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Background Pressure measurement for the duration of the wave-free period (WFP) is considered essential for resting-state physiological assessment of coronary stenosis severity using the instantaneous wave-free ratio (iFR). Objectives The aim of this study was to compare other diastolic resting indexes to iFR. Methods In the population of the VERIFY2 (Pd/Pa vs iFR in an Unselected Population Referred for Invasive Angiography) study, iFR calculated by proprietary software (Volcano Harvest, Volcano Corporation, Rancho Cordova, California) was compared with the ratio of resting distal coronary pressure and aortic pressure during the complete duration of diastole (dPR), 25% to 75% of diastole (dPR25–75), and midpoint of diastole (dPRmid), along with Matlab calculated iFR (iFRmatlab) and iFR-like indexes shortening the length of the WFP by 50 and 100 ms (iFR−50ms and iFR−100ms), respectively. Mutual differences, Spearman correlations, area under the curve values from receiver-operating characteristic analyses, and diagnostic performance with respect to iFR and fractional flow reserve (FFR) were calculated for all indexes. Results Median iFR in 197 patients with 257 vessels was 0.91 with an interquartile range of 0.87 to 0.95. The mutual differences (± SD) with iFR were 0.006 ± 0.011 (dPR), 0.001 ± 0.007 (dPR25–75), 0.001 ± 0.008 (dPRmid), 0.005 ± 0.009 (iFRmatlab), 0.003 ± 0.008 (iFR−50ms), and 0.001 ± 0.009 (iFR−100ms). Correlations for all indexes with iFR were >0.99 (p < 0.001 for all). Area under the curve values for predicting iFR were >0.99 for all indexes as well. Diagnostic accuracy compared with FFR was 76% to 77% for all indexes including iFR. Conclusions All diastolic resting indexes tested were identical to iFR, both numerically and with respect to their agreement with FFR. A numerically equal value to iFR can be determined without restriction to the WFP. Cutoff values, guidelines, and clinical recommendations for iFR can therefore be extended to these other indexes. (Pd/Pa vs iFR in an Unselected Population Referred for Invasive Angiography [VERIFY2]; NCT02377310)

Objective: We propose a novel technique called pressure-bounded coronary flow reserve (pb-CFR) and demonstrate its application to the randomized DEFER trial. Background: Intracoronary flow reserve assessment remains underutilized relative to pressure measurements partly due to less robust tools. Methods: While rest and hyperemic intracoronary pressure measurements cannot quantify CFR exactly, they do provide upper and lower bounds. We validated pb-CFR invasively against traditional CFR, then applied it to high fractional flow reserve (FFR ≥ 0.75) lesions in DEFER randomized to revascularization or medical therapy. Results: pb-CFR showed an 84.4% accuracy to predict invasive CFR < 2 or CFR ≥ 2 in 107 lesions. In its proof of concept application to DEFER lesions with FFR ≥ 0.75, the 28 with pb-CFR < 2 compared to 28 with pb-CFR ≥ 2 had a non-significant reduction in freedom from angina (61% vs. 71% at 5 years, P = 0.57) and a non-significantly higher rate of major adverse cardiac events (MACE, 25% vs. 15%, P = 0.34). Lesions with FFR ≥ 0.75 but pb-CFR < 2 showed no difference in freedom from angina (61% vs. 50%, P = 0.54) or MACE (25% vs. 38%, P = 0.27) between the 28 randomized to medical therapy and the 16 randomized to revascularization. Conclusions: pb-CFR offers a new method for studying FFR/CFR discordances using regular pressure wire measurements. As an example application, DEFER suggested that low pb-CFR with high FFR may be a risk marker for more angina and worse outcomes, but that this risk cannot be modified by revascularization.

Hypothermia may attenuate reperfusion injury and thereby improve acute myocardial infarction therapy. Systemic cooling trials failed to reduce infarct size, perhaps because the target temperature was not reached fast enough. The use of selective intracoronary hypothermia combined with intracoronary temperature monitoring allows for titrating to target temperature and optimizing the cooling rate. We aimed to the test the feasibility of intracoronary cooling for controlled, selective myocardial hypothermia in an isolated beating pig heart. In five porcine hearts the left anterior descending artery (LAD) was occluded by an over-the-wire balloon (OTWB). After occlusion, saline at 22°C was infused through the OTWB lumen for 5 minutes into the infarct area at a rate of 30 ml/min. Thereafter the balloon was deflated but infusion continued with saline at 4°C for 5 minutes. Distal coronary temperature was continuously monitored by a pressure/temperature guidewire. Myocardial temperature at several locations in the infarct and control areas was recorded using needle thermistors. In the occlusion phase, coronary temperature decreased by 11.4°C (range 9.4-12.5°C). Myocardial temperature throughout the infarct area decreased by 5.1°C (range 1.8-8.1°C) within three minutes. During the reperfusion phase, coronary temperature decreased by 6.2°C (range 4.1-10.3°C) and myocardial temperature decreased by 4.5°C (range 1.5-7.4°C). Myocardial temperature outside the infarct area was not affected. In the isolated beating pig heart with acute occlusion of the LAD, we were able to rapidly “induce, maintain, and control” a stable intracoronary and myocardial target temperature of at least 4°C below body temperature without side effects and using standard PCI equipment, justifying further studies of this technique in humans.

Background In ST-elevation myocardial infarction (STEMI), reduction in time to reperfusion of the occluded coronary artery reduces infarct size. In animal models, an additional reduction of infarct size was observed when hypothermia was induced before reperfusion, despite a longer ischemic time. However, several human studies did not corroborate this positive effect, which is believed to be in part due to the inability of systemic induced hypothermia to induce sufficient decrease of local myocardial temperature before reperfusion. Providing rapid local myocardial hypothermia by intracoronary infusion of saline before reperfusion in patients with STEMI may overcome this problem. In this study, we evaluate the safety and feasibility of providing rapid intracoronary myocardial hypothermia in patients undergoing intracoronary blood flow measurements based on thermodilution with continuous infusion of saline at room temperature. Methods and Results In 53 patients with stable angina (SA) and 20 patients with STEMI, a total of 215 measurements were performed. The measurements consisted of continuous selective intracoronary infusion of saline at room temperature with rates between 10 ml/min and 30 ml/min. Temperature changes compared to initial blood temperature (Tb) were measured at the tip of the infusion catheter (Ti) and distally in the coronary artery (Td). In patients with SA, Ti was -5.65 ± 1.41°C (range -9.27 to -2.28) and Td was -0.78 ± 0.51°C (range -3.27 to -0.23°C). In patients with STEMI, Ti was -7.45 ± 0.51°C (range -8.21 to -6.56) and Td was -1.37 ± 0.82°C (range -4.62 to -0.74°C). In all patients, steady-state intracoronary hypothermia was achieved within 15 sec and could be maintained without noticeable complications. Conclusion This study demonstrates the safety and feasibility of inducing intracoronary hypothermia by selective infusion of saline at room temperature in patients with SA and STEMI. Steady-state hypothermia could be achieved and maintained quickly, easily, and safely using common PCI techniques. Therefore, our findings warrant further studies to the use of intracoronary hypothermia to enhance myocardial salvage in acute myocardial infarction.

The isolated beating pig heart model is an accessible platform to investigate the coronary circulation in its truly morphological and physiological state, whereas its use is beneficial from a time, cost, and ethical perspective. However, whether the coronary autoregulation is still intact is not known. Here, we study the autoregulation of coronary blood flow in the working isolated pig heart in response to brief occlusions of the coronary artery, to step-wise changes in left ventricular loading conditions and contractile states, and to pharmacologic vasodilating stimuli. Six slaughterhouse pig hearts (473¿±¿40¿g) were isolated, prepared, and connected to an external circulatory system. Through coronary reperfusion and controlled cardiac loading, physiological cardiac performance was achieved. After release of a coronary occlusion, coronary blood flow rose rapidly to an equal (maximum) level as the flow during control beats, independent of the duration of occlusion. Moreover, a linear relation was found between coronary blood flow and coronary driving pressure for a wide variation of preload, afterload, and contractility. In addition, intracoronary administration of papaverine did not yield a transient increase in blood flow indicating the presence of maximum coronary hyperemia. Together, this indicates that the coronary circulation in the isolated beating pig heart is in a permanent state of maximum hyperemia. This makes the model excellently suitable for testing and validating cardiovascular devices (i.e., heart valves, stent grafts, and ventricular assist devices) under well-controlled circumstances, whereas it decreases the necessity of sacrificing large mammalians for performing classical animal experiments.

Background Previous studies on gender differences in outcome in patients with ST segment elevation myocardial infarction (STEMI) have been performed, but most of those are from before the current era of PCI technique and medical therapy and have a short duration of follow-up. The objective of our study is to assess the influence of gender on long-term outcome in patients with STEMI who underwent primary percutaneous intervention (PCI) between January 2006 and May 2008. Methods Two-year follow-up data from 202 female and 668 male patients undergoing primary PCI for STEMI were available from the DEBATER (A Comparison of Drug Eluting and Bare Metal Stents for Primary Percutaneous Coronary Intervention with or without Abciximab in ST-segment elevation Myocardial Infarction: The Eindhoven Reperfusion Study) trial database. The primary endpoint was major adverse cardiac events (MACE), defined as the composite of death, myocardial infarction, and target vessel revascularization. Results Women were older (64.7 +/- 11.7 vs. 59.0 +/- 10.7; P

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Objectives The goal of this study was to demonstrate superiority of sirolimus-eluting stents (SES) over baremetal stents (BMS) and of abciximab over no abciximab in primary percutaneous coronary intervention (PCI). Background Drug-eluting stents (DES) are increasingly used in primary PCI, but the recommendations for use in primary PCI are based on a few randomized controlled trials with selected patients. The usefulness of abciximab in primary PCI is not established. Methods Nine hundred seven patients referred to the Catharina Hospital were randomized to SES or BMS, and to abciximab or no abciximab in a prospective, randomized, open 2 X 2 factorial trial with blinded evaluation. Primary endpoint was major adverse cardiac and cerebrovascular events (MACCE), defined as the composite of death, myocardial infarction (MI), stroke, repeat revascularization, and bleeding at 1 year (stent arm) and the composite of death, target vessel MI, target vessel revascularization (TVR), and bleeding at 30 days (abciximab arm). Results At 1 year, the rate of MACCE was lower in the SES arm (16.5% vs. 25.8%, p = 0.001), mainly driven by less repeat revascularization (9.8% vs. 16.8%; p = 0.003) and without influencing the cumulative incidence of death and MI (5.2% vs. 5.8%; p = 0.68). At 30 days, the rate of the composite of death, target vessel MI, TVR, and bleeding was lower in the abciximab arm (8.2% vs. 12.4%, p = 0.04), mainly driven by less TVR due to less stent thrombosis (1.2% vs.7.4%, p

The use of fractional flow reserve (FFR) to guide percutaneous coronary intervention (PCI) is well established in stable angina (SA) but has not been prospectively researched in unstable angina (UA) or non–ST-segment elevation myocardial infarction (NSTEMI). The FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) study compared angiography-guided PCI with FFR-guided PCI in patients with multivessel disease and included patients with SA and UA or NSTEMI. At 2 years, the benefit of using FFR to guide PCI does not differ between patients with UA or NSTEMI, compared with patients with SA.

The Impella 2.5 left percutaneous (LP), a relatively new transvalvular assist device, challenges the position of the intra-aortic balloon pump (IABP), which has a long record in supporting patients after myocardial infarction and cardiac surgery. However, while more costly and more demanding in management, the advantages of the Impella 2.5 LP are yet to be established. The aim of this study was to evaluate the benefits of the 40 cc IABP and the Impella 2.5 LP operating at 47 000 rpm in vitro, and compare their circulatory support capabilities in terms of cardiac output, coronary flow, cardiac stroke work, and arterial blood pressure. Clinical scenarios of cardiogenic preshock and cardiogenic shock (CS), with blood pressure depression, lowered cardiac output, and constant heart rate of 80 bpm, were modeled in a model-controlled mock circulation, featuring a systemic, pulmonary, and coronary vascular bed. The ventricles, represented by servomotor-operated piston pumps, included the Frank–Starling mechanism. The systemic circulation was modeled with a flexible tube having close-to-human aortic dimensions and compliance properties. Proximally, it featured a branch mimicking the brachiocephalic arteries and a physiological correct coronary flow model. The rest of the systemic and pulmonary impedance was modeled by four-element Windkessel models. In this system, the enhancement of coronary flow and blood pressure was tested with both support systems under healthy and pathological conditions. Hemodynamic differences between the IABP and the Impella 2.5 LP were small. In our laboratory model, both systems approximately yielded a 10% cardiac output increase and a 10% coronary flow increase. However, since the Impella 2.5 LP provided significantly better left ventricular unloading, the circulatory support capabilities were slightly in favor of the Impella 2.5 LP. On the other hand, pulsatility was enhanced with the IABP and lowered with the Impella 2.5 LP. The support capabilities of both the IABP and the Impella 2.5 LP strongly depended on the simulated hemodynamic conditions. Maximum hemodynamic benefits were achieved when mechanical circulatory support was applied on a simulated scenario of deep CS.

AIMS: The influence of atherosclerosis and its risk factors on coronary microvascular function remain unclear as current methods of assessing microvascular function do not specifically test the microcirculation in isolation. We examined the influence of epicardial vessel atherosclerosis on coronary microvascular function using the index of myocardial resistance (IMR). METHODS AND RESULTS: IMR (a measure of microvascular function) and fractional flow reserve (FFR, a measure of the epicardial compartment) were measured in 143 coronary arteries (116 patients). Fifteen patients (22 arteries, mean age 48+/-16 years) had no clinical evidence of atherosclerosis (control group). One hundred and one patients (121 arteries, mean age 63+/-11 years) had established atherosclerosis and multiple cardiovascular risk factors (atheroma group). Mean IMR in the control group (19+/-5, range 8-28) was significantly lower than in the atheroma group (25+/-13, range 6-75) (P

Background: It can be difficult to determine on the coronary angiogram which lesions cause ischemia. Revascularization of coronary stenoses that induce ischemia improves a patient's functional status and outcome. For stenoses that do not induce ischemia, however, the benefit of revascularization is less clear. Methods: In the FAME study, routine measurement of the fractional flow reserve (FFR) was compared with angiography for guiding percutaneous coronary intervention in patients with multivessel coronary artery disease. The use of the FFR in addition to angiography significantly reduced the rate of all major adverse cardiac events at 1 year. Of the 1,414 lesions (509 patients) in the FFR-guided arm of the FAME study, 1,329 were successfully assessed by the FFR and are included in this analysis. Results: Before FFR measurement, these lesions were categorized into 50% to 70% (47% of all lesions), 71% to 90% (39% of all lesions), and 91% to 99% (15% of all lesions) diameter stenosis by visual assessment. In the category 50% to 70% stenosis, 35% were functionally significant (FFR 0.80) and 65% were not (FFR >0.80). In the category 71% to 90% stenosis, 80% were functionally significant and 20% were not. In the category of subtotal stenoses, 96% were functionally significant. Of all 509 patients with angiographically defined multivessel disease, only 235 (46%) had functional multivessel disease (2 coronary arteries with an FFR 0.80). Conclusions: Angiography is inaccurate in assessing the functional significance of a coronary stenosis when compared with the FFR, not only in the 50% to 70% category but also in the 70% to 90% angiographic severity category.

Objectives: The purpose of this study was to investigate the 2-year outcome of percutaneous coronary intervention (PCI) guided by fractional flow reserve (FFR) in patients with multivessel coronary artery disease (CAD). Background: In patients with multivessel CAD undergoing PCI, coronary angiography is the standard method for guiding stent placement. The FAME (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) study showed that routine FFR in addition to angiography improves outcomes of PCI at 1 year. It is unknown if these favorable results are maintained at 2 years of follow-up. Methods: At 20 U.S. and European medical centers, 1,005 patients with multivessel CAD were randomly assigned to PCI with drug-eluting stents guided by angiography alone or guided by FFR measurements. Before randomization, lesions requiring PCI were identified based on their angiographic appearance. Patients randomized to angiography-guided PCI underwent stenting of all indicated lesions, whereas those randomized to FFR-guided PCI underwent stenting of indicated lesions only if the FFR was 0.80. Results: The number of indicated lesions was 2.7 ± 0.9 in the angiography-guided group and 2.8 ± 1.0 in the FFR-guided group (p = 0.34). The number of stents used was 2.7 ± 1.2 and 1.9 ± 1.3, respectively (p 0.80, the rate of myocardial infarction was 0.2 % and the rate of revascularization was 3.2 % after 2 years. Conclusions: Routine measurement of FFR in patients with multivessel CAD undergoing PCI with drug-eluting stents significantly reduces mortality and myocardial infarction at 2 years when compared with standard angiography-guided PCI. (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation [FAME]; NCT00267774)

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ObjectivesThe purpose of this study was to investigate the appropriateness of stenting a functionally nonsignificant stenosis.BackgroundPercutaneous coronary intervention (PCI) of an intermediate stenosis without evidence of ischemia is often performed, but its benefit is unproven. Coronary pressure-derived fractional flow reserve (FFR) is an invasive index used to identify a stenosis responsible for reversible ischemia.MethodsIn 325 patients scheduled for PCI of an intermediate stenosis, FFR was measured just before the planned intervention. If FFR was ≥0.75, patients were randomly assigned to deferral (Defer group; n = 91) or performance (Perform group; n = 90) of PCI. If FFR was

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