on resource utilization and patient outcomes.

Quantitative flow ratio virtual stenting and post stenting correlations to post stenting fractional flow reserve measurements from the DOCTORS (Does Optical Coherence Tomography Optimize Results of Stenting) study population.

OBJECTIVE: We sought to evaluate the correlations of pre-PCI QFR analysis with virtual PCI called residual QFR and post-PCI QFR compared to post-PCI FFR. BACKGROUND: Quantitative flow ratio (QFR) is a computation of fractional flow reserve (FFR) based on angiography without use of a pressure wire. The ability to evaluate post-PCI FFR using pre-PCI QFR analysis with a virtual PCI and the correlation between post-PCI QFR compared to post-PCI FFR remains unknown. METHODS: From the DOCTORS (Does Optical Coherence Tomography Optimize Results of Stenting) study population, we blindly analyzed residual QFR and post-PCI QFR from angiographies and compared them to post-PCI FFR. RESULTS: Ninety-three post-PCI QFR measurements and 84 pre-PCI residual QFR measurements were compared to post-PCI FFR measurements. No significant difference were observed between mean post-PCI FFR value (0.92 ± 0.05) compared to mean residual (0.93 ± 0.05) QFR and between mean post-PCI FFR value compared to mean post-PCI QFR values were (0.93 ± 0.05) (p > .05 for both). The correlation coefficient of residual QFR with post-PCI FFR was 0.68 (95% CI: 0.53-0.78) and the correlation coefficient of post-PCI-QFR with post-PCI FFR was 0.79 (95% CI: 0.70-0.86). CONCLUSIONS: Residual QFR corresponding to pre-PCI QFR analysis with virtual PCI, and post-PCI QFR analysis, correlated well with post-PCI FFR. Further studies are needed to prospectively validate a QFR-guided PCI strategy.

In vitro test-retest repeatability of invasive physiological indices to assess coronary flow.

AIMS: Several invasive techniques are available in clinical practice to assess coronary flow. Nevertheless, the test-retest repeatability of these techniques in a controlled setting has not been reported. Therefore, we sought to evaluate fractional flow reserve (FFR), coronary flow reserve (CFR), index of microvascular resistance (IMR), and absolute coronary blood flow (ABF) with absolute microvascular resistance (AMR) test-retest repeatability using a coronary flow simulator. METHODS AND RESULTS: Using a coronary flow simulator (FFR WetLab version 2.0; Abbott Vascular, Santa Clara, CA), we created stenoses ranging from 0% to 70%, with 10% increments. Three different flows were established with their hyperemic phases, and two consecutive measurements were obtained, evaluating the following indices: FFR, CFR, IMR, ABF, and AMR, using a pressure/temperature wire and an infusion catheter. One hundred and thirty-eight pairs of measurements were performed. Test-retest reliability was compared in 48 FFR, 18 CFR, 24 IMR, 24 ABF, and 24 AMR. Test-retest repeatability showed excellent reproducibility for FFR, ABF, and AMR; respectively 0.98 (0.97-0.99), 0.92 (0.81-0.97) and 0.91 (0.79-0.96) (P < 0.0001 for all). However, test-retest repeatability was weaker for IMR and poor for CFR; respectively 0.53 (0.16-0.77) (P = 0.006) and 0.27 (-0.26-0.67) (P = 0.30). CONCLUSIONS: Using a coronary flow simulator, FFR and ABF with AMR had excellent test-retest reliability. IMR and CFR demonstrated weaker test-retest reliability.

In vitro flow and optical coherence tomography comparison of two bailout techniques after failed provisional stenting for bifurcation percutaneous coronary interventions.

OBJECTIVES: To evaluate, in vitro, SB stenting techniques after failed provisional stenting. We aimed to compare flows and stent strut apposition of T and protrusion (TAP) versus Reversed String (RS) techniques using a flow simulator, optical coherence tomography (OCT) using silicon bifurcation phantoms with different bifurcation angulations. BACKGROUND: While bifurcation coronary artery stenoses are preferably treated with provisional T-stenting strategy, the preferred bailout two stents technique to treat the side branch remains unclear. METHODS AND RESULTS: Eleven 30°-angle and ten 60°-angle bifurcation phantoms were used. After performing provisional stenting, TAP and RS techniques were compared in six phantoms with 30° and five with 60° angles. Flow measurement was performed using absolute coronary flow and particle image velocimetry techniques. Strut apposition was evaluated using OCT. Flow analyses showed that disturbed flow regions were observed in the vicinity of floating struts protruded into the lumen both regardless of TAP and RS techniques. OCT analysis showed a higher proportion of floating struts protruding into the main branch with TAP compared to RS, respectively (13% vs. 1%; P <0.001) in both angles. CONCLUSIONS: RS reduces the proportion of floating struts protruding into the main branch compared to TAP, at comparable flow rates. Clinical studies are needed to evaluate feasibility and potential clinical benefit of this technique.

Predictive factors of discordance between the instantaneous wave-free ratio and fractional flow reserve.

OBJECTIVES: To identify clinical, angiographic and hemodynamic predictors of discordance between instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR). BACKGROUND: The iFR was found to be non-inferior to the gold-standard FFR for guiding coronary revascularization, although it is discordant with FFR in 20% of cases. A better understanding of the causes of discordance may enhance application of these indices. METHODS: Both FFR and iFR were measured in the prospective multicenter CONTRAST study. Clinical, angiographic and hemodynamic variables were compared between patients with concordant values of FFR and iFR (cutoff ≤0.80 and ≤0.89, respectively). RESULTS: Out of the 587 patients included, in 466 patients (79.4%) FFR and iFR agreed: both negative, n = 244 (41.6%), or positive, n = 222 (37.8%). Compared with FFR, iFR was negative discordant (FFR+/iFR-) in 69 (11.8%) patients and positive discordant (FFR-/iFR+) in 52 (8.9%) patients. On multivariate regression, stenosis location (left main or proximal left anterior descending) (OR: 3.30[1.68;6.47]), more severe stenosis (OR: 1.77[1.35;2.30]), younger age (OR: 0.93[0.90;0.97]), and slower heart rate (OR: 0.59[0.42;0.75]) were predictors of a negative discordant iFR. Absence of a beta-blocker (OR: 0.41[0.22;0.78]), older age (OR: 1.04[1.00;1.07]), and less severe stenosis (OR: 0.69[0.53;0.89]) were predictors of a positive discordant iFR. CONCLUSIONS: During iFR acquisition, stenosis location, stenosis degree, heart rate, age and use of beta blockers influence concordance with FFR and should be taken into account when interpreting iFR.

Reversed single string technique for coronary bifurcation stenting-First report of case demonstrations in vitro.

OBJECTIVES: This work reports the concept and the practical feasibility of Reversed Single String bifurcation stenting technique by demonstrating three in vitro cases. BACKGROUND: Provisional T stenting is the most used interventional technique to treat coronary bifurcation lesions. However, after main branch (MB) stenting, treatment of the side branch (SB) may become indicated to provide a good final result. Currently applied methods all have their structural limitations with respect to wall coverage, multiple strut layers, poor apposition rate. We reasoned that reversing the Single String technique principle could be used as a bail out after inadequate provisional T stenting. METHODS AND RESULTS: We simulated in three silicone bifurcation phantoms a scenario whereby stenting the SB becomes indicated after provisional T stenting. Thereafter, as first step of Reversed Single String, a stent was deployed into the SB ostium with one single protruding stent-cell into the MB. After wiring that stent-cell and positioning MB balloon across it, final kissing balloon dilation was performed. Results of the in vitro Reversed Single String cases were evaluated by X-ray angiography, optical frequency domain imaging, and 3-Dimensional (3D) reconstruction (OFDI). Each case was successfully performed and completed. In the bifurcation area, perfect apposition was documented in over 81% of the struts. Malapposition remained below 4% of struts in each case. 3D OFDI reconstruction did not reveal any strut fracture. CONCLUSION: This report suggests that Reversed Single String technique might offer a potential bail out solution for provisional T-stenting cases, when treatment of the SB becomes indicated. © 2017 Wiley Periodicals, Inc.

Use of Simulator-Based Teaching to Improve Medical Students' Knowledge and Competencies: Randomized Controlled Trial.

BACKGROUND: Simulator-based teaching for coronary angiography (CA) is an attractive educational tool for medical students to improve their knowledge and skills. Its pedagogical impact has not been fully evaluated yet. OBJECTIVE: The aim of this study was to compare traditional face-to-face teaching with a simulator-based teaching for the acquisition of coronary anatomy knowledge and CAs interpretation. METHODS: A total of 118 medical school students in their fourth to sixth year were prospectively randomized in 2 groups: (1) a control teaching group (n=59, CONT group) and (2) a simulator group (using the Mentice VIST-Lab CA simulator; n=59, SIM group). The CONT group received a PowerPoint-based course, whereas the SIM group received a simulator-based course including the same information. After the course, all students were evaluated by 40 multiple choice questions (maximum of 100 points), including questions on coronary anatomy (part 1), angiographic projections (part 2), and real CAs interpretation (part 3). Satisfaction of the students was also evaluated by a simple questionnaire. RESULTS: Student characteristics were identical in both the groups: 62/118 (52.5%) were female and age was 22.6 (SD 1.4) years. Moreover, 35.6% (42/118) were in their fourth year, 35.6% (42/118) were in the fifth year, and 28.8% (34/118) in the sixth year. During the evaluation, SIM students had higher global scores compared with CONT students, irrespective of their year of medical school (59.5 [SD 10.8] points vs 43.7 [SD 11.3] points, P<.001). The same observations were noted for each part of the test (36.9 [SD 6.6] points vs 29.6 [SD 6.9] points, P<.001; 5.9 [SD 3.0] points vs 3.1 [SD 2.8] points, P<.001; and 16.8 [SD 6.9] points vs 10.9 [SD 6.5] points, P<.001; for parts 1, 2, and 3, respectively). Student satisfaction was higher in the SIM group compared with the CONT group (98% vs 75%, P<.001). CONCLUSIONS: This study suggests that simulator-based teaching could potentially improve students' knowledge of coronary anatomy, angiography projections, and interpretation of real clinical cases, suggesting better clinical skills. These results should encourage further evaluation of simulator-based teaching in other medical specialties and how they can translate into clinical practice.

[Cardiology update 2017]. / Cardiologie.

As usual, numerous papers published in 2017 contributed to optimize the management of patients in all clinical cardiologic fields. It is of course impossible to summarize them all in such an article. Subjects and papers were thus selected if they were thought to be particularly important for non-cardiologist physicians, especially general practitioners. The authors would also like to take the opportunity of this article to honor the memory of Pr Daniel Wagner who unfortunately passed away after less than six months at the head of our Cardiology Department. He was well recognized for his generosity as well as his clinical and scientific competence. This article is dedicated to him.

Comme à l'accoutumée, l'année 2017 a été marquée par la publication de nombreux travaux permettant d'optimaliser la prise en charge de nos patients dans tous les domaines de la cardiologie et il est évidemment impossible de les synthétiser ici de façon exhaustive. Nous avons donc sélectionné les sujets et les travaux qui nous ont paru les plus saillants et surtout les plus utiles pour nos collègues non cardiologues et particulièrement pour nos collègues médecins de premier recours. Cette revue de l'année 2017 ne serait toutefois pas complète sans un hommage au Pr Daniel Wagner qui a débuté son activité de chef du service de cardiologie du CHUV au 1er janvier et nous a quittés après seulement quelques mois passés parmi nous. Daniel fut un chef de service apprécié tant pour ses qualités humaines que pour ses compétences scientifiques et cliniques. Cet article lui est donc dédié.

Significance of Intermediate Values of Fractional Flow Reserve in Patients With Coronary Artery Disease.

BACKGROUND: The fractional flow reserve (FFR) value of 0.75 has been validated against ischemic testing, whereas the FFR value of 0.80 has been widely accepted to guide clinical decision making. However, revascularization when FFR is 0.76 to 0.80, within the so-called gray zone, is still debatable. METHODS AND RESULTS: From February 1997 to June 2013, all patients with single-segment disease and an FFR value within the gray zone or within the 2 neighboring FFR strata (0.70-0.75 and 0.81-0.85) were included. Study end points consisted of major adverse cardiovascular events (death, myocardial infarction, and any revascularization) up to 5 years. Of 17 380 FFR measurements, 1459 patients were included. Of them, 449 patients were treated with revascularization and 1010 patients were treated with medical therapy. In the gray zone, the major adverse cardiovascular events rate was similar (37 [13.9%] versus 21 [11.2%], respectively; P=0.3) between medical therapy and revascularization, whereas a strong trend toward a higher rate of death or myocardial infarction (25 [9.4] versus 9 [4.8], P=0.06) and overall death (20 [7.5] versus 6 [3.2], P=0.059) was observed in the medical therapy group. Among medical therapy patients, a significant step-up increase in major adverse cardiovascular events rate was observed across the 3 FFR strata, especially with proximal lesion location. In revascularization patients, the major adverse cardiovascular events rate was not different across the 3 FFR strata. CONCLUSIONS: FFR in and around the gray zone bears a major prognostic value, especially in proximal lesions. These data confirm that FFR≤0.80 is valid to guide clinical decision making.

Diabetes does not impact the diagnostic performance of contrast-based fractional flow reserve: insights from the CONTRAST study.

BACKGROUND: Adenosine-free coronary pressure wire metrics have been proposed to test the functional significance of coronary artery lesions, but it is unexplored whether their diagnostic performance might be altered in patients with diabetes. METHODS: We performed a post-hoc analysis of the CONTRAST study, which prospectively enrolled an international cohort of patients undergoing routine fractional flow reserve (FFR) assessment for standard indications. Paired, repeated measurements of all physiology metrics (Pd/Pa, iFR, contrast-based FFR, and FFR) were made. A central core laboratory analyzed blinded pressure tracings in a standardized fashion. RESULTS: Of 763 subjects enrolled at 12 international centers, 219 (29%) had diabetes. The two groups were well-balanced for age, clinical presentation (stable or unstable), coronary vessel studied, volume and type of intracoronary contrast, and volume of intracoronary adenosine. A binary threshold of cFFR ≤ 0.83 produced an accuracy superior to both Pd/Pa and iFR when compared with FFR ≤ 0.80 in the absence of significant interaction with diabetes status; indeed, accuracy in subgroups of patients with or without diabetes was similar for cFFR (86.7 vs 85.4% respectively; p = 0.76), iFR (84.2 vs 80.0%, p = 0.29) and Pd/Pa (81.3 vs 78.9%, p = 0.55). There was no significant heterogeneity between patients with or without diabetes in terms of sensitivity and specificity of all metrics. The area under the receiver operating characteristic (ROC) curve was largest for cFFR compared with Pd/Pa and iFR which were equivalent (cFFR 0.961 and 0.928; Pd/Pa 0.916 and 0.870; iFR 0.911 and 0.861 in diabetic and non-diabetic patients respectively). CONCLUSIONS: cFFR provides superior diagnostic performance compared with Pd/Pa or iFR for predicting FFR irrespective of diabetes (clinicaltrials.gov identifier NCT02184117).

Measuring Absolute Coronary Flow and Microvascular Resistance by Thermodilution: JACC Review Topic of the Week.

Diagnosing coronary microvascular dysfunction remains challenging, primarily due to the lack of direct measurements of absolute coronary blood flow (Q) and microvascular resistance (Rµ). However, there has been recent progress with the development and validation of continuous intracoronary thermodilution, which offers a simplified and validated approach for clinical use. This technique enables direct quantification of Q and Rµ, leading to precise and accurate evaluation of the coronary microcirculation. To ensure consistent and reliable results, it is crucial to follow a standardized protocol when performing continuous intracoronary thermodilution measurements. This document aims to summarize the principles of thermodilution-derived absolute coronary flow measurements and propose a standardized method for conducting these assessments. The proposed standardization serves as a guide to ensure the best practice of the method, enhancing the clinical assessment of the coronary microcirculation.