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Jang IK, Brown DF, Giugliano RP, Anderson HV, Losordo D, Nicolau JC, Dutra OP, Bazzino O, Viamonte VM, Norbady R, Liprandi AS, Massey TJ, Dinsmore R, Schwarz RP. A multicenter, randomized study of argatroban versus heparin as adjunct to tissue plasminogen activator (TPA) in acute myocardial infarction: myocardial infarction with novastan and TPA (MINT) study. J Am Coll Cardiol 1999; 33:1879-85. [PMID: 10362188 DOI: 10.1016/s0735-1097(99)00107-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES This study examined the effect of a small-molecule, direct thrombin inhibitor, argatroban, on reperfusion induced by tissue plasminogen activator (TPA) in patients with acute myocardial infarction (AMI). BACKGROUND Thrombin plays a crucial role in thrombosis and thrombolysis. In vitro and in vivo studies have shown that argatroban has advantages over heparin for the inhibition of clot-bound thrombin and for the enhancement of thrombolysis with TPA. METHODS One hundred and twenty-five patients with AMI within 6 h were randomized to heparin, low-dose argatroban or high-dose argatroban in addition to TPA. The primary end point was the rate of thrombolysis in myocardial infarction (TIMI) grade 3 flow at 90 min. RESULTS TIMI grade 3 flow was achieved in 42.1% of heparin, 56.8% of low-dose argatroban (p = 0.20 vs. heparin) and 58.7% of high-dose argatroban patients (p = 0.13 vs. heparin). In patients presenting after 3 h, TIMI grade 3 flow was significantly more frequent in high-dose argatroban versus heparin patients: 57.1% versus 20.0% (p = 0.03 vs. heparin). Major bleeding was observed in 10.0% of heparin, and in 2.6% and 4.3% of low-dose and high-dose argatroban patients, respectively. The composite of death, recurrent myocardial infarction, cardiogenic shock or congestive heart failure, revascularization and recurrent ischemia at 30 days occurred in 37.5% of heparin, 32.0% of low-dose argatroban and 25.5% of high-dose argatroban patients (p = 0.23). CONCLUSIONS Argatroban, as compared with heparin, appears to enhance reperfusion with TPA in patients with AMI, particularly in those patients with delayed presentation. The incidences of major bleeding and adverse clinical outcome were lower in the patients receiving argatroban.
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Affiliation(s)
- I K Jang
- Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA.
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Abstract
This article focuses on the optimal treatment of postinfarction, refractory, or recurrent angina based on the results of recent clinical trials. Many of our recommendations hold true for the general management of unstable angina, but special considerations for the high-risk subsets are emphasized. Specifically, we discuss acute medical management and suggest that an early aggressive strategy that leads to early coronary angiography with the goal of revascularization when feasible best serves this subset. A special emphasis on the emerging role of glycoprotein IIb-IIIa antagonists is made because the important role of platelets in coronary thrombosis has dominated recent views on the pathophysiology of unstable angina.
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Affiliation(s)
- C Tung
- Department of Internal Medicine, Northwestern University, McGaw Medical Center, Chicago, Illinois, USA
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Abstract
The development of new antithrombotic agents has been stimulated by clinical needs and by advances in biotechnology that have made it possible to produce drugs that target specific steps in thrombogenesis. Heparin has pharmacokinetic and biophysical limitations that are overcome by new anticoagulants. Of these, low-molecular-weight heparin and direct inhibitors of thrombin have been evaluated clinically. Coumarins require careful laboratory monitoring because of concerns about safety. Orally active direct inhibitors of thrombin and factor Xa may replace coumarins. Aspirin is of limited efficacy because it inhibits only one pathway of platelet activation. Inhibitors of adenosine diphosphate receptor and glycoprotein IIb/IIIa antagonists are more effective than aspirin and are used in the clinic.
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Affiliation(s)
- J Hirsh
- Hamilton Civic Hospitals Research Centre and Department of Medicine, Ontario, Canada
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204
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Ferrario M, Merlini PA, Lucreziotti S, Poli A, Cantù F, Gobbi G, Bramucci E, Mussini A, Ardissino D. Antithrombotic therapy of unstable angina and non-Q-wave myocardial infarction. Int J Cardiol 1999; 68 Suppl 1:S63-71. [PMID: 10328613 DOI: 10.1016/s0167-5273(98)00293-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Unstable angina and non-Q-wave myocardial infarction still represent an unsolved problem for clinicians, owing to their unpredictable evolution and high incidence of coronary events in the follow-up. Traditional antithrombotic agents, unfractionated heparin and aspirin, have been proved to be highly effective, but show some important limitations. New potent antithrombotic therapy have been studied to improve their efficacy, with encouraging results. Among these drugs, low molecular weight heparins (for subcutaneous administration) and inhibitors of platelet glycoprotein receptor IIb/IIIa (for intravenous, and possibly oral, administration) are the most promising and are now under extensive investigation.
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Affiliation(s)
- M Ferrario
- Divisione di Cardiologia, IRCCS Policlinico S. Matteo, Pavia, Italy
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205
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Affiliation(s)
- C P Cannon
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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Frostfeldt G, Ahlberg G, Gustafsson G, Helmius G, Lindahl B, Nygren A, Siegbahn A, Swahn E, Venge P, Wallentin L. Low molecular weight heparin (dalteparin) as adjuvant treatment of thrombolysis in acute myocardial infarction--a pilot study: biochemical markers in acute coronary syndromes (BIOMACS II). J Am Coll Cardiol 1999; 33:627-33. [PMID: 10080461 DOI: 10.1016/s0735-1097(98)00612-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES This randomized, double blind, placebo-controlled pilot trial evaluated the effect of dalteparin as an adjuvant to thrombolysis in patients with acute myocardial infarction regarding early reperfusion, recurrent ischemia and patency at 24 h. BACKGROUND Low-molecular-weight heparin, given subcutaneously twice daily without monitoring, might be an attractive alternative to conventional intravenous heparin in the treatment of acute myocardial infarction. METHODS In 101 patients dalteparin/placebo 100 IU/kg was given just before streptokinase and a second injection 120 IU/kg after 12 h. Monitoring with continuous vector-ECG was done to obtain signs of early reperfusion and later ischemic episodes. Blood samples for myoglobin were obtained at start and after 90 min to evaluate signs of reperfusion. Coronary angiography was performed after 20-28 h to evaluate TIMI-flow in the infarct-related artery. RESULTS Dalteparin added to streptokinase tended to provide a higher rate of TIMI grade 3 flow in infarct-related artery compared to placebo, 68% versus 51% (p = 0.10). Dalteparin had no effects on noninvasive signs of early reperfusion. In patients with signs of early reperfusion, there seemed to be a higher rate of TIMI grade 3 flow, 74% versus 46% (myoglobin) (p = 0.04) and 73% versus 52% (vector-ECG) (p = 0.11). Ischemic episodes 6-24 h. after start of treatment were fewer in the dalteparin group, 16% versus 38% (p = 0.04). CONCLUSIONS When dalteparin was added as an adjuvant to streptokinase and aspirin, there were tendencies for less ECG monitoring evidence of recurrent ischemia and better patency at 24 h, warranting further study.
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Affiliation(s)
- G Frostfeldt
- Department of Cardiology, Cardiothoracic Centre, University Hospital, Uppsala, Sweden.
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207
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208
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Becker RC, Hochman JS, Cannon CP, Spencer FA, Ball SP, Rizzo MJ, Antman EM. Fatal cardiac rupture among patients treated with thrombolytic agents and adjunctive thrombin antagonists: observations from the Thrombolysis and Thrombin Inhibition in Myocardial Infarction 9 Study. J Am Coll Cardiol 1999; 33:479-87. [PMID: 9973029 DOI: 10.1016/s0735-1097(98)00582-8] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES The purpose of this study was to determine the incidence and demographic characteristics of patients experiencing cardiac rupture after thrombolytic and adjunctive anticoagulant therapy and to identify possible associations between the mechanism of thrombin inhibition (indirect, direct) and the intensity of systemic anticoagulation with its occurrence. BACKGROUND Cardiac rupture is responsible for nearly 15% of all in-hospital deaths among patients with myocardial infarction (MI) given thrombolytic agents. Little is known about specific patient- and treatment-related risk factors. METHODS Patients (n = 3,759) with MI participating in the Thrombolysis and Thrombin Inhibition in Myocardial Infarction 9A and B trials received intravenous thrombolytic therapy, aspirin and either heparin (5,000 U bolus, 1,000 to 1,300 U/h infusion) or hirudin (0.1 to 0.6 mg/kg bolus, 0.1 to 0.2 mg/kg/h infusion) for at least 96 h. A diagnosis of cardiac rupture was made clinically in patients with sudden electromechanical dissociation in the absence of preceding congestive heart failure, slowly progressive hemodynamic compromise or malignant ventricular arrhythmias. RESULTS A total of 65 rupture events (1.7%) were reported-all were fatal, and a majority occurred within 48 h of treatment Patients with cardiac rupture were older, of lower body weight and stature and more likely to be female than those without rupture (all p < 0.001). By multivariable analysis, age >70 years (odds ratio [OR] 3.77; 95% confidence interval [CI] 2.06, 6.91), female gender (OR 2.87; 95% CI 1.44, 5.73) and prior angina (OR 1.82; 95% CI 1.05, 3.16) were independently associated with cardiac rupture. Independent predictors of nonrupture death included age >70 years (OR 3.68; 95% CI 2.53, 5.35) and prior MI (OR 2.14; 95%, CI 1.45, 3.17). There was no association between the type of thrombin inhibition, the intensity of anticoagulation and cardiac rapture. CONCLUSIONS Cardiac rupture following thrombolytic therapy tends to occur in older patients and may explain the disproportionately high mortality rate among women in prior dinical trials. Unlike major hemorrhagic complications, there is no evidence that the intensity of anticoagulation associated with heparin or hirudin administration influences the occurrence of rupture.
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Affiliation(s)
- R C Becker
- Cardiovascular Thrombosis Research Center, University of Massachusetts Medical School, Worcester 01655-0214, USA.
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Abstract
Eroded or disrupted atherosclerotic plaques act as a substrate for thrombosis, leading to ischemic coronary artery and cerebrovascular disease. Plaques vary greatly in composition, size, and the degree of stenosis they cause. Plaques can be categorized based on these features, which helps to estimate the likelihood of rupture and subsequent thrombosis. Vascular plaques often begin at regions with low and oscillatory shear forces that cause chronic minimal endothelial damage or dysfunction. Lipoproteins enter the vessel wall, promoting the recruitment of monocytes, which imbibe lipids and become foam cells. Smooth muscle cells invade these early plaques, producing connective tissue fibrils that form a fibrous cap over the lipid center; rupture of this cap is an important cause of thrombosis. Passive plaque disruption occurs when physical forces cause cap rupture; active disruption occurs when the cap is attacked by macrophages and proteolytic enzymes. Tissue factor is one of many factors within plaque that stimulates thrombosis.
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Affiliation(s)
- V Fuster
- Mount Sinai Medical Center, New York, NY 10029-6574, USA
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Kleiman NS, Granger CB, White HD, Armstrong P, Ardissino D, de Werf FV, Zoldeyhi P, Thompson TD, Califf RM, Topol EJ. Death and nonfatal reinfarction within the first 24 hours after presentation with an acute coronary syndrome: experience from GUSTO-IIb. Global Utilization of Strategies for Total Occlusion. Am Heart J 1999; 137:12-23. [PMID: 9878932 DOI: 10.1016/s0002-8703(99)70455-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND A large proportion of deaths among patients with myocardial infarction occurs within the first 24 hours after presentation. It is not clear whether this phenomenon is also true of patients without ST-segment elevation who may or may not have infarction at the time of presentation. Thrombin activity may also be greatest during the first 24 hours after plaque rupture. Accordingly, this study was designed to examine the pattern of early ischemic events among patients with acute coronary syndromes and to determine whether the direct thrombin inhibitor desirudin (r-hirudin) would be most effective during this period. METHODS AND RESULTS Among the 11,142 patients enrolled in GUSTO-II, death or (re)infarction occurred within 24 hours in 210 patients (1.7%), representing 19% of the 1135 deaths that had occurred by 30 days. Death or (re)infarction occurred within 24 hours in 113 patients (2. 7%) with ST-segment elevation and in 97 patients without ST-segment elevation (1.2%, P <.001), representing 26% and 14% of the 30-day event rates, respectively, for the 2 enrollment strata. Among patients with ST-segment elevation, most of these events were deaths, whereas among patients without ST-segment elevation, most events were (re)infarctions. Death or (re)infarction by 24 hours occurred in 80 (1.3%) patients treated with desirudin and 130 (2.1%) patients treated with heparin (P =.01). This finding predominantly consisted of prevention of death among patients with ST-segment elevation and of (re)infarction among patients without ST-segment elevation. CONCLUSIONS These findings have important implications for early triage of patients with acute coronary syndromes and for the development of new therapies directed at stabilizing the unstable atherosclerotic plaque.
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Affiliation(s)
- N S Kleiman
- Baylor College of Medicine and the Methodist Hospital, Houston, Texas 77030, USA.
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213
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Kizer JR, Cannon CP, McCabe CH, Mueller HS, Schweiger MJ, Davis VG, Perritt R, Antman EM. Trends in the use of pharmacotherapies for acute myocardial infarction among physicians who design and/or implement randomized trials versus physicians in routine clinical practice: the MILIS-TIMI experience. Multicenter Investigation on Limitation of Infarct Size. Thrombolysis in Myocardial Infarction. Am Heart J 1999; 137:79-92. [PMID: 9878939 DOI: 10.1016/s0002-8703(99)70462-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Although studies have documented that randomized, controlled trials (RCTs) have a measurable influence on clinical practice, investigators have uncovered important deficiencies in the application of RCT findings to the management of acute myocardial infarction (AMI). Little is known about the extent to which physicians who design and/or implement clinical trials differ from physicians in routine practice in their translation of the literature. METHODS Our aims were to (1) evaluate recent trends in selected treatments of AMI in relation to the publication of RCTs, statistical overviews, and task-force guidelines, and (2) compare prescribing practices in AMI management between physicians in routine clinical practice and physicians who design and/or implement RCTs. We reviewed the use of aspirin, beta-blockers, angiotensin-converting enzyme inhibitors, and calcium channel blockers on entry and at discharge in patients enrolled in the MILIS, TIMI 1, 2, 4, 5, 6, and 9B trials with ST-elevation (and depression in MILIS) myocardial infarction for a period approaching 2 decades (August 1978 to September 1995). We hypothesized that physicians who participate in RCTs apply the findings of the published literature more promptly and thoroughly than physicians in routine practice. RESULTS Use of aspirin, beta-blockers, and angiotensin converting enzyme inhibitors exhibited a statistically significant time-related increase at discharge and, excepting beta-blockers, at enrollment across the trials. Prescription of calcium channel blockers showed a statistically significant decrease at discharge only. For all medications under study, increases and decreases in use associated with publication of clinical data occurred earlier and more steeply for the discharge cohort (prescriptions by physicians participating in RCTs) than for the enrollment cohort (prescriptions by physicians in routine practice). Recent prescribing practices (1994 to 1995) among RCT investigators and their colleagues have higher concordance with published findings than those of physicians in routine practice. CONCLUSIONS Physicians who design and/or implement RCTs translate the results of the medical literature more promptly and to a greater extent than physicians in routine clinical practice. Differences between different physician classes need to be studied further amid efforts to reconfigure health care delivery that currently favor more dominant roles for primary care physicians.
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Affiliation(s)
- J R Kizer
- Cardiovascular Division, University of Pennsylvania Medical Center, Philadelphia, USA
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Grubb NR, Bloomfield P, Ludlam CA. The end of the heparin pump? Low molecular weight heparin has many advantages over unfractionated heparin. BMJ (CLINICAL RESEARCH ED.) 1998; 317:1540-2. [PMID: 9836650 PMCID: PMC1114382 DOI: 10.1136/bmj.317.7172.1540] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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217
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Abstract
Thrombin mediates acute vascular thrombosis following mechanical denuding injury or spontaneous rupture of atherosclerotic plaques. In the process of generating thrombin, factor VII/VIIa binds avidly with tissue factor exposed on cellular membranes, leading to sequential activation of coagulation serine proteases via macromolecular catalytic complexes on phospholipid surfaces. At sites of disrupted arteries thrombin activates platelets, blood leukocytes, endothelium, and vascular SMCs by cleaving G protein-coupled TRs, mediating SMC intimal proliferation in the formation of neointimal vascular lesions. Therapeutic strategies targeting thrombin include inactivation of bound thrombin, inhibition of TR activation by thrombin, and interruption of thrombin production. In patients having orthopedic surgery, inactivating bound thrombin with direct antithrombins markedly reduces venous thromboembolism as compared with heparin or its derivatives, without significant impairment of hemostasis. Antithrombotic effects in arterial thromboembolism, such as acute coronary syndrome, are not conclusively benefitted by systemic direct antithrombins when administered at safe levels, because interrupting TR-dependent platelet thrombosis demands systemic levels of direct antithrombins that compromise hemostatic function. Alternative safer strategies evolving from preclinical studies include (1) inhibiting thrombin activation of TRs, thereby abolishing platelet recruitment in arterial thrombogenesis, while sparing fibrin formation in hemostatic plugs; (2) enhancing the formation of endogenous activated protein C by protein C-selective thrombin mutants; and (3) preventing thrombin production by inhibiting precursor serine protease function and interrupting the formation of both acute thrombosis and vascular lesion formation. Tissue factor pathway antagonists are particularly promising because they exhibit both efficacy and safety in the prevention of thrombosis and vascular lesions.
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Affiliation(s)
- L A Harker
- Division of Hematology and Oncology, Emory University School of Medicine, Atlanta, Georgia, USA
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218
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Combining thrombolysis with the platelet glycoprotein IIb/IIIa inhibitor lamifiban: results of the Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction (PARADIGM) trial. J Am Coll Cardiol 1998; 32:2003-10. [PMID: 9857885 DOI: 10.1016/s0735-1097(98)00474-4] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVES The trial was designed to assess the safety, pharmacodynamics and effects on reperfusion of the platelet glycoprotein (GP) IIb/IIIa inhibitor lamifiban when given with thrombolysis to patients with ST segment elevation acute myocardial infarction. BACKGROUND Studies of fibrinolytic agents in acute myocardial infarction have demonstrated a direct relationship between early complete reperfusion and survival. Blockade of the platelet GP IIb/IIIa receptor complex inhibits platelet aggregation and may speed reperfusion when given in conjunction with thrombolysis to patients with acute myocardial infarction. METHODS Patients with ST segment elevation presenting within 12 h of symptom onset who were treated with either tissue-plasminogen activator or streptokinase were enrolled in this three-part Phase II dose exploration study. In Part A, all patients received the GP IIb/IIIa inhibitor lamifiban in an open-label, dose escalation scheme. Parts B and C were a randomized, double-blind comparison of a bolus plus 24-h infusion of lamifiban versus placebo with patients randomized in a 2:1 ratio. The goal was to identify a dose(s) of lamifiban that provided >85% adenosine diphosphate (ADP)-induced platelet aggregation inhibition. A composite of angiographic, continuous electrocardiographic and clinical markers of reperfusion was the primary efficacy end point, and bleeding was the primary safety end point. RESULTS Platelet aggregation was inhibited by lamifiban in a dose-dependent manner with the highest doses exceeding 85% ADP-induced platelet aggregation inhibition. There was more bleeding associated with lamifiban (transfusions in 16.1% lamifiban-treated vs. 10.3% placebo-treated patients). Lamifiban induced more rapid reperfusion as measured by all continuous electrocardiographic (ECG) parameters. CONCLUSIONS Lamifiban given with thrombolytic therapy appears to be associated with more rapid and complete reperfusion than placebo. As expected in this small sample, there were no obvious clinical benefits to lamifiban over placebo. Reconciliation of ECG monitoring with clinical outcomes will require a larger, adequately powered clinical trial.
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Affiliation(s)
- J A Cairns
- Faculty of Medicine, University of British Columbia, Vancouver, Canada
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220
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White HD. Direct thrombin inhibition and thrombolytic therapy: rationale for the Hirulog and Early Reperfusion/Occlusion (HERO-2) trial. Am J Cardiol 1998; 82:57P-62P. [PMID: 9809893 DOI: 10.1016/s0002-9149(98)00663-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Worldwide, streptokinase continues to be used widely in the treatment of myocardial infarction because it is inexpensive and causes fewer intracranial hemorrhages than other thrombolytic regimens. However, in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO-I) trial, the 90-minute angiographic Thrombolysis in Myocardial Infarction (TIMI) trial grade 3 flow rate with streptokinase was 43% lower than that with accelerated tissue plasminogen activator, and there was a higher incidence of death or disabling stroke with streptokinase (7.8% vs 6.9%, p <0.01). In the first Hirulog and Early Reperfusion/Occlusion (HERO-1) trial, 48% of patients given the direct thrombin inhibitor bivalirudin (formerly Hirulog, The Medicines Company) after streptokinase had TIMI 3 patency at 90 minutes, compared with 35% of patients given intravenous heparin (p <0.05). Other angiographic and clinical studies and animal research have shown that early infarct artery blood flow may be increased markedly if a direct thrombin inhibitor is administered before the thrombolytic agent. In the HERO-2 trial, 17,000 patients presenting within 6 hours after the onset of acute myocardial infarction will be given aspirin and randomized to receive either intravenous heparin or bivalirudin before streptokinase is administered. The primary endpoint will be 30-day mortality, and secondary endpoints will include death or myocardial infarction within 30 days, and death or nonfatal disabling stroke. If the thrombin hypothesis is supported by improved clinical outcomes with bivalirudin in the HERO-2 trial, large-scale clinical trials will be needed to evaluate the administration of direct thrombin inhibitors before other thrombolytic regimens.
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Affiliation(s)
- H D White
- Cardiology Department, Green Lane Hospital, Auckland, New Zealand
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221
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Bates SM, Weitz JI. Direct thrombin inhibitors for treatment of arterial thrombosis: potential differences between bivalirudin and hirudin. Am J Cardiol 1998; 82:12P-18P. [PMID: 9809887 DOI: 10.1016/s0002-9149(98)00660-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Given the central role of thrombin in arterial thrombogenesis, most treatment strategies for acute coronary syndromes are aimed at inhibiting its generation or blocking its activity. Although heparin has been widely used, it has limitations in the setting of arterial thrombosis. These limitations reflect the inability of heparin to inactivate thrombin bound to fibrin, a major stimulus for thrombus growth. In addition, the anticoagulant response to heparin varies from patient to patient, and heparin is neutralized by platelet Factor IV, large quantities of which are released from platelets activated at sites of plaque rupture. Consequently, heparin requires careful laboratory monitoring to ensure an adequate anticoagulant effect. Direct thrombin inhibitors, such as hirudin and bivalirudin, overcome the limitations of heparin. These agents inhibit fibrin-bound thrombin, as well as fluid-phase thrombin, and produce a predictable anticoagulant response. Bivalirudin has both safety and potential efficacy advantages over hirudin. Bivalirudin appears to have a wider therapeutic window than hirudin, possibly because bivalirudin only transiently inhibits the active site of thrombin. The better safety profile of bivalirudin permits administration of higher doses, which may give it an efficacy advantage. Hirudin prevents thrombin from activating protein C, thereby suppressing this natural anticoagulant pathway. In contrast, bivalirudin may promote protein C activation by transiently inhibiting thrombin until it can be bound by thrombomodulin. Differences between bivalirudin and hirudin, as well as other direct thrombin inhibitors, highlight the pitfalls of considering all direct thrombin inhibitors to have equivalent risk-benefit profiles.
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Affiliation(s)
- S M Bates
- McMaster University and Hamilton Civic Hospitals Research Centre, Ontario, Canada
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Abstract
With the establishment of thrombosis as the cause of myocardial infarction, the pivotal role of thrombolytics and primary angioplasty has evolved. Large randomized trials with innovative methodologies have examined the role of these reperfusion therapies in the management of acute coronary syndromes. Intravenous thrombolytic therapy decreases mortality in a broad group of patients with acute myocardial infarction. The GUSTO trial established intravenous tissue plasminogen activator (tPA) used in combination with intravenous heparin as the most effective thrombolytic therapy. Importantly, the time to achieve reperfusion is crucial to the mortality benefit observed, and rapid attainment of Thrombolysis in Myocardial Infarction (TIMI) trial grade 3 flow is achieved in only approximately 55% of patients who receive thrombolytics. Reocclusion, cellular damage, and microvascular dysfunction may contribute to less than optimal results. Percutaneous transluminal coronary angioplasty (PTCA) may be the preferred method of acute reperfusion therapy based on higher rates of TIMI grade 3 flow and lower rates of reocclusion and recurrent myocardial infarction. However, marked variation exists in outcomes and utilization rates among individual institutions, and the benefits of PTCA have not been consistently maintained at 6 months. The use of stents and anticoagulants may improve results, and pre-PTCA strategies also are under investigation. Limitations remain in the efficacy of current reperfusion therapies, supporting the search for improved thrombolytic agents, primary angioplasty, stents, and antithrombotics with the goal of improving TIMI 3 flow rates and achieving reperfusion more rapidly.
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Affiliation(s)
- B J Gersh
- Division of Cardiology, Georgetown University Medical Center, Washington, DC 20007-2197, USA
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Califf RM. Role and significance of coagulation markers in understanding and treating acute coronary syndromes. Introduction. Am Heart J 1998; 136:S1-S6. [PMID: 9778083 DOI: 10.1053/hj.1998.v136.93437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- R M Califf
- Duke University Medical Center, Durham, NC, USA
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Cohen M, Demers C, Gurfinkel EP, Turpie AG, Fromell GJ, Goodman S, Langer A, Califf RM, Fox KA, Premmereur J, Bigonzi F. Low-molecular-weight heparins in non-ST-segment elevation ischemia: the ESSENCE trial. Efficacy and Safety of Subcutaneous Enoxaparin versus intravenous unfractionated heparin, in non-Q-wave Coronary Events. Am J Cardiol 1998; 82:19L-24L. [PMID: 9737476 DOI: 10.1016/s0002-9149(98)00108-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Combination antithrombotic therapy with heparin plus aspirin decreases the risk of recurrent ischemic events in patients with acute coronary syndromes without persistent ST-segment elevation. Compared with standard unfractionated heparin, low-molecular-weight heparin (LMWH) has a more predictable antithrombotic effect, is easier to administer, and does not require coagulation monitoring. At 176 hospitals in 3 continents, 3,171 patients with rest unstable angina or non-wave myocardial infarction were randomly assigned to either enoxaparin (a LMWH), 1 mg/kg twice daily subcutaneously, or to continuous intravenous unfractionated heparin, for a minimum of 48 hours to a maximum of 8 days. Trial medication was administered in a double-blind, placebo-controlled fashion. At 14 days, the primary endpoint, the composite risk of death, myocardial infarction, or recurrent angina with electrocardiographic changes or prompting intervention, was significantly lower in patients assigned to enoxaparin compared with heparin (16.6% vs 19.8%; odds ratio [OR] 1.24; 95% confidence interval [CI] 1.04-1.49; p = 0.019). At 30 days, the composite risk of death, myocardial infarction, or recurrent angina remained significantly lower in the enoxaparin group compared with the unfractionated heparin group (19.8% vs 23.3%, OR 1.23; 95% CI 1.0-1.46, p = 0.016). The rate of revascularization procedures at 30 days was also significantly lower in patients assigned to enoxaparin (27.1% vs 32.2%, p = 0.001). The 30-day incidence of major bleeding complication was 6.5% versus 7.0% (p = not significant), but the incidence of minor bleeding was significantly higher in the enoxaparin group (13.8% vs 8.8%, p <0.001) due primarily to injection-site ecchymosis. Thus, combination antithrombotic therapy with enoxaparin plus aspirin is more effective than unfractionated heparin plus aspirin in decreasing ischemic outcomes in patients with unstable angina or non-Q-wave myocardial infarction in the early (30 days) phase. The lower recurrent ischemic event rate seen with the LMWH, enoxaparin, is achieved without an increase in major bleeding, but with an increase in minor bleeding complications due mainly to injection-site ecchymosis.
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Affiliation(s)
- M Cohen
- Division of Cardiology, Allegheny University of the Health Sciences-Hahnemann Division, Philadelphia, Pennsylvania 19102-1192, USA
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225
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Abstract
Although the use of coronary stents has virtually abolished the threat of periprocedural obstructive dissection, subacute and acute intracoronary thrombosis and late restenosis remain a major problem with catheter-guided transluminal coronary interventions, despite significant technical advances over the last 10 years. Acute stent thrombosis emerged as a new problem with the introduction of metallic coronary prostheses (stents), which unfortunately represent an ideal stimulus for platelet deposition. Recently, dramatic progress has been achieved by focusing on the inhibition of thrombin and platelets, before and during interventional procedures. This has stimulated the search for powerful and well-tolerated antithrombotic agents-platelet inhibitors and antithrombins-so that long-term (oral) administration may become possible, if necessary. The current roles of unfractionated and low-molecular-weight heparins (LMWHs), direct thrombin inhibitors (such as hirulog and hirudin), antiplatelet agents (such as aspirin, clopidogrel, and ticlopidine) and the potential of the glycoprotein IIb/IIa receptor blockers are reviewed and put into perspective with respect to their acute and long-term clinical value.
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Affiliation(s)
- T A Ischinger
- Kardiologie und Pneumologie Städt Krankenhaus, München-Bogenhausen, Germany
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226
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MacFadyen R, Pringle SD. The Evolving Management of Unstable Coronary Artery Disease and Its Impact on Practice Outwith the Tertiary Hospital. J R Coll Physicians Edinb 1998. [DOI: 10.1177/147827159802800314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- R.J. MacFadyen
- Cardiac Unit, Raigmore Hospital. Old Perth Road, Inverness
| | - S. D. Pringle
- Department of Cardiology, Ninewells Hospital and Medical School, Dundee
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227
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Affiliation(s)
- N Curzen
- Department of Cardiology, London Chest Hospital, UK
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228
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Granger CB. Heparin management in acute myocardial infarction (AMI). AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 1998; 28:541-7. [PMID: 9777136 DOI: 10.1111/j.1445-5994.1998.tb02107.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Antithrombotic agents have been shown to be beneficial in the setting of acute coronary syndromes, and as an adjunct to thrombolysis for acute myocardial infarction (AMI). The optimal type and dosing of antithrombotic drug, however, remains elusive. Heparin, the agent most commonly used, has several limitations, the most important of which may be its inability to inhibit clot-bound thrombin. Newer, direct thrombin inhibitors (such as hirudin) provide potent and predictable thrombin inhibition and are able to inhibit clot-bound thrombin. Both heparin and hirudin can carry a substantial risk of haemorrhage, however, and thrombin activity is likely to rebound after discontinuation of either agent. Further, the relationships of antithrombotic/thrombolytic dosing, measures of anticoagulation (such as APTT), and clinical outcomes are not always clear. Nonetheless, from the data available from large, randomised trials, intravenous heparin should remain a standard adjunct to thrombolytic therapy for AMI.
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Affiliation(s)
- C B Granger
- Duke University Medical Center, Durham, NC, USA
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229
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Aylward P. The GUSTO 2b and related studies. Global Use of Strategies to Open Occluded Coronary Arteries. AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 1998; 28:548-50. [PMID: 9777137 DOI: 10.1111/j.1445-5994.1998.tb02108.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct anti-thrombin inhibitors such as hirudin have theoretical advantages over heparin. Two large studies in acute coronary syndromes were designed to test the thrombin hypothesis by demonstrating improved outcomes in hirudin treated patients. TIMI 9 assessed the effect of hirudin in patients with ST elevation receiving thrombolytic therapy. GUSTO 2 assessed the full spectrum of acute coronary syndromes of ST elevation and non-ST elevation. Over 15,000 patients were entered into the studies and no major benefit was demonstrated for hirudin. This may, however, relate to endpoints measured and the timing of the anti-thrombin.
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Affiliation(s)
- P Aylward
- Flinders Medical Centre, Adelaide, SA
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230
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White HD, Ellis CJ, French JK, Aylward P. Hirudin (desirudin) and Hirulog (bivalirudin) in acute ischaemic syndromes and the rationale for the Hirulog/Early Reperfusion Occlusion (HERO-2) Study. AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 1998; 28:551-4. [PMID: 9777138 DOI: 10.1111/j.1445-5994.1998.tb02109.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Unlike unfractionated heparin, direct thrombin inhibitors such as hirudin and Hirulog inhibit clot-bound as well as fluid-phase thrombin, escape neutralisation by platelet secretion products, do not require monitoring, and are unassociated with immune thrombocytopenia. They have been shown to have modest advantages over heparin when given after thrombolytic therapy, reducing reinfarction by 14%. In the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO 2b) trial, patients treated with streptokinase and adjunctive hirudin had a reduction in death or myocardial infarction of 40% at 30 days (8.6% with hirudin versus 14.4% with heparin, p = 0.004). In the Hirulog Early Reperfusion/Occlusion (HERO 1) trial, 48% of patients who received Hirulog as adjunctive therapy with streptokinase had Thrombolysis in Myocardial Infarction (TIMI) trial grade 3 flow in the infarct-related artery, compared with 35% of patients who received heparin with streptokinase (p < 0.05). The HERO 2 study, involving 17,000 patients, will test the hypothesis that Hirulog and aspirin given before streptokinase will reduce mortality compared with aspirin plus heparin. Early administration of direct thrombin inhibitors may potentially improve the outcome of patients treated with thrombolytic therapy.
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Affiliation(s)
- H D White
- Green Lane Hospital, Auckland, New Zealand
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231
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Thrombin Generation in Patients with Acute Myocardial Infarction Treated with Front-Loaded rt-PA and Recombinant Hirudin (HBW 023). J Thromb Thrombolysis 1998; 5:203-207. [PMID: 10767116 DOI: 10.1023/a:1008839824942] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Thrombin contributes to the pathogenesis of acute myocardial infarction and reocclusion after thrombolysis. Thrombolytic therapy is known to induce a paradoxic increase in thrombin generation. Specific thrombin inhibition enhances thrombolytic therapy in experimental models. The aim of this study was to determine thrombin generation in patients with acute myocardial infarction treated with rt-PA and conjunctive therapy with the specific thrombin inhibitor, recombinant hirudin. Thrombin generation was determined in 17 patients with acute myocardial infarction treated with front-loaded rt-PA (100 mg/90 min) and conjunctive therapy with recombinant hirudin (HBW 023 bolus 0.4 mg/kg, infusion of 0.15 mg/kg/h) over 48 hours. Mean free hirudin plasma levels of 1320-1545 ng/mL produced a stable anticoagulation with mean aPTT values between 63 and 81 seconds throughout the treatment period. Thrombin generation increased during thrombolysis, indicated by a transient elevation of prothrombin fragment 1.2 levels, which were 3.0 nmol/L at baseline, 11.1 nmol/L after 30 minutes, 8.3 nmol/L after 60 minutes, 3.1 nmol/L after 12 hours, and 1.5 nmol/L after 24 hours, respectively. In contrast, thrombin-antithrombin III complex levels during and after thrombolysis did not exceed the baseline level of 21.8 ug/L. Thrombin-hirudin complex levels increased constantly during the 48-hour treatment period from 3.1 ug/L at baseline to 64.2 ug/L. All patients had an open infarct vessel (TIMI 2/3 potency) after 36-48 hours. Thrombolysis with rt-PA is associated with a significant increase in thrombin generation, which is not blocked by r-hirudin, whereas circulating thrombin seems to be effectively inhibited by r-hirudin.
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232
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Abstract
Thrombin remains a molecule of great interest to scientists and clinicians alike because of its important role in hemostasis, thrombosis, inflammation and vascular remodeling. Yet one of the great challenges has been the inhibition of thrombin generation to a degree that minimizes intravascular thrombosis while preserving physiologic hemostasis. It has become increasingly clear that high levels of anticoagulation with either direct or indirect thrombin antagonists are not beneficial and, in fact, are quite detrimental. Despite the overwhelming shift of interest toward the platelet in clinical trials of acute coronary syndromes, much can be gained through further investigation of coagulation processes responsible for thrombin generation and activity.
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233
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Bizjak ED, Mauro VF. Thrombolytic therapy: a review of its use in acute myocardial infarction. Ann Pharmacother 1998; 32:769-84. [PMID: 9681094 DOI: 10.1345/aph.17350] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
OBJECTIVE To review the literature on the use of thrombolytic agents in the pharmacotherapeutic management of acute myocardial infarction (AMI). DATA SOURCE English-language clinical trials, reviews, and editorials derived from MEDLINE (January 1966-September 1997) and/or cross-referencing of selected articles. STUDY SELECTION Articles that were selected best represent the clinical trials researching the role for thrombolytics in the therapy of AMI to improve morbidity and mortality. DATA SYNTHESIS AMI is one of the leading causes of mortality in the US. Following supportive data that the most common cause of an AMI is an intracoronary thrombus, clinical investigation has demonstrated that intravenous thrombolytic agents improve survival rates in patients who experience an AMI. Several clinical trials have been conducted to determine whether one thrombolytic agent is superior to others with respect to improving mortality. At present, only the first Global Use of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) trial has reported any statistically significant difference in mortality rate. In this trial, "front-loaded" alteplase induced a statistically significant (p < 0.001) 1% absolute reduction in 30-day and 1-year mortality compared with streptokinase. This has led to alteplase being the preferred thrombolytic at many US institutions. However, the results of GUSTO-I have been questioned by some on the basis of either study design or clinical significance. CONCLUSIONS Thrombolytic agents have secured a place in the treatment of AMI due to their well-proven reduction in mortality rates. In general, comparative trials have demonstrated minimal differences in efficacy among these agents. Probably just as important as choosing which thrombolytic agent to use is ensuring that a patient experiencing an AMI is administered thrombolytic therapy unless a contraindication to receive such therapy exists in the patient and/or the patient is a candidate to receive an emergent intracoronary procedure. Trials also indicate that the sooner thrombolytics can be administered, the greater the benefit to the patient.
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Affiliation(s)
- E D Bizjak
- College of Pharmacy, University of Toledo, OH 43606, USA
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234
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235
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Metz BK, White HD, Granger CB, Simes RJ, Armstrong PW, Hirsh J, Fuster V, MacAulay CM, Califf RM, Topol EJ. Randomized comparison of direct thrombin inhibition versus heparin in conjunction with fibrinolytic therapy for acute myocardial infarction: results from the GUSTO-IIb Trial. Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO-IIb) Investigators. J Am Coll Cardiol 1998; 31:1493-8. [PMID: 9626825 DOI: 10.1016/s0735-1097(98)00138-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES We sought to show that hirudin might interact differently with streptokinase (SK) and tissue-type plasminogen activator (t-PA), which could reduce the incidence of death or reinfarction at 30 days. BACKGROUND In a large-scale trial of patients with acute coronary syndromes, hirudin provided modest benefit compared with heparin. However, the interaction with thrombolytic agents was not specifically assessed. METHODS Patients with symptoms of acute myocardial infarction and electrocardiographic ST segment elevation were treated with thrombolytic therapy and randomly assigned to receive hirudin or heparin. RESULTS A total of 2,274 patients received t-PA, and 1,015 received SK. Baseline characteristics were balanced by antithrombin assignment. Among SK-treated patients, death or reinfarction at 30 days occurred more often in those treated with adjunctive heparin (14.4%) rather than hirudin (8.6%, odds ratio [OR] 1.78, 95% confidence interval [CI] 1.20 to 2.66, p = 0.004). Among t-PA-treated patients, the rates were 10.9% with heparin and 10.3% with hirudin (OR 1.06, 95% CI 0.81 to 1.38, p = 0.68; for treatment heterogeneity: chi-square 4.20, degrees of freedom [df] 1, p = 0.04). After adjustment for baseline differences between thrombolytic groups, the rates were 9.1% for SK with hirudin, 10.3% for t-PA with hirudin, 10.5% for t-PA with heparin and 14.9% for SK with heparin (for treatment heterogeneity: chi-square 4.5, df 1, p = 0.03), suggesting that the beneficial treatment effect of hirudin was limited to the SK-treated patients. CONCLUSIONS Hirudin interacts favorably with SK but not t-PA, highlighting the importance of thrombin activity after SK therapy and the potential for simulating the effects of a more potent fibrinolytic agent through direct antithrombin therapy.
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Affiliation(s)
- B K Metz
- Cleveland Clinic Foundation, Ohio 44195, USA
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236
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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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237
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Abstract
Unfractionated heparin (UFH) is widely used to both treat and prevent venous thromboembolism. More recently, UFH has been used to prevent death and myocardial infarction in patients with unstable angina or acute myocardial infarction and acute occlusion in those undergoing percutaneous coronary revascularization. However, its poor bioavailability (when administered in low doses subcutaneously), its mechanism of clearance, and its short half-life make its anticoagulant activity difficult to predict and maintain. To overcome these limitations, low-molecular-weight heparins (LMWHs) have been developed that have greater bioavailability and a longer half-life in plasma. Because LMWHs provide more predictable anticoagulant activity compared with subcutaneous UFH, it is not necessary to monitor the activated partial thromboplastin time during treatment. These newer agents are as effective as UFH in the prophylaxis and treatment of thromboembolic and cardiac disorders and, by allowing shorter hospital stays, are more cost effective. Thus LMWHs offer clear pharmacokinetic advantages over UFH. More studies are needed to determine the extent to which clinically available LMWHs can be used in place of UFH.
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Affiliation(s)
- A G Turpie
- McMaster University, Hamilton, Ontario, Canada
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238
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Abstract
Heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is being encountered more frequently in patients with cardiovascular disease as use of anticoagulant therapy becomes more widespread. Our understanding of the pathophysiology of this immune-mediated condition has improved in recent years, with heparin-platelet factor 4 complex as the culprit antigen in most patients. New sensitive laboratory assays for the pathogenic antibody are now available and should permit an earlier, more reliable diagnosis, but their optimal application remains to be defined. For patients in whom HIT is diagnosed, immediate discontinuation of heparin infusions and elimination of heparin from all flushes and ports are mandatory. Further management of patients with HIT is problematic at present, as there are no readily available alternative anticoagulant agents in the United States with proven efficacy in acute coronary disease. The direct thrombin inhibitors appear to be the most promising alternatives to heparin, when continued use of heparin is contraindicated, and the results of several multicenter trials evaluating their application in patients with HIT are awaited.
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Affiliation(s)
- D B Brieger
- Department of Cardiology, Joseph J. Jacobs Center for Vascular Biology, The Cleveland Clinic Foundation, Ohio 44195, USA
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239
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Abstract
An understanding of the coagulation process and the role of platelets is essential to recognizing the shortcomings of older anticoagulant therapies and appreciating the clinical potential of newer forms of antiplatelet and anticoagulant therapy for acute coronary syndromes. The anticoagulant actions of heparin are severely limited by dependence on antithrombin III, neutralization by platelet factor 4, and the resistance of clot-bound thrombin and platelet membrane-bound factor Xa to the heparin-antithrombin III complex. Unlike heparin, the direct thrombin inhibitors (such as hirudin) are active against both circulating and clot-bound thrombin. However, in recent clinical trials they have not resulted in major improvements in patient outcome. Another new class of drugs, the glycoprotein IIb/IIIa receptor antagonists, blocks the final common pathway of platelet aggregation and is capable of preventing platelet accumulation at sites of injury. The net effect is a dramatic reduction in the amount of platelet membrane available to support the process of coagulation. Clinical trials with the glycoprotein IIb/IIIa inhibitors have suggested that this class of agents may be particularly effective in reducing the thrombotic complications associated with coronary interventional procedures and may be useful in the treatment of acute coronary syndromes.
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240
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Sitges M, Bosch X, Betriu A. [Optimization of thrombolytic treatment in acute myocardial infarct: the role of new fibrinoselective drugs and their combination with new antithrombotics]. Rev Esp Cardiol 1998; 51:178-91. [PMID: 9577163 DOI: 10.1016/s0300-8932(98)74731-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although reperfusion therapy is well recognized as the mainstay of treatment of acute myocardial infarction, mortality of myocardial infarction is still high, thrombolytic treatment remains underutilized and, usually, applied too late. Additionally, most of the patients do not experience optimal reperfusion because of the suboptimal flow rate in the infarct-related artery, abnormal microvascular flow, and reocclusion of the infarct-related artery. Strategies to enhance the results of reperfusion therapy include, expanding the population of potential candidates, earlier treatment, and newer methods to improve infarct-related artery flow rates. In this sense, new thrombolytic agents, and combination therapies with or without addition of more potent and specific new antithrombotic agents are being extensively investigated. Also, it is important to promote studies of ancillary treatments to reduce reperfusion injury, which may be one cause of decreased microvascular flow. Although aspirin and heparin have been the conventionally used agents for inhibiting thrombin and platelet function, newer agents such as hirudin or hirulog and inhibitors of the platelet glycoprotein IIb-IIIa receptors are becoming available, and their clinical application will increase in the future.
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Affiliation(s)
- M Sitges
- Institut de Malalties Cardiovasculars, Hospital Clínic, Universidad de Barcelona
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241
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Altman R. Controversies in Antithrombotic Therapy in Cardiovascular Diseases. Clin Appl Thromb Hemost 1998. [DOI: 10.1177/107602969800400105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Antithrombotic treatment became an important point in human medical treatment. Dicoumarols, heparin, aspi rin, and more recently, direct antithrombins and platelet glyco protein IIb/IIIa receptor blockers are the most frequent medi cations used as antithrombotics. The role of these drugs in the treatment of cardiovascular diseases remains controversial. Low-dose aspirin (80-100 mg/day) should be used for second ary prevention in patients with a history of coronary disease. Primary prevention in patients with no risk factors is not rec ommended. Studies using oral anticoagulant therapy indicated that long-term therapy achieves substantial benefit in arterial complications in patient survivors of myocardial infarction. Combined therapy of aspirin and a higher dose of oral antico agulant than that used in the CARS trial seem necessary after myocardial infarction, and further studies should be under taken. In the treatment of unstable angina, the combined use of aspirin and unfractioned heparin (UFH) is widely accepted. Low molecular weight heparin (LMWH) was also proposed for the treatment of these patients, but the beneficial effect of LMWH over UFH is a matter of discussion, and more prospec tive studies with different LMWHs should be undertaken be fore reaching a definitive answer. The use of hirudin needs additional studies because its superiority over heparin is un- proved. The initial clinical experience with blockers/inhibitors of platelet glycoprotein IIb/IIIa receptors has been promising, although some increase of bleeding was reported. According to published trials on the use of antiplatelet drugs and antithrom botic therapy in the prevention of acute closure after PTCA or after stent implantation, antithrombotic therapy decreased the incidence of abrupt closure or reocclusion at 30 days postan gioplasty, but neither antiplatelet agents nor other pharmaco logical agents have been shown to reduce significantly the rate of restenosis. Finally, oral anticoagulant in a target INR of 2.0 to 3.0 together with aspirin 100 mg/day provide good protec tion from thromboembolism and diminish the rate of minor bleeding complications in patients with cardiac valve replace ment.
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Affiliation(s)
- Raul Altman
- Centro de Trombosis de Buenos Aires, Buenos Aires, Argentina
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242
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Suzuki S, Sakamoto S, Koide M, Matsuo M, Fujii K, Matsuo T. Effective anticoagulation by argatroban during coronary stent implantation in a patient with heparin-induced thrombocytopenia. Thromb Res 1997; 88:499-502. [PMID: 9610961 DOI: 10.1016/s0049-3848(97)00284-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S Suzuki
- Department of Internal Medicine, Hyogo Prefectural Awaji Hospital, Sumoto, Japan
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243
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Low molecular weight heparins: Promising therapy for unstable angina and non-Q wave myocardial infarction. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1328-0163(97)90025-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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244
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245
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Schussheim AE, Fuster V. Thrombosis, antithrombotic agents, and the antithrombotic approach in cardiac disease. Prog Cardiovasc Dis 1997; 40:205-38. [PMID: 9406677 DOI: 10.1016/s0033-0620(97)80035-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To develop a rational approach to antithrombotic therapy, in cardiac disease, a sound understanding is required (1) of the hemostatic processes leading to thrombosis, (2) of the various antithrombotic agents, and (3) of the relative risks of thrombosis and thromboembolism in the various cardiac disease entities. With the understanding of pathogenesis and risk of thrombus formation, a rational approach to the use of antiplatelet and anticoagulant agents can be formulated. Those at high risk of thrombus formation should generally receive a high degree of antithrombotics and, depending on the pathophysiology of the thrombus, may benefit from the concomitant use of antiplatelet and anticoagulant agents. Those with a medium risk of thrombus formation may benefit with the use of an antiplatelet agent alone or anticoagulants alone. Patients at low risk of thrombus formation should not receive antithrombotics. Such rational approach to antithrombotic therapy serves as the basis of this article.
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Affiliation(s)
- A E Schussheim
- Cardiovascular Institute, Mount Sinai Medical Center, New York, NY 10029-6574, USA
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246
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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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247
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Shah PB, Ahmed WH, Ganz P, Bittl JA. Bivalirudin compared with heparin during coronary angioplasty for thrombus-containing lesions. J Am Coll Cardiol 1997; 30:1264-9. [PMID: 9350925 DOI: 10.1016/s0735-1097(97)00274-x] [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: 02/05/2023]
Abstract
OBJECTIVES We investigated whether bivalirudin is more effective than heparin in preventing ischemic complications in high risk patients undergoing coronary angioplasty for thrombus-containing lesions detected by angiography. BACKGROUND Heparin is administered during coronary angioplasty to prevent closure of the dilated vessel. Bivalirudin (Hirulog) is a direct thrombin inhibitor that can be safely substituted for heparin during angioplasty. Bivalirudin has several theoretic advantages over heparin as an anticoagulant agent. METHODS We performed an observational analysis of the Hirulog Angioplasty Study in which 4,098 patients with unstable or postinfarction angina were randomized to receive either bivalirudin or heparin during coronary angioplasty. The study group for this analysis consisted of 567 patients who had thrombus-containing lesions on angiography. The primary end point was death, myocardial infarction, emergency coronary artery bypass graft surgery or abrupt vessel closure before hospital discharge. RESULTS Patients with thrombus-containing lesions had a higher incidence of myocardial infarction (5.1% vs. 3.2%, p = 0.03) and abrupt vessel closure (13.6% vs. 8.3%, p < 0.001) than those without thrombus. In patients with thrombus-containing lesions, however, the incidence of the primary end point was not different between the bivalirudin and heparin treatment groups. Furthermore, no difference in the incidence of ischemic events at 6 months was seen between the treatment groups. CONCLUSIONS Bivalirudin is not more effective than heparin in preventing ischemic complications in patients undergoing coronary angioplasty for thrombus-containing lesions detected by angiography. Other approaches, perhaps involving potent anti-platelet agents, should be considered for patients with thrombus-containing lesions.
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Affiliation(s)
- P B Shah
- Department of Internal Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
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248
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Cannon CP, Sharis PJ, Schweiger MJ, McCabe CH, Diver DJ, Shah PK, Sequeira RF, Greene RM, Perritt RL, Poole WK, Braunwald E. Prospective validation of a composite end point in thrombolytic trials of acute myocardial infarction (TIMI 4 and 5). Thrombosis In Myocardial Infarction. Am J Cardiol 1997; 80:696-9. [PMID: 9315571 DOI: 10.1016/s0002-9149(97)00497-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Although the use of composite end points in clinical trials has increased in recent years, few data are available on the validity of such an approach. In the Thrombolysis In Myocardial Infarction (TIMI) 4 and 5 trials, we set out to validate prospectively the nonfatal components of the "unsatisfactory outcome" end point. This end point consisted of the in-hospital occurrence or observation of new-onset severe congestive heart failure/shock, left ventricular ejection fraction <40% (or <30% for patients with prior myocardial infarction), reinfarction, reocclusion by sestamibi perfusion imaging, TIMI flow grade <2 at 90 minutes or 18 to 36 hours, intracranial hemorrhage, major spontaneous hemorrhage, or anaphylaxis. Among 576 patients in TIMI 4 and 5 with 1-year follow-up, a nonfatal unsatisfactory outcome end point was reached in hospital in 45% of patients. Compared with patients without such an end point, patients with an end point had a relative risk of 1-year mortality of 2.5 (95% confidence interval 1.4 to 5.6, p = 0.001). For individual components, new-onset severe congestive heart failure/shock had a relative risk of 4.6 (p = 0.001), left ventricular ejection fraction <40% had a relative risk of 3.5 (p = 0.006), recurrent myocardial infarction had a relative risk of 2.2 (p = 0.047), and TIMI flow grade <2 at 90 minutes had a relative risk of 2.2 (p = 0.005). Our findings show that these nonfatal in-hospital end points and the composite end point are associated with an increased risk of 1-year mortality and as such are valid predictive survival markers for use in clinical trials.
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Affiliation(s)
- C P Cannon
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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249
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Whisenant BK, Wolfe CL. Acute myocardial infarction. Recommendations for medical management and primary angioplasty. Postgrad Med 1997; 102:159-60, 163-8, 170-2 passim. [PMID: 9300025 DOI: 10.3810/pgm.1997.09.319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Deaths from acute myocardial infarction have declined in recent years, thanks to the introduction of thrombolytic drugs and therapy with other types of medication that are beneficial when appropriately used. In this article, the authors review the mechanism of action of these agents and focus on recent clinical trials, indications and contraindications, and proper administration. They also discuss the place of primary angioplasty as an alternative to thrombolytic therapy.
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Affiliation(s)
- B K Whisenant
- University of California, San Francisco, School of Medicine 94143, USA
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250
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Cohen M, Demers C, Gurfinkel EP, Turpie AG, Fromell GJ, Goodman S, Langer A, Califf RM, Fox KA, Premmereur J, Bigonzi F. A comparison of low-molecular-weight heparin with unfractionated heparin for unstable coronary artery disease. Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events Study Group. N Engl J Med 1997; 337:447-52. [PMID: 9250846 DOI: 10.1056/nejm199708143370702] [Citation(s) in RCA: 914] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Antithrombotic therapy with heparin plus aspirin reduces the rate of ischemic events in patients with unstable coronary artery disease. Low-molecular-weight heparin has a more predictable anticoagulant effect than standard unfractionated heparin, is easier to administer, and does not require monitoring. METHODS In a double-blind, placebo-controlled study, we randomly assigned 3171 patients with angina at rest or non-Q-wave myocardial infarction to receive either 1 mg of enoxaparin (low-molecular-weight heparin) per kilogram of body weight, administered subcutaneously twice daily, or continuous intravenous unfractionated heparin. Therapy was continued for a minimum of 48 hours to a maximum of 8 days, and we collected data on important coronary end points over a period of 30 days. RESULTS At 14 days the risk of death, myocardial infarction, or recurrent angina was significantly lower in the patients assigned to enoxaparin than in those assigned to unfractionated heparin (16.6 percent vs. 19.8 percent, P=0.019). At 30 days, the risk of this composite end point remained significantly lower in the enoxaparin group (19.8 percent vs. 23.3 percent, P=0.016). The need for revascularization procedures at 30 days was also significantly less frequent in the patients assigned to enoxaparin (27.1 percent vs. 32.2 percent, P=0.001). The 30-day incidence of major bleeding complications was 6.5 percent in the enoxaparin group and 7.0 percent in the unfractionated-heparin group, but the incidence of bleeding overall was significantly higher in the enoxaparin group (18.4 percent vs. 14.2 percent, P=0.001), primarily because of ecchymoses at injection sites. CONCLUSIONS Antithrombotic therapy with enoxaparin plus aspirin was more effective than unfractionated heparin plus aspirin in reducing the incidence of ischemic events in patients with unstable angina or non-Q-wave myocardial infarction in the early phase. This benefit of enoxaparin was achieved with an increase in minor but not in major bleeding.
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Affiliation(s)
- M Cohen
- Division of Cardiology, Allegheny University Hospitals-Hahnemann Division, Philadelphia, PA 19102, USA
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