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The need for a quantitative and operator-independent assessment of coronary microvascular function is increasingly recognized. We propose the theoretical framework of microvascular resistance reserve (MRR) as an index specific for the microvasculature, independent of autoregulation and myocardial mass, and based on operator-independent measurements of absolute values of coronary flow and pressure. In its general form, MRR equals coronary flow reserve (CFR) divided by fractional flow reserve (FFR) corrected for driving pressures. In 30 arteries, pressure, temperature, and flow velocity measurements were obtained simultaneously at baseline (BL), during infusion of saline at 10 mL/min (rest) and 20 mL/min (hyperemia). A strong correlation was found between continuous thermodilution-derived MRR and Doppler MRR (r = 0.88; 95% confidence interval: 0.72-0.93; P < 0.001). MRR was independent from the epicardial resistance, the lower the FFR value, the greater the difference between MRR and CFR. Therefore, MRR is proposed as a specific, quantitative, and operator-independent metric to quantify coronary microvascular dysfunction.

Aims Fractional flow reserve (FFR) has never been investigated in patients with reduced ejection fraction and associated coronary artery disease (CAD). We evaluated the impact of FFR on the management strategies of these patients and related outcomes. Methods and results From 2002 to 2010, all consecutive patients with left ventricular ejection fraction (LVEF) ≤50% undergoing coronary angiography with ≥1 intermediate coronary stenosis [diameter stenosis (DS)% 50–70%] treated based on angiography (Angiography-guided group) or according to FFR (FFR-guided group) were screened for inclusion. In the FFR-guided group, 433 patients were matched with 866 contemporary patients of the Angiography-guided group. For outcome comparison, 617 control patients with LVEF >50% were included. After FFR, stenotic vessels per patient were significantly downgraded compared with the Angiography-guided group (1.43 ± 0.98 vs. 1.97 ± 0.84; P Conclusions In patients with reduced LVEF and CAD, FFR-guided revascularization was associated with lower rates of death and MACCE at 5 years as compared with the Angiography-guided strategy. This beneficial impact was observed in parallel with less coronary artery bypass grafting and more patients deferred to percutaneous coronary intervention or medical therapy.

Background: Among patients with documented stable coronary artery disease and in whom no revascularization was performed, we compared the respective values of angiographic diameter stenosis (DS) and fractional flow reserve (FFR) in predicting natural history. Methods: The present analysis included the 607 patients from the FAME 2 trial (Fractional Flow Reserve Versus Angiography in Multivessel Evaluation 2) in whom no revascularization was performed. FFR varied from 0.20 to 1.00 (average 0.74±0.16), and DS (by quantitative coronary analysis) varied from 8% to 98% (average 53±15). The primary end point, defined as vessel-oriented clinical end point (VOCE) at 2 years, was a composite of prospectively adjudicated cardiac death, vessel-related myocardial infarction, vessel-related urgent, and not urgent revascularization. The stenoses were divided into 4 groups according to FFR and %DS values: positive concordance (FFR≤0.80; DS≥50%), negative concordance (FFR>0.80; DS0.80; DS≥50%). Results: The rate of VOCE was highest in the positive concordance group (log rank: X 2 =80.96; P =0.001) and lowest in the negative concordance group. The rate of VOCE was higher in the positive mismatch group than in the negative mismatch group (hazard ratio, 0.38; 95% confidence interval, 0.21–0.67; P =0.001). There was no significant difference in VOCE between the positive concordance and positive mismatch groups (FFR≤0.80; hazard ratio, 0.77; 95% confidence interval, 0.57–1.09; P =0.149) and no significant difference in rate of VOCE between the negative mismatch and negative concordance groups (FFR>0.80; hazard ratio, 1.89; 95% confidence interval, 0.96–3.74; P =0.067). Conclusions: In patients with stable coronary disease, physiology (FFR) is a more important determinant of the natural history of coronary stenoses than anatomy (DS). Clinical Trial Registration: URL: https://clinicaltrials.gov . Unique identifier: NCT01132495.

Aims The aim of this study was to assess prospectively the clinical benefits of fractional flow reserve (FFR) in guiding coronary artery bypass grafting (CABG). Methods and results GRAFFITI is a single-blinded, prospective, multicentre, randomised controlled trial of FFR-guided versus angiography-guided CABG. We enrolled patients undergoing coronary angiography, having a significantly diseased left anterior descending artery or left main stem and at least one more major coronary artery with intermediate stenosis, assessed by FFR. Surgical strategy was defined based on angiography, blinded to FFR values prior to randomisation. After randomisation, patients were operated on either following the angiography-based strategy (angiography-guided group) or according to FFR, i.e., with an FFR ≤0.80 as cut-off for grafting (FFR-guided group). The primary endpoint was graft patency at 12 months. Between March 2012 and December 2016, 172 patients were randomised either to the angiography-guided group (84 patients) or to the FFR-guided group (88 patients). The patients had a median of three [3; 4] lesions; diameter stenosis was 65% (50%; 80%), FFR was 0.72 (0.50; 0.82). Compared to the angiography-guided group, the FFR-guided group received fewer anastomoses (3 [3; 3] vs 2 [2; 3], respectively; p=0.004). One-year angiographic follow-up showed no difference in overall graft patency (126 [80%] vs 113 [81%], respectively; p=0.885). One-year clinical follow-up, available in 98% of patients, showed no difference in the composite of death, myocardial infarction, target vessel revascularisation and stroke. Conclusions FFR guidance of CABG has no impact on one-year graft patency, but it is associated with a simplified surgical procedure. ClinicalTrials.gov Identifier: NCT01810224.

Aims To assess the effect of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) with contemporary drug-eluting stents on the composite of cardiac death or myocardial infarction (MI) vs. medical therapy in patients with stable coronary lesions. Methods and results We performed a systematic review and meta-Analysis of individual patient data (IPD) of the three available randomized trials of contemporary FFR-guided PCI vs. medical therapy for patients with stable coronary lesions: FAME 2 (NCT01132495), DANAMI-3-PRIMULTI (NCT01960933), and Compare-Acute (NCT01399736). FAME 2 enrolled patients with stable coronary artery disease (CAD), while the other two focused on non-culprit lesions in stabilized patients after acute coronary syndrome. A total of 2400 subjects were recruited from 54 sites world-wide with 1056 randomly assigned to FFR-guided PCI and 1344 to medical therapy. The pre-specified primary outcome was a composite of cardiac death or MI. We included data from extended follow-ups for FAME 2 (up to 5.5 years follow-up) and DANAMI-3-PRIMULTI (up to 4.7 years follow-up). After a median follow-up of 35 months (interquartile range 12-60months), a reduction in the composite of cardiac death or MI was observed with FFR-guided PCI as compared with medical therapy (hazard ratio 0.72, 95% confidence interval 0.54-0.96; P= 0.02). The difference between groups was driven by MI. Conclusion In this IPD meta-Analysis of the three available randomized controlled trials to date, FFR-guided PCI resulted in a reduction of the composite of cardiac death or MI compared with medical therapy, which was driven by a decreased risk of MI.

Background— The principle of continuous thermodilution can be used to calculate absolute coronary blood flow and microvascular resistance (R). The aim of the study is to explore the safety, feasibility, and reproducibility of coronary blood flow and R measurements as measured by continuous thermodilution in humans. Methods and Results— Absolute coronary flow and R can be calculated by thermodilution by infusing saline at room temperature through a dedicated monorail catheter. The temperature of saline as it enters the vessel, the temperature of blood and saline mixed in the distal part of the vessel, and the distal coronary pressure were measured by a pressure/temperature sensor-tipped guidewire. The feasibility and safety of the method were tested in 135 patients who were referred for coronary angiography. No significant adverse events were observed; in 11 (8.1%) patients, bradycardia and concomitant atrioventricular block appeared transiently and were reversed immediately on interruption of the infusion. The reproducibility of measurements was tested in a subgroup of 80 patients (129 arteries). Duplicate measurements had a strong correlation both for coronary blood flow (ρ=0.841, P P P P Conclusions— Absolute coronary blood flow (in L/min) and R (in mm Hg/L/min or Wood units) can be safely and reproducibly measured with continuous thermodilution. This approach constitutes a new opportunity for the study of the coronary microcirculation.

Background: we hypothesized that fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) would be superior to medical therapy as initial treatment in patients with stable coronary artery disease.Methods: among 1220 patients with angiographically significant stenoses, those in whom at least one stenosis was hemodynamically significant (FFR, ≤0.80) were randomly assigned to FFR-guided PCI plus medical therapy or to medical therapy alone. Patients in whom all stenoses had an FFR of more than 0.80 received medical therapy and were entered into a registry. The primary end point was a composite of death, myocardial infarction, or urgent revascularization.Results: a total of 888 patients underwent randomization (447 patients in the PCI group and 441 in the medical-therapy group). At 5 years, the rate of the primary end point was lower in the PCI group than in the medical-therapy group (13.9% vs. 27.0%; hazard ratio, 0.46; 95% confidence interval [CI], 0.34 to 0.63; PConclusions: in patients with stable coronary artery disease, an initial FFR-guided PCI strategy was associated with a significantly lower rate of the primary composite end point of death, myocardial infarction, or urgent revascularization at 5 years than medical therapy alone. Patients without hemodynamically significant stenoses had a favorable long-term outcome with medical therapy alone. (Funded by St. Jude Medical and others; FAME 2 ClinicalTrials.gov number, NCT01132495 .).

Background— Fractional flow reserve (FFR)-guided coronary artery bypass graft (CABG) surgery has been associated with lower number of graft anastomoses, lower rate of on-pump surgery, and higher graft patency rate as compared with angiography-guided CABG surgery. However, no clinical benefit has been reported to date. Methods and Results— Consecutive patients (n=627) treated by CABG between 2006 and 2010 were retrospectively included. In 198 patients, at least 1 stenosis was grafted according to FFR (FFR-guided group), whereas in 429 patients all stenoses were grafted based on angiography (angiography-guided group). The 2 coprimary end points were overall death or myocardial infarction and major adverse cardiovascular events (composite of overall death, myocardial infarction, and target vessel revascularization) up to 6-year follow-up. In the FFR-guided group, patients were significantly younger (66 [57–73] versus 70 [63–76]; P P =0.008), and less often diabetic (21% versus 30%; P =0.023). Clinical follow-up (median, 85 [66–104] months) was analyzed in 396 patients after 1:1 propensity-score matching for these 3 variables. The rate of overall death or myocardial infarction was significantly lower in the FFR-guided (n=31 [16%] versus n=49 [25%]; hazard ratio, 0.59 [95% confidence interval, 0.38–0.93]; P =0.020) as compared with the angiography-guided group. Major adverse cardiovascular events rate was also numerically lower in the FFR-guided than in the angiography-guided group (n=42 [21%] versus n=52 [26%]; hazard ratio, 0.77 [95% confidence interval, 0.51–1.16]; P =0.21). Conclusions— FFR-guided CABG is associated with a significant reduction in the rate of overall death or myocardial infarction at 6-year follow-up as compared with angiography-guided CABG.

Clinical benefit of invasive functionally guided revascularization has been mostly investigated and proven for percutaneous coronary intervention. It has never been prospectively evaluated whether a systematic fractional flow reserve (FFR) assessment is also beneficial in guiding coronary artery bypass graft surgery (CABG). The objective of the GRAft patency after FFR-guided versus angiography-guIded CABG (GRAFFITI) trial was to compare an FFR-guided revascularization strategy to the traditional angiography-guided revascularization strategy for patients undergoing CABG. Patients were enrolled with significantly diseased left anterior descending or left main stem and at least one major coronary artery with angiographically intermediate stenosis (30-90% diameter stenosis) that was assessed by FFR. Thereafter, while the FFR values were kept concealed, cardiac surgeons decided their intended procedural strategy based on the coronary angiography alone. At this point, patients underwent 1:1 randomization to either an FFR-guided or an angiography-guided CABG strategy. In case the patient was randomized to angiography-guided arm, cardiac surgeons kept their intended procedural strategy, i.e., CABG was guided solely on the basis of the coronary angiography. In case the patient was randomized to the FFR-guided arm, FFR values were disclosed to the surgeons who revised the surgical protocol according to the functional significance of each coronary stenosis. The primary endpoint of the trial was the rate of graft occlusion at 12 months, assessed by coronary computed tomography or coronary angiography. The secondary endpoints were (1) length of postoperative hospital stay; (2) changes in surgical strategy depending upon FFR results (in FFR-guided group only); and (3) rate of major adverse cardiac and cerebrovascular events, i.e., composite of death, myocardial infarction, stroke, and any revascularization during the follow-up period. This study is the first prospective randomized trial investigating potential clinical benefits, associated with FFR-guided surgical revascularization. info:eu-repo/semantics/publishedVersion

Background: Whether the benefit in quality of life (QOL) after percutaneous coronary intervention depends on the severity of the stenosis as determined by fractional flow reserve (FFR) remains unknown. This study sought to investigate the relationship between FFR values and improvement in QOL. Methods: From the FAME 1 and 2 trials (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation), we identified 706 stable patients with coronary artery disease who had at least 1 lesion with an FFR≤0.80 that was treated with percutaneous coronary intervention and 185 patients with coronary artery disease who had no lesion with an FFR≤0.80 and were treated medically who served as a reference group. QOL was assessed by the European Quality of Life–5 Dimensions index at baseline, 1 month, and 1 year. We assessed the relationship between QOL improvement (defined as the change in European Quality of Life–5 Dimensions index from baseline) and FFR as a continuous value and according to abnormal FFR tertile. Results: QOL improved significantly after percutaneous coronary intervention in each abnormal FFR tertile, whereas it did not change in the reference group. The lowest abnormal FFR subgroup had the greatest improvement in QOL at 1 month ( P P =0.002 for 1 month and 0.049 for 1 year), greater delta FFR ( P =0.021 for 1 month and 0.025 for 1 year), and higher angina class ( P =0.001 for 1 month and Conclusions: Among patients with stable coronary artery disease, FFR and angina severity predict QOL improvement after percutaneous coronary intervention. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifiers: NCT00267774 and NCT01132495.