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)

Engineered microparticles and nanoparticles for fibrinolysis

Fibrinolytic agents including plasmin and plasminogen activators improve outcomes in acute ischemic stroke and thrombosis by recanalizing occluded vessels. In the decades since their introduction into clinical practice, several limitations of have been identified in terms of both efficacy and bleeding risk associated with these agents. Engineered nanoparticles and microparticles address some of these limitations by improving circulation time, reducing inhibition and degradation in circulation, accelerating recanalization, improving targeting to thrombotic occlusions, and reducing off-target effects; however, many particle-based approaches have only been used in preclinical studies to date. This review covers four advances in coupling fibrinolytic agents with engineered particles: (a) modifications of plasminogen activators with macromolecules, (b) encapsulation of plasminogen activators and plasmin in polymer and liposomal particles, (c) triggered release of encapsulated fibrinolytic agents and mechanical disruption of clots with ultrasound, and (d) enhancing targeting with magnetic particles and magnetic fields. Technical challenges for the translation of these approaches to the clinic are discussed.

Low molecular weight heparins for arterial thrombosis

The use of low molecular weight heparin (LMWH) for the prevention and treatment of venous thromboembolism has been validated by numerous clinical trials and meta-analyses over the past 25 years. More recently, the possibility of extending treatment with LMWH to the arterial disease where thrombosis is a prominent feature has led to the planning of many clinical trials, several of which have been already published. LMWH has been tested in settings such as acute coronary syndromes, including myocardial infarction, surgery or percutaneous revascularization for coronary and peripheral arteries, and stroke. In most indications, LMWH has proved to be superior to or at least as effective as unfractionated heparin and it is also easier to administer.

Efficacy and Safety of Low-Molecular-Weight Heparins As An Adjunct to Thrombolysis in Acute ST-Elevation Myocardial Infarction

A 48-hour course of intravenous unfractionated heparin (UFH) is the standard of treatment in conjunction with fibrin-specific thrombolysis in ST-elevation myocardial infarction (STEMI). In recent trials, the efficacy and safety of in-hospital administration of subcutaneous low-molecular-weight heparins (LMWH), previously proven effective in non-ST-elevation acute coronary syndromes, have been investigated in the setting of STEMI. The aim of this review was to evaluate the available evidence supporting the use of LMWH in STEMI.

Overall, about 27,000 patients treated with various thrombolytic regimens, were included in 12 open-label randomized clinical trials, where dalteparin, reviparin or enoxaparin were administered. While acknowledging the wide variability in study dimensions, designs and end-points, a higher efficacy of LMWH was observed overall as compared to placebo, and also to UFH (mainly as regards the occurrence of reinfarction). As regards safety, bleedings were more frequent than placebo and comparable to UFH in LMWH groups, with the exception of the pre-hospital ASSENT-3 PLUS trial, where in elderly patients, enoxaparin had an incidence of intracranial hemorrhage twice higher than UFH. In a recent double-blind, randomized, mega-trial including over 20,000 patients, the superior efficacy on in-hospital and 30-day adverse cardiac events (namely reinfarction), and comparable safety on intracranial bleedings, of enoxaparin compared to UFH, was shown.

In conclusion, in-hospital subcutaneous administration of dalteparin, reviparin and enoxaparin, as an adjunct to various thrombolytics in STEMI, appears feasible and at least as effective and safe as 48-hour intravenous treatment with UFH. In accordance with the available strongest evidence, an initial intravenous bolus of enoxaparin followed by twice daily subcutaneous administration for about 1 week should be the preferred regimen, and should be strongly considered instead of intravenous UFH. Along with its easiness of use, not requiring laboratory monitoring, subcutaneous administration of LMWH following STEMI treated with thrombolysis allows extended antithrombotic treatment, while permitting early mobilization (and rehabilitation) of patients.

Adjunctive low molecular weight heparin during fibrinolytic therapy in acute ST-segment elevation myocardial infarction: a meta-analysis of randomized control trials

BACKGROUND

Recent data suggests that low molecular weight heparins (LMWHs) may be superior to unfractionated heparin (UFH) as an adjunct to fibrinolytic therapy in patients with acute ST-segment elevation myocardial infarction (STEMI).

HYPOTHESIS

We evaluated cardiac outcomes and the risk of major bleeding with LMWHs vs UFH in the management of STEMI.

METHODS

Seven randomized trials of patients with acute STEMI treated with fibrinolytic therapy and adjunctive LMWHs through the index hospitalization or weight-based UFH for at least 48 hours were identified. We analyzed both primary endpoints (death and nonfatal recurrent myocardial infarction through 30 days), and secondary endpoints (death, recurrent myocardial infarction, and major bleeding during index hospitalization at 7 days). Outcomes were computed using the Mantel-Haenszel fixed-effect model. A 2-sided alpha error of < 0.05 was considered significant.

RESULTS

Compared to UFH, LMWH significantly reduced reinfarction (p < 0.001) during hospitalization at 7 days and the effect remained consistent at 30 d (p < 0.001). When analyzed for mortality at 7 days and 30 days follow-up, there were no statistically significant differences observed between the 2 groups. Additionally the LMWH group had higher risk of major bleeding (p < 0.001).

CONCLUSIONS

The present meta-analysis suggests in patients receiving fibrinolytic therapy for STEMI, LMWHs as an adjunctive therapy is superior to UFH in reducing reinfarction during hospitalization at 7 days and at 30 days. The mortality was not significant between the 2 groups during hospitalization at 7 days and at 30 days. However, UFH is superior to LMWHs in the reduction of major bleeding at 7 days index hospitalization.

Low-molecular-weight heparins in acute myocardial infarction: rationale and results of a pilot study

BACKGROUND

Antithrombotic adjuncts to fibrinolytic drugs for acute myocardial infarction increase the rate and speed of infarct artery recanalization.

HYPOTHESIS

A low-molecular-weight heparin might be preferable to unfractionated heparin for this indication, as it has been shown to be in several other thrombus-related vascular disorders.

METHODS

We performed a pilot study in 20 patients, all receiving aspirin and recombinant tissue plasminogen activator. Randomization was to standard dose intravenous unfractionated heparin or enoxaparin (the first dose given intravenously and followed by a subcutaneous administration). The endpoint was stability of anticoagulant effect.

RESULTS

Enoxaparin produced stable therapeutic anti-Xa levels with minimal effect on activated partial thromboplastin times. Unfractionated heparin produced wide swings of these parameters, often outside desired levels.

CONCLUSIONS

Enoxaparin may be a better antithrombotic agent than conventional unfractionated heparin when used in conjunction with fibrinolytics.

The low-molecular-weight heparin dalteparin as adjuvant therapy in acute myocardial infarction: the ASSENT PLUS study

Rapid reperfusion of an infarct-related artery reduces the extent of myocardial damage and improves survival in acute myocardial infarction (AMI). Currently, anticoagulant treatment with unfractionated heparin (UFH) is used as adjuvant therapy to fibrinolytic treatment. The low-molecular-weight heparin (LMWH) dalteparin is at least as effective as UFH in unstable coronary artery disease. The ASSENT PLUS trial was carried out to evaluate whether dalteparin is as effective as UFH as an adjunct to recombinant tissue-plasminogen activator (rt-PA) and aspirin in obtaining patency and Thrombolysis in Myocardial Infarction (TIMI)-3 flow in patients with AMI. The primary assessment of this phase II trial was TIMI flow, determined by coronary angiography. Patients with ST-elevation MI were randomized to receive aspirin and either rt-PA and UFH for 48 h, or rt-PA and dalteparin for 4 to 7 days. Evaluation was by TIMI flow after 4 to 7 days and clinical events (death, reinfarction, or revascularization) up to 30 days. There was a clear trend toward greater TIMI 3 flow with dalteparin compared with UFH. There was significantly less TIMI 0-1 flow or thrombus in the dalteparin group. Bleeding rates were similar. The occurrence of reinfarction was reduced during dalteparin treatment. These findings suggest that dalteparin could be substituted for UFH as an adjunct to rt-PA/aspirin in the management of patients with AMI.

Low-molecular-weight heparins : mechanisms, trials, and role in contemporary interventional medicine

The clinical spectrum of acute coronary syndromes (ACS) encompasses unstable angina, non-ST-elevation, and ST-elevation myocardial infarction (STEMI). Within an atherosclerotic plaque, disruption of the endothelium can lead to exposure of tissue factor, with platelet adhesion, activation and aggregation, along with activation of the coagulation cascade, culminating in thrombin formation and the development of a cross-linked fibrin clot at the site of injury. Therapy aimed at blocking thrombin formation is now an integral part of the current cardiovascular guidelines in the treatment of ACS. Although unfractionated heparin (UFH) has been the mainstay of antithrombin therapy in the past, it has numerous clinical and biochemical limitations, including substantial protein binding (leading to inconsistent bioavailability), a need for frequent monitoring and adjustment, unreliable and variable degrees of anticoagulation, significant platelet activation, risk of heparin-induced thrombocytopenia, and the inability to block clot bound thrombin. With all of these limitations of UFH, low-molecular-weight heparins (LMWHs) have emerged as attractive alternatives. This review discusses the mechanism of action of LMWHs, and summarizes available literature concerning the use of LMWHs in a variety of clinical settings. Included in this review is an analysis of both current and prior data showing LMWH is as effective as UFH in the conservative and invasive management of patients with ACS. As well, very recent data are evaluated showing the safety and efficacy of LMWHs used in patients transitioning to the cardiac catheterization laboratory, and in those patients undergoing elective or urgent percutaneous coronary intervention (PCI). We also appraise the literature, along with the very recent studies investigating the use of LMWHs as adjunctive therapy to fibrinolytics in patients with STEMI. Finally, we set forth real-world conclusions concerning the use of LMWHs in contemporary interventional practice, including elective PCI and the treatment of ischemic coronary artery disease in the context of rapid invasive management of ACS.

Use of anticoagulants in ST-segment elevation myocardial infarction patients; a focus on low-molecular-weight heparin

INTRODUCTION

Primary percutaneous coronary intervention (PCI) is the treatment of choice for patients with ST-segment elevation myocardial infarction (STEMI), but given logistics, many patients are still managed with thrombolytics. Unfractionated heparin (UFH) is recommended for routine use in STEMI patients treated with thrombolytics. However, other anticoagulants have been evaluated for use in STEMI patients treated with thrombolysis, including the low-molecular-weight heparins (LMWHs, enoxaparin, dalteparin, and reviparin), fondaparinux and bivalirudin.

METHODS AND RESULTS

A review of the available randomized controlled study data shows that most evidence, in terms of number of trials and number of patients treated with anticoagulants in STEMI has accumulated for LMWHs. The use of enoxaparin and reviparin improves hard clinical efficacy endpoints although there is an excess of bleeding events. Trials with dalteparin have failed to demonstrate improvement in hard clinical efficacy endpoints compared with UFH.

SUMMARY

Enoxaparin is currently the only LMWH with FDA approval for use in STEMI patients and should be considered as a preferable alternative to UFH in STEMI patients treated with fibrinolysis.

[The use of low molecular weight heparins in patients with acute ST-elevated myocardial infarction]

INTRODUCTION According to the published guidelines for the management of acute coronary syndromes (ACS), treatment of acute ST-elevated myocardial infarction is based on rapid revascularization, either mechanical or pharmacological. Pharmacological revascularization consists of fibrinolytic therapy with antiplatelet and anticoagulant therapy. In regard to the anticoagulant therapy, low molecular weight heparins (LMWHs) are of special importance. LMWHs cause less complications (bleeding, thrombocytopenia, better bioviability) in comparison with unfractionated heparin (UFH). Some studies on use of LMWHs in ACS, show that LMWHs are equally efficient and safe as UFH, causing less complications (different types of hemorrhagic complications) (ESSENCE, TIMI 11B (enoxaparin), FRAXIS-fraxiparin), whereas some studies show better efficacy and safety of enoxaparin in therapy of acute ST-elevated myocardial infarction (ASSENT 3, ASSENT 3 PLUS, HART II, AMI-SK).

MATERIAL AND METHODS

INCLUSION CRITERIA

acute anterior myocardial infarction with ST-elevation, first myocardial infarction, no other structural heart defects, no signs of cardiogenic shock. Our study included 30 patients receiving fibrinolytic therapy with streptokinase, antiplatelet therapy and LMWH during 6 days, and 30 patients receiving UFH instead of LMWH. The follow-up period lasted for 6 months.

RESULTS

Significantly more patients receiving unfractionated heparin presented with major adverse cardiac events (73.3%) in regard to patients in the study group (44.2% nadroparin, 39.8% enoxaparin) (p = 0.025). In the group receiving UFH, 6.7% patients had hemorrhagic complications, while none of patients receiving LMWHs. An equal number of patients died.

CONCLUSION

Patients who were treated with LMWHs experienced less major adverse cardiac events and lower mortality. None suffered from hemorrhagic complications.

Low-Molecular-Weight Heparins in Conjunction with Thrombolysis for ST-Elevation Acute Myocardial Infarction

BACKGROUND

Intravenous unfractionated heparin (UFH) is recommended in ST-elevation acute myocardial infarction (STEMI), following thrombolysis with fibrin-specific agents. Subcutaneous low-molecular-weight heparins (LMWH), previously proven effective in non-ST-elevation acute coronary syndromes, have been recently investigated in the setting of STEMI. We aimed at evaluating the current level of evidence supporting the use of LMWH in STEMI.

METHODS

A Medline search of the English language literature between January 1995 and December 2005 was performed and randomized clinical trials comparing LMWH to either placebo or UFH in conjunction with thrombolysis were selected.

RESULTS

About 26,800 patients treated with various thrombolytic regimens were included in 12 randomized clinical trials. Dalteparin was superior to placebo on left ventricular thrombosis/arterial thromboembolism, with no significant effect on the early patency rate of the infarct-related artery (IRA). Compared to UFH, dalteparin had no significant effect on clinical events and on the IRA late patency, although less thrombus was present. Enoxaparin was superior to placebo on the medium-term death/reinfarction/angina rate and late IRA patency, and superior also to UFH on in-hospital and medium-term occurrence of death/reinfarction/angina. The effect of enoxaparin on IRA patency rate was not univocal. Compared to placebo, reviparin significantly reduced early and medium-term mortality and reinfarction rates, without a substantial increase in overall stroke rate. As regards safety, bleedings were more frequent than placebo and comparable to UFH in LMWH groups, with the exception of the pre-hospital ASSENT-3 PLUS trial, where in elderly patients, enoxaparin had an incidence of intracranial hemorrhage twice higher than UFH.

CONCLUSIONS

In-hospital subcutaneous administration of dalteparin, enoxaparin or reviparin, as an adjunct to various thrombolytics in STEMI, appears feasible and at least as effective and safe as intravenous UFH. Before LMWH might be recommended, however, some yet unresolved issues (i.e. use in elderly patients, in severe renal insufficiency, in association with glycoprotein IIb/IIIa inhibitors and during interventional procedures), need to be addressed.

Unfractionated and low-molecular-weight heparin as adjuncts to thrombolysis in aspirin-treated patients with ST-elevation acute myocardial infarction: a meta-analysis of the randomized trials

BACKGROUND

There is uncertainty about the role of intravenous unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) in patients with ST-elevation myocardial infarction (STEMI) treated with aspirin and thrombolysis.

METHODS AND RESULTS

We performed a meta-analysis of the randomized trials to assess the effect of UFH and LMWH on reinfarction, death, stroke, and bleeding. Fourteen trials involving a total of 25,280 patients were included (1239 comparing intravenous UFH versus placebo or no heparin; 16,943 comparing LMWH versus placebo; and 7098 comparing LMWH versus intravenous UFH). Intravenous UFH during hospitalization did not reduce reinfarction (3.5% versus 3.3%; odds ratio [OR], 1.08; 95% CI, 0.58 to 1.99) or death (4.8% versus 4.6%; OR, 1.04; 95% CI, 0.62 to 1.78) and did not increase major bleeding (4.2% versus 3.4%; OR, 1.21; 95% CI, 0.67 to 2.18) but increased minor bleeding (19.6% versus 12.5%; OR, 1.72; 95% CI, 1.22 to 2.43). During hospitalization/at 7 days, LMWH compared with placebo reduced the risk of reinfarction by approximately one quarter (1.6% versus 2.2%; OR, 0.72; 95% CI, 0.58 to 0.90; number needed to treat [NNT]=167) and death by &10% (7.8% versus 8.7%; OR, 0.90; 95% CI, 0.80 to 0.99; NNT=111) but increased major bleeding (1.1% versus 0.4%; OR, 2.70; 95% CI, 1.83 to 3.99; number needed to harm [NNH]=143) and intracranial bleeding (0.3% versus 0.1%; OR, 2.18; 95% CI, 1.07 to 4.52; NNH=500). The reduction in death with LMWH remained evident at 30 days. LMWH compared with UFH during hospitalization/at 7 days reduced reinfarction by &45% (3.0% versus 5.2%; OR, 0.57; 95% CI, 0.45 to 0.73; NNT=45), did not reduce death (4.8% versus 5.3%; OR, 0.92; 95% CI, 0.74 to 1.13) or increase major bleeding (3.3% versus 2.5%; OR, 1.30; 95% CI, 0.98 to 1.72), but increased minor bleeding (22.8% vs 19.4%; OR, 1.26; 95% CI, 1.12 to 1.43). The reduction in reinfarction remained evident at 30 days.

CONCLUSIONS

In aspirin-treated patients with STEMI who are treated with thrombolysis, intravenous UFH has not been shown to prevent reinfarction or death. LMWH given for 4 to 8 days compared with placebo reduces reinfarction by approximately one quarter and death by &10% and when directly compared with UFH reduces reinfarction by almost one half. These data suggest that LMWH should be the preferred antithrombin in this setting.

Low-molecular-weight heparin vs. unfractionated heparin in percutaneous coronary intervention: A combined analysis

This meta-analysis assessed the rates of the efficacy and safety endpoints with intravenous low-molecular-weight heparin (LMWH) compared with unfractionated heparin (UFH) in patients undergoing percutaneous coronary intervention (PCI). Subcutaneous LMWH has compared favorably with UFH, but limited experience exists with intravenous LMWH for immediate anticoagulation in PCI. The meta-analysis included data from eight randomized trials in which patients received LMWH (n = 1,037) or UFH (n = 978) during PCI. Seven additional nonrandomized studies/registries were analyzed to assess the efficacy and safety of LMWH during PCI. Efficacy endpoints were ischemic events (usually a composite of death, myocardial infarction, and urgent revascularization) and the safety endpoint was bleeding (major, minor, or all bleeding). In the randomized studies, LMWH was comparable with UFH in terms of efficacy (6.2% vs. 7.5%) and major bleeding (0.9% vs. 1.8%). The analysis of pooled data, randomized or not, suggests potential improved efficacy (5.8% vs. 7.6%) and reduced major bleeding (0.6% vs. 1.8%) with LMWH (n = 3,787) compared with UFH (n = 978). During PCI, intravenous LMWH without coagulation monitoring has the potential to be at least as safe and efficacious as intravenous UFH. Further studies of LMWHs in PCI are therefore required.

Low-molecular-weight heparin in patients with acute ST-segment elevation myocardial infarction

One of the primary goals of physicians treating patients presenting to a hospital with acute ST-segment elevation myocardial infarction is to restore the flow of blood in the infarct-related artery as quickly as possible. Prompt and successful reperfusion limits the size of the myocardial infarction, reduces left ventricular dysfunction, and improves the patient's chance of survival. Approximately two thirds of patients with ST-segment elevation myocardial infarction do not present to a hospital capable of conducting urgent direct percutaneous coronary intervention or cardiac surgery when it is needed. They must receive pharmacological reperfusion therapy, a combination of fibrinolytic, antiplatelet, and anticoagulant drugs. Earlier and simpler administration of pharmacological reperfusion therapy could result in significantly improved outcomes. Fibrinolytic therapy, in combination with adjunctive antithrombin therapy that is simpler and quicker to administer (e.g., tenecteplase with enoxaparin), may be more efficacious and easier to use than regimens involving unfractionated heparin.

Low-molecular-weight heparins in ischemic heart disease

PURPOSE OF REVIEW

The objective of this review was to summarize the recent developments regarding the use of low-molecular-weight heparins in the management of acute coronary syndromes.

RECENT FINDINGS

In the setting of unstable angina and non-ST-elevation myocardial infarction, enoxaparin is superior to unfractionated heparin in reducing death, myocardial infarction, and recurrent ischemia both in the short-term and to 1 year. However, this does not necessarily imply a class effect of low-molecular-weight heparins in general. When combined with glycoprotein IIb/IIIa inhibitors, enoxaparin appears to be effective and safe even for patients treated according to an early invasive strategy. In patients receiving fibrinolytics for ST-elevation myocardial infarction, low-molecular-weight heparins are as effective as unfractionated heparin in maintaining patency of the infarct-related artery and in reducing the composite endpoint of death and reinfarction. However, serious bleeding is more common, especially among the elderly, and the optimal dosing regimen in ST-elevation myocardial infarction remains to be defined.

SUMMARY

Low-molecular-weight heparins are safe and effective in the management of unstable angina and non-ST-elevation myocardial infarction, with or without concurrent administration of glycoprotein IIb/IIIa inhibitors. Ongoing studies will clarify the role of low-molecular-weight heparins as adjunctive therapy for fibrinolysis.

Evolving Role of Low-Molecular-Weight Heparins in ST-Elevation Myocardial Infarction

OBJECTIVE:

To review the available literature on the efficacy and safety of low-molecular-weight heparin (LMWH) in the treatment of ST-elevation myocardial infarction (STEMI) in patients treated with fibrinolytic therapy or conservative medical management.

DATA SOURCES:

A MEDLINE search (1966–March 2004) using the key words myocardial infarction, STEMI, LMWH, enoxaparin, and dalteparin identified pertinent articles. The references of these articles were reviewed for additional pertinent references.

STUDY SELECTION AND DATA EXTRACTION:

All human trials of LMWH in STEMI were evaluated. All pertinent studies were included in the review.

DATA SYNTHESIS:

LMWH did not show a benefit in STEMI without fibrinolytic therapy. Enoxaparin is similar to intravenous unfractionated heparin (UFH) in combination with nonspecific fibrinolytic therapy with regard to invasive reperfusion markers and 30-day clinical outcomes. Enoxaparin decreases composite endpoints in combination with fibrin-specific fibrinolytic therapy compared with UFH, primarily through a reduction in the incidence of reinfarction at 30 days. Bleeding rates with LMWH in combination with fibrinolytic agents are not greater than those with UFH.

CONCLUSIONS:

Enoxaparin is a reasonable alternative to UFH in patients with STEMI treated with fibrin-specific fibrinolytic therapy. LMWH in patients managed with nonspecific fibrinolytic therapy or conservative medical treatment does not provide an advantage over standard management. Large clinical trials are ongoing which will provide more definitive recommendations.

Development of myocardial microcirculation and metabolism in acute ST-elevation myocardial infarction evaluated with positron emission tomography

BACKGROUND

Early reperfusion is an established therapeutic objective in acute myocardial infarction (MI). The relationship of regional myocardial microcirculation and metabolism toward outcome in acute human MI is not well known.

METHODS AND RESULTS

In 8 patients, positron emission tomography (PET) was performed with oxygen 15-labeled water at 3 hours, 24 hours, and 3 weeks after the start of fibrinolytic treatment, with carbon 11 acetate at 3 hours and with fluorine 18 fluorodeoxyglucose at 24 hours and 3 weeks. Absolute quantification of perfusion and water-perfusable tissue fraction (PTF), metabolic activity, and substrate extraction in 4 regions of interest was performed. Coronary angiography was performed at 24 hours. Short-term outcome at 3 weeks was evaluated by contractile reserve with dobutamine stress echocardiography and lung water measurements with PET. Early regional perfusion, PTF, and extraction and utilization of oxygen and glucose decreased closer to the infarct region ( P < .001 for all). Infarct-related oxygen utilization and extraction of oxygen and glucose were closely related to outcome ( P < .01 for all). PTF improved significantly in the infarct-related regions over time in proportion to early oxygen extraction and utilization.

CONCLUSIONS

This pilot study indicates that PET might be useful in the evaluation of treatment efficacy and that restoration of oxidative metabolism is more closely related to myocardial damage recovery than perfusion in the early phase after MI.

Challenges in the conduct of large simple trials of important generic questions in resource-poor settings: the CREATE and ECLA trial program evaluating GIK (glucose, insulin and potassium) and low-molecular-weight heparin in acute myocardial infarction

Background

Approximately 15.5 million deaths from cardiovascular diseases occur every year. About half are due to acute myocardial infarction (AMI), and 80% occur in low- and middle-income countries. Therefore, low-cost therapies would be invaluable. Although glucose-insulin-potassium (GIK) infusion and low-molecular-weight heparin (LMWH) appear to be promising in AMI, the available trials are inconclusive and these treatments require rigorous evaluation.

Methods

The Clinical Trial of Reviparin and Metabolic Modulation in Acute Myocardial Infarction Treatment and Evaluation-Estudios Clínicos Latino America (CREATE-ECLA) study is a randomized controlled trial in ST-elevation AMI patients evaluating a 24-hour infusion of Glucose-Insulin-Potassium (GIK) intravenous vs usual care (control) on 30-day mortality in 20 000 patients from 21 countries. Patients from India and China (n = 15 000) are also randomized using a factorial design to receive low-molecular-weight heparin (Reviparin) or placebo injection twice daily for 7 days to assess the impact on the composite outcomes of death, reinfarction or stroke (first co-primary outcome) or the composite + refractory ischemia (second co-primary outcome).

Results

Twenty thousand two hundred and one (20,201) GIK/control patients and 15,570 Reviparin/placebo patients have been included, with results expected in November 2004.

Conclusions

The CREATE-ECLA trial will provide definitive answers to the role of 2 practical, promising and low-cost therapies, LMWH and GIK, in AMI patients. If effective, these therapies could be used in small medical centers in low- and middle- income countries. The experiences in this trial indicate that large trials of important questions can be successfully conducted in resource-poor settings, by academic groups without industry involvement.

Thrombolysis and Adjunctive Therapy in Acute Myocardial Infarction

This chapter about antithrombotic therapy for acute myocardial infarction (MI) is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following: For patients with ischemic symptoms characteristic of acute MI of < 12 h in duration, and ST-segment elevation or left bundle-branch block (of unknown duration) on the ECG, we recommend administration of any approved fibrinolytic agent (Grade 1A). We recommend the use of streptokinase, anistreplase, alteplase, reteplase, or tenecteplase over placebo (all Grade 1A). For patients with symptom duration < 6 h, we recommend the administration of alteplase over streptokinase (Grade 1A). For patients with known allergy or sensitivity to streptokinase, we recommend alteplase, reteplase, or tenecteplase (Grade 1A). For patients with acute posterior MI of < 12 h duration, we suggest fibrinolytic therapy (Grade 2C). In patients with any history of intracranial hemorrhage, closed head trauma, or ischemic stroke within past 3 months, we recommend against administration of fibrinolytic therapy (Grade 1C+). For patients with acute ST-segment elevation MI whether or not they receive fibrinolytic therapy, we recommend aspirin, 160 to 325 mg p.o., at initial evaluation by health-care personnel followed by indefinite therapy, 75 to 162 mg/d p.o. (both Grade 1A). In patients allergic to aspirin, we suggest use of clopidogrel as an alternative therapy to aspirin (Grade 2C). For patients receiving streptokinase, we suggest administration of either i.v. unfractionated heparin (UFH) [Grade 2C] or subcutaneous UFH (Grade 2A). For all patients at high risk of systemic or venous thromboembolism (anterior MI, pump failure, previous embolus, atrial fibrillation, or left ventricular thrombus), we recommend administration of IV UFH while receiving streptokinase (Grade 1C+).

Is the use of unfractionated heparin in acute coronary syndrome outmoded?

Because of the key role of thrombin in the pathogenesis of acute coronary syndrome (ACS), the appropriate selection of antithrombotic therapy is important. Unfractionated heparin (UFH) has been the agent of choice for decades. Unfortunately, UFH has a number of limitations related to its pharmacokinetic and pharmacodynamic properties. Low molecular weight heparins (LMWHs) are attractive alternatives to UFH for several reasons, including predictable anticoagulation and ease of administration. Two LMWHs (dalteparin and enoxaparin) have been approved as alternatives to UFH in patients presenting with unstable angina and non-ST-segment elevation myocardial infarction. Randomized, controlled trials, in addition to open-label series, indicate that LMWH can safely be the agent of choice with or without glycoprotein IIb/IIIa in the medical and upstream management of patients with ACS. Although the data are not definitive, several trials suggest that given intravenously, enoxaparin is safe as the sole antithrombotic agent in the catheterization laboratory.

Optimizing adjunctive antithrombotic therapy in the treatment of acute myocardial infarction: a role for low-molecular-weight heparin

Thrombotic complications account for a large proportion of in-hospital deaths from acute myocardial infarction (MI). Although thrombolytic therapy has greatly improved clinical outcomes following MI, thrombin released during clot lysis has a prothrombotic effect, and the thrombolytic agents themselves may directly activate platelets. Antithrombotic therapy as an adjunct to thrombolysis improves the speed and extent of artery recanalization and reduces the incidence of secondary ischemic complications. The current treatment standard is unfractionated heparin (UFH) administered intravenously for 24-48 h. However, UFH has not been unequivocally shown to improve outcomes in large-scale, randomized clinical trials, and shows no evidence of benefit when used as an adjunct to streptokinase-based thrombolysis. Unfractionated heparin also has several clinical and practical disadvantages, such as the need for coagulation monitoring, difficulties attaining a stable and reliable anticoagulant effect, and the risk of hemorrhagic side effects. Low-molecular-weight heparin (LMWH) represents a safe and effective alternative antithrombotic therapy, with a stable and predictable anticoagulant effect, potential for use in combination with either fibrin-specific or streptokinase-based thrombolysis, no need for anticoagulation monitoring, and a low risk of hemorrhagic and other heparin-related complications. Several randomized clinical trials have shown that adjunctive LMWH is at least as effective as UFH in the acute phase of MI, is associated with fewer in-hospital recurrent ischemic events, and has an acceptable safety profile.

The evolution of thrombolytic therapy and adjunctive antithrombotic regimens in acute ST-segment elevation myocardial infarction

Acute ST-segment elevation myocardial infarction continues to be associated with substantial mortality rates. Despite much advancement in care, current treatments have also failed to eliminate the significant risk of morbidity, including reinfarction, reocclusion of the infarct-related artery, and thromboembolic stroke. The potential benefit of early thrombolytic therapy in reducing mortality was first established in 1986. Further benefits of conjunctive therapy with aspirin were demonstrated soon thereafter. This review examines the most significant trends in the pharmacologic therapy of ST-segment elevation myocardial infarction since the publication of these early studies: the development of fibrinolytic drugs with improved clot selectivity and improved pharmacokinetic profiles that simplify administration, making ED or even prehospital thrombolysis more practical. More recent data can be interpreted as showing that regimens that are simpler and easier to administer are also clinically superior. This article reviews pharmacologic advances and evaluates the evidence for their use in EDs.

The use of low molecular weight heparin to predict clinical outcome in patients with unstable angina that had undergone percutaneous coronary intervention

BACKGROUND

Antithrombotic therapy with heparin reduces the rate of ischemic events in patients with acute coronary syndrome. Low-molecular-weight heparin, given subcutaneously twice daily, has a more predictable anticoagulant effect than standard unfractionated heparin. Moreover, it is easier to administer and does not require monitoring.

METHODS

We prospectively analyzed 180 patients with unstable angina who had undergone percutaneous coronary intervention (PCI) between 1999 and 2001 at Chonnam National University Hospital and had received either 120 U/kg of dalteparin (Fragmin), administered subcutaneously twice daily (Group I; n = 90, 61.8 +/- 8.9 years, male 67.8%), or had received continuous intravenous unfractionated heparin (Group II; n = 90, 62.6 +/- 9.7 years, male 70.0%). During hospitalization and at 6 month after PCI, major adverse cardiac events such as acute myocardial infarction, target vessel revascularization, death, and restenosis were examined.

RESULTS

During hospitalization, the incidence of acute myocardial infarction, target vessel revascularization and death were not different between the two groups. At follow-up coronary angiography 6 months after PCI, the incidence of restenosis was lower in group I than in group II (Group I; 26/90, 28.8% vs. Group II; 32/90, 35.6%, p = 0.041) and the incidence of target vessel revascularization was lower in group I than in group II (Group I; 21/90, 23.3% vs. Group II; 27/90, 30.0%, p = 0.039). No difference was found in the rates of major and minor hemorrhages, ischemic strokes or thrombocytopenia between two groups. By multivariate analysis, the factors related to restenosis were lesion length, postprocedural minimal luminal diameter, CRP on admission, diabetes mellitus, the type of heparin, and stent use.

CONCLUSION

Dalteparin, a low molecular weight heparin, is superior to standard unfractionated heparin in terms of reducing the restenosis rate and target vessel revascularization without increasing bleeding complications.

Efficacy and safety of tenecteplase in combination with the low-molecular-weight heparin enoxaparin or unfractionated heparin in the prehospital setting: the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT)-3 PLUS randomized trial in acute myocardial infarction

BACKGROUND

The combination of a single-bolus fibrinolytic and a low-molecular-weight heparin may facilitate prehospital reperfusion and further improve clinical outcome in patients with ST-elevation myocardial infarction.

METHODS AND RESULTS

In the prehospital setting, 1639 patients with ST-elevation myocardial infarction were randomly assigned to treatment with tenecteplase and either (1) intravenous bolus of 30 mg enoxaparin (ENOX) followed by 1 mg/kg subcutaneously BID for a maximum of 7 days or (2) weight-adjusted unfractionated heparin (UFH) for 48 hours. The median treatment delay was 115 minutes after symptom onset (53% within 2 hours). ENOX tended to reduce the composite of 30-day mortality or in-hospital reinfarction, or in-hospital refractory ischemia to 14.2% versus 17.4% for UFH (P=0.080), although there was no difference for this composite end point plus in-hospital intracranial hemorrhage or major bleeding (18.3% versus 20.3%, P=0.30). Correspondingly, there were reductions in in-hospital reinfarction (3.5% versus 5.8%, P=0.028) and refractory ischemia (4.4% versus 6.5%, P=0.067) but increases in total stroke (2.9% versus 1.3%, P=0.026) and intracranial hemorrhage (2.20% versus 0.97%, P=0.047). The increase in intracranial hemorrhage was seen in patients >75 years of age.

CONCLUSIONS

Prehospital fibrinolysis allows 53% of patients to receive reperfusion treatment within 2 hours after symptom onset. The combination of tenecteplase with ENOX reduces early ischemic events, but lower doses of ENOX need to be tested in elderly patients. At present, therefore, tenecteplase and UFH are recommended as the routine pharmacological reperfusion treatment in the prehospital setting.

The role of low-molecular-weight heparin in the management of acute coronary syndromes

A substantial number of clinical studies have consistently demonstrated that low-molecular-weight heparin (LMWH) compounds are effective and safe alternative anticoagulants to unfractionated heparins (UFHs). They have been found to improve clinical outcomes in acute coronary syndromes and to provide a more predictable therapeutic response, longer and more stable anticoagulation, and a lower incidence of UFH-induced thrombocytopenia. Of the several LMWH agents that have been studied in large clinical trials, including enoxaparin, dalteparin, and nadroparin, not all have shown better efficacy than UFH. Enoxaparin is the only LMWH compound to have demonstrated sustained clinical and economic benefits in comparison with UFH in the management of unstable angina/ non-ST-segment elevation myocardial infarction (NSTEMI). Also, LMWH appears to be a reliable and effective antithrombotic treatment as adjunctive therapy in patients undergoing percutaneous coronary intervention. Clinical trials with enoxaparin indicate that LMWH is effective and safe in this indication, with or without the addition of a glycoprotein IIb/IIIa inhibitor. The efficacy demonstrated by enoxaparin in improving clinical outcomes in unstable angina/NSTEMI patients has led to investigations of its role in the management of ST-segment elevation myocardial infarction. Initial results are very encouraging, and they indicate that enoxaparin may potentially substitute for UFH as adjunctive therapy in fibrin-specific thrombolytic regimens and improve coronary reperfusion rates in streptokinase-based regimens.

Use of low-molecular-weight heparins in the management of acute coronary artery syndromes and percutaneous coronary intervention

CONTEXT

Low-molecular-weight heparins (LMWHs) possess several potential pharmacological advantages over unfractionated heparin as an antithrombotic agent.

OBJECTIVE

To systematically summarize the clinical data on the efficacy and safety of LMWHs compared with unfractionated heparin across the spectrum of acute coronary syndromes (ACSs), and as an adjunct to percutaneous coronary intervention (PCI).

DATA SOURCES

We searched MEDLINE for articles from 1990 to 2002 using the index terms heparin, enoxaparin, dalteparin, nadroparin, tinzaparin, low molecular weight heparin, myocardial infarction, unstable angina, coronary angiography, coronary angioplasty, thrombolytic therapy, reperfusion, and drug therapy, combination. Additional data sources included bibliographies of articles identified on MEDLINE, inquiry of experts and pharmaceutical companies, and data presented at recent national and international cardiology conferences.

STUDY SELECTION

We selected for review randomized trials comparing LMWHs against either unfractionated heparin or placebo for treatment of ACS, as well as trials and registries examining clinical outcomes, pharmacokinetics, and/or phamacodynamics of LMWHs in the setting of PCI. Of 39 studies identified, 31 fulfilled criteria for analysis.

DATA EXTRACTION

Data quality was determined by publication in the peer-reviewed literature or presentation at an official cardiology society-sponsored meeting.

DATA SYNTHESIS

The LMWHs are recommended by the American Heart Association and the American College of Cardiology for treatment of unstable angina/non-ST-elevation myocardial infarction. Clinical trials have demonstrated similar safety with LMWHs compared with unfractionated heparin in the setting of PCI and in conjunction with glycoprotein IIb/IIIa inhibitors. Finally, LMWHs show promise as an antithrombotic agent for the treatment of ST-elevation myocardial infarction.

CONCLUSIONS

The LMWHs could potentially replace unfractionated heparin as the antithrombotic agent of choice across the spectrum of ACSs. In addition, they show promise as a safe and efficacious antithrombotic agent for PCI. However, further study is warranted to define the benefit of LMWHs in certain high-risk subgroups before their use can be universally recommended.

Influence on coagulation activity by subcutaneous LMW heparin as an adjuvant treatment to fibrinolysis in acute myocardial infarction

In this study, which includes 101 patients with acute ST segment-elevated myocardial infarction, we investigated the influence on the increased coagulation activity after streptokinase treatment by adding low-molecular-weight (LMW) heparin or placebo and the relation between the coagulation activity and ischemic episodes, coronary patency, and mortality. The expected increase of prothrombin fragment 1+2 (F1+2), thrombin-antithrombin (TAT), and D-dimer were significantly attenuated at 2, 6, and 18 h (D-dimer only at 18 h) in the dalteparin group compared to placebo. Ischemic episodes during the first 24 h appeared significantly more often in patients with F1+2 levels above the median at 18 h. There was a tendency to a lower frequency of Thrombolysis In Myocardial Infarction Trial (TIMI) grade 3 flow in the infarct-related artery in patients with TAT and D-dimer levels above the median at 18 h. F1+2, TAT, and D-dimer were significantly higher after 18, 6, and 18 h, respectively, in the deceased compared to surviving patients. Also, the lack of reduction of the levels of F1+2 between 6 and 18 h was related to a raised mortality. In conclusion, adjuvant treatment with LMW heparin to streptokinase attenuates increased coagulation activity. This might be of importance as remaining high coagulation activity is associated with signs of early reocclusion and raised mortality.

Acute ischemic syndromes. Adjunctive therapy

The acute coronary syndromes (ACS) represent a heterogeneous group of patients along a continuum of risk from unstable angina to non-ST-segment elevation myocardial infarction. ACS is a term that has been used to describe the constellation of clinical symptoms that represent acute myocardial ischemia. This article reviews the adjunctive medications that are used during emergency cardiovasculare care for the early management of patients experiencing the ACS. The adjunctive therapies are divided into early immediate treatment and then subsequent management in the acute care setting.

The role of low-molecular-weight heparin in the management of acute coronary syndromes

Optimized medical treatment for the non-ST segment elevation acute coronary syndromes (NSTE ACS) should consist of a combined antithrombotic/anti-anginal regimen. Standard antithrombotic treatment is currently unfractionated heparin and aspirin, and in high-risk patients glycoprotein IIb/IIIa inhibitors. However, low-molecular-weight heparins (LMWHs) have practical and clinical advantages over UFH and can be considered an effective alternative in the medical treatment of ACS and in patients proceeding to surgical interventions. Benefits include a more predictable and stable therapeutic response, no need for coagulation monitoring and a reduced incidence heparin-induced thrombocytopenia. In this context, the LMWH enoxaparin has demonstrated sustained clinical and economic benefits compared with UFH, with no increase in major bleeding complications. In addition, recently published studies indicate that LMWHs can improve reperfusion of the arteries and reduce reocclusion when used as adjunctive anticoagulant therapy in patients with ST segment elevation (STE) ACS undergoing thrombolysis with fibrin-specific agents or streptokinase.

Randomized comparison of enoxaparin, a low-molecular-weight heparin, with unfractionated heparin adjunctive to recombinant tissue plasminogen activator thrombolysis and aspirin: second trial of Heparin and Aspirin Reperfusion Therapy (HART II)

BACKGROUND

Adjunctive unfractionated heparin (UFH) during thrombolytic therapy for acute myocardial infarction (AMI) promotes the speed and magnitude of coronary artery recanalization and reduces reocclusion. Low-molecular-weight heparins offer practical and potential pharmacological advantages over UFH in multiple applications but have not been systematically studied as adjuncts to fibrinolysis in AMI.

METHODS AND RESULTS

Four hundred patients undergoing reperfusion therapy with an accelerated recombinant tissue plasminogen activator regimen and aspirin for AMI were randomly assigned to receive adjunctive therapy for at least 3 days with either enoxaparin or UFH. The study was designed to show noninferiority of enoxaparin versus UFH with regard to infarct-related artery patency. Ninety minutes after starting therapy, patency rates (thrombolysis in myocardial infarction [TIMI] flow grade 2 or 3) were 80.1% and 75.1% in the enoxaparin and UFH groups, respectively. Reocclusion at 5 to 7 days from TIMI grade 2 or 3 to TIMI 0 or 1 flow and TIMI grade 3 to TIMI 0 or 1 flow, respectively, occurred in 5.9% and 3.1% of the enoxaparin group versus 9.8% and 9.1% in the UFH group. Adverse events occurred with similar frequency in both treatment groups.

CONCLUSIONS

Enoxaparin was at least as effective as UFH as an adjunct to thrombolysis, with a trend toward higher recanalization rates and less reocclusion at 5 to 7 days.

Randomized comparison of a novel anticoagulant, vasoflux, and heparin as adjunctive therapy to streptokinase for acute myocardial infarction: results of the VITAL study (Vasoflux International Trial for Acute Myocardial Infarction Lysis)

BACKGROUND

Vasoflux is a low-molecular-weight heparin derivative that inhibits factor IXa activation of factor X and catalyzes fibrin-bound thrombin inactivation by heparin cofactor II. We studied whether vasoflux improves the results of thrombolysis with streptokinase for acute myocardial infarction.

METHODS AND RESULTS

We randomized 277 patients with acute myocardial infarction to standard intravenous unfractionated heparin (UFH) or intravenous vasoflux 1, 4, 8, or 16 mg/kg as a bolus followed by 1, 4, 8, or 16 mg/kg per hour infusion, on top of streptokinase and aspirin, until angiography at 90 minutes. Patency and corrected Thrombolysis in Myocardial Infarction (TIMI) frame count were studied at 60 and 90 minutes. Rates of TIMI grade 3 flow with vasoflux at any dose (35% to 42%) were not different from UFH (41%) at either time point, nor was the corrected TIMI frame count. However, there was an excess of bleeding in the patients randomized to vasoflux 8 or 16 mg/kg: 78% and 71%, compared with 53% for UFH (P =.004 and.043, respectively). Major bleeding was observed in 13% and 28% at these vasoflux doses compared with 8% with UFH (P =.558 and.01, respectively).

CONCLUSION

At doses that increase the risk of bleeding, the addition of vasoflux to streptokinase and aspirin did not lead to improved patency rates compared with UFH. Targeting factor IXa and heparin cofactor II may not be a useful adjunct to thrombolysis.

Dalteparin sodium

Dalteparin sodium (Fragmin, Pharmacia Corporation) is a low molecular weight heparin (LMWH) with a mean molecular weight of approximately 5000 Da. As with the other LMWHs, dalteparin sodium has certain advantages over unfractionated heparin (UFH), most important of which are improved bio-availability by sc. injection, a prolonged antithrombotic activity which is highly correlated with body weight permitting the o.d. administration of the drug. Dalteparin sodium has been subjected to a large number of well-designed randomised clinical trials for the prevention and treatment of thrombotic disorders. Based on data from the randomised clinical trials, dalteparin sodium has been approved internationally for a wide spectrum of clinical indications (e.g., prevention of thromboembolic events after surgery). Dalteparin sodium has also been studied in randomised controlled trials in the maintenance of graft patentcy following peripheral vascular surgery, in place of warfarin for the long-term treatment of patients presenting with deep vein thrombosis (DVT), in the prevention of upper extremity thrombosis in patients with indwelling portacath devices and in pregnant patients with a history of previous venous thromboembolism with or without thrombophilia. Dalteparin sodium has been compared with heparin for the prevention of thrombotic complications during haemodyalisis and haemofiltration. These studies have shown promising results but further work is required before dalteparin sodium can be recommended for these indications.

New data in treatment of acute coronary syndromes

BACKGROUND

Anticoagulants are important in the treatment of acute coronary syndromes (ACS). When given in combination with aspirin, unfractionated heparin (UHF) improves the clinical outcome in patients who have ACS without ST-segment elevation. UHF also has potential benefits when administered in conjunction with fibrinolytic agents, especially those that are fibrin-specific. The anticoagulant effect of standard heparin is unpredictable, and excessive bleeding complications have been observed in nearly all trials.

METHODS

New anticoagulants, including direct antithrombins, low-molecular-weight heparins, and more recently, agents with a pure anti-Factor Xa effect, have been tested in patients with ACS and found to have varying degrees of clinical relevance.

RESULTS

One new synthetic pentasaccharide, Org31540/SR90107A, an antithrombin III-binding selective inhibitor of Factor Xa, has been studied in more than 300 patients with acute myocardial infarction with ST-segment elevation (PENTALYSE trial). In an ongoing trial (PENTUA), Org31540/SR90107A is being compared with enoxaparin in patients with ACS, with and without ST-segment elevation.

CONCLUSIONS

Org31540/SR90107A has shown promising results in ACS with ST-segment elevation. Efficacy in ACS without ST-segment elevation is currently under evaluation.

Update on strategies to improve thrombolysis for acute myocardial infarction

Therapy for acute myocardial infarction involves rapid restoration of blood flow through a coronary artery that has been occluded by a ruptured atherosclerotic plaque. Thrombolytic therapy, the pharmacologic standard to achieve this outcome, significantly improves survival; however, current regimens have limitations: they can fail to achieve complete reperfusion, they can cause significant bleeding events, and they can result in reocclusion. In addition, complex regimens of some agents can cause dosing errors. Accordingly, newer compounds were developed to address some of these issues, and alternative strategies are being implemented. The combination of platelet glycoprotein IIb-IIIa receptor inhibitors plus thrombolytic agents produced promising results in clinical trials, including faster clot lysis and greater flow rates than either therapy alone. The addition of unfractionated heparin or low-molecular-weight heparin to thrombolytic-antiplatelet therapy is being evaluated, as is administration of thrombolytic-antiplatelet before percutaneous coronary intervention.

Possible reasons for the prognostic value of troponin-T on admission in patients with ST-elevation myocardial infarction

BACKGROUND

In patients with acute myocardial infarction and ST-segment elevation, increased troponin-T (TnT) on admission implies an increased mortality.

OBJECTIVE

To elucidate the underlying mechanisms of the prognostic value of TnT.

METHODS AND RESULTS

One hundred and one patients were included and all received thrombolytic treatment. The patients were compared according to TnT level on admission (cut-off 0.1 microg/l). Elevation of TnT was associated with long-term mortality and also with longer delay, more episodes of chest pain during the last 24 h and fewer noninvasive signs of reperfusion at 90 min. In the group with elevated TnT, the coronary angiography at 24 h showed a strong trend towards lower patency in the infarct-related artery. TnT was also associated with increased infarct size if a higher cut-off level (0.43 microg/l) was used. In univariate analysis, elevated TnT, longer delay, repeated chest pain, Q-waves on admission and reduced left ventricular (LV) function were significantly associated with long-term mortality. In multivariate models, only reduced LV function and less than TIMI (thrombolysis in myocardial infarction) grade 3 flow turned out to be significant independent risk factors.

CONCLUSIONS

The prognostic value of TnT level on admission regarding long-term mortality was confirmed and seems mainly to be explained by its association with longer delay and recent myocardial damage, but its association with reduced effect of thrombolytic treatment, larger infarct size and impaired LV function might also be of importance.

Thrombolytics: drug interactions of clinical significance

Thrombolytic agents activate plasminogen and induce a systemic fibrinolytic and anticoagulant state. Interaction of fibrinolysis with coagulation and platelet aggregation might be important for synergistic interactions with other antiplatelet or anticoagulant drugs. Thrombolytic agents are most often used in patients with coexisting cardiovascular medication, including various antihypertensives, beta-blocking agents, nitrates and aspirin (acetylsalicylic acid). In acute coronary syndromes, anticoagulants and antiplatelet compounds such as clopidogrel or glycoprotein IIb/IIIa receptor antagonists might be given. Inducers or inhibitors of the cytochrome P450 system are not reported to affect the pharmacokinetics of any thrombolytic agent. Since the elimination of the recombinant plasminogen activators saruplase and alteplase is dependent on liver blood flow, drugs affecting hepatic blood flow could theoretically affect the hepatic clearance of these agents. In fact, a reduction in thrombolytic activity has only been demonstrated for alteplase with nitroglycerin (glyceryl trinitrate). Pharmacodynamic interactions occur more often. The additive and beneficial effect of aspirin as concomitant therapy to thrombolysis has been demonstrated without excessive bleeding rates. No data are available on the interaction between ticlopidine or clopidogrel and thrombolytic agents in humans. Anticoagulation by heparin concomitantly with thrombolysis improves the patency rate of the occluded coronary vessel, but bleeding complications are seen more frequently. Although there has been no controlled study on the interaction between oral anticoagulants and thrombolytic agents, patients with myocardial infarction who were taking an oral anticoagulant before admission seem to be at higher risk for intracranial haemorrhage during thrombolytic therapy. Currently, no recommendations can be given for possible dose adjustment of thrombolytic therapy in patients receiving antiplatelet comedication. For comedication with heparin, it has been advised to monitor activated partial thromboplastin time frequently and to avoid values >2.5-fold normal. Patients receiving thrombolytic treatment should be monitored frequently for bleeding and the physician should be aware of any comedication exerting antiplatelet (e.g. aspirin, clopidogrel and ticlopidine) or anticoagulant (e.g. warfarin) effects.

Medical treatment for acute coronary syndromes

The medical treatment of acute coronary syndromes with thrombolytic, antithrombin, and antiplatelet agents is a major area of research and a vast topic for clinical review. This review summarizes important recent findings on the background of existing pathological and clinical knowledge to provide an understanding of the basis of current therapy and the new therapies that are likely to be introduced in the near future. Current controversies regarding the management of these conditions and the choice between medical, interventional, and combined strategies in different situations are also discussed.