Heparin in acute stroke with atrial fibrillation: clinical relevance of very early treatment

Reduced Ischemic Lesion Growth with Heparin in Acute Ischemic Stroke

OBJECTIVE

The role of heparin in acute ischemic stroke is controversial. We investigated the effect of heparin on ischemic lesion growth.

METHODS

Data were analyzed on nonthrombolyzed ischemic stroke patients in whom diffusion-weighted imaging (DWI)/perfusion-weighted imaging (PWI) MRI was performed less than 12 hours of last known well and showed a PWI-DWI lesion mismatch, and who underwent follow-up neuroimaging at least 4 days after admission. Lesion growth was assessed by (1) absolute lesion growth and (2) percentage mismatch lost (PML). Univariate and multivariate regression analysis, and propensity score matching, were used to determine the effects of heparin on ischemic lesion growth.

RESULTS

Of the 113 patients meeting study criteria, 59 received heparin within 24 hours. Heparin use was associated with ∼5-fold reductions in PML (3.5% versus 19.2%, P = .002) and absolute lesion growth (4.7 versus 20.5 mL, P = .009). In multivariate regression models, heparin independently predicted reduced PML (P = .04) and absolute lesion growth (P = .04) in the entire cohort, and in multiple subgroups (patients with and without proximal artery occlusion; DWI volume greater than 5 mL; cardio-embolic mechanism; DEFUSE-3 target mismatch). In propensity score matching analysis where patients were matched by admission NIHSS, DWI volume and proximal artery occlusion, heparin remained an independent predictor of PML (P = .048) and tended to predict absolute lesion growth (P = .06). Heparin treatment did not predict functional outcome at discharge or 90 days.

CONCLUSION

Early heparin treatment in acute ischemic stroke patients with PWI-DWI mismatch attenuates ischemic lesion growth. Clinical trials with careful patient selection are warranted to investigate the potential ischemic protective effects of heparin.

Timing of anticoagulation therapy in patients with acute ischaemic stroke and atrial fibrillation

In patients with acute stroke and atrial fibrillation (AF), the risk of early recurrence has been reported to range between 0.1% and 1.3% per day. Anticoagulants are the most effective therapy for the prevention of recurrent ischaemic stroke in these patients, but randomised clinical trials have failed to produce any evidence supporting the administration of heparin within 48 hours from stroke onset as it has been associated with a non-significant reduction in the recurrence of ischaemic stroke, no substantial reduction in death and disability, and an increase in intracranial bleeding. As early haemorrhagic transformation is a major concern in the acute phase of stroke patients with AF, determining the optimal time to start anticoagulant therapy is essential. This review which focuses on the epidemiology of recurrent ischaemic stroke and haemorrhagic transformation in patients with acute ischaemic stroke and AF, proposes a model for decision making on optimal timing for initiating anticoagulation, based on currently available evidence.

Therapeutic monitoring of unfractionated heparin - trials and tribulations

INTRODUCTION

Heparin is one of the oldest biological medicines with an established role in prevention and treatment of arterial and venous thromboembolism. Published therapeutic ranges for unfractionated heparin (UFH) mostly precede the large increase in the number of activated partial thromboplastin time (APTT) reagent/instrument combinations that now show wide variability. Areas covered: This paper explores the use of UFH, the development of heparin therapeutic ranges (HTRs), and the strengths and limitations of the methods used to monitor heparin's anticoagulant effect. Expert commentary: Despite longstanding use of UFH for management of thromboembolic conditions, the optimal test for monitoring UFH remains undetermined. Although used extensively for monitoring UFH, routine APTT-derived HTRs are based on limited science that may have little relevance to current laboratory practice. Anti-FXa levels may provide better and more reliable HTRs; however, even these levels show considerable inter-laboratory variation, and there are insufficient clinical studies proving improved clinical efficacy. Alternative tests for monitoring UFH reported over time have not been proven effective nor feasible, secondary to technical or cost issues, or lack of general adoption. Thus, despite limited evidence of clinical utility, an uncomfortable marriage of convenience represented by heparin laboratory monitoring is unlikely to be terminated in the immediate future.

Comparison of 2 weight-based heparin dosing nomograms in neurology and vascular surgical patients

BACKGROUND

Unfractionated heparin sodium (UFH) is used in neurology and vascular surgical patients to treat and prevent thromboembolic occlusions and requires weight-based dosing to achieve a therapeutic range; however, the optimal dosing strategy is not known. This study sought to determine whether an intravenous (IV) weight-based UFH dosing nomogram based on an 80-unit/kg bolus and 18-unit · kg(-1) · h(-1) initial infusion rate achieves therapeutic anticoagulation [activated partial thromboplastin time (aPTT), 65-110 seconds] more rapidly than that based on a 60-unit/kg bolus and 12-unit · kg(-1) · h(-1) initial infusion rate in 98 neurology and vascular surgery patients.

METHODS

The study consisted of a retrospective chart review of adults prescribed and administered IV UFH for >6 hours, admitted under the neurology or vascular surgery teams and administered UFH for transient ischemic attack, stroke, acute ischemic limb, or postoperative revascularization.

RESULTS

The time to therapeutic aPTT analysis showed superiority of the higher dose (P = 0.04, log-rank test). At 6 hours, there was a significantly greater proportion of patients within the therapeutic range in the higher dose group (36.0% versus 16.7%, P = 0.03), with fewer subtherapeutic aPTTs (34.0% versus 70.8%, P < 0.001) and more supratherapeutic aPTTs (30.0% versus 12.5%, P = 0.034).

CONCLUSIONS

A weight-based nomogram for IV UFH using an 80-unit/kg bolus and an initial infusion rate of 18 units · kg(-1) · h(-1) showed a more rapid achievement of therapeutic aPTT when compared with a 60:12 dosing nomogram. Future research assessing a 70-unit/kg bolus dose is recommended.

Early Anti-Coagulation after Ischemic Stroke due to Atrial Fibrillation is Safe and Prevents Recurrent Stroke

Background: Patients with acute cardio-embolic stroke from atrial fibrillation (AF) are at risk for recurrence with up to 50% of recurrent stroke occurring within two weeks of the index event. Anti-coagulation with heparinoids within 48 hours of stroke has been shown to increase risk of symptomatic intracranial hemorrhage (ICH) with no clear benefit on early stroke recurrence. Methods: This study was a retrospective chart review of consecutive patients who were admitted to the stroke service at the Foothills Medical Centre between 2009 and 2011. All patients with an acute stroke with a cardio-embolic etiology and a diagnosis of atrial fibrillation were reviewed. We hypothesized that anti-coagulation within two weeks of stroke, appropriately begun because of a diagnosis of AF, decreased rates of recurrent stroke without causing an increase in rates of symptomatic ICH. Results: Between 2009-2011, 324 patients were identified with cardio-embolic stroke secondary to AF. Within two weeks of stroke onset 61.4% (199/324) of patients were therapeutic on anti-coagulation. Patients who were anti-coagulated had a smaller median index stroke volume (3.2 ml vs 18.4 ml). Three (0.9%) patients suffered a clinically significant ICH. Recurrent stroke occurred in 11 patients (3.4%) within the two-week period. Therapeutic anti-coagulation within two weeks of initial stroke was associated with a decreased risk of recurrent stroke (RR 0.1, 95% CI 0.03-0.64). Conclusions: Anti-coagulation within two weeks of acute stroke in patients with AF appears to be safe among patients with smaller infarcts and prevents early recurrent infarction.

Role of heparin and low-molecular-weight heparins in the management of acute ischemic stroke

The numerous large-scale randomized clinical trials performed during the last decade on either unfractionated heparin, or low molecular weight heparin have not been able to demonstrate undisputed benefits in patients with acute ischemic stroke, compared with no treatment or aspirin. However, a large number of these trials, including the International Stroke Trial and Chinese Acute Stroke Trial, exhibit severe methodological limitations and need to be interpreted with caution. Knowledge of thromboembolism pathophysiology and clinical experience leads to the theory that heparins will prevent red thrombus formation, propagation and embolism. Heparins effectively prevent venous thrombosis and pulmonary embolism. More trials are needed to test heparins in patients whose cardiocerebrovascular lesions are better defined by newer neuroimaging techniques. The efficacy of heparins has not been adequately tested in patients with defined stroke subtypes and occlusive vascular lesions. Heparins should not be indiscriminately given to all patients with acute ischemic stroke. High-quality, randomized trials that adequately study heparin use in patients using modern technology for vascular lesions and stroke subtypes are lacking, and need to be performed.

Risks and benefits of early antithrombotic therapy after thrombolytic treatment in patients with acute stroke

Background

Current guidelines recommend withholding antithrombotic therapy (ATT) for at least 24 h in patients with acute ischemic stroke treated with thrombolytic therapy. Herein, we report a retrospective analysis of a single-centre experience on the safety and efficacy of antithrombotic therapy (ATT) started before or after 24 h of intravenous thrombolysis in a cohort of acute ischemic stroke patients.

Methods

A total of 139 patients (Rapid ATT group) received antithrombotic therapy before 24 h of thrombolysis, and 33 patients (Standard ATT group) after 24 h. The brain parenchyma and vessel status were assessed using simple CT scan on admission, multimodal CT scan at the end of thrombolysis, and angio-CT/MRI scan at day 3. Functional outcome was scored using the modified Rankin Scale (mRS) at day 90.

Results

The two ATT groups had similar demographics, stroke subtypes, baseline NIHSS, thrombolytic strategies, vessel-patency rates at the end of thrombolysis, and incidence of bleeding complications at follow up. At day 3, the Rapid ATT group had a non-significant improved vessel-patency rate than the Standard ATT group. At day 90, a greater proportion of patients in the rapid ATT group had shifted down the mRS, and had improved in the NIHSS score.

Conclusions

ATT initiated before 24 h of intravenous thrombolytic therapy in acute stroke patients disclosed no safety concerns compared with a conventional antithrombotic therapy delay of 24 h and showed better functional outcome at follow up. The value of early initiation of ATT after thrombolysis deserves further assessment in randomized controlled trials.

Antithrombotic therapy in cardiac embolism

Anticoagulation is indicated in most cardioembolic ischemic strokes for secondary prevention. In many cardiac conditions, anticoagulation is also indication for primary stroke prevention, mainly when associated to vascular risk factors. Anticoagulation should be started as soon as possible, as it is safe even in moderate acute strokes. The efficacy of early anticoagulation after cardioembolic stroke in relation to outcome has not been assessed adequately, but there is evidence from animal models and clinical studies that anticoagulation with unfractionated heparin is associated with a better outcome mediated in part by its anti-inflammatory properties.

Anticoagulation for atrial fibrillation: should warfarin be temporarily stopped or continued after acute cardioembolic stroke?

Despite anticoagulation for atrial fibrillation, some patients still suffer an ischaemic stroke. The issue of whether to stop or continue warfarin, or possibly to reverse the anticoagulation is an area of uncertainty. Continued anticoagulation may, however, increase haemorrhagic transformation of the infarct. In this article we review the published evidence in an attempt to quantify the risks and benefits of each treatment strategy and identify areas for further research.

Acute ischemic stroke update

Stroke is the third most common cause of death in the United States and is the number one cause of long-term disability. Legislative mandates, largely the result of the American Heart Association, American Stroke Association, and Brain Attack Coalition working cooperatively, have resulted in nationwide standardization of care for patients who experience a stroke. Transport to a skilled facility that can provide optimal care, including immediate treatment to halt or reverse the damage caused by stroke, must occur swiftly. Admission to a certified stroke center is recommended for improving outcomes. Most strokes are ischemic in nature. Acute ischemic stroke is a heterogeneous group of vascular diseases, which makes targeted treatment challenging. To provide a thorough review of the literature since the 2007 acute ischemic stroke guidelines were developed, we performed a search of the MEDLINE database (January 1, 2004-July 1, 2009) for relevant English-language studies. Results (through July 1, 2009) from clinical trials included in the Internet Stroke Center registry were also accessed. Results from several pivotal studies have contributed to our knowledge of stroke. Additional data support the efficacy and safety of intravenous alteplase, the standard of care for acute ischemic stroke since 1995. Due to these study results, the American Stroke Association changed its recommendation to extend the time window for administration of intravenous alteplase from within 3 hours to 4.5 hours of symptom onset; this recommendation enables many more patients to receive the drug. Other findings included clinically useful biomarkers, the role of inflammation and infection, an expanded role for placement of intracranial stents, a reduced role for urgent carotid endarterectomy, alternative treatments for large-vessel disease, identification of nontraditional risk factors, including risk factors for women, and newly published pediatric stroke guidelines. In addition, new devices for thrombolectomy are being developed, and neuroprotective therapies such as the use of magnesium, statins, and induced hypothermia are being explored. As treatment interventions become more clearly defined in special subgroups of patients, outcomes in patients with acute ischemic stroke will likely continue to improve.

Optimal dosing of intravenous unfractionated heparin bolus in transient ischemic attack or stroke

Early initiation of heparin therapy for treatment of stroke is not only associated with an improved outcome, but also with the risk of hemorrhagic transformation. We compared the efficacy of three unfractionated heparin bolus regimens (0 U/kg, 30 U/kg, or 80 U/kg) in achieving a therapeutic activated partial thromboplastin time over the first 6-hour period in a cohort of 54 patients admitted with transient ischemic attack or stroke. Patients treated with the low bolus dose (30 U/kg) were more often within the therapeutic range for activated partial thromboplastin time at two hours after the initial bolus than patients treated with the other regimens. The percentage of therapeutic activated partial thromboplastin time results within the first six hours of treatment was greater in the group treated with the low bolus dose. Using the low bolus dose may reduce complication rates and improve clinical outcomes in the future clinical trials.

Heparin in acute ischemic stroke revisited

The evidence gathered in clinical trials of low molecular weight heparins (LMWHs) or with unfractionated heparin (UH) given subcutaneously at low or medium doses to patients with acute stroke cannot be extrapolated to the insufficiently tested effects of intravenous, weight-adjusted UH. Recent small studies have provided encouraging results but are potentially confounded and deserve confirmation in larger randomized controlled trials. In accordance with the current understanding of the biology of acute ischemic stroke and the pharmacology of UH, the new randomized controlled trials on heparin should give appropriate credit to the importance of a short therapeutic window, adequate dose adjustment of the drug, intravenous administration, and close monitoring of biological effects. UH is an orphan drug and only an academic driven trial would be able to face such an enterprise. Meanwhile, recommendations against the value of "early" anticoagulation with full dose of weight adjusted UH in the setting of acute ischemic stroke are not based on direct evidence but on extrapolations.

Anticoagulation after cardioembolic stroke: to bridge or not to bridge?

BACKGROUND

Most patients with cardioembolic stroke require long-term anticoagulation. Still, uncertainty exists regarding the best mode of starting long-term anticoagulation. Design, Setting, and Patients We conducted a retrospective review of all patients with cardioembolic stroke admitted to our center from April 1, 2004, to June 30, 2006, and not treated with tissue plasminogen activator. Patients were grouped by treatment: no treatment, aspirin only, aspirin followed by warfarin sodium, intravenous heparin sodium in the acute phase followed by warfarin (heparin bridging), and full-dose enoxaparin sodium combined with warfarin (enoxaparin bridging). Outcome measures and adverse events were collected prospectively. Laboratory values were captured from the records.

MAIN OUTCOME MEASURES

Symptomatic hemorrhagic transformation, stroke progression, and discharge modified Rankin Scale score.

RESULTS

Two hundred four patients were analyzed. Recurrent stroke occurred in 2 patients (1%). Progressive stroke was the most frequent serious adverse event, seen in 11 patients (5%). Hemorrhagic transformation occurred in a bimodal distribution-an early benign hemorrhagic transformation and a late symptomatic hemorrhagic transformation. All of the symptomatic hemorrhagic transformation cases were in the enoxaparin bridging group (10%) (P = .003). Systemic bleeding occurred in 2 patients (1%) and was associated with heparin bridging (P = .04).

CONCLUSIONS

Anticoagulation of patients with cardioembolic stroke can be safely started with warfarin shortly after stroke. Heparin bridging and enoxaparin bridging increase the risk for serious bleeding.

Efficacy and Safety of Anticoagulant Treatment in Acute Cardioembolic Stroke

Background and Purpose— The role of anticoagulant treatment for acute cardioembolic stroke is uncertain. We performed an updated meta-analysis of all randomized trials to obtain the best estimates of the efficacy and safety of anticoagulants for the initial treatment of acute cardioembolic stroke.

Methods— Using electronic and manual searches of the literature, we identified randomized trials comparing anticoagulants (unfractionated heparin or low-molecular-weight heparin or heparinoids), started within 48 hours, with other treatments (aspirin or placebo) in patients with acute ischemic cardioembolic stroke. Two reviewers independently selected studies and extracted data on study design, quality, and clinical outcomes, including death or disability, all strokes, recurrent ischemic stroke, and cerebral symptomatic bleeding. Odds ratios for individual outcomes were calculated for each trial and data from all the trials were pooled using the Mantel-Haenszel method.

Results— Seven trials, involving 4624 patients with acute cardioembolic stroke, met the criteria for inclusion. Compared with other treatments, anticoagulants were associated with a nonsignificant reduction in recurrent ischemic stroke within 7 to 14 days (3.0% versus 4.9%, odds ratio 0.68, 95% CI: 0.44 to 1.06, P =0.09, number needed to treat=53), a significant increase in symptomatic intracranial bleeding (2.5% versus 0.7%, odds ratio 2.89; 95% CI: 1.19 to 7.01, P =0.02, number needed to harm=55), and a similar rate of death or disability at final follow up (73.5% versus 73.8%, odds ratio 1.01; 95% CI: 0.82 to 1.24, P =0.9).

Conclusions— Our findings indicate that in patients with acute cardioembolic stroke, early anticoagulation is associated with a nonsignificant reduction in recurrence of ischemic stroke, no substantial reduction in death and disability, and an increased intracranial bleeding.

Antithrombotic and interventional treatment options in cardioembolic transient ischaemic attack and ischaemic stroke

Peer-reviewed data pertaining to anti-thrombotic and interventional therapy for transient ischaemic attack (TIA) or ischaemic stroke patients with non-valvular atrial fibrillation, atrial flutter, interatrial septal abnormalities, or left ventricular thrombus were reviewed. Long-term oral anticoagulant therapy with warfarin is the treatment of choice for secondary stroke prevention following TIA or minor ischaemic stroke in association with persistent or paroxysmal non-valvular atrial fibrillation or atrial flutter. If warfarin is contraindicated, long-term aspirin is a safe, but much less effective alternative treatment option in this subgroup of patients with cerebrovascular disease. Management of young patients with TIA or stroke in association with an interatrial septal defect is controversial. Various treatment options are outlined, but readers are encouraged to include these patients in one of the ongoing randomised clinical trials in this area. It is reasonable to consider empirical anticoagulation in patients with TIA or ischaemic stroke in association with left ventricular thrombus formation following myocardial infarction or in association with idiopathic dilated cardiomyopathy. If warfarin is prescribed, one should aim for a target international normalised ratio of 2.5 (range 2-3) to achieve the best balance between adequate secondary prevention of cardioembolic events and the risk of major haemorrhagic complications.

Accuracy of bedside diagnosis versus Allen and Siriraj stroke scores in Turkish patients

Computerized tomography and magnetic resonance imaging allow the accurate diagnosis in stroke and distinction of ischemic from hemorrhagic lesions. However, clinical diagnosis is still critical where neuroimaging techniques are not available, especially to establish first-aid measures in a stroke patient. In this prospective study of 300 patients with stroke, the diagnosis of ischemic and hemorrhagic strokes was made as an informal bedside diagnosis prior to neuroimaging. The accuracy of bedside diagnosis was also compared with the results of the Allen and Siriraj stroke scores. Then, the reliability of these scores and our informal bedside diagnosis, along with the final diagnosis, were compared with each other. Our informal bedside diagnosis was correct in 250 of the 300 patients (83.3%). The diagnostic sensitivity and positive predictive value (PPV) of bedside diagnosis for ischemic stroke were 87.8% and 86.0% and for intracerebral hemorrhage 75.7% and 78.5%, respectively. Sensitivity and PPV for every cut-off value of the Allen and Siriraj stroke scores were less than that of sensitivity and PPV of informal bedside diagnosis. When the receiver operating curves obtained from the Allen and Siriraj stroke scores were compared, the Allen stroke score was found to be a better predictor in the final diagnosis. Our data suggest that an informal bedside diagnoses is as good as diagnoses made on certain intracerebral hemorrhages and on certain ischemic strokes by the Siriraj and Allen stroke scores; when compared, the Allen score seems to be better than the Siriraj stroke score. Hence, the use of both scores is recommended in epidemiologic studies as a screening tool as suggested by previous studies employing other diagnostic tools in clinics.

Symptomatic intracerebral hematomas in posterior circulation stroke patients anticoagulated with heparin

BACKGROUND

A lot of clinicians use heparin in patients with posterior circulation stroke. Frequency and risk factors of symptomatic intracerebral hematoma (ICH) in posterior circulation infarct patients anticoagulated with unfractionated heparin are not known.

METHODS

To determine the incidence and the risk factors of the heparin-related ICH in posterior circulation infarct patients, we retrospectively reviewed the clinical features of 37 patients who had acute posterior circulation infarct and received intravenous heparin after they underwent brain computed tomographic scans and diffusion-weighted imaging (DWI). Follow-up brain scans were obtained at any time if clinical symptoms worsened. Volumes of acute posterior circulation infarction were calculated on DWI.

RESULTS

Of 37 patients, four (10.8%) developed symptomatic ICH during heparin infusion. The location of ICH was cerebellum in all the hemorrhagic worsening patients. We found that the size of an acute infarction calculated on DWI is the risk factor of symptomatic ICH during intravenous heparin therapy in patients with posterior circulation infarct.

CONCLUSIONS

Until a large prospective study is performed, it may be prudent to avoid heparin infusion in patients with large posterior circulation infarct documented on DWI.

Antithrombotic and Thrombolytic Therapy for Ischemic Stroke

Thrombolytic and antithrombotic agents form the cornerstone of stroke treatment and prevention. Recombinant tissue plasminogen activator improves outcome in patients treated within 3 hours of stroke onset. Emerging trials are directed to extend the therapeutic window and identify agents that could provide better safety profiles. Large, randomized trials have also highlighted the effectiveness and safety of early and continuous antiplatelet therapy in reducing atherothrombotic stroke recurrence. Aspirin has become the antiplatelet treatment standard against which several other antiplatelet agents have been shown to be more effective. The prevention of cardioembolic stroke is best accomplished with oral anticoagulation, barring any contraindications.

Pharmacological treatment of ischemic stroke

Current pharmacological strategies for acute ischemic stroke largely mirror those employed in acute coronary syndromes. However, important differences in the effectiveness and versatility of the principal agents have emerged between these 2 clinical settings. In general, the level of success achieved with drugs in acute coronary syndromes has not carried over to the same extent when the same drug types are used in stroke. The principal reason is that reperfusion or anticoagulant therapies in the setting of brain infarction run a significant risk of hemorrhagic transformation that has no direct equivalent in myocardial infarction. Consequently, a significant challenge in acute stroke therapeutics is the ability to select patients for drugs where only a narrow therapeutic margin exists and to identify methods that can minimize hemorrhage risk. Other brain-specific vascular factors also pertain in explaining differences in outcome of drugs generally regarded as having a broad cardiovascular remit. The relatively limited efficacy of antiplatelets in stroke might relate to the composition and heterogeneity of the cerebrovascular lesion, while the poor outcome associated with acute anti-hypertensive use is partly due to loss of cerebrovascular autoregulation. Finally, downstream consequences of arterial occlusion within the brain such as excitotoxicity and plasticity are organ specific and, as such, deserve their own pharmacological approaches. In this review, we describe the general mechanism of each drug class used in ischemic stroke and then report on the clinical experience and application for each.

Steady plasma concentration of unfractionated heparin reduces infarct volume and prevents inflammatory damage after transient focal cerebral ischemia in the rat

Unfractionated heparin (UH) decreases the extent of infarction after transient focal brain ischemia in the rat and abridges neuroinflammatory damage in patients with acute stroke. This study was aimed at assessing whether controlled and steady heparinemia in plasma can reduce infarct volume and exert neuroprotective effects after ischemia. Infarct volume was measured at 24 and 7 days following a 1-hr intraluminal middle cerebral artery (MCA) occlusion in rats treated with UH or with vehicle. After testing several UH administration protocols, we choose to give a bolus of 200 U/kg, which was started 3 hr after the occlusion, followed by a 24-hr intraperitoneal perfusion of 70 U/kg/hr, which maintained a 24-hr steady plasma heparinemia (0.3-0.6 U/ml) and caused no CNS or systemic bleeding. In addition, plasma IL-10 concentration was measured by ELISA, endothelial VCAM-1 expression was evaluated by i.v. injection of a (125)I-labeled monoclonal antibody against VCAM-1, and brain hemeoxygenase-1 (HO-1) expression was determined by Western blot. UH-treated rats showed smaller infarctions than rats treated with vehicle, as well as higher IL-10 plasma levels and HO-1 brain expression and lower endothelial VCAM-1 induction. The study shows that a stable plasma concentration of UH given at nonhemorrhagic doses reduces infarct volume after ischemia-reperfusion in the rat. It also shows that UH prevented the induction of cell adhesion molecules in the cerebral vasculature and increased the expression of molecules with antiinflammatory and prosurvival properties. These findings support further testing of the clinical value of parenteral, adjusted, high-dose UH in patients with acute stroke.

Antithrombotic and Thrombolytic Therapy for Ischemic Stroke

This chapter about treatment and prevention of stroke is part of the 7th 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). Among the key recommendations in this chapter are the following: For patients with acute ischemic stroke (AIS), we recommend administration of i.v. tissue plasminogen activator (tPA), if treatment is initiated within 3 h of clearly defined symptom onset (Grade 1A). For patients with extensive and clearly identifiable hypodensity on CT, we recommend against thrombolytic therapy (Grade 1B). For unselected patients with AIS of > 3 h but < 6 h, we suggest clinicians not use i.v. tPA (Grade 2A). For patients with AIS, we recommend against streptokinase (Grade 1A) and suggest clinicians not use full-dose anticoagulation with i.v. or subcutaneous heparins or heparinoids (Grade 2B). For patients with AIS who are not receiving thrombolysis, we recommend early aspirin therapy, 160 to 325 mg qd (Grade 1A). For AIS patients with restricted mobility, we recommend prophylactic low-dose subcutaneous heparin or low molecular weight heparins or heparinoids (Grade 1A); and for patients who have contraindications to anticoagulants, we recommend use of intermittent pneumatic compression devices or elastic stockings (Grade 1C). In patients with acute intracerebral hematoma, we recommend the initial use of intermittent pneumatic compression (Grade 1C+). In patients with noncardioembolic stroke or transient ischemic attack (TIA) [ie, atherothrombotic, lacunar or cryptogenic], we recommend treatment with an antiplatelet agent (Grade 1A) including aspirin, 50 to 325 mg qd; the combination of aspirin and extended-release dipyridamole, 25 mg/200 mg bid; or clopidogrel, 75 mg qd. In these patients, we suggest use of the combination of aspirin and extended-release dipyridamole, 25/200 mg bid, over aspirin (Grade 2A) and clopidogrel over aspirin (Grade 2B). For patients who are allergic to aspirin, we recommend clopidogrel (Grade 1C+). In patients with atrial fibrillation and a recent stroke or TIA, we recommend long-term oral anticoagulation (target international normalized ratio, 2.5; range, 2.0 to 3.0) [Grade 1A]. In patients with venous sinus thrombosis, we recommend unfractionated heparin (Grade 1B) or low molecular weight heparin (Grade 1B) over no anticoagulant therapy during the acute phase.

Antithrombotic and Hypofibrinogenetic Therapy in Acute Ischemic Stroke: What Is the Next Step?

A thrombus occluding a brain artery is the leading mechanism underlying ischemic stroke. In the light of this pathophysiology, antithrombotic therapies have been among the most widely studied and used in the management of patients with ischemic stroke. Aspirin has a significant but modest benefit by reducing recurrent ischemic stroke and death given within 48 h of stroke onset. The use of anticoagulants including heparin, low molecular weight heparin, and heparinoids has not been supported by results of randomized clinical trials. Any reductions in ischemic stroke recurrence were offset by an increase in major bleeding. However, acute anticoagulation is widely used in specific disorders, including patients with high-risk cardiac sources of embolus, arterial dissection, venous sinus thrombosis, and hypercoagulable states. Early recurrent ischemic strokes in patients with atrial fibrillation and acute ischemic stroke have not been shown to be reduced with the heparins, when the effects of major bleeding and hemorrhagic worsening are considered. Recent clinical trials have suggested that other antithrombotic agents may be beneficial in acute ischemic stroke. Two such agents are ancrod and abciximab. Abciximab is currently being investigated in a large randomized clinical trial.

Cardioembolic stroke: an update

Embolism of cardiac origin accounts for about one fifth of ischaemic strokes. Strokes due to cardioembolism are in general severe and prone to early recurrence. The risk of long term recurrence and mortality are high after a cardioembolic stroke. Cardioembolism can be reliably predicted on clinical grounds but is difficult to document. MRI, transcranial doppler, echocardiogram, Holter monitoring, and electrophysiological studies increase our ability to identify the source of cardioembolism. Non-valvular atrial fibrillation is the commonest cause of cardioembolic stroke. Despite its enormous preventive potential, continuous oral anticoagulation is prescribed for less than half of patients with atrial fibrillation who have risk factors for cardioembolism and no contraindications for anticoagulation. Alternatives to oral anticoagulation in this setting include safer and easier to use antithrombotic drugs and definitive treatment of atrial fibrillation. Available evidence does not support routine immediate anticoagulation of acute cardioembolic stroke.

Unfractionated heparin is associated with a lower rise of serum vascular cell adhesion molecule-1 in acute ischemic stroke patients

We sought to assess the anti-inflammatory properties of unfractionated heparin (UFH) in patients with ischemic stroke treated within 24 h from the onset of symptoms. We studied prospectively 167 patients that received 1000 IU/h intravenous UFH (n=70) or 300 mg oral aspirin (n=97) at a mean treatment delay of 6.7 h. Repeated plasma levels of interleukin (IL)-6, IL-10, IL-4, tumor necrosis factor (TNF)-alpha, soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) were compared in both groups using multivariate analyses. Whereas TNF-alpha and sICAM-1 decreased at 48 h, IL-6, IL-4, and sVCAM-1 increased compared with baseline values (P<0.01). The rise of sVCAM-1 levels at 48 h was significantly lower in patients treated with UFH (P=0.017) and a two-fold increase of baseline sVCAM-1 was an independent predictor of poor outcome (odds ratio, 2.19, 1.1-4.39). These results suggest that adjusted high-dose UFH has anti-inflammatory effects which might improve recovery if administered early after stroke onset.

Considering the role of heparin and low-molecular-weight heparins in acute ischemic stroke

BACKGROUND AND PURPOSE

The utility of parenteral anticoagulation therapy in acute ischemic stroke has engendered much controversy and discussion. Recent studies of low-molecular-weight heparins in multiple acute stroke subtypes have not demonstrated improved outcome or reduced recurrence risk. Beneficial treatment effects may occur in subgroups such as patients with large artery atherothrombotic stroke, but further studies will be needed to prove this possibility.

SUMMARY OF REVIEW

The benefits of unfractionated intravenous heparin for reducing early stroke recurrence and improving outcome remain to be established, with the current lack of appropriately powered trials in stroke subgroups at high risk for such early recurrence. To most clinicians, the primary reason to use early intravenous anticoagulation is to prevent early stroke recurrence, not to improve outcome of an established stroke. Unfortunately, effects of reduction of recurrent stroke risk may be counterbalanced by a substantial increased risk of intracerebral hemorrhage with intravenous anticoagulation.

CONCLUSIONS

Unfractionated intravenous heparin should therefore not be used routinely in acute ischemic stroke, but it may be considered in select stroke groups at high risk for early recurrent ischemic events (ie, patients with atrial fibrillation or acute myocardial infarction and large mural thrombi). However, even in these select populations, new clinical trials will be needed to define the risk-benefit ratio.

Anticoagulant therapy with a selective thrombin inhibitor for acute cerebral infarction: usefulness of coagulation markers for evaluation of efficacy

BACKGROUND

Argatroban is a selective thrombin inhibitor used for the treatment of atherothrombotic infarction. We evaluated its therapeutic effect using coagulation markers in 30 patients with cardioembolic infarction and 30 patients with atherothrombotic infarction during the immediate period after ischemic stroke.

METHODS

Argatroban therapy was initiated within 24 hours of the onset of stroke and the course was followed until 7 days after the start of treatment. Neurological evaluation was performed using the Hemispheric Stroke Scale (HSS). We also monitored the serial changes in activated partial thromboplastin time, prothrombin time, thrombin-antithrombin complex (TAT), and prothrombin fragments 1 + 2 (F1 + 2).

RESULTS

Both groups of patients showed significant improvement of HSS after 7 days of argatroban therapy (p < 0.05). Hemorrhagic infarction developed in 8 of patients with cardioembolic infarction, but no worsening of symptoms was noted in any of these patients. There was no significant prolongation of activated partial thromboplastin time or prothrombin time after 7 days, while levels of both TAT and F1 + 2 were significantly decreased from day 2.

CONCLUSION

The decrease in TAT and F1 + 2 during argatroban therapy suggested improvement of hypercoagulability, which might explain how this drug prevents the recurrence of both ATI and CEI in the acute stage. Our findings also suggested that TAT and F1 + 2 might be useful indices for evaluation of argatroban efficacy.

Evaluation and management of acute ischemic stroke

Stroke continues to be a major cause of adult mortality and disability. After numerous clinical trials and hundreds of millions of dollars spent on research, only two drugs are effective in treating patients with acute stroke. Recombinant tissue-plasminogen activator improves the chance of an excellent outcome in treated patients by 30%. Danaparoid sodium improves the chance of a very favorable outcome in treated patients with stroke due to large artery atherosclerosis. Although acute treatments are limited, our understanding of stroke pathogenesis and the importance of preventing poststroke complications has improved patient outcome significantly.

Neurologic manifestations of cardiogenic embolism: an update

Cardiogenic embolism is increasingly appreciated as an important and preventable cause of stroke. Several potential sources of embolism have been identified with the advent of transoesophageal echocardiography. Their role as independent risk factors for stroke and management implications based on recent evidence, along with characterization of schemes for antithrombotic management of patients with atrial fibrillation are reviewed.

Selection of anticoagulants or antiplatelet-aggregating agents for prevention of stroke

Stroke is one of leading causes of mortality and morbidity in the United States. Stroke prevention includes treatment of the stroke risk factors and long-term use of antithrombotic agents. Various agents have been studied for stroke prevention and other trials are ongoing. The aim of this article is to provide an overview of the recent guidelines, recommendations, and clinical trial results using antithrombotic therapy for stroke prevention.