Emanuele Barbato

Fractional flow reserve-guided PCI versus medical therapy in stable coronary disease

BACKGROUND The preferred initial treatment for patients with stable coronary artery disease is the best available medical therapy. We hypothesized that in patients with functionally significant stenoses, as determined by measurement of fractional flow reserve (FFR), percutaneous coronary intervention (PCI) plus the best available medical therapy would be superior to the best available medical therapy alone. METHODS In patients with stable coronary artery disease for whom PCI was being considered, we assessed all stenoses by measuring FFR. Patients in whom at least one stenosis was functionally significant (FFR, ≤0.80) were randomly assigned to FFR-guided PCI plus the best available medical therapy (PCI group) or the best available medical therapy alone (medical-therapy group). Patients in whom all stenoses had an FFR of more than 0.80 were entered into a registry and received the best available medical therapy. The primary end point was a composite of death, myocardial infarction, or urgent revascularization. RESULTS Recruitment was halted prematurely after enrollment of 1220 patients (888 who underwent randomization and 332 enrolled in the registry) because of a significant between-group difference in the percentage of patients who had a primary end-point event: 4.3% in the PCI group and 12.7% in the medical-therapy group (hazard ratio with PCI, 0.32; 95% confidence interval [CI], 0.19 to 0.53; P<0.001). The difference was driven by a lower rate of urgent revascularization in the PCI group than in the medical-therapy group (1.6% vs. 11.1%; hazard ratio, 0.13; 95% CI, 0.06 to 0.30; P<0.001); in particular, in the PCI group, fewer urgent revascularizations were triggered by a myocardial infarction or evidence of ischemia on electrocardiography (hazard ratio, 0.13; 95% CI, 0.04 to 0.43; P<0.001). Among patients in the registry, 3.0% had a primary end-point event. CONCLUSIONS In patients with stable coronary artery disease and functionally significant stenoses, FFR-guided PCI plus the best available medical therapy, as compared with the best available medical therapy alone, decreased the need for urgent revascularization. In patients without ischemia, the outcome appeared to be favorable with the best available medical therapy alone. (Funded by St. Jude Medical; ClinicalTrials.gov number, NCT01132495.).

Fractional Flow Reserve–Guided PCI for Stable Coronary Artery Disease

BACKGROUND We hypothesized that in patients with stable coronary artery disease and stenosis, percutaneous coronary intervention (PCI) performed on the basis of the fractional flow reserve (FFR) would be superior to medical therapy. METHODS In 1220 patients with stable coronary artery disease, we assessed the FFR in all stenoses that were visible on angiography. Patients who had at least one stenosis with an FFR of 0.80 or less were randomly assigned to undergo FFR-guided PCI plus medical therapy or to receive medical therapy alone. Patients in whom all stenoses had an FFR of more than 0.80 received medical therapy alone and were included in a registry. The primary end point was a composite of death from any cause, nonfatal myocardial infarction, or urgent revascularization within 2 years. RESULTS The rate of the primary end point was significantly lower in the PCI group than in the medical-therapy group (8.1% vs. 19.5%; hazard ratio, 0.39; 95% confidence interval [CI], 0.26 to 0.57; P<0.001). This reduction was driven by a lower rate of urgent revascularization in the PCI group (4.0% vs. 16.3%; hazard ratio, 0.23; 95% CI, 0.14 to 0.38; P<0.001), with no significant between-group differences in the rates of death and myocardial infarction. Urgent revascularizations that were triggered by myocardial infarction or ischemic changes on electrocardiography were less frequent in the PCI group (3.4% vs. 7.0%, P=0.01). In a landmark analysis, the rate of death or myocardial infarction from 8 days to 2 years was lower in the PCI group than in the medical-therapy group (4.6% vs. 8.0%, P=0.04). Among registry patients, the rate of the primary end point was 9.0% at 2 years. CONCLUSIONS In patients with stable coronary artery disease, FFR-guided PCI, as compared with medical therapy alone, improved the outcome. Patients without ischemia had a favorable outcome with medical therapy alone. (Funded by St. Jude Medical; FAME 2 ClinicalTrials.gov number, NCT01132495.).

Intracoronary and intravenous adenosine 5'-triphosphate, adenosine, papaverine, and contrast medium to assess fractional flow reserve in humans

Background—Inducing both maximal and steady-state coronary hyperemia is of clinical importance to take full advantage of fractional flow reserve measurements. The present study compares different dosages and routes of administration of adenosine 5′-triphosphate (ATP), adenosine, contrast medium, and papaverine regarding their potential to achieve both maximal and steady-state hyperemia. Methods and Results—In 21 patients with an isolated coronary stenosis, coronary vasodilation was induced successively by papaverine (20 mg intracoronary), adenosine (20 and 40 &mgr;g intracoronary), ATP (20 and 40 &mgr;g intracoronary), iohexol (6 mL intracoronary), adenosine or ATP through an antecubital vein (140 and 180 &mgr;g · kg−1 · min−1), or adenosine or ATP through a femoral vein (140 and 180 &mgr;g · kg−1 · min−1). Because vessel dimensions did not change, the ratio of distal coronary pressure (Pd) to aortic pressure (Pa) was used as an index of myocardial resistance. Pd/Pa was 0.77±0.21 at rest and decreased to 0.61±0.21 after papaverine. Pd/Pa decreased to a similar level with all other vasodilators, except with contrast medium (0.68±0.21;P <0.01 versus papaverine). Steady-state hyperemia could only be obtained by intracoronary papaverine and by intravenous ATP or adenosine. In another 23 patients, an intravenous infusion of ATP was varied from 0 to 280 &mgr;g · kg−1 · min−1. At doses >140 &mgr;g · kg−1 · min−1, there was neither a further decrease in Pd/Pa ratio nor a further increase in coronary flow velocities. Conclusion—Provided sufficient dosages are used, ATP, adenosine, and papaverine (but not contrast medium) induce maximal hyperemia and are therefore suitable to assess fractional flow reserve. Only intracoronary papaverine and intravenous ATP or adenosine induce steady-state hyperemia enabling a pressure pullback maneuver that is useful in assessing diffuse coronary atherosclerosis.

Prognostic Value of Fractional Flow Reserve: Linking Physiologic Severity to Clinical Outcomes

BACKGROUND Fractional flow reserve (FFR) has become an established tool for guiding treatment, but its graded relationship to clinical outcomes as modulated by medical therapy versus revascularization remains unclear. OBJECTIVES The study hypothesized that FFR displays a continuous relationship between its numeric value and prognosis, such that lower FFR values confer a higher risk and therefore receive larger absolute benefits from revascularization. METHODS Meta-analysis of study- and patient-level data investigated prognosis after FFR measurement. An interaction term between FFR and revascularization status allowed for an outcomes-based threshold. RESULTS A total of 9,173 (study-level) and 6,961 (patient-level) lesions were included with a median follow-up of 16 and 14 months, respectively. Clinical events increased as FFR decreased, and revascularization showed larger net benefit for lower baseline FFR values. Outcomes-derived FFR thresholds generally occurred around the range 0.75 to 0.80, although limited due to confounding by indication. FFR measured immediately after stenting also showed an inverse relationship with prognosis (hazard ratio: 0.86, 95% confidence interval: 0.80 to 0.93; p < 0.001). An FFR-assisted strategy led to revascularization roughly half as often as an anatomy-based strategy, but with 20% fewer adverse events and 10% better angina relief. CONCLUSIONS FFR demonstrates a continuous and independent relationship with subsequent outcomes, modulated by medical therapy versus revascularization. Lesions with lower FFR values receive larger absolute benefits from revascularization. Measurement of FFR immediately after stenting also shows an inverse gradient of risk, likely from residual diffuse disease. An FFR-guided revascularization strategy significantly reduces events and increases freedom from angina with fewer procedures than an anatomy-based strategy.

Coronary thermodilution to assess flow reserve : validation in humans

Background—Guide wire–based simultaneous measurement of fractional flow reserve (FFR) and coronary flow reserve (CFR) is important to understand microvascular disease of the heart. The aim of this study was to investigate the feasibility of simultaneous measurement of FFR and CFR by one pressure-temperature sensor-tipped guide wire with the use of coronary thermodilution and to compare CFR by thermodilution (CFRthermo) with simultaneously measured Doppler CFR (CFRDoppl). Methods and Results—In 103 coronary arteries in 50 patients, a pressure-temperature sensor-tipped 0.014-inch floppy guide wire and a 0.014-inch Doppler guide wire were introduced. Both normal vessels and a wide range of stenotic vessels were included. With 3 mL of saline at room temperature used as an indicator, by hand-injection, thermodilution curves in the coronary artery were obtained in triplicate, both at baseline and at intravenous adenosine-induced maximum hyperemia. After adequate curve-fitting, CFRthermo was calculated from the ratio of inverse mean transit times and compared with CFRDoppl calculated by velocities at hyperemia and baseline. Adequate sets of thermodilution curves and corresponding CFRthermo could be obtained in 87% of the arteries versus 91% for Doppler CFR and 100% for FFR. CFRthermo correlated fairly well to CFRDoppl (CFRthermo=0.84 CFRDoppl+0.17;r =0.80;P <0.001), although individual differences of >20% between both indexes were seen in a quarter of all arteries. Conclusions—This study shows the feasibility of simultaneous measurement of FFR (by coronary pressure) and CFR (by coronary thermodilution) in humans by one single guide wire in a practical and straightforward way and will facilitate assessment of microvascular disease.

Fractional Flow Reserve for the Assessment of Nonculprit Coronary Artery Stenoses in Patients With Acute Myocardial Infarction

OBJECTIVES We investigated the reliability of fractional flow reserve (FFR) of nonculprit coronary stenoses during percutaneous coronary intervention (PCI) in acute myocardial infarction. BACKGROUND Assessing the hemodynamic severity of the nonculprit coronary artery stenoses at the acute phase of a myocardial infarction could improve risk stratification and shorten the diagnostic work-up. METHODS One hundred one patients undergoing PCI for an acute myocardial infarction (n = 75 with ST-segment elevation myocardial infarction [STEMI], and n = 26 with non-ST-segment elevation myocardial infarction) were prospectively recruited. The FFR measurements in 112 nonculprit stenoses were obtained immediately after PCI of the culprit stenosis and were repeated 35 ± 4 days later. In addition, left ventricular ejection fraction, quantitative coronary angiographic measurements of the nonculprit stenoses, Thrombolysis In Myocardial Infarction (TIMI) flow, corrected TIMI frame count (cTFC), and the index of microcirculatory resistance (n = 14) of the nonculprit vessels were assessed in the acute phase and at control angiogram. RESULTS The FFR value of the nonculprit stenoses did not change between the acute and follow-up (0.77 ± 0.13 vs. 0.77 ± 0.13, respectively, p = NS). In only 2 patients, the FFR value was higher than 0.8 at the acute phase and lower than 0.75 at follow-up. The TIMI flow, cTFC, percentage diameter stenosis, minimum lumen diameter, and index of microcirculatory resistance did not change. Left ventricular ejection fraction increased significantly in patients with STEMI (from 54 ± 13% to 57 ± 13%, p = 0.03). CONCLUSIONS During the acute phase of acute coronary syndromes, the severity of nonculprit coronary artery stenoses can reliably be assessed by FFR. This allows a decision about the need for additional revascularization and might contribute to a better risk stratification.

VERIFY (VERification of Instantaneous Wave-Free Ratio and Fractional Flow Reserve for the Assessment of Coronary Artery Stenosis Severity in EverydaY Practice): a multicenter study in consecutive patients.

OBJECTIVES This study sought to compare fractional flow reserve (FFR) with the instantaneous wave-free ratio (iFR) in patients with coronary artery disease and also to determine whether the iFR is independent of hyperemia. BACKGROUND FFR is a validated index of coronary stenosis severity. FFR-guided percutaneous coronary intervention (PCI) improves clinical outcomes compared to angiographic guidance alone. iFR has been proposed as a new index of stenosis severity that can be measured without adenosine. METHODS We conducted a prospective, multicenter, international study of 206 consecutive patients referred for PCI and a retrospective analysis of 500 archived pressure recordings. Aortic and distal coronary pressures were measured in duplicate in patients under resting conditions and during intravenous adenosine infusion at 140 μg/kg/min. RESULTS Compared to the FFR cut-off value of ≤0.80, the diagnostic accuracy of the iFR value of ≤0.80 was 60% (95% confidence interval [CI]: 53% to 67%) for all vessels studied and 51% (95% CI: 43% to 59%) for those patients with FFR in the range of 0.60 to 0.90. iFR was significantly influenced by the induction of hyperemia: mean ± SD iFR at rest was 0.82 ± 0.16 versus 0.64 ± 0.18 with hyperemia (p < 0.001). Receiver operating characteristics confirmed that the diagnostic accuracy of iFR was similar to resting Pd/Pa and trans-stenotic pressure gradient and significantly inferior to hyperemic iFR. Analysis of our retrospectively acquired dataset showed similar results. CONCLUSIONS iFR correlates weakly with FFR and is not independent of hyperemia. iFR cannot be recommended for clinical decision making in patients with coronary artery disease.

Fractional flow reserve versus angiography for guidance of PCI in patients with multivessel coronary artery disease (FAME): 5-year follow-up of a randomised controlled trial

BACKGROUND In the Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) study, fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) improved outcome compared with angiography-guided PCI for up to 2 years of follow-up. The aim in this study was to investigate whether the favourable clinical outcome with the FFR-guided PCI in the FAME study persisted over a 5-year follow-up. METHODS The FAME study was a multicentre trial done in Belgium, Denmark, Germany, the Netherlands, Sweden, the UK, and the USA. Patients (aged ≥ 18 years) with multivessel coronary artery disease were randomly assigned to undergo angiography-guided PCI or FFR-guided PCI. Before randomisation, stenoses requiring PCI were identified on the angiogram. Patients allocated to angiography-guided PCI had revascularisation of all identified stenoses. Patients allocated to FFR-guided PCI had FFR measurements of all stenotic arteries and PCI was done only if FFR was 0·80 or less. No one was masked to treatment assignment. The primary endpoint was major adverse cardiac events at 1 year, and the data for the 5-year follow-up are reported here. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00267774. FINDINGS After 5 years, major adverse cardiac events occurred in 31% of patients (154 of 496) in the angiography-guided group versus 28% (143 of 509 patients) in the FFR-guided group (relative risk 0·91, 95% CI 0·75-1·10; p=0·31). The number of stents placed per patient was significantly higher in the angiography-guided group than in the FFR-guided group (mean 2·7 [SD 1·2] vs 1·9 [1·3], p<0·0001). INTERPRETATION The results confirm the long-term safety of FFR-guided PCI in patients with multivessel disease. A strategy of FFR-guided PCI resulted in a significant decrease of major adverse cardiac events for up to 2 years after the index procedure. From 2 years to 5 years, the risks for both groups developed similarly. This clinical outcome in the FFR-guided group was achieved with a lower number of stented arteries and less resource use. These results indicate that FFR guidance of multivessel PCI should be the standard of care in most patients. FUNDING St Jude Medical, Friends of the Heart Foundation, and Medtronic.

Evolving concepts of angiogram: fractional flow reserve discordances in 4000 coronary stenoses

AIMS The present analysis addresses the potential clinical and physiologic significance of discordance in severity of coronary artery disease between the angiogram and fractional flow reserve (FFR) in a large and unselected patient population. METHODS AND RESULTS Between September 1999 and December 2011, FFR and percent diameter stenosis (DS) as assessed by quantitative coronary angiography were obtained in 2986 patients (n = 4086 coronary stenoses), in whom at least one stenosis was of intermediate angiographic severity. Fractional flow reserve correlated slightly but significantly with DS [-0.38 (95% CI: -0.41; -0.36); P < 0.001]. The sensitivity, specificity, and diagnostic accuracy of a ≥ 50% DS for predicting FFR ≤ 0.80 were 61% (95% CI: 59; 63), 67% (95% CI: 65; 69), and 0.64 (95% CI: 0.56; 0.72), respectively. In different anatomical settings, sensitivity and specificity showed marked variations between 35 to 74% and 58 to 76%, respectively, resulting in a discordance in 35% of all cases for these thresholds. For an angiographic threshold of 70% DS, the diagnostic performance by the Youdens index decreased from 0.28 to 0.11 for the overall population. CONCLUSION The data confirm that one-third of a large patient population shows discordance between angiogram ≥ 50%DS and FFR ≤ 0.8 thresholds of stenosis severity. Left main stenoses are often underestimated by the classical 50% DS cut-off compared with FFR. This discordance offers physiologic insights for future trials. It is hypothesized that the discordance between angiography and FFR is related to technical limitations, such as imprecise luminal border detection by angiography, as well as to physiologic factors, such as variable minimal microvascular resistance.

Outcome Comparison of 600- and 300-mg Loading Doses of Clopidogrel in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction Results From the ARMYDA-6 MI (Antiplatelet therapy for Reduction of MYocardial Damage during Angioplasty-Myocardial Infarction) Randomized Study

OBJECTIVES The purpose of this study was to compare 600- and 300-mg clopidogrel loading doses in patients with ST-segment elevation myocardial infarction (STEMI). BACKGROUND Given the high thrombotic risk of patients with STEMI, greater platelet inhibition may improve outcome in those patients receiving percutaneous coronary intervention (PCI). Although observational data suggest that pretreatment with a 600-mg clopidogrel loading dose may be more effective than the 300-mg regimen in primary PCI, this hypothesis has never been tested in a randomized study. METHODS A total of 201 patients undergoing primary PCI for STEMI randomly received a 600-mg (n = 103) or 300-mg (n = 98) clopidogrel loading dose before the procedure. The primary endpoint was the evaluation of the infarct size, defined as the area under the curve of cardiac markers. RESULTS Infarct size was significantly lower in the high-dose regimen: median creatine kinase-myocardial band 2,070 ng/ml (interquartile range [IQR]: 815 to 2,847 ng/ml) versus 3,049 ng/ml (IQR: 1,050 to 7,031 ng/ml) in the 300-mg group, p = 0.0001; troponin-I 255 ng/ml (IQR: 130 to 461 ng/ml) versus 380 ng/ml (IQR: 134 to 1,406 ng/ml), p < 0.0001. In the 600-mg arm, Thrombolysis In Myocardial Infarction flow grade <3 after PCI was less frequent (5.8% vs. 16.3%, p = 0.031), left ventricular ejection fraction at discharge was improved (52.1 ± 9.5% vs. 48.8 ± 11.3%, p = 0.026), 30-day major adverse cardiovascular events were fewer (5.8% vs. 15%, p = 0.049), and bleeding/entry site complications were not increased (secondary endpoints). CONCLUSIONS In STEMI patients, pre-treatment with a 600-mg clopidogrel loading dose before primary PCI was associated with a reduction of the infarct size compared with a 300-mg loading dose, as well as with improvement of angiographic results, residual cardiac function, and 30-day major adverse cardiovascular events; further studies are warranted to evaluate impact of such strategy on survival.