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Razzuk MA, Pierce TB, Razzuk AM. Platelets and Hemostasis: The Role of Glycoprotein IIb/IIIa in Platelet Aggregation. Proc (Bayl Univ Med Cent) 2018. [DOI: 10.1080/08998280.1997.11930019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Maruf A. Razzuk
- Department of Thoracic and Cardiovascular Surgery, Baylor University Medical Center
| | - Tada B. Pierce
- Department of Thoracic and Cardiovascular Surgery, Baylor University Medical Center
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2
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Alexander D, Jeremias A. Rivaroxaban in the contemporary treatment of acute coronary syndromes. Expert Opin Investig Drugs 2011; 20:849-57. [DOI: 10.1517/13543784.2011.580274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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3
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Abstract
Acute myocardial infarction (AMI) is a subset of the acute coronary syndromes and can be classified as being either a ST-segment elevation myocardial infarction (STEMI) or a non-ST-elevation myocardial infarction (NSTEMI). A clear distinction between STEMI and NSTEMI is essential because of the differences in management. The purpose of this review was to first discuss the epidemiology, pathophysiology, and diagnosis of AMI. The risk stratification and therapy of patients with STEMI and NSTEMI will then be reviewed as well as the complications of AMI.
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Affiliation(s)
- Eric H Yang
- University of North Carolina-Chapel Hill, USA
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4
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Kidane AG, Salacinski H, Tiwari A, Bruckdorfer KR, Seifalian AM. Anticoagulant and antiplatelet agents: their clinical and device application(s) together with usages to engineer surfaces. Biomacromolecules 2005; 5:798-813. [PMID: 15132664 DOI: 10.1021/bm0344553] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An essential aspect of the treatment of patients with cardiovascular disease is the use of anticoagulant and antiplatelet agents for the prevention of further ischaemic events and vascular death resulting from thrombosis. Aspirin and heparin have been the standard therapy for the management of such conditions to date. Recently, numerous more potent platelet inhibitors together with anticoagulant agents have been developed and tested in randomized clinical trials. This article reviews the current state of the art of antiplatelet and anticoagulant therapy in light of its potential clinical efficacy. It then focuses on the usages of these agents in order to improve the performance of clinical devices such as balloon catheters, coronary stents, and femoropopliteal bypass grafting and extra corporeal circuits for cardiopulmonary bypass. The article then goes on to look at the usage of these agents more specifically heparin, heparan, hirudin, and coumarin in the development of more biocompatible scaffolds for tissue engineering.
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Affiliation(s)
- Asmeret G Kidane
- University Department of Surgery, Royal Free and University College Medical School, University College London, Royal Free Hospital, London NW3 2QG, United Kingdom
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5
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De La Cruz JP, Arrebola MM, Villalobos MA, Pinacho A, Guerrero A, González-Correa JA, Sánchez de la Cuesta F. Influence of glucose concentration on the effects of aspirin, ticlopidine and clopidogrel on platelet function and platelet–subendothelium interaction. Eur J Pharmacol 2004; 484:19-27. [PMID: 14729378 DOI: 10.1016/j.ejphar.2003.10.055] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Clinical studies have shown that the ability of aspirin to prevent cerebrovascular accidents is weaker in patients with diabetes. The aim of this study was to determine whether high concentrations of glucose modified the effect of aspirin, ticlopidine and clopigodrel on platelet function and platelet-subendothelium interactions. This in vitro study tested three different concentrations of glucose. The effects were analyzed by comparing platelet aggregometry in whole blood, nitric oxide and prostacyclin production in cultures of human endothelial cells, and by quantitative analysis of morphological features of the platelet-subendothelium interaction under flow conditions. High concentrations of glucose increased platelet aggregation (13.9 Omega with 5 mM glucose vs. 21.6 Omega with 16.6 mM) and platelet-subendothelium interactions (28.9% with 5 mM glucose vs.35.2% with 16.6 mM), and decreased nitric oxide and prostacyclin production. In the presence of high concentrations of glucose, the antiaggregant effect of aspirin and its influence on nitric oxide production were diminished (IC50 54 microM with 5 mM glucose vs.556 microM with 16.6 mM glucose), and its effect on the platelet-subendothelium interaction was reduced (10.5% platelet occupancy with 5 mM glucose vs.23% with 16.6 mM glucose). The effects of ticlopidine and clopidogrel were not significantly modified.
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Affiliation(s)
- José Pedro De La Cruz
- Department of Pharmacology and Therapeutics, School of Medicine, University of Málaga, Campus de Teatinos s/n, 29071 Málaga, Spain.
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6
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Park HD, Kim HJ, Oh YS, Kim IC, Kim YZ, Koh HC, Shin IC, Lee YH, Lee CH. LB30057, an orally effective direct thrombin inhibitor, prevents arterial and venous thrombosis in rats and dogs. Arch Pharm Res 2003; 26:224-31. [PMID: 12723936 DOI: 10.1007/bf02976834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The anti-thrombotic effects of LB30057, a direct thrombin inhibitor, were evaluated with in vivo rat and dog thrombosis models. In rats, 1 mg/kg of LB30057 inhibited half of the clot formations in the inferior vena cava at 5 minutes after intravenous application. When measured at 2 hours after oral application, 100 mg/kg prevented approximately half of the clot formations in the inferior vena cava and 50 mg/kg prolonged the mean occlusion time from 15.6 +/- 1.3 minutes to 47.2 +/- 8.3 minutes in the carotid artery. In dogs, the formation of thrombus in the jugular vein was reduced to half at a dose range of 20-30 mg/kg at 6 hours after oral application. In addition, the LB30057 dosage required to reduce venous clot formation by approximately 80-90% in dogs was only about 10% of that required for the same reduction in rats. This is probably due to the variation in its time-dependent blood concentration profiles in each species; for example, the plasma half-life of LB71350 in dogs was longer than that in rats (153.0 +/- 3.0 vs. 129.7 +/- 12.7 min at 30 mg/kg, i.v., respectively). AUC, T(max), C(max), and BA in dogs were 59, 8.9, 9.17, and 13.3 times higher than those in rats at oral 30 mg/kg, respectively. Taken together, these results suggest that LB30057 administered orally is effective in the prevention of arterial and venous thrombosis in rats and dogs. It therefore represents a good lead compound for investigations to discover a new, orally available, therapeutic agent for treating thrombotic diseases.
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Affiliation(s)
- Hee Dong Park
- LG Biotech Research Institute, LG Chem, Daejeon 305-380, Korea
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7
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Albirini A, Brener SJ. Platelet glycoprotein IIb/IIIa receptor inhibition in primary angioplasty for acute myocardial infarction: The new paradigm of direct revascularization. INTERNATIONAL JOURNAL OF CARDIOVASCULAR INTERVENTIONS 2001; 4:7-14. [PMID: 12431334 DOI: 10.1080/146288401316922634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Acute myocardial infarction results from thrombotic occlusion superimposed on a ruptured athersoclerotic plaque. Immediate restoration of normal flow in the infarct-related artery can be achieved either with fibrinolytic or with direct mechanical revascularization. Primary PTCA has been shown to be superior to fibrinolytic therapy with respect to mortality, reinfarction, non-fatal stroke and length of hospitalization. Its results can be further improved by the addition of potent platelet inhibitors directed against the final common component of all stimuli for platelet aggregation, the glycoprotein (GP) IIb/IIIa receptor. In randomized clinical trials, primary angioplasty with adjunctive abciximab - a monoclonal antibody against the GP IIb/IIIa - was better than conventional primary angioplasty with heparin only. Abciximab use was associated with a significant reduction in reinfarction, need for urgent target vessel revascularization, microcirculatory dysfunction and regional left ventricular dysfunction as well as with a strong trend towards a reduction in mortality, even in patients receiving coronary stents.
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8
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Rocha E, Panizo C, Lecumberri R. [Direct thrombin inhibitors: their role in the treatment of arterial and venous thrombosis]. Med Clin (Barc) 2001; 116:63-74. [PMID: 11181274 DOI: 10.1016/s0025-7753(01)71721-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- E Rocha
- Servicio de Hematología y Hemoterapia. Clínica Universitaria. Facultad de Medicina. Universidad de Navarra. Pamplona.
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9
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Fink L, Massoll N, Pappas A. Anticoagulation. Diagn Pathol 2000. [DOI: 10.1201/b13994-33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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10
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Iqbal O, Messmore H, Hoppensteadt D, Fareed J, Wehrmacher W. Thrombolytic drugs in acute myocardial infarction. Clin Appl Thromb Hemost 2000; 6:1-13. [PMID: 10726042 DOI: 10.1177/107602960000600101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- O Iqbal
- Department of Pathology, Loyola University Medical Center, Maywood, Illinois 60153, USA
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11
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Anand SS. The Organization to Assess Strategies for Ischemic Syndromes (OASIS) Pilot Study: evaluation of acute and long-term therapies for patients with acute coronary syndromes without ST elevation. Am J Cardiol 1999; 84:13M-19M. [PMID: 10505538 DOI: 10.1016/s0002-9149(99)00396-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The objectives of the Organization to Assess Strategies for Ischemic Syndromes (OASIS) Pilot Study (phase 2) were (1) to compare the efficacy, safety, and feasibility of recombinant hirudin versus unfractionated heparin as short-term therapy in patients with acute coronary syndromes without ST elevation and (2) to compare the efficacy and safety of long-term therapy with warfarin and aspirin versus standard therapy with aspirin alone in the same patient population. Investigators at 31 Canadian centers randomized 909 patients to receive either medium-dose hirudin, low-dose hirudin, or unfractionated heparin. The incidence of the 7-day primary composite outcome of cardiovascular death, new myocardial infarction (MI), or refractory angina was significantly lower among patients who received hirudin than among those assigned to unfractionated heparin. A subset of these patients was subsequently randomized to long-term, low-intensity (international normalized ratio [INR] < 1.5) or moderate-intensity (INR 2-2.5) anticoagulant treatment with warfarin or to standard therapy. In this substudy, promising results were observed in favor of moderate-intensity warfarin. These findings provided the rationale for the design and conduct of the large-scale, phase III OASIS-2 trial.
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Affiliation(s)
- S S Anand
- Department of Preventive Cardiology and Therapeutics, McMaster University, Hamilton, Ontario, Canada
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12
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Zusman RM, Chesebro JH, Comerota A, Hartmann JR, Massin EK, Raps E, Wolf PA. Antiplatelet therapy in the prevention of ischemic vascular events: literature review and evidence-based guidelines for drug selection. Clin Cardiol 1999; 22:559-73. [PMID: 10486695 PMCID: PMC6655822 DOI: 10.1002/clc.4960220905] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/1998] [Accepted: 12/01/1998] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND New antiplatelet drugs are being developed and many clinical trials evaluating the benefits of antiplatelet drugs for the secondary prevention of ischemic events in patients with atherosclerotic vascular disease have been performed. HYPOTHESIS An updated systematic review and evidence-based guidelines for the appropriate selection of antiplatelet drugs may be beneficial to physicians and healthcare organizations attempting to create or update current clinical practice guidelines or clinical pathways aimed at caring for these patients. METHODS (1) A systematic review of the recent literature on the relative efficacy and safety of aspirin, ticlopidine, and clopidogrel was undertaken; (2) an evidence-based, expert panel approach using a modified Delphi technique to create explicit guidelines for prescribing antiplatelet therapy was instituted; and (3) the recommendations of an expert panel were summarized. RESULTS Consensus guidelines were developed for the utilization of aspirin, ticlopidine, or clopidogrel for the prevention of ischemic events in patients with manifestations of atherosclerotic vascular disease (prior myocardial infarction, prior ischemic stroke, or established peripheral arterial disease) who are at increased risk for recurrent ischemic events. Based on efficacy and safety, clopidogrel was recommended as the drug of choice for patients with established peripheral arterial disease; aspirin or clopidogrel should be considered in patients with prior myocardial infarction (with clopidogrel favored for patients who have had a recurrent event while on aspirin or in whom aspirin is contraindicated); aspirin or clopidogrel should be considered as first-line treatment in patients with prior ischemic (nonhemorrhagic) stroke--however, clopidogrel is the favored drug in patients in whom other antiplatelet drugs are either contraindicated or who have had recurrent events while on therapy. CONCLUSIONS Myocardial infarction, ischemic stroke, and peripheral arterial disease are all clinical manifestations of the same underlying disease process (atherosclerosis), with thrombus formation on the disrupted atherosclerotic plaque (atherothrombosis) being a common precipitating factor of ischemic events in patients suffering from these disorders. An evidence-based approach was used to develop a practice guideline, based on available published evidence, for the appropriate utilization of antiplatelet agents (aspirin, ticlopidine, or clopidogrel). These guidelines may be of use to multidisciplinary teams wishing to create or update clinical guidelines or clinical pathways which address the care of patients with atherosclerotic vascular disease. New antiplatelet agents such as clopidogrel may be more effective and associated with lower risk of selected adverse effects (such as gastrointestinal distress, gastrointestinal hemorrhage, and neutropenia) than those previously used to prevent thrombus formation in the setting of atherosclerotic arterial disease. Combination antiplatelet therapy is being evaluated as an option for those patients who experience recurrent events on a single antiplatelet agent.
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Affiliation(s)
- R M Zusman
- Harvard Medical School, Massachusetts General Hospital, Division of Hypertension and Vascular Medicine, Boston, MA 02114, USA
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13
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Januzzi JL, Jang IK. Heparin induced thrombocytopenia: diagnosis and contemporary antithrombin management. J Thromb Thrombolysis 1999; 7:259-64. [PMID: 10375387 DOI: 10.1023/a:1008979010033] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) may be complicated by severe thrombotic complications and death. Currently no specific laboratory test is available to make the diagnosis. When HIT is clinically suspected, heparin should be discontinued immediately. While no specific therapy for HIT exists, there is increasing evidence that acute antithrombin therapy may significantly reduce morbidity and mortality. Among several agents, the direct antithrombins, such as r-hirudin and argatroban, look the most promising for acute treatment.
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Affiliation(s)
- J L Januzzi
- Cardiology Division, Massachusetts General Hospital, Harvard Medical School Boston, Massachusetts 02114, USA
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14
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Antman EM, Giugliano RP, Gibson CM, McCabe CH, Coussement P, Kleiman NS, Vahanian A, Adgey AA, Menown I, Rupprecht HJ, Van der Wieken R, Ducas J, Scherer J, Anderson K, Van de Werf F, Braunwald E. Abciximab facilitates the rate and extent of thrombolysis: results of the thrombolysis in myocardial infarction (TIMI) 14 trial. The TIMI 14 Investigators. Circulation 1999; 99:2720-32. [PMID: 10351964 DOI: 10.1161/01.cir.99.21.2720] [Citation(s) in RCA: 392] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The TIMI 14 trial tested the hypothesis that abciximab, the Fab fragment of a monoclonal antibody directed to the platelet glycoprotein (GP) IIb/IIIa receptor, is a potent and safe addition to reduced-dose thrombolytic regimens for ST-segment elevation MI. METHODS AND RESULTS Patients (n=888) with ST-elevation MI presenting <12 hours from onset of symptoms were treated with aspirin and randomized initially to either 100 mg of accelerated-dose alteplase (control) or abciximab (bolus 0.25 mg/kg and 12-hour infusion of 0.125 microg. kg-1. min-1) alone or in combination with reduced doses of alteplase (20 to 65 mg) or streptokinase (500 000 U to 1.5 MU). Control patients received standard weight-adjusted heparin (70-U/kg bolus; infusion of 15 U. kg-1. h-1), whereas those treated with a regimen including abciximab received low-dose heparin (60-U/kg bolus; infusion of 7 U. kg-1. h-1). The rate of TIMI 3 flow at 90 minutes for patients treated with accelerated alteplase alone was 57% compared with 32% for abciximab alone and 34% to 46% for doses of streptokinase between 500 000 U and 1.25 MU with abciximab. Higher rates of TIMI 3 flow at both 60 and 90 minutes were observed with increasing duration of administration of alteplase, progressing from a bolus alone to a bolus followed by either a 30- or 60-minute infusion (P<0.02). The most promising regimen was 50 mg of alteplase (15-mg bolus; infusion of 35 mg over 60 minutes), which produced a 76% rate of TIMI 3 flow at 90 minutes and was tested subsequently in conjunction with either low-dose or very-low-dose (30-U/kg bolus; infusion of 4 U. kg-1. h-1) heparin. TIMI 3 flow rates were significantly higher in the 50-mg alteplase plus abciximab group versus the alteplase-only group at both 60 minutes (72% versus 43%; P=0.0009) and 90 minutes (77% versus 62%; P=0.02). The rates of major hemorrhage were 6% in patients receiving alteplase alone (n=235), 3% with abciximab alone (n=32), 10% with streptokinase plus abciximab (n=143), 7% with 50 mg of alteplase plus abciximab and low-dose heparin (n=103), and 1% with 50 mg of alteplase plus abciximab with very-low-dose heparin (n=70). CONCLUSIONS Abciximab facilitates the rate and extent of thrombolysis, producing early, marked increases in TIMI 3 flow when combined with half the usual dose of alteplase. This improvement in reperfusion with alteplase occurred without an increase in the risk of major bleeding. Substantial reductions in heparin dosing may reduce the risk of bleeding even further. Modest improvements in TIMI 3 flow were seen when abciximab was combined with streptokinase, but there was an increased risk of bleeding.
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Affiliation(s)
- E M Antman
- Brigham and Women's Hospital, Boston, MA, USA
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Abstract
Activation of coagulation is a normal component of the acute inflammatory response. Inflammatory cytokines initiate coagulation events locally at sites of inflammation by converting endothelium from an antithrombotic surface to a prothrombotic surface; by stimulating tissue factor production, which activates both the extrinsic and intrinsic coagulation systems; and by stimulating production of platelet-activating factors. The fibrinolytic system is initially activated but is subsequently inhibited. This results in a marked imbalance in coagulation and fibrinolysis resulting in a net procoagulant state. When thrombin generation and platelet activation exceed the body's capacity to inactivate or remove these factors, disseminated intravascular coagulation (DIC) results. DIC directly contributes to multiple organ failure and death associated with sepsis. Presently available treatments (i.e., heparin and aspirin) are relatively ineffective in treating DIC; however, newer, more potent drugs may soon be available for clinical use.
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Affiliation(s)
- D J Weiss
- Department of Veterinary PathoBiology, Colege of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA.
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Gibson CM, Goel M, Cohen DJ, Piana RN, Deckelbaum LI, Harris KE, King SB. Six-month angiographic and clinical follow-up of patients prospectively randomized to receive either tirofiban or placebo during angioplasty in the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis. J Am Coll Cardiol 1998; 32:28-34. [PMID: 9669245 DOI: 10.1016/s0735-1097(98)00192-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVES This study sought to investigate the effects of tirofiban versus placebo on the incidence of adverse cardiac outcomes and coronary artery restenosis at 6 months. BACKGROUND Tirofiban is a highly selective, short-acting inhibitor of fibrinogen binding to platelet glycoprotein IIb/IIIa. In a recent clinical study, tirofiban reduced the incidence of adverse cardiovascular events at both 2 and 7 days after coronary angioplasty or directional coronary atherectomy. This reduction persisted but was no longer statistically significant at 30 days. METHODS The Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis (RESTORE) trial was a randomized, double-blind, placebo-controlled trial of tirofiban in patients undergoing balloon angioplasty or directional atherectomy within 72 h of presentation with either unstable angina pectoris or acute myocardial infarction. All patients received an initial bolus (10 microg/kg body weight over 3 min), followed by a 36-h infusion (0.15 microg/kg per min) of either tirofiban or placebo. RESULTS At 6 months the composite end point (either death from any cause, new myocardial infarction, bypass surgery for angioplasty failure or recurrent ischemia, repeat target vessel angioplasty or stent insertion for actual or threatened abrupt closure) occurred in 1,070 placebo group patients (27.1%) and 1,071 tirofiban group patients (24.1%, p = 0.11). Analysis of 6-month coronary arteriograms by means of quantitative coronary arteriography showed no significant difference between placebo- and tirofiban-treated patients in either the incidence of a > or =50% diameter stenosis (57% vs. 51%, p = NS), a loss of > or =50% of lumen diameter gained (50% vs. 50%, p = NS) or a loss of > or =0.72 mm of lumen diameter (44% vs. 42%, p = NS). CONCLUSIONS The 3% absolute reduction in the incidence of the composite end point at 6 months (27.1% placebo vs. 24.1% tirofiban) was similar to that previously reported at 2 days (8.7% vs. 5.4%, p < 0.005), and there does not appear to be any late effect of tirofiban on clinical end points between day 2 and 6 months. Tirofiban did not reduce the incidence of restenosis at 6 months when defined in a number of ways.
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Affiliation(s)
- C M Gibson
- Veterans Affairs Medical Center, West Roxbury, Massachusetts, USA
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17
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Abstract
Thrombosis after the rupture of an atherosclerotic plaque often precipitates the acute coronary syndromes of unstable angina and myocardial infarction. The combination of aspirin and heparin has been shown to reduce the occurrence of both symptomatic and asymptomatic ("silent") ischemia, myocardial infarction, and death in patients with these syndromes. However, heparin and aspirin each have significant limitations as antithrombotic drugs. Additionally, coagulation abnormalities may persist for several months after an acute ischemic event, and long-term anticoagulation may be beneficial. Because of the need for frequent anticoagulation monitoring and dosage adjustment, the use of heparin is limited to short-term treatment during the acute in-hospital phase. Recently several novel antithrombotic treatments have been developed. The benefits of direct thrombin inhibitors, platelet fibrinogen receptor antagonists, and low-molecular-weight heparins in the treatment of acute coronary syndromes have been demonstrated in randomized clinical trials.
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Affiliation(s)
- M Cohen
- MCP-Hahnemann School of Medicine and Allegheny University of the Health Sciences, Philadelphia, PA 19102-1192, USA
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18
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Hermida J, Montes R, Páramo JA, Rocha E. Endotoxin-induced disseminated intravascular coagulation in rabbits: effect of recombinant hirudin on hemostatic parameters, fibrin deposits, and mortality. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1998; 131:77-83. [PMID: 9452130 DOI: 10.1016/s0022-2143(98)90080-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We evaluated the effect of r-hirudin on an experimental model of disseminated intravascular coagulation (DIC) in rabbits, through the continuous infusion of 100 microg/kg/hr of Escherichia coli endotoxin for a period of 6 hours. r-Hirudin (0.05, 0.3, and 0.6 mg/kg/hr) as treatment, or saline solution as placebo, were administered simultaneously with endotoxin. Severe DIC in the endotoxin control group was shown by impairment in hemostatic parameters, kidney fibrin deposition, and a high mortality rate. Medium and high doses of r-hirudin led to an improvement in such DIC-related parameters as platelet numbers and fibrinogen and protein C concentrations. High-dose r-hirudin also reduced consumption of antithrombin III (ATIII). All doses of r-hirudin prevented decreases in tissue plasminogen activator (t-PA) and reduced the increase in plasminogen activator inhibitor-1 (PAI-1) activity observed at 2 hours after endotoxin administration. A significant reduction in kidney fibrin deposition was seen in medium- and high-dose r-hirudin groups. Additionally, the mortality rate in rabbits receiving medium- and high-dose r-hirudin was 10%, and that in rabbits receiving low-dose r-hirudin was 20%, as compared with a mortality rate of 70% in the control group. Protein C activity was significantly lower (p < 0.001) in nonsurviving rabbits. Moreover, there was a strong positive correlation (r = 0.68, p < 0.001) between protein C consumption and kidney fibrin deposition. We conclude that r-hirudin can be a useful drug in the clinical treatment of DIC.
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Affiliation(s)
- J Hermida
- Laboratory of Vascular Biology and Thrombosis, School of Medicine, University of Navarra, Pamplona, Spain
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19
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Théroux P. Antiplatelet therapy: do the new platelet inhibitors add significantly to the clinical benefits of aspirin? Am Heart J 1997; 134:S62-70. [PMID: 9396636 DOI: 10.1016/s0002-8703(97)70011-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The inhibitors of the platelet membrane glycoprotein IIb/IIIa show considerable promise as antiplatelet agents. These drugs are easily titrated when administered intravenously and are associated with less frequent and serious bleeding than initially feared. They add significant benefit to that attributable to aspirin in preventing the complications associated with coronary angioplasty. Pilot studies have suggested that benefits could also be realized in acute myocardial infarction and unstable angina. The most effective means of administering these agents, their relative efficacy, and the consequences of long-term modulation of the glycoprotein IIb/IIIa receptor by oral agents are challenging areas for clinical investigation.
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Affiliation(s)
- P Théroux
- Department of Medicine, University of Montreal, and Montreal Heart Institute, Quebec, Canada
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20
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Effects of platelet glycoprotein IIb/IIIa blockade with tirofiban on adverse cardiac events in patients with unstable angina or acute myocardial infarction undergoing coronary angioplasty. The RESTORE Investigators. Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis. Circulation 1997; 96:1445-53. [PMID: 9315530 DOI: 10.1161/01.cir.96.5.1445] [Citation(s) in RCA: 597] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Adverse cardiovascular events associated with thrombotic occlusion occur in 4% to 12.8% of patients after coronary angioplasty. Recently, potent antiplatelet agents have been used to reduce those thrombotic complications. Tirofiban is a highly selective, short-acting inhibitor of fibrinogen binding to platelet glycoprotein (GP) IIb/IIIa that inhibits ex vivo platelet aggregation in response to a variety of agonists. METHODS AND RESULTS The RESTORE trial (Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis) was a randomized, double-blind, placebo-controlled trial of tirofiban in patients undergoing coronary interventions (balloon angioplasty or directional atherectomy) within 72 hours of presentation with an acute coronary syndrome (unstable angina pcctoris or acute myocardial infarction). The end points of the study were death from any cause, myocardial infarction, coronary bypass surgery due to angioplasty failure or recurrent ischemia, repeat target-vessel angioplasty for recurrent ischemia, and insertion of a stent due to actual or threatened abrupt closure of the dilated artery, and the primary end point was a composite representing the occurrence of any of these events. The prespecified primary hypothesis of the study was that tirofiban, administered as a bolus of 10 microg/kg over a 3-minute period and followed by a 36-hour infusion of 0.15 microg x kg(-1) x min(-1), would result in a reduction in the 30-day composite end point compared with placebo. Patients (n=2139) who were already receiving treatment with aspirin and heparin were randomized to receive tirofiban or placebo. The primary composite end point at 30 days was reduced from 12.2% in the placebo group to 10.3% in the tirofiban group, a 16% relative reduction (P=.160). However, 2 days after angioplasty, the tirofiban group had a 38% relative reduction in the composite end point (P< or =.005), and at 7 days there was a 27% relative reduction (P=.022), largely because of a reduction in nonfatal myocardial infarction and the need for repeat angioplasty. When repeat angioplasty or coronary artery bypass surgery procedures were included in the composite only if performed on an urgent or emergency basis, the composite 30-day event rates were 10.5% for the placebo group and 8.0% for the tirofiban group, a relative reduction of 24% (P=.052). Major bleeding, including transfusion, was not significantly different between the two groups (3.7% in the placebo group and 5.3% in the tirofiban group; P=.096). When the Thrombolysis In Myocardial Infarction (TIMI) criteria for major bleeding were used, the incidence was 2.1% in the placebo group compared with 2.4% in the tirofiban group (P=.662). Thrombocytopenia was similar in the placebo and tirofiban groups (0.9% for the placebo group versus 1.1% for the tirofiban group; P=.709). CONCLUSIONS In patients undergoing coronary angioplasty for acute coronary syndromes, tirofiban protects against early adverse cardiac events related to thrombotic closure. At 30 days, however, the reduction in adverse cardiac events was no longer statistically significant. The bleeding observed with tirofiban was not statistically different from that observed with placebo.
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Callas DD, Fareed J. Comparative anticoagulant effects of various thrombin inhibitors, as determined in the ecarin clotting time method. Thromb Res 1996; 83:463-8. [PMID: 8885140 DOI: 10.1016/0049-3848(96)00155-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- D D Callas
- Department of Pathology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
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Antman EM. Hirudin in acute myocardial infarction. Thrombolysis and Thrombin Inhibition in Myocardial Infarction (TIMI) 9B trial. Circulation 1996; 94:911-21. [PMID: 8790025 DOI: 10.1161/01.cir.94.5.911] [Citation(s) in RCA: 313] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND The TIMI 9 trial evaluated whether the direct antithrombin hirudin is more effective than an indirect-acting antithrombin, heparin, as adjunctive therapy for thrombolysis in myocardial infarction. METHODS AND RESULTS Patients (n = 3002) with acute myocardial infarction were treated with aspirin and either accelerated-dose tissue plasminogen activator (TPA) or streptokinase. They were randomized within 12 hours of symptoms to receive either intravenous heparin (5000 U bolus followed by infusion of 1000 U/h) or hirudin (0.1 mg/kg bolus followed by infusion of 0.1 mg/ kg per hour). The infusions of both antithrombins were titrated to a target activated partial thromboplastin time (aPTT) of 55 to 85 seconds and were administered for 96 hours. Patients randomized to hirudin were significantly more likely to have an aPTT measurement in the target range (P < .0001). The primary end point (death, recurrent nonfatal myocardial infarction, or development of severe congestive heart failure or cardiogenic shock by 30 days) occurred in 11.9% of the 1491 patients in the heparin group and 12.9% of the 1511 patients in the hirudin group (P = NS). Subgroup analyses did not reveal any profile of patients who benefited more from one of the antithrombins. The rate of major hemorrhage was similar in the heparin (5.3%) and hirudin (4.6%) groups; intracranial hemorrhage occurred in 0.9% of the heparin and 0.4% of the hirudin patients. CONCLUSIONS Heparin and hirudin have an equal effect as adjunctive therapy to TPA and streptokinase in preventing unsatisfactory outcome in patients with acute myocardial infarction. Similar rates of major bleeding were observed for patients in the heparin and hirudin groups.
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Affiliation(s)
- E M Antman
- Department of Medicine, Brigham and Women's Hospital, Boston, Mass 02115, USA
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Carter CJ. New developments in acute anticoagulation therapy. Postgrad Med 1996; 99:129-136. [DOI: 10.1080/00325481.1996.11946140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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