Coenzyme Q10 Upregulates Platelet cAMP/PKA Pathway and Attenuates Integrin αIIbß3 Signaling and Thrombus Growth.

SCOPE: Platelet integrin αIIbß3 is the key mediator of atherothrombosis. Supplementation of coenzyme Q10 (CoQ10), a fat-soluble molecule that exists in various foods, exerts protective cardiovascular effects. This study aims to investigate whether and how CoQ10 acts on αIIbß3 signaling and thrombosis, the major cause of cardiovascular diseases. METHODS AND RESULTS: Using a series of platelet functional assays in vitro, it is demonstrated that CoQ10 reduces human platelet aggregation, granule secretion, platelet spreading, and clot retraction. It is further demonstrated that CoQ10 inhibits platelet integrin αIIbß3 outside-in signaling. These inhibitory effects are mainly mediated by upregulating cAMP/PKA pathway, where CoQ10 stimulates the A2A adenosine receptor and decreases phosphodiesterase 3A phosphorylation. Moreover, CoQ10 attenuates murine thrombus growth and vessel occlusion in a ferric chloride (FeCl3 )-induced thrombosis model in vivo. Importantly, the randomized, double-blind, placebo-controlled clinical trial in dyslipidemic patients demonstrates that 24 weeks of CoQ10 supplementation increases platelet CoQ10 concentrations, enhances the cAMP/PKA pathway, and attenuates αIIbß3 outside-in signaling, leading to decreased platelet aggregation and granule release. CONCLUSION: Through upregulating the platelet cAMP/PKA pathway, and attenuating αIIbß3 signaling and thrombus growth, CoQ10 supplementation may play an important protective role in patients with risks of cardiovascular diseases.

Isorhapontigenin, a resveratrol analogue selectively inhibits ADP-stimulated platelet activation.

Isorhapontigenin is a polyphenolic compound found in Chinese herbs and grapes. It is a methoxylated analogue of a stilbenoid, resveratrol, which is well-known for its various beneficial effects including anti-platelet activity. Isorhapontigenin possesses greater oral bioavailability than resveratrol and has also been identified to possess anti-cancer and anti-inflammatory properties. However, its effects on platelet function have not been reported previously. In this study, we report the effects of isorhapontigenin on the modulation of platelet function. Isorhapontigenin was found to selectively inhibit ADP-induced platelet aggregation with an IC50 of 1.85 µM although it displayed marginal inhibition on platelet aggregation induced by other platelet agonists at 100 µM. However, resveratrol exhibited weaker inhibition on ADP-induced platelet aggregation (IC50 > 100 µM) but inhibited collagen induced platelet aggregation at 50 µM and 100 µM. Isorhapontigenin also inhibited integrin αIIbß3 mediated inside-out and outside-in signalling and dense granule secretion in ADP-induced platelet activation but interestingly, no effect was observed on α-granule secretion. Isorhapontigenin did not exert any cytotoxicity on platelets at the concentrations of up to 100 µM. Furthermore, it did not affect haemostasis in mice at the IC50 concentration (1.85 µM). In addition, the mechanistic studies demonstrated that isorhapontigenin increased cAMP levels and VASP phosphorylation at Ser157 and decreased Akt phosphorylation. This suggests that isorhapontigenin may interfere with cAMP and PI3K signalling pathways that are associated with the P2Y12 receptor. Molecular docking studies emphasised that isorhapontigenin has greater binding affinity to P2Y12 receptor than resveratrol. Our results demonstrate that isorhapontigenin has selective inhibitory effects on ADP-stimulated platelet activation possibly via P2Y12 receptor.

Intralesional versus intracoronary administration of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention in patients with acute coronary syndromes: A meta-analysis of randomized controlled trials.

BACKGROUND: Glycoprotein IIb/IIIa inhibitors (GPIs) have been regarded as an adjuvant regimen to deal with no-reflow. However, whether intralesional (IL) administration of GPIs improves myocardial reperfusion without increasing bleeding in patients with acute coronary syndrome (ACS) compared with intracoronary (IC) administration has not been well addressed. Our meta-analysis aimed to evaluate the efficacy and safety of IL versus IC administration of GPIs for patients with ACS during percutaneous coronary intervention. METHODS: We systematically searched Medline, Embase, the Cochrane Central Register of Controlled Trials, and Cambridge Scientific Abstracts from January 2007 to May 2017. Thrombolysis in Myocardial Infarction (TIMI) 3 flow, corrected TIMI frame count (CTFC), and complete ST-segment resolution (>70%) were selected as the primary outcomes. Major adverse cardiac events (MACEs) were the secondary outcome, and major bleeding complications were the safety outcome. Data analysis was conducted using the Review Manager 5.3 software. RESULTS: Six randomized controlled trials were included in our meta-analysis. Compared with IC, IL obtained better results in terms of TIMI grade 3 flow [odds ratio (OR) 2.29; 95% confidence intervals (CIs) 1.31-4.01; P = .004], CTFC [weighted mean difference (WMD) -4.63; 95% CI -8.82 to -0.43; P = .03], and complete ST-segment resolution (OR 1.55; 95% CI 1.12-2.14; P = .008). There was a trend toward decreased MACE in the IL administration groups, which was not of statistical significance (OR 0.63; 95% CI 0.30-1.31; P = .22). No significant difference was found between the two groups in terms of in-hospital major bleeding events (OR 2.52; 95% CI .66 to 9.62; P = .18). CONCLUSION: IL administration yielded favorable outcomes in terms of myocardial tissue reperfusion as evidenced by the improved TIMI flow grade, CTFC, complete ST-segment resolution, and decreased MACE without increasing in-hospital major bleeding events. The IL administration of GPIs can be recommended as the preferred regimen to guard against no-reflow.

Xanthohumol from hop cones (Humulus lupulus L.) prevents ADP-induced platelet reactivity.

Hop cones (Humulus lupulus L.), very rich source of phenolic compounds, possessing anticancer, antioxidant and anti-inflammatory activities, are considered as beneficial diet ingredients improving human health. In this study, the antiplatelet action of xanthohumol (XN), the principal flavonoid in hop cones, was investigated. XN significantly attenuated ADP-induced blood platelet aggregation (97.2 ± 35.7 AU for 6 µg/ml of XN vs. 120.4 ± 30.1 AU for 0.17% dimethyl sulfoxide (DMSO), p < 0.001) and significantly reduced the expression of fibrinogen receptor (activated form of GPIIbIIIa) on platelets' surface (47.6 ± 15.8 for 1.5 µg/ml XN, 44.6 ± 17.3% for 3 µg/ml XN vs. 54.5 ± 19.2% for control or 43.3 ± 18.4% for 6 µg/ml XN vs. 49.7 ± 19.4% for 0.17% DMSO, p < 0.05 or less). These findings suggest that the phenolic compounds originating from hops (XN) have a novel role as antiplatelet agents and can likely be used as dietary supplements in prophylactic approaches.

The association of the coronary thrombus burden with all-cause mortality and major cardiac events in ST-segment elevation myocardial infarction patients treated with tirofiban.

BACKGROUND: The aim of this study was to investigate the association of the coronary thrombus burden with all-cause mortality and major adverse cardiac events (MACE) in ST-segment elevation myocardial infarction (STEMI) patients treated with 'in-cath lab' (downstream) high-dose bolus tirofiban. METHODS: This study included 2452 patients with STEMI treated with a primary percutaneous coronary intervention. All glycoprotein IIb/IIIa receptor inhibitor (GPI) (tirofiban) infusions were started in the catheterization laboratory according to the coronary thrombus burden; tirofiban was not administered to patients who did not have coronary thrombus burden. All patients with small, moderate, or large thrombus burden received tirofiban therapy. The primary study endpoint was the incidence of all-cause mortality. The secondary study endpoints were major bleeding and MACE, which included all-cause death, nonfatal acute coronary syndrome, and target lesion revascularization. RESULTS: The patients were followed up for a mean period of 28.3±10.4 months. The groups showed similar in-hospital and long-term event rates (MACE, major bleeding, and all-cause mortality). The 3-year Kaplan-Meier overall survivals for no thrombus, small thrombus, moderate thrombus, and large thrombus were 91.9, 92.6, 92.3, and 89.5%, respectively. CONCLUSION: Despite the fact that the large coronary thrombus was found to be a predictor of MACE and mortality in many previous studies, we found that the large thrombus was not associated with MACE or in-hospital mortality or long-term mortality. This can be an effect of downstream GPI therapy. We suggest the use of downstream GPI therapy for STEMI patients with large coronary thrombus without an increased risk of bleeding.

A randomized trial assessing the impact of three different glycoprotein IIb/IIIa antagonists on glycoprotein IIb/IIIa platelet receptor inhibition and clinical endpoints in patients with acute coronary syndromes.

AIMS: To compare three glycoprotein IIb/IIIa receptor antagonists (GPIs) in terms of platelet inhibition and major adverse cardiac events (MACEs), and assess the rate of bleeding and MACEs between GPIs and coadministered P2Y12 agents. METHODS: Eighty-three acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) with planned GPI use were randomized to receive high-dose bolus tirofiban, double-bolus eptifibatide, or abciximab followed by a 12-hour infusion. Glycoprotein IIb/IIIa platelet receptor inhibition was measured at baseline and at 10 minutes, 1 hour, and 24 hours postbolus dose. Major adverse cardiac events and bleeding complications at 30 days were documented. The incidence of MACEs and bleeding in patients receiving ticagrelor or prasugrel were compared to those given clopidogrel. RESULTS: There were no statistically significant differences in platelet inhibition between GPIs at 10 minutes (P=.085) and 1 hour (P=.337). At 24 hours, abciximab achieved statistically significantly higher median [interquartile range] platelet inhibition (75 [65-88]%) compared to tirofiban (28 [3-56]%; P<.0001) and eptifibatide (44 [31-63]%; P=.007). There were no differences in bleeding or MACEs depending on GPI or P2Y12 inhibitor administered. CONCLUSIONS: Glycoprotein receptor inhibitors achieve similar levels of platelet inhibition at 10 minutes and 1 hour; however, abciximab maintains this benefit 24 hours after bolus dose. We did not witness an increased rate of bleeding in patients given new potent P2Y12 inhibitors and a GPI in the modern era.

Glycoprotein IIb/IIIa inhibitors: The resurgence of tirofiban.

Glycoprotein (GP) IIb/IIIa inhibitors block platelet aggregation, reducing thrombotic events in acute coronary syndrome. They are most often utilized in patients who likely have an intracoronary thrombus. Tirofiban, eptifibatide, and abciximab are the three GP IIb/IIIa inhibitors approved for use in the United States. Each agent has unique pharmacological properties. They all have a rapid onset and are most often utilized in conjunction with heparin. Tirofiban, in particular, fell out of favor due to inferior dosing with its original Food and Drug Administration (FDA) approved indication, but has re-emerged in the market with a high-dose bolus regimen that is considered equally as effective as the FDA approved dosing regimens of other GP IIb/IIIa inhibitors. This review looks at pharmacological properties of all three agents, significant clinical trials associated with their use, and their place in current guidelines.

Design, Virtual Screening, and Synthesis of Antagonists of αIIbß3 as Antiplatelet Agents.

This article describes design, virtual screening, synthesis, and biological tests of novel αIIbß3 antagonists, which inhibit platelet aggregation. Two types of αIIbß3 antagonists were developed: those binding either closed or open form of the protein. At the first step, available experimental data were used to build QSAR models and ligand- and structure-based pharmacophore models and to select the most appropriate tool for ligand-to-protein docking. Virtual screening of publicly available databases (BioinfoDB, ZINC, Enamine data sets) with developed models resulted in no hits. Therefore, small focused libraries for two types of ligands were prepared on the basis of pharmacophore models. Their screening resulted in four potential ligands for open form of αIIbß3 and four ligands for its closed form followed by their synthesis and in vitro tests. Experimental measurements of affinity for αIIbß3 and ability to inhibit ADP-induced platelet aggregation (IC50) showed that two designed ligands for the open form 4c and 4d (IC50 = 6.2 nM and 25 nM, respectively) and one for the closed form 12b (IC50 = 11 nM) were more potent than commercial antithrombotic Tirofiban (IC50 = 32 nM).

Mechanism of action of antiplatelet drugs on decompression sickness in rats: a protective effect of anti-GPIIbIIIa therapy.

Literature highlights the involvement of disseminated thrombosis in the pathophysiology of decompression sickness (DCS). We examined the effect of several antithrombotic treatments targeting various pathways on DCS outcome: acetyl salicylate, prasugrel, abciximab, and enoxaparin. Rats were randomly assigned to six groups. Groups 1 and 2 were a control nondiving group (C; n = 10) and a control diving group (CD; n = 30). Animals in Groups 3 to 6 were treated before hyperbaric exposure (HBE) with either prasugrel (n = 10), acetyl salicylate (n = 10), enoxaparin (n = 10), or abciximab (n = 10). Blood samples were taken for platelet factor 4 (PF4), thiobarbituric acid reactive substances (TBARS), and von Willebrand factor analysis. Onset of DCS symptoms and death were recorded during a 60-min observation period after HBE. Although we observed fewer outcomes of DCS in all treated groups compared with the CD, statistical significance was reached in abciximab only (20% vs. 73%, respectively, P = 0.007). We also observed significantly higher levels of plasmatic PF4 in abciximab (8.14 ± 1.40 ng/ml; P = 0.004) and enoxaparin groups (8.01 ± 0.80 ng/ml; P = 0.021) compared with the C group (6.45 ± 1.90 ng/ml) but not CD group (8.14 ± 1.40 ng/ml). Plasmatic levels of TBARS were significantly higher in the CD group than the C group (49.04 ± 11.20 µM vs. 34.44 ± 5.70 µM, P = 0.002). This effect was prevented by all treatments. Our results suggest that abciximab pretreatment, a powerful glycoprotein IIb/IIIa receptor antagonist, has a strong protective effect on decompression risk by significantly improving DCS outcome. Besides its powerful inhibitory action on platelet aggregation, we suggest that abciximab could also act through its effects on vascular function, oxidative stress, and/or inflammation.

Discovery of novel antagonists of glycoprotein IIb/IIIa-mediated platelet aggregation through virtual screening.

The glycoprotein IIb/IIIa receptor is the final common pathway of platelet aggregation, regardless of the agonist, and thus represents an ideal therapeutic target for blocking thrombus formation. RUC-2 is a novel glycoprotein IIb/IIIa inhibitor of adenosine-5'-diphosphate (ADP)-induced platelet aggregation, importantly which exhibits a unique mode of binding with respect to classical Arg-Gly-Asp (RGD)-based glycoprotein IIb/IIIa antagonists. To identify new chemotypes that inhibit glycoprotein IIb/IIIa-mediated platelet aggregation like RUC-2, we performed a combination of structure-based pharmacophore screening and structure-based virtual screening approach to screen over 7.3 million small molecules based on the RUC-2-glycoprotein IIb/IIIa crystal structure. Three of the eleven hit compounds identified by virtual screening showed promising activity with IC50 values between 16.9 and 90.6µmolL(-1) in a human platelet aggregation assay induced by ADP and thrombin. The binding conformations of these three were analyzed to provide a rationalization of their activity profile. These compounds may serve as potential novel scaffolds for further development of glycoprotein IIb/IIIa antagonists.

+Ophitoxaemia and myocardial infarction--the issues during primary angioplasty: a review.

'The Big four' are the most poisonous snakes in India, and especially in Kerala. These include the cobra, the viper, the krait and the sea snake. Most of the poisonous snakebites in India occur in Kerala. We believe there are only a few reports of myocardial infarction after snakebites and most of these are viper bites. We believe this is the second case of primary angioplasty for a snakebite. There are at least a few potential issues in performing a primary angioplasty in a snakebite case, namely (1) Is it a thrombus or a spasm? (2) Are the bleeding parameters deranged? Will the patient tolerate tirofiban and other glycoprotein (GB) 2b3a inhibitors? Will he develop dangerous bleeding due to the high dose of heparin needed? Further, would we save the patient from myocardial infarction only to lose him to renal failure, both due to the nephrotoxicity of the venom, the kidney being further damaged by the contrast media used for the angioplasty? We discuss all these issues as they crossed our mind, and hope it will help further treatment in others. We would like to review the available literature on these points and describe a recent case of ours.

Anticoagulation and antiplatelet therapy in acute coronary syndromes.

Antiplatelet and anticoagulant drugs are the mainstay of treatment of acute coronary syndrome (ACS). The last 30 years have seen the development of various agents, a deeper understanding of the pathobiology of this disease, and an evolution in its treatment. We review the role of contemporary agents in ACS and highlight key clinical trials of these agents.

Adjunctive and alternative approaches to current reperfusion therapy.

BACKGROUND AND PURPOSE: Current ischemic stroke reperfusion therapy consists of intravenous thrombolysis given in eligible patients after review of a noncontrast CT scan and a time-based window of opportunity. Rapid clot lysis has a strong association with clinical improvement but remains incomplete in many patients. This review appraises novel adjunctive or alternative approaches to current reperfusion strategies being tested in all trial phases. Summary of Review- Alternative approaches to current reperfusion therapy can be separated into 4 main categories: (1) combinatory approaches with other drugs or devices; (2) novel systemic thrombolytic agents; (3) endovascular medical or mechanical reperfusion treatments; and (4) noninvasive or minimally invasive methods to augment cerebral blood flow and alleviate intracranial blood flow steal. CONCLUSIONS: Reperfusion treatments must be provided as fast as possible in patients most likely to benefit. Patients who fail to rapidly reperfuse may benefit from other strategies that maintain collateral flow or protect tissue at risk.

RGD mimetics containing phthalimidine fragment as novel ligands of fibrinogen receptor.

The novel RGD mimetics with phthalimidine central fragment were synthesized with the use of 4-piperidine-4-yl-butyric, 4-piperidine-4-yl-benzoic, 4-piperazine-4-yl-benzoic and 1,2,3,4-tetrahydroisoquinoline-7-carboxylic acids as surrogates of Arg motif. The synthesized compounds potently inhibited platelet aggregation in vitro and blocked FITC-Fg binding to α(IIb)ß(3) integrin in a suspension of washed human platelets. The key α(IIb)ß(3) protein-ligand interactions were determined in docking experiments.

A randomized two-by-two comparison of high-dose bolus tirofiban versus abciximab and unfractionated heparin versus bivalirudin during percutaneous coronary revascularization and stent placement: the tirofiban evaluation of novel dosing versus abciximab with clopidogrel and inhibition of thrombin (TENACITY) study trial.

BACKGROUND: In the absence of high-dose thienopyridines, placebo-controlled trials have demonstrated a reduction in ischemic events with intravenous glycoprotein IIb/IIIa antagonists during percutaneous coronary intervention (PCI). One head-to-head trial comparing abciximab and tirofiban among PCI patients found tirofiban to be inferior, and laboratory evidence confirmed that the bolus dose of tirofiban tested in that trial to be less effective than abciximab. Whether a higher bolus dose of tirofiban would be as efficacious as abciximab during PCI is uncertain. METHODS AND RESULTS: Patients undergoing PCI were randomized equally to abciximab or to tirofiban, given as high-dose bolus (25 µg/kg) plus 12-hr infusion (0.15 µg/kg/min). All patients received aspirin and clopidogrel and were additionally randomized to unfractionated heparin or bivalirudin. Approximately 8,000 patients were to be studied, but after 383 were enrolled, the study sponsor discontinued the trial for financial reasons. The primary endpoint of 30-day death, myocardial infarction, or urgent target vessel revascularization occurred in 8.8% of patients randomized to abciximab and 6.9% of those randomized to tirofiban. The respective rates of major bleeding were 1.5 and 1.6%. Additionally, the primary endpoint occurred in 8.1% of patients randomized to unfractionated heparin and 7.6% of those randomized to bivalirudin. The respective rates of major bleeding were 2.5% and 0.5%. CONCLUSION: With limited assessment, this direct comparison of high-dose bolus tirofiban versus abciximab produced encouraging results and suggests that further study of this tirofiban dose regimen is warranted. The limited assessments comparing heparin and bivalirudin are consistent with prior observations.

Antiplatelet activity of Phellinus baummii methanol extract is mediated by cyclic AMP elevation and inhibition of collagen-activated integrin-α(IIb) ß3 and MAP kinase.

Phellinus baumii is a mushroom that has been used as folk medicine against various diseases and is reported to have antidiabetic, anticancer, antioxidant, antiinflammatory and antihypertensive activities. However, information on the effects of P. baumii extract in platelet function is limited. Therefore, the aim of this study was to examine the impact of a P. baumii methanol extract (PBME) on platelet activation and to investigate the mechanism behind its antiplatelet activity. PBME effects on agonist-induced platelet aggregation, granule secretion, [Ca²âº](i) mobilization, α(IIb) ß3 activation, cyclic AMP release and mitogen-activated protein kinase (MAPK) phosphorylations were studied using rat platelets. PBME dose-dependently inhibited collagen, thrombin and ADP-induced platelet aggregation with an IC50 of 51.0 ± 2.4, 54.0 ± 2.1 and 53.0 ± 4.3 µg/mL, respectively. Likewise, thrombin-induced [Ca²âº](i) and collagen-activated ATP secretions were suppressed in PBME treated platelets. Aggregation and ATP secretion were also markedly attenuated by PBME alone or in combination with PP2 (Src inhibitor) and U-73122 (PLC inhibitor) in collagen-stimulated platelets. Besides, PBME treatment elevated basal cyclic AMP levels and inhibited collagen-induced integrin-α(IIb) ß3 activation. Moreover, PBME attenuated extracellular-signal-regulated protein kinase 2 (ERK2) and c-Jun N-terminal kinase 1 (JNK1) phosphorylations. Further PD98059 (ERK inhibitor) and SP60025 (JNK inhibitor) reduced collagen-induced platelet aggregation and ATP secretion. In conclusion, the observed PBME antiplatelet activity may be mediated by activation of cyclic AMP and inhibition of ERK2 and JNK1 phosphorylations. Finally, these data suggest that PBME may have therapeutic potential for the treatment of cardiovascular diseases that involve aberrant platelet function.

Antiplatelet effects of Spatholobus suberectus via inhibition of the glycoprotein IIb/IIIa receptor.

ETHNOPHARMACOLOGICAL RELEVANCE: The vine stem of Spatholobus suberectus is a widely used blood-activating and stasis-dispelling medicine for the treatment of diseases related to blood stasis syndrome in traditional medicine in Korea, Japan, and China. AIM OF THE STUDY: To demonstrate the clinical effects of Spatholobus suberectus against blood stasis syndromes using in vitro and in vivo platelet aggregation studies and to investigate its exact mechanisms. MATERIALS AND METHODS: We extracted vine stems of Spatholobus suberectus, using 95% EtOH (SSE) and investigated its antiplatelet activity on platelet aggregation induced by collagen and ADP in human platelet-rich plasma (PRP). For the mechanism study, a glycoprotein IIb/IIIa (GP IIb/IIIa) assay using flow cytometric analysis and a thromboxane A(2) (TXA(2)) assay were performed. In addition, we investigated the effects of SSE in a thromboembolic mouse model. RESULTS: SSE significantly inhibited ADP- and collagen-induced platelet aggregation in human PRP concentration-dependently without affecting plasma clotting time. It also significantly inhibited fibrinogen binding to the GP IIb/IIIa receptor and partly inhibited the formation of TXA(2). In the in vivo study, oral administration of SSE dose-dependently suppressed the death of thromboembolism model mice induced by intravenous injection of collagen plus epinephrine. CONCLUSIONS: SSE showed antiplatelet activity without anticoagulant effects mainly through the inhibition of fibrinogen binding to the GP IIb/IIIa receptor. Our current results support the clinical usage of SSE in the East Asian region treating atherothrombotic diseases and may represent a new natural source to develop antiplatelet agents.

Pre-hospital administration of tirofiban in diabetic patients with ST-elevation myocardial infarction undergoing primary angioplasty: a sub-analysis of the On-Time 2 trial.

AIMS: Glycoprotein IIb/IIIa blocking agents seem to improve percutaneous coronary intervention (PCI) results in patients with ST-elevation myocardial infarction (STEMI). We aimed to compare the effect of pre-hospital administration of tirofiban in STEMI patients with and without diabetes mellitus (DM) treated with primary PCI. METHODS AND RESULTS: We performed a pre-specified sub-analysis of the randomised On-Time II trial (n=984) and it's open label run-in phase (n=414), which investigated pre-hospital administration of high dose tirofiban in STEMI patients treated with primary PCI. Two-hundred and twenty (16%) diabetic patients (known DM or Hba1C ≥6.2%) were included, 101 in the placebo group and 119 in the tirofiban group. In patients with DM, randomisation to tirofiban resulted in a lower residual ST deviation (5.1±8.5 mm vs. 6.2±5.6 mm, p=0.003), a reduced infarct size (CK 1694±1925 U/L vs. CK 2040±1829 U/L, p=0.02) and a trend towards lower one-year mortality (4.6% vs. 11.6%, p=0.07). The beneficial effects of tirofiban were more pronounced in diabetic patients compared to patients without diabetes. CONCLUSIONS: Pre-hospital administration of tirofiban in diabetic STEMI patients treated with primary PCI improves ST resolution and reduces myocardial infarct size. Tirofiban seems particularly beneficial in patients with diabetes.

Tirofiban for myocardial infarction.

IMPORTANCE OF THE FIELD: Inhibition of platelet aggregation plays a key role in treatment of coronary artery disease. AREAS COVERED IN THIS REVIEW: Studies on the effects of tirofiban in patients with either ST elevation or non-ST elevation myocardial infarction are reviewed. WHAT THE READER WILL GAIN: Tirofiban is a small-molecule glycoprotein IIb/IIIa receptor inhibitor. If discontinued, the action of tirofiban is faster reversed as abciximab. The dose varied between low (bolus of 0.4 microg/kg administered over 30 min followed by an infusion of 0.10 microg/kg/min), intermediate (bolus of 10 microg/kg administered over 3 min followed by an infusion of 0.15 microg/kg/min) and high (bolus of 25 microg/kg administered over 3 min followed by an infusion of 0.15 microg/kg/min). The high-dose administration especially may be beneficial in patients with ST elevation myocardial infarction undergoing primary percutaneous coronary intervention (PCI). There is no indication for tirofiban in patients treated with thrombolysis. Patients with non-ST elevation myocardial infarction requiring PCI are most likely to benefit from tirofiban if they have ongoing ischemia and/or dynamic ECG changes. The risk of serious bleeding with tirofiban is low and there is a very low risk of thrombocytopenia. TAKE HOME MESSAGE: Use of tirofiban for myocardial infarction is effective and has an acceptable safety profile.