Binding and antiplatelet activity of quercetin, rutin, diosmetin, and diosmin flavonoids.

Platelets exert an essential role in vascular inflammation and thrombosis. Flavonoids are natural compounds employed for the clinical management of vascular disorders preventing capillary permeability, working as phlebotonics and improving the blood rheology, although their mechanism of action remains partially unknown. The effects of quercetin, rutin, diosmetin and diosmin were investigated in platelet activation utilizing blood from healthy and non-treated volunteers. The arrangement of the different activation states of platelets and GPIIb/IIIa receptor occupation was computed by flow cytometry working with calcium ionophore as pro-aggregant to provoke platelet activation and aggregation. The flavonoids studied demonstrated relevant antiplatelet activity through the blocked of GPIIb/IIIa receptors, the suppression of the platelet activation, as well as the pro-aggregate effect of calcium ionophore. Therefore, whichever of the active ingredients examined could be beneficious in the prevention of cardiovascular disease and this article also contributes to elucidate a new mechanism of action for these drugs.

The Antithrombotic Agent Pterostilbene Interferes with Integrin αIIbß3-Mediated Inside-Out and Outside-In Signals in Human Platelets.

Platelets play a crucial role in the physiology of primary hemostasis and pathological processes such as arterial thrombosis; thus, developing a therapeutic target that prevents platelet activation can reduce arterial thrombosis. Pterostilbene (PTE) has remarkable pharmacological activities, including anticancer and neuroprotection. Few studies have reported the effects of pterostilbene on platelet activation. Thus, we examined the inhibitory mechanisms of pterostilbene in human platelets and its role in vascular thrombosis prevention in mice. At low concentrations (2-8 µM), pterostilbene strongly inhibited collagen-induced platelet aggregation. Furthermore, pterostilbene markedly diminished Lyn, Fyn, and Syk phosphorylation and hydroxyl radical formation stimulated by collagen. Moreover, PTE directly hindered integrin αIIbß3 activation through interfering with PAC-1 binding stimulated by collagen. In addition, pterostilbene affected integrin αIIbß3-mediated outside-in signaling, such as integrin ß3, Src, and FAK phosphorylation, and reduced the number of adherent platelets and the single platelet spreading area on immobilized fibrinogen as well as thrombin-stimulated fibrin clot retraction. Furthermore, pterostilbene substantially prolonged the occlusion time of thrombotic platelet plug formation in mice. This study demonstrated that pterostilbene exhibits a strong activity against platelet activation through the inhibition of integrin αIIbß3-mediated inside-out and outside-in signaling, suggesting that pterostilbene can serve as a therapeutic agent for thromboembolic disorders.

Correlations of inhaled NO with the cTnI levels and the plasma clotting factor in rabbits with acute massive pulmonary embolism.

PURPOSE: To investigate the correlation of inhaled nitric oxide (NO) on plasma levels of cardiac troponin I (cTnI) and von Willebrand factor (vWF), glycoprotein (GP) IIb/IIIa, granule membrane protein 140 (GMP-140) in rabbits with acute massive pulmonary embolism (PE). METHODS: Thirty apanese white rabbits were divided into 3 groups, thrombus were injected in model group (n = 10), NO were inhalated for 24 h after massive PE in NO group (n = 10), saline were injected in control group (n = 10). The concentrations of vWF, GP IIb/IIIa, GMP-140 and cTnI were tested at 4, 8, 12, 16, 20, and 24 h, Correlation analyses were conducted between cTnI and vWF, GP IIb/IIIa, and GMP-140 by Pearson's correlation. RESULTS: The concentration of cTnI and vWF, GP IIb/IIIa, and GMP-140 was increased in the model group, compared to control group. In the inhaled group, the concentrations of cTnI, vWF, GP IIb/IIIa, and GMP-140 were reduced compared to model group. There was a positive correlation between cTnI and vWF, GP IIb/IIIa, and GMP-140. CONCLUSION: Inhaled nitric oxide can lead to a decrease in levels of cardiac troponin I, von Willebrand factor, glycoprotein, and granule membrane protein 140, after an established myocardial damage, provoked by acute massive pulmonary embolism.

Correlations of inhaled NO with the cTnI levels and the plasma clotting factor in rabbits with acute massive pulmonary embolism

Abstract Purpose: To investigate the correlation of inhaled nitric oxide (NO) on plasma levels of cardiac troponin I (cTnI) and von Willebrand factor (vWF), glycoprotein (GP) IIb/IIIa, granule membrane protein 140 (GMP-140) in rabbits with acute massive pulmonary embolism (PE). Methods: Thirty apanese white rabbits were divided into 3 groups, thrombus were injected in model group (n = 10), NO were inhalated for 24 h after massive PE in NO group (n = 10), saline were injected in control group (n = 10). The concentrations of vWF, GP IIb/IIIa, GMP-140 and cTnI were tested at 4, 8, 12, 16, 20, and 24 h, Correlation analyses were conducted between cTnI and vWF, GP IIb/IIIa, and GMP-140 by Pearson's correlation. Results: The concentration of cTnI and vWF, GP IIb/IIIa, and GMP-140 was increased in the model group, compared to control group. In the inhaled group, the concentrations of cTnI, vWF, GP IIb/IIIa, and GMP-140 were reduced compared to model group. There was a positive correlation between cTnI and vWF, GP IIb/IIIa, and GMP-140. Conclusion: Inhaled nitric oxide can lead to a decrease in levels of cardiac troponin I, von Willebrand factor, glycoprotein, and granule membrane protein 140, after an established myocardial damage, provoked by acute massive pulmonary embolism.

Ginsenoside-Rp3 inhibits platelet activation and thrombus formation by regulating MAPK and cyclic nucleotide signaling.

BACKGROUND & PURPOSE: Ginseng (Panax ginseng C.A. Mayer) contains saponin fractions called ginsenosides, which are thought to be the main components responsible for its various pharmacological activities. Ginsenosides have cardioprotective and antiplatelet effects. In the present study, we evaluated the effects of ginsenoside Rp3 (G-Rp3) on platelet function. METHODS: The in vitro effects of G-Rp3 were evaluated on agonist-induced human and rat platelet aggregation, while [Ca2+]i mobilization, granule secretion, integrin αIIbß3 activation, and clot retraction were assessed in rat platelets. Its effects on vasodilator-stimulated phosphoprotein (VASP) expression, phosphorylation of MAPK signaling molecules, and PI3K/Akt activation were also studied. Moreover, the tyrosine phosphorylation of components of the P2Y12 receptor downstream signaling pathway was also examined. The in vivo effects of G-Rp3 were studied using an acute pulmonary thromboembolism model and lung histopathology. KEY RESULTS: G-Rp3 significantly inhibited collagen, ADP, and thrombin-induced platelet aggregation. G-Rp3 elevated cAMP levels and VASP phosphorylation and suppressed agonist-induced [Ca2+]i mobilization, ATP release, and P-selectin expression along with fibrinogen binding to integrin αIIbß3, fibronectin adhesion, and clot retraction. G-Rp3 also attenuated the phosphorylation of MAPK, Src, and PLCγ2 as well as PI3K/Akt activation. Furthermore, it inhibited tyrosine phosphorylation of the Src family kinases (Src, Fyn, and Lyn) and PLCγ2 and protected mice from thrombosis. CONCLUSION AND IMPLICATION: G-Rp3 modulates agonist-induced platelet activation and thrombus formation by inhibiting granule secretion, integrin αIIbß3 activation, MAPK signaling, and Src, PLCγ2, and PI3K/Akt activation, and VASP stimulation. Our data suggest that G-Rp3 has therapeutic potential as a treatment for platelet-related cardiovascular disorders.

The efficacy of early versus delayed P2Y12 inhibition in percutaneous coronary intervention for ST-elevation myocardial infarction: a systematic review and meta-analysis.

AIMS: The aim of this meta-analysis was to compare the benefit of "early" vs. "delayed" P2Y12 inhibition in patients undergoing percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). METHODS AND RESULTS: We conducted a meta-analysis including seven randomised controlled trials (RCTs) which compared early vs. delayed P2Y12inhibition in STEMI patients scheduled for PCI, providing data on major adverse cardiac events (MACE), all-cause death, and major bleeding. The primary endpoint was MACE. Secondary endpoints included stent thrombosis and the use of GP IIb/IIIa inhibitors (GPI). All endpoints were analysed at the shortest follow-up available. A total of 9,648 patients were included ("early"=4,792, "delayed"=4,856). "Early" P2Y12 inhibition was associated with a significant reduction in MACE rate (OR 0.73, 95% CI: 0.61-0.88, p=0.0008), myocardial infarction (OR 0.71, 95% CI: 0.57-0.90, p=0.004), bail-out GPI use (OR 0.87, 95% CI: 0.75-1.00, p=0.04) and improved coronary reperfusion before PCI (OR for Thrombolysis In Myocardial Infarction [TIMI] flow grade 2-3=1.12, 95% CI: 1.00-1.26, p=0.04). Major bleeding was not increased (OR 0.87, 95% CI: 0.62-1.21, p=0.41). CONCLUSIONS: A strategy of early effective P2Y12 inhibition in PCI of STEMI appears to improve coronary reperfusion before PCI, and reduce MACE, MI and bail-out GPI use without increase of major bleeding.

Short fungal fractions of ß-1,3 glucans affect platelet activation.

Platelets are capable of binding, aggregating, and internalizing microorganisms, which enhances the elimination of pathogens from the blood. The yeast Candida albicans is a pathobiont causing life-threatening invasive infections. Its cell wall contains ß-1,3 glucans that are known to trigger a wide range of host cell activities and to circulate during infection. We studied the effect of ß-1,3 glucan fractions (BGFs) consisting of diglucosides (Glc2), tetraglucosides (Glc4), and pentaglucosides (Glc5) on human platelets, their mechanisms of action, and their possible impact on host defenses. The effect of BGFs on the coagulation process was determined by measuring thrombin generation. Platelets pretreated with BGFs were analyzed in terms of activation, receptor expression, aggregation, and adhesion to neutrophils and to C. albicans The results show that BGFs affected the endogenous thrombin potential in a concentration-dependent manner. For platelet activation, BGFs at a low concentration (2 µmol/l) reduced ATP release and prevented the phosphorylation of protein kinase C. BGFs diminished the expression of P-selectin and the activation of αIIbß3 BGFs decreased platelet aggregation and the interaction between thrombin-stimulated platelets and neutrophils, fibrinogen, and C. albicans GLc5 decreased ATP release and TGF-ß1 production in response to TLR4 upregulation in thrombin-stimulated platelets, but TLR4 blockage abolished the effect of BGFs on platelets. This study provides evidence that fungal pentaglucosides modulate platelet activity mediated via TLR4 stimulation and reduce platelet-neutrophil interaction.

The Antiplatelet Effect of Clopidogrel Decreases With Patient Age.

Recent data suggest that clopidogrel-mediated platelet inhibition is age dependent. However, so far the effect of age on adenosine diphosphate (ADP)-inducible platelet reactivity has only been investigated by test systems measuring surrogate markers of platelet aggregation. We therefore sought to study the impact of age on platelet inhibition by clopidogrel by whole-blood flow cytometry. Platelet surface P-selectin expression, activated glycoprotein (GP) IIb/IIIa, and monocyte-platelet aggregate (MPA) formation were determined by flow cytometry in 302 patients with dual antiplatelet therapy after successful angioplasty and stenting. Patient age was independently associated with ADP-inducible P-selectin expression, GPIIb/IIIa, and MPA formation (all P < .05). Moreover, platelet surface expressions of P-selectin and activated GPIIb/IIIa were significantly higher in patients ≥75 years compared with younger patients (both P ≤ .004). Likewise, MPA formation was significantly more pronounced in patients ≥75 years ( P = .02). Finally, high P-selectin and high GPIIb/IIIa were significantly more frequent in patients ≥75 years compared with younger patients (both P < .001). Further, high MPA ADP occurred more frequently in patients ≥75 years compared to younger patients ( P < .05). In conclusion, the antiplatelet effect of clopidogrel decreases with patient age.

Access-site bleeding and radial artery occlusion in transradial primary percutaneous coronary intervention: influence of adjunctive antiplatelet therapy.

BACKGROUND: The aim of this study was to evaluate access-site complications in patients with ST-segment elevation myocardial infarction treated with a transradial primary percutaneous coronary intervention relative to three different P2Y12 platelet inhibitors. PATIENTS AND METHODS: We enrolled 334 consecutive patients (76.9% men, age: 59.4±9.1 years) treated by one of the following: clopidogrel (n=118), prasugrel (n=102), and ticagrelor (n=114). The use of the IIb/IIIa inhibitor, abciximab, was left to the operators' discretion. The time needed to achieve patent hemostasis, compression time, and local complications were analyzed. RESULTS: The baseline characteristics were similar in all three P2Y12 platelet inhibitor groups. Abciximab was used in 72 (21.6%) patients. Administration of abciximab was associated with a higher incidence of grade II and III hematomas (23.6 vs. 5.0%, P<0.0001, and 5.6 vs. 1.1%, P=0.041, respectively). Among different platelet P2Y12 receptor inhibitor groups, the incidences of hematomas grade II and III were similar in patients who did (P≥0.14) and did not (P≥0.31) receive abciximab. There were no grade IV or V hematomas in any of the groups. Patent hemostasis was achieved faster (24.5±13.4 vs. 43.5±30.0 min, P<0.0001) and compression time was shorter (113.2±53.6 vs. 217.8±115.5 min, P<0.0001) when abciximab was not used. Radial artery occlusion occurred in one (0.3%) patient. CONCLUSION: After transradial primary percutaneous coronary intervention, early patent hemostasis and short artery compression times were associated with a higher incidence of local hematomas. The incidence of hematomas was dependent on the use of abciximab, but unrelated to the type of P2Y12 inhibitor used. All hematomas were without clinical consequences.

Achieving safe femoral arterial access.

Percutaneous coronary intervention can lead to vascular access complications that prolong patient hospital stay and costs as well as increase patient morbidity and mortality. Given its ease of use and familiarity, transfemoral access is still the preferred method of approach by many operators. The transfemoral approach is used when large bore access is required or if transradial access is not feasible due to variations in the anatomy of the upper extremity artery. The use of fluoroscopy, ultrasonography, and femoral angiography can help the operator obtain proper arteriotomy of the common femoral artery. Measures to decrease vascular access complications include proper technique, optimal pharmacotherapy, and avoiding the use of arterial sheaths >6 Fr. Optimal pharmacotherapy includes the use of bivalirudin and weight-based unfractionated heparin to avoid supratherapeutic activated clotting times, and to avoid glycoprotein IIb/IIIa inhibitors. When used appropriately, vascular closure devices can decrease the risk of bleeding complications. Randomized trials are needed to confirm these recommendations.

Can the antiplatelet effects of cangrelor be reliably studied in mice under in vivo and in vitro conditions using flow cytometry?

BACKGROUND: The effects of blood platelet inhibitors are often not quite equivalent under in vivo and in vitro conditions. Amongst various models of human pathology using laboratory animals, mice offer several benefits that make them convenient tools for studying the putative therapeutic value of various compounds. However, despite its advantages, the mouse model has methodological limitations concerning the small amount of blood available and technical difficulties with its collection. Among the variety of available methods used to study blood platelet activation and/or reactivity, flow cytometry seems an attractive technique that largely minimizes the constraints of using small rodents and enables outcomes of laboratory research to be transferred successfully to clinical practice. In this study we aimed at a critical evaluation of the optimal discriminative flow cytometric protocol, useful for reliable studies of the effect of cangrelor, a P2Y12 receptor antagonist, on mouse platelets under in vitro and in vivo conditions. METHODS: Blood samples were drawn from two-month-old female BALB/c mice. Protocols differing in methods of anesthesia, blood withdrawal, anticoagulation, gating antibodies, blood preparation and fixation were tested to optimize the one best suited to discrimination between resting and activated platelets. The antiplatelet capabilities of cangrelor were tested in vitro (140 µM in whole blood) and in vivo (7.8 mg/kg b.w. administered once, directly into the bloodstream through the vena cava of the anesthetized animal, 15 min prior to blood withdrawal). Expressions of P-selectin, activated α(IIb)ß3 complex and GPIba were monitored using two-color flow cytometry. RESULTS: "Washed blood" anticoagulated with low molecular weight heparin demonstrated the best discrimination between circulating (resting) platelets and upon their in vitro response to thrombin, collagen or ADP in freshly-stained unfixed cell suspensions. Cangrelor inhibited the expression of the active form of the integrin a(IIb)ß3 to approximately the same extent under in vitro and in vivo conditions (84.5 ± 7.7% vs. 75.4 ± 19.5% for the in vitro and in vivo approaches, respectively, n.s.). CONCLUSIONS: The agreement between the in vivo and in vitro approaches with respect to cangrelor-inhibited hallmarks of blood platelet activation and reactivity supports our proposal that flow cytometry is useful and reliable for determining the effects of antiplatelet agents on the activation of circulating platelets in the mouse model, as well as the in vitro response of platelets to agonists.

Comparative assessment of platelet GpIIb/IIIa receptor occupancy ratio with Eptifibatide/Tirofiban in patients presenting with ACS and undergoing PCI.

BACKGROUND: The level of platelet inhibition by a Glycoprotein IIb/IIIa (GpIIb/IIIa) antagonist therapy necessary to minimize thrombotic complications in patients undergoing percutaneous coronary intervention (PCI) is a subject of debate. The degree of platelet inhibition obtained 10 min after start of GpIIb/IIIa antagonist therapy predicts adverse events after PCI. The aim of this study was to look at platelet inhibition and to compare platelet GpIIb/IIIa receptors occupancy ratio (GpRO) with Eptifibatide and Tirofiban using various dose regimens and correlate with 30-day clinical outcomes in patients presenting with high-risk acute coronary syndromes (ACS) and undergoing PCI. METHODS: The patients were divided into four sub groups: (1) Eptifibatide two intracoronary bolus (180 µg/kg) alone (E(B)); or (2) two intravenous bolus (180 µg/kg) followed by infusion at 2 µg/kg/min for 24 h (E(B + Inf)); and (3) Tirofiban standard bolus dose (0.4 µg/kg) over 30 min followed by infusion at 0.1 µg/kg/min (T(Std)); or (4) at ADVANCE dose bolus (25 µg/kg) over 3 min, followed by infusion at 0.1 µg/kg/min (T(Adv)). Number of GpIIb/IIIa receptors was assessed by flow cytometry at baseline and 10 min after the bolus and percentage of free receptors was determined to calculate the GpRO. Patients were followed for 30 days for any major adverse cardiac events (MACE). RESULTS: 200 consecutive patients (including 74% with ST-elevation ACS) were enrolled. GpRO in groups E(B) (n = 48) and E(B + Inf) (n = 44) were 62.7% ± 27.2% and 61.4% ± 6.1% respectively while in the groups T(Std) (n = 96) and T(Adv) (n = 12) groups were 35.1% ± 17.74% and 68.8% ± 27.3% respectively. The GpRO was similar in E(B), E(B + Inf) and T(Adv) groups and was significantly higher than T(Std) group (p < 0.0001). The 30-day MACE rates in E(B) (4.2%), E(B + Inf) (4.5%) and T(Adv) (4.2%) were significantly lower than T(Std) group (12.5%) (p < 0.01). CONCLUSIONS: Standard dose Tirofiban results in significantly lower rates of GpIIb/IIIa receptor occupancy ratio and this correlated with higher incidence of 30-day MACE in high-risk ACS patients undergoing PCI.

Differences between mainstream and sidestream tobacco smoke extracts and nicotine in the activation and aggregation of platelets subjected to cardiovascular conditions in diabetes.

Mainstream and sidestream tobacco smoke extracts have been shown to increase platelet activation directly. Furthermore, advanced glycation end products, which are present in the diabetic vasculature, have also been shown to enhance platelet activity. However, the combined effects of these two risk factors on platelet functions remain unclear. Platelets were exposed to tobacco extracts concurrently with advanced glycation end products. Timed samples were removed to assess the extent of platelet activity. The presence of smoke extracts enhanced platelet activity as compared to control conditions, this was especially prevalent for sidestream extracts. With the addition of irreversibly glycated albumin, there was an additive effect, further enhancing platelet responses. This was at least partially regulated by α-granule release and CD41 expression. The combination of cardiovascular risk factors can significantly enhance platelet activation and aggregation, and therefore it is possible to accelerate cardiovascular diseases through the interactions of multiple cardiovascular risk factors.

The ADP receptor P2RY12 regulates osteoclast function and pathologic bone remodeling.

The adenosine diphosphate (ADP) receptor P2RY12 (purinergic receptor P2Y, G protein coupled, 12) plays a critical role in platelet aggregation, and P2RY12 inhibitors are used clinically to prevent cardiac and cerebral thrombotic events. Extracellular ADP has also been shown to increase osteoclast (OC) activity, but the role of P2RY12 in OC biology is unknown. Here, we examined the role of mouse P2RY12 in OC function. Mice lacking P2ry12 had decreased OC activity and were partially protected from age-associated bone loss. P2ry12-/- OCs exhibited intact differentiation markers, but diminished resorptive function. Extracellular ADP enhanced OC adhesion and resorptive activity of WT, but not P2ry12-/-, OCs. In platelets, ADP stimulation of P2RY12 resulted in GTPase Ras-related protein (RAP1) activation and subsequent αIIbß3 integrin activation. Likewise, we found that ADP stimulation induced RAP1 activation in WT and integrin ß3 gene knockout (Itgb3-/-) OCs, but its effects were substantially blunted in P2ry12-/- OCs. In vivo, P2ry12-/- mice were partially protected from pathologic bone loss associated with serum transfer arthritis, tumor growth in bone, and ovariectomy-induced osteoporosis: all conditions associated with increased extracellular ADP. Finally, mice treated with the clinical inhibitor of P2RY12, clopidogrel, were protected from pathologic osteolysis. These results demonstrate that P2RY12 is the primary ADP receptor in OCs and suggest that P2RY12 inhibition is a potential therapeutic target for pathologic bone loss.

Pharmacodynamic properties of antiplatelet agents: current knowledge and future perspectives.

Platelets play an important role in atherothrombotic disease. The currently available antiplatelet drugs target key steps of platelet activation including thromboxane A(2) synthesis, ADP-mediated signaling, and glycoprotein IIb/IIIa-mediated platelet aggregation. The improvement of our understanding on the pharmacokinetic and pharmacodynamic characteristics of these drugs enables the tailoring of the most appropriate anti-thrombotic therapy to the individual patient and risk situation in the daily clinical practice. However, current antiplatelet therapies are associated with increased bleeding risk. Thus, further research on platelet functions may give rise to numerous new antiplatelet agents with high anti-thrombotic efficiency and low adverse hemorrhagic side effects.

Short-acting P2Y12 blockade to reduce platelet dysfunction and coagulopathy during experimental extracorporeal circulation and hypothermia.

BACKGROUND: Extracorporeal circulation (ECC) and hypothermia are routinely used in cardiac surgery to maintain stable circulatory parameters and to increase the ischaemic tolerance of the patient. However, ECC and hypothermia cause platelet activation and dysfunction possibly followed by a devastating coagulopathy. Stimulation of the adenosinediphosphate (ADP) receptor P(2)Y(12) plays a pivotal role in platelet activation. This experimental study tested P(2)Y(12) receptor blockade as an approach to protect platelets during ECC. METHODS: Human blood was treated with the short-acting P(2)Y(12) blocker cangrelor (1 µM, t(1/2)<5 min) or the P(2)Y(12) inhibitor 2-MeSAMP (100 µM) and circulated in an ex vivo ECC model at normothermia (37°C) and hypothermia (28°C). Before and after circulation, markers of platelet activation and of coagulation (thrombin-antithrombin complex generation) were analysed. During hypothermic ECC in pigs, the effect of reversible P(2)Y(12) blockade on platelet function was evaluated by cangrelor infusion (0.075 µg kg(-1) min(-1)). RESULTS: During ex vivo hypothermic ECC, P(2)Y(12) blockade inhibited platelet granule release (P<0.01), platelet-granulocyte binding (P<0.05), and platelet loss (P<0.001), whereas no effects on platelet-ECC binding, platelet CD42bα expression, glycoprotein IIb/IIIa activation, or thrombin-antithrombin complex generation were observed. During hypothermic ECC in pigs, cangrelor inhibited platelet-fibrinogen binding (P<0.05) and ADP-induced platelet aggregation (P<0.001). Platelet function was rapidly restored after termination of cangrelor infusion. CONCLUSIONS: P(2)Y(12) blockade by cangrelor prevents platelet activation during ECC and hypothermia. Owing to its short half-life, platelet inhibition can be well controlled, thus potentially reducing bleeding complications. This novel pharmacological strategy has the potential to reduce complications associated with ECC and hypothermia.

Intracoronary eptifibatide bolus administration during percutaneous coronary revascularization for acute coronary syndromes with evaluation of platelet glycoprotein IIb/IIIa receptor occupancy and platelet function: the Intracoronary Eptifibatide (ICE) Trial.

BACKGROUND: Eptifibatide reduces major adverse cardiac events in patients with acute coronary syndromes undergoing percutaneous coronary intervention (PCI). Intracoronary bolus administration of eptifibatide may result in higher levels of platelet glycoprotein IIb/IIIa receptor occupancy in the local coronary bed, disaggregate thrombus in the epicardial artery and microvasculature, and thereby improve coronary flow. METHODS AND RESULTS: Patients undergoing PCI for an acute coronary syndrome were randomized to either intracoronary or intravenous bolus administration of eptifibatide. The primary end point was the local glycoprotein IIb/IIIa receptor occupancy measured in the coronary sinus. There were no angiographic, electrophysiological, or other adverse findings attributable to intracoronary eptifibatide. Platelet glycoprotein IIb/IIIa receptor occupancy was significantly greater with intracoronary versus intravenous administration: first bolus, 94+/-9% versus 51+/-15% (P<0.001); and second bolus, 99+/-2% versus 91+/-4% (P=0.001), respectively. Microvascular perfusion was significantly improved as measured by the corrected thrombolysis in myocardial infarction frame count (cTFC) with intracoronary versus intravenous administration: pre-PCI, 36 (median) (25th and 75th percentiles, 16 and 64) versus 31 (25th and 75th percentiles, 23 and 45; P=0.8); and post-PCI, 18 (25th and 75th percentiles, 10 and 22) versus 25 (25th and 75th percentiles, 22 and 35; P=0.007), respectively. The only multivariate predictor associated with a post-PCI cTFC rank score was the first bolus glycoprotein IIb/IIIa receptor occupancy (P<0.001). CONCLUSIONS: Intracoronary bolus administration of eptifibatide during PCI in patients with acute coronary syndromes results in higher local platelet glycoprotein IIb/IIIa receptor occupancy, which is associated with improved microvascular perfusion demonstrated by an improved cTFC.

Efficacy and safety of fondaparinux versus enoxaparin in patients with acute coronary syndromes treated with glycoprotein IIb/IIIa inhibitors or thienopyridines: results from the OASIS 5 (Fifth Organization to Assess Strategies in Ischemic Syndromes) trial.

OBJECTIVES: This study sought to evaluate the relative safety and efficacy of fondaparinux and enoxaparin in patients with acute coronary syndromes (ACS) treated with glycoprotein (GP) IIb/IIIa inhibitors or thienopyridines. BACKGROUND: The OASIS 5 (Fifth Organization to Assess Strategies in Ischemic Syndromes) trial showed that fondaparinux reduced major bleeding by 50% compared with enoxaparin while preserving similar efficacy. Whether this benefit is consistent in the presence or absence of concurrent antiplatelet therapy with clopidogrel and GP IIb/IIIa inhibitors is unknown. METHODS: Patients with ACS (n = 20,078) were randomized as a part of the OASIS 5 trial to receive either fondaparinux or enoxaparin. The use of GP IIb/IIIa inhibitors or thienopyridines was at the discretion of the treating physician. A Cox proportional hazard model was used to compare outcomes. RESULTS: Of the 20,078 patients randomized, 3,630 patients received GP IIb/IIIa and 13,531 received thienopyridines. There was a 40% reduction in major bleeding with fondaparinux compared with enoxaparin in those treated with GP IIb/IIIa (5.2% vs. 8.3%, hazard ratio [HR]: 0.61, p < 0.001). A similar reduction was found in those treated with thienopyridines (3.4% vs. 5.4%, HR: 0.62, p < 0.001). Ischemic events were similar between the groups, resulting in a superior net clinical outcome (death, myocardial infarction, refractory ischemia, or major bleeding) favoring fondaparinux (GP IIb/IIIa subgroup 14.8% vs. 18.9%, HR: 0.77, p = 0.001 and thienopyridines subgroup 11.0% vs. 13.2%, HR: 0.82, p < 0.001). CONCLUSIONS: In patients receiving GP IIb/IIIa inhibitors or thienopyridines, fondaparinux reduces major bleeding and improves net clinical outcome compared with enoxaparin.