Antithrombotic and thrombolytic therapy for ischemic stroke

Nanoparticles-mediated emerging approaches for effective treatment of ischemic stroke

Ischemic stroke leads to high disability and mortality. The limited delivery efficiency of most therapeutic substances is a major challenge for effective treatment of ischemic stroke. Inspired by the prominent merit of nanoscale particles in brain targeting and blood-brain barrier (BBB) penetration, various functional nanoparticles have been designed as promising drug delivery platforms that are expected to improve the therapeutic effect of ischemic stroke. Based on the complex pathological mechanisms of ischemic stroke, this review outline and summarize the rationally designed nanoparticles-mediated emerging approaches for effective treatment of ischemic stroke, including recanalization therapy, neuroprotection therapy, and combination therapy. On this bases, the potentials and challenges of nanoparticles in the treatment of ischemic stroke are revealed, and new thoughts and perspectives are proposed for the design of feasible nanoparticles for effective treatment of ischemic stroke.

Multipotent bone marrow stromal cell therapy promotes endogenous cell proliferation following ischemic stroke

Despite extensive research over the years, there still exists some debate as to what constitutes the optimal therapeutic strategy to promote recovery following stroke. Due to the complexity of injured brain pathophysiology, treatment approaches should ideally address numerous factors, ultimately aiming to promote tissue protection, axonal regrowth and functional recovery. This study extends the understanding of the effects of bone marrow stromal cell (BMSC) treatment following experimentally induced ischemic stroke in rats. Focal ischemic brain injury was experimentally induced in rats by placing a preformed clot into the middle cerebral artery. Animals were injected intravenously with BMSCs at 24 h after stroke and were killed 7 days post injury. When administered BMSCs following stroke, the neurological outcome was significantly improved relative to controls. There was an increase in the number of BMSCs labelled with BrdU present in the injured hemisphere of the brain compared to the non-injured side. Furthermore, administration of BMSCs also led to increases in astrocytosis, vascularization and endogenous proliferation. These findings provide insight into the mechanisms of action of BMSC treatment and further argue for the therapeutic potential of BMSCs as an effective treatment following cerebral stroke.

[Antithrombotic treatment as primary and secondary prevention of stroke]

The use of antithrombotic drugs (ATD) is necessary in the treatment and prevention of thrombosis. The correction of risk factors of ischemic stroke (IS) and transitory ischemic attacks (TIA) is important as well. The drugs inhibiting the activation and aggregation of thrombocytes allow to decrease the number of myocardial infarctions by 35%, stroke by 25% and mortality from cardiovascular causes by 15%. Currently, the clinical efficacy of acetylsalicylic acid (ASA), thienopyridines (ticlopidine, clopidogrel), dipyridamole or the combination of dipyridamole and ASA as well as glycoprotein antagonists IIb-IIIa for intravenous introduction have been confirmed. A review of experimental and clinical studies confirming the efficacy of dipyridamole in the treatment of acute stage of stroke and primary and secondary prevention of II is presented.

Targeting caspase-6 and caspase-8 to promote neuronal survival following ischemic stroke

Previous studies show that caspase-6 and caspase-8 are involved in neuronal apoptosis and regenerative failure after trauma of the adult central nervous system (CNS). In this study, we evaluated whether caspase-6 or -8 inhibitors can reduce cerebral or retinal injury after ischemia. Cerebral infarct volume, relative to appropriate controls, was significantly reduced in groups treated with caspase-6 or -8 inhibitors. Concomitantly, these treatments also reduced neurological deficits, reduced edema, increased cell proliferation, and increased neurofilament levels in the injured cerebrum. Caspase-6 and -8 inhibitors, or siRNAs, also increased retinal ganglion cell survival at 14 days after ischemic injury. Caspase-6 or -8 inhibition also decreased caspase-3, -6, and caspase-8 cleavage when assayed by western blot and reduced caspase-3 and -6 activities in colorimetric assays. We have shown that caspase-6 or caspase-8 inhibition decreases the neuropathological consequences of cerebral or retinal infarction, thereby emphasizing their importance in ischemic neuronal degeneration. As such, caspase-6 and -8 are potential targets for future therapies aimed at attenuating the devastating functional losses that result from retinal or cerebral stroke.

Use of antithrombotic medications among elderly ischemic stroke patients

BACKGROUND

The use of antithrombotic medications after ischemic stroke is recommended for deep vein thrombosis prophylaxis and secondary stroke prevention. We assessed the rate of receipt of these therapies among eligible ischemic stroke patients age ≥65 years and determined the effects of age and other patient characteristics on treatment.

METHODS AND RESULTS

The analysis included Medicare fee-for-service beneficiaries discharged with ischemic stroke (ICD 433.x1, 434.x1, 436) randomly selected for inclusion in the Medicare Health Care Quality Improvement Program's National Stroke Project 1998 to 1999, 2000 to 2001. Patients discharged from nonacute facilities, transferred, or terminally ill were excluded. Receipt of in-hospital pharmacological deep vein thrombosis prophylaxis, antiplatelet medication, anticoagulants for atrial fibrillation, and antithrombotic medications at discharge were assessed in eligible patients, stratified by age (65 to 74, 75 to 84, and 85+ years). Descriptive models identified characteristics associated with treatment. Among 31 554 patients, 14.9% of those eligible received pharmacological deep vein thrombosis prophylaxis, 83.9% antiplatelet drugs, 82.8% anticoagulants for atrial fibrillation, and 74.2% were discharged on an antithrombotic medication. Rates of treatment decreased with age and were lowest for patients ages 85 years or older. Admission from a skilled nursing facility and functional dependence were associated with lower treatment rates.

CONCLUSIONS

There was substantial underutilization of antithrombotic therapies among elderly ischemic stroke patients, particularly among the very elderly, those admitted from skilled nursing facilities, and patients with functional dependence. The reasons for low use of antithrombotic therapies, including the apparent underutilization of deep vein thrombosis prophylaxis in otherwise eligible patients, require further investigation.

Impact of persistence with antiplatelet therapy on recurrent ischemic stroke and predictors of nonpersistence among ischemic stroke survivors

OBJECTIVE

Medication adherence is an important component of effective secondary stroke prevention. The objectives of this study were to examine the impact of persistence with two prescription antiplatelet therapies on the outcome of recurrent hospitalized stroke, and to identify the predictors of nonpersistence with these antiplatelet therapies.

RESEARCH DESIGN AND METHODS

Administrative claims from a large, geographically diverse US health plan were used to evaluate acetylsalicylic acid / extended-release dipyridamole (ASA/ERDP) treated and clopidogrel treated patients from November 1, 2002 - December 31, 2005 who had an ischemic stroke requiring hospitalization. Nonpersistence was defined as failure to refill index medication within 30 days from the run-out date of the prior prescription. A Cox proportional hazards model was used to identify key factors associated with time to nonpersistence.

MAIN OUTCOME MEASURES

Patient demographic variables, clinical characteristics, comorbidities hypothesized to affect the risk of current stroke, stroke outcomes, treatment patterns, and compliance were assessed.

RESULTS

A total of 1413 patients hospitalized for ischemic stroke were identified. Mean age was 63.4 years and 44.2% were female. The proportion of patients persistent per person-year was 45.1%. Persistence with medication was significantly associated with a longer time to recurrent hospitalized stroke (HR 0.275; 95% CI 0.134-0.564; p < 0.0004). A medication copayment of >$40 (relative to a copayment of < or =$20) was the only significant factor predicting time to nonpersistence (HR 1.320; 95% CI 1.091-1.596; p < 0.0042).

CONCLUSIONS

Persistence with antiplatelet medication within a cohort of hospitalized ischemic stroke patients was associated with a 72.5% lower likelihood of recurrent hospitalized stroke. Higher medication copayment was found to negatively impact patient persistence with antiplatelet therapy. The findings of this study must be considered within the limitations of database analysis, as claims data are collected for the purpose of payment and not research.

Systemic hyperthermia masks the neuroprotective effects of MK-801, but not rosiglitazone in brain ischaemia

The use of neuroprotective agents has been under investigation for the treatment of ischaemic brain stroke. In this study, we examined the effects of rosiglitazone and MK-801, two potential neuroprotectants, on thromboembloic focal stroke in hyperthermic rats. The animals were assigned into groups of rosiglitazone, MK-801 and control, all under both normothermic and hyperthermic conditions. A focal ischaemia was induced by injection of preformed clot into the origin of the middle cerebral artery. The animals were assessed by measuring infarct size and brain oedema and also evaluating neurological deficit and seizure activity. Rosiglitazone improved infarct volume and neurological deficit in both normo- (36%) and hyperthermic (63%) animals; but MK-801 only improved normothermic animals. Our results do not support the use of MK-801 in hyperthermic conditions of brain stroke but suggest that rosiglitazone may preserve its efficiency even in hyperthermia.

Use of antithrombotic agents among U.S. stroke survivors, 2000-2006

BACKGROUND

Secondary stroke prevention guidelines recommend antithrombotic agents such as over-the-counter aspirin, prescription antiplatelet agents, or anticoagulant agents.

PURPOSE

The study was designed to measure whether use of outpatient antithrombotic agents is increasing among stroke survivors.

METHODS

The sample consisted of 4168 people who self-reported cerebrovascular disease and who participated in the Medical Expenditure Panel Survey, an annual representative sample of the U.S., during the years 2000-2006. Use of antithrombotic agents was calculated from face-to-face interviews about the use of aspirin and from pharmacies about the use of prescription medications. Cochran-Armitage tests were used to detect temporal trends and multivariate models to identify predictors of use of antithrombotic agents.

RESULTS

Pooling results across the 7 years, it was found that 57% were taking aspirin, 66% were using any antiplatelet agent, and 75% were using any antithrombotic agent. After excluding people who said aspirin was unsafe, 81% were using any antithrombotic agent. During the study period, use of prescription antiplatelet agents increased (p<0.001) but there was no temporal change in use of antithrombotic agents overall. In multivariate models, being aged >65 years, male gender, non-Hispanic ethnicity, having a usual source of care, and poor or fair health status were associated with use of an antithrombotic agent (p<0.05).

CONCLUSIONS

Although a high percentage of stroke survivors appear to use an antithrombotic agent, further research should investigate whether and how to improve care among the remaining 20% of stroke survivors, particularly among younger, female, and Hispanic patients.

Partial intra-aortic occlusion improves perfusion deficits and infarct size following focal cerebral ischemia

Reperfusion with intravenous tissue plasminogen activator (tPA) has been the goal of therapy for acute ischemic stroke; however, tPA is contraindicated in many patients, has low recanalization rates in major occlusions, and carries a substantial risk of symptomatic intracerebral hemorrhage. In the present study, we hypothesized that partial intra-aortic occlusion of the abdominal aorta would increase salvage of ischemic penumbra and reduce infarct volume after focal embolic stroke in rats. We examined the effects of aortic occlusion on infarct volume, expression and activation of matrix metalloprotease-9, and hemorrhagic transformation with or without treatment with tPA. We then examined the effects of aortic occlusion on perfusion deficits following embolic occlusion. Results showed that partial aortic occlusion significantly reduces brain infarction volume with or without treatment with tPA after focal ischemia, but does not increase risk for hemorrhagic transformation or matrix metalloprotease-9 expression and activation. Partial intra-aortic occlusion also reduces perfusion deficits after focal cerebral ischemia as compared to control. The present study shows that partial intra-aortic occlusion significantly decreases infarction volume and perfusion deficits following ischemic injury in an embolic model of cerebral ischemia. Moreover, combination treatment with tPA and partial intra-aortic occlusion further reduces infarction volume without any increase in hemorrhagic transformation.

Vascular risk factor awareness before and pharmacological treatment before and after stroke and TIA

BACKGROUND AND PURPOSE

Educating the public to screen for vascular risk factors and have them treated is a major public health issue. We assessed the vascular risk factor awareness and frequency of treatment in a cohort of patients with cerebral ischaemia.

METHODS

Data on awareness and pharmacological treatment of vascular risk factors before hospital admission of patients with confirmed ischaemic stroke/transient ischaemic attack (TIA) were analyzed. A follow-up questionnaire assessed the frequency of treatment 1 year after discharge and assessed non-adherence to antithrombotic medication.

RESULTS

At time of stroke/TIA, individual awareness regarding existing hypertension, diabetes, hyperlipidemia and atrial fibrillation (AF) was 83%, 87%, 73% and 69% respectively (n = 558). Pharmacological treatment for hypertension, diabetes, hyperlipidemia and AF was being administered in 80%, 77%, 37% and 62% of patients aware of their conditions. The follow-up was completed by 383 patients (80% recall rate): of the patients with hypertension, diabetes, hyperlipidemia and AF, 89%, 78%, 45% and 86% were receiving risk factor targeted medication. This represents a significant increase concerning AF and hyperlipidemia. Non-adherence to recommended antithrombotics (15%) was higher in patients who had had a TIA.

CONCLUSIONS

All risk factors leave room for improvement in screening and treatment efforts. Adherence to treatment is higher for hypertension and diabetes than for hyperlipidemia. Education efforts should bear in mind less well recognized risk factors.

Secondary prevention of atherothrombotic events after ischemic stroke

Atherosclerotic vascular disease is the leading cause of ischemic stroke, resulting in occlusive or severely stenotic lesions of major intracranial or extracranial arteries and narrowing of small penetrating arteries of the brain. Atherosclerosis of the coronary arteries (ie, coronary artery disease) is an indirect cause of cardioembolic stroke secondary to myocardial infarction. Ischemic heart disease may also be complicated by atrial fibrillation and cardioembolic stroke. Prevention of recurrent stroke and other ischemic events, including myocardial infarction, is a key component of treatment for patients with symptomatic ischemic cerebrovascular disease. Prevention of recurrent stroke involves controlling those factors that promote the course of atherosclerosis, including hypertension, hyperlipidemia, diabetes mellitus, and smoking, as well as such local interventions as carotid endarterectomy and endovascular treatment. Nevertheless, administration of antiplatelet agents remains the core of management for preventing recurrent stroke and other cardiovascular events in at-risk patients.

Secondary prevention of atherothrombotic events after ischemic stroke

Atherosclerotic vascular disease is the leading cause of ischemic stroke, resulting in occlusive or severely stenotic lesions of major intracranial or extracranial arteries and narrowing of small penetrating arteries of the brain. Atherosclerosis of the coronary arteries (ie, coronary artery disease) is an indirect cause of cardioembolic stroke secondary to myocardial infarction. Ischemic heart disease may also be complicated by atrial fibrillation and cardioembolic stroke. Prevention of recurrent stroke and other ischemic events, including myocardial infarction, is a key component of treatment for patients with symptomatic ischemic cerebrovascular disease. Prevention of recurrent stroke involves controlling those factors that promote the course of atherosclerosis, including hypertension, hyperlipidemia, diabetes mellitus, and smoking, as well as such local interventions as carotid endarterectomy and endovascular treatment. Nevertheless, administration of antiplatelet agents remains the core of management for preventing recurrent stroke and other cardiovascular events in at-risk patients.

Reduction of ischemic brain injury in rats with normothermic and hyperthermic conditions

Object

Statins have been used for induction of ischemic tolerance after cerebral ischemia. The authors have previously shown that simvastatin is protective after ischemic cerebral injury in normothermic conditions. In this study they further examined whether treatment with simvastatin can reduce ischemic brain injury in a hyperthermic condition.

Methods

Focal ischemic brain injury was induced by embolizing a preformed clot into the middle cerebral artery in rats. The authors initially examined whether treatment with simvastatin could reduce ischemic brain injury without or with hyperthermia. The infarct volume, edema, and neurological deficits were examined. They then studied whether simvastatin could reduce the perfusion deficits, damage to the blood–brain barrier (BBB), and degeneration of neurons in the ischemic injured brain.

Results

Simvastatin significantly reduced the infarct volume in both normothermic and hyperthermic conditions, compared with appropriate controls. Concomitantly, this treatment also significantly reduced neurological deficits and brain edema. Administration of simvastatin significantly decreased perfusion deficits, BBB permeability, and degenerated neurons.

Conclusions

These studies suggest that simvastatin is an effective agent for ischemic brain injury not only in normothermic but also in hyperthermic conditions, which may be through the decrease of BBB permeability, degenerated neurons, and perfusion deficits.

A Novel, Self-Expanding, Nitinol Stent in Medically Refractory Intracranial Atherosclerotic Stenoses

Background and Purpose— The purpose of this study was to assess the safety and performance of the Wingspan stent system and Gateway percutaneous transluminal angioplasty balloon catheter in the treatment of high-grade, intracranial atherosclerotic lesions in patients who had failed medical therapy.

Methods— In this prospective, multicenter, single-arm study, medically refractory patients with a modified Rankin score ≤3 and recurrent symptoms attributable to angiographically demonstrated intracranial stenosis ≥50% in a vessel 2.5 to 4.5 mm in diameter were enrolled. Intracranial lesions were predilated with an undersized Gateway balloon catheter to 80% of the native vessel diameter, followed by deployment of the self-expanding Wingspan stent to facilitate further remodeling of the atherosclerotic plaque and to maintain vessel patency. Neurologic examinations and angiograms were performed at 6 months after the procedure.

Results— Among the 45 patients enrolled, the degree of stenosis was reduced from a baseline of 74.9±9.8% to 31.9±13.6% after stenting and 28±23.2% at the 6-month follow-up. The 30-day composite ipsilateral stroke/death rate was 4.5% (2/44); at the 6-month follow-up, the ipsilateral stroke/death rate was 7.0%, the rate for all strokes was 9.7%, and all-cause mortality was 2.3%. Physician-reported follow-up in 43 patients (average of 13 months) conducted outside the study protocol (not adjudicated by the clinical event committee) reported 1 additional ipsilateral stroke.

Conclusions— In medically refractory patients with high-grade intracranial atherosclerotic stenoses, a new treatment paradigm involving predilation with an undersized Gateway percutaneous transluminal angioplasty balloon catheter and placement of a self-expanding Wingspan stent system appears to be safe, may facilitate remodeling, and may contribute to favorable angiographic outcomes.

Combination treatment with dipyridamole, aspirin, and tPA in an embolic model of stroke in rats

Antithrombotic therapy has been shown to be effective in preventing secondary strokes. Inhibition of platelet function may reduce formation of thrombi thereby reducing the incidence of stroke. However, stronger inhibition of platelets is correlated with increased risk of bleeding events. The purpose of this study was to test the protective effects of combination therapy with dipyridamole and acetylsalicylic acid (ASA) in comparison to ASA alone, and whether such combination treatment may produce any added benefits when tissue plasminogen activator (tPA) treatment is also used. The study was divided into three parts. In part A, effect of antiplatelets on infarct volume was assessed. In part B, perfusion deficits were measured. In part C, efficacy of antiplatelet therapy in combination with tPA was assessed. In part A, dipyridamole and aspirin treatment significantly reduced infarct volume (P<0.05). In part B, treatment with dipyridamole significantly reduced the perfusion deficits as compared to control (P<0.05). In part C, dipyridamole plus tPA or dipyridamole and aspirin plus tPA significantly decreased infarct volume as compared to tPA alone (P<0.05). The present study suggests that there is significant protection with dipyridamole as both infarct volume and perfusion deficits are significantly reduced. Dipyridamole with tPA also significantly reduced infarct volume as compared to tPA alone. Our data suggests that higher doses of antithrombotic therapy with dipyridamole offer best neuroprotection.

Parkinsonian syndromes

The term parkinsonian syndromes refers to a group of disorders whose clinical features overlap those of idiopathic Parkinson's disease. The four major entities include three important neurodegenerations, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration, and a lacunar cerebrovascular disorder, vascular parkinsonism. This article reviews the epidemiology, pathology, clinical features, diagnosis, and management of these disorders.

Use of 3-D magnetic resonance electrical impedance tomography in detecting human cerebral stroke: a simulation study

We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245+/-0.0068 and 8.9997%+/-0.0084%, for hemorrhagic stroke, and 0.6748+/-0.0197 and 8.8986%+/-0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.

Treatments for stroke

Stroke is the third leading cause of death and the leading cause of disability in developed countries, yet remains a poorly treated condition. Treatments for stroke can be aimed at acutely improving blood flow or protecting brain tissue against ischaemia, enhancing stroke recovery or reducing the risk of stroke recurrence. This paper reviews each of these approaches, particularly focusing on mechanisms for which there are agents in clinical trials. There are a number of appealing neuroprotective agents in Phase II and III clinical trials. However, the majority of acute treatments are likely to suffer from a narrow therapeutic time window and hence limited patient access. Combinations of acute approaches are likely to offer the greatest benefit, but present challenges in development. Promotion of recovery following stroke offers enormous potential for successful therapeutic intervention. Excitingly, new developments in preclinical research have identified possible ways in which this may be achieved.

Hyperthermia Masks the Neuroprotective Effects of Tissue Plaminogen Activator

BACKGROUND AND PURPOSE

Previously, we have shown that hyperthermia significantly increased neuronal damage after ischemic injury in a focal embolic model of stroke in rats. In the present study, we examined the effects of hyperthermia on the efficacy of thrombolytic therapy in this stroke model.

METHODS

In part A, efficacy of tissue plaminogen activator (tPA) treatment was examined in normothermic and hyperthermic rats after embolization of preformed clots into middle cerebral artery (MCA). In part B, brain perfusion deficits were assessed in rats after MCA occlusion. In part C, blood-brain barrier (BBB) permeability was examined in rats after MCA occlusion. In part D, we examined the influence of hyperthermia on fibrinolytic activity of tPA in vitro.

RESULTS

Results showed that treatment with tPA significantly reduced infarct volume in normothermic and 38 degrees C hyperthermic rats. When compared with normothermic rats, perfusion deficits in hyperthermic rats were significantly increased at both 3 hours and 6 hours after ischemic injury. Compared with normothermic sham-operated rats, Evans blue dye extravasation was increased in the injured rats with 39 degrees C hyperthermia. In vitro study showed that hyperthermia increased the fibrinolytic activity of tPA.

CONCLUSIONS

The present study shows that hyperthermia masks the neuroprotective effects of tPA treatment after ischemic injury and that this may be caused by increased BBB permeability, increased edema, and early progression of ischemic penumbral region to irreversibly damaged tissue as shown by progressively increasing perfusion deficits in hyperthermic rats.

Venous Thromboembolism After Acute Ischemic Stroke

Background and Purpose— We prospectively evaluated the prevalence and clinical risk factors for venous thromboembolism (VTE) after acute ischemic stroke using magnetic resonance direct thrombus imaging, a highly accurate noninvasive technique that directly visualizes thrombus.

Method—102 unselected patients with AIS receiving standard prophylaxis with aspirin and graded compression stockings (GCS) were sequentially recruited, underwent regular clinical assessments, and were screened for VTE.

Results— The prevalence of all VTE, proximal deep vein thrombosis (PDVT), and pulmonary embolism (PE) after 21 days were 40%, 18%, and 12%, increasing to 63%, 30%, and 20% in patients with Barthel indices (BI) of ≤9 2 days after stroke (BI-2≤9). Clinical deep vein thrombosis and PE occurred in 3% and 5% overall; half these events were overlooked by the attending team. The true incidence of clinical events is probably higher because the natural history of subclinical PDVT was modified by screening and anticoagulation. BI-2≤9 or nonambulatory status 2 days after stroke were the clinical factors most strongly associated with subsequent VTE on univariate analysis. Odds ratios for any VTE and PDVT for BI-2≤9 versus >9 were 8.3 (95% CI, 2.7 to 25.2) and 8.1 (95% CI, 1.7 to 38.3) on multivariable analysis.

Conclusion— BI ≤9 or nonambulatory status around the time of admission identifies a subgroup of acute ischemic stroke patients at very high risk for VTE in whom the current strategy of thromboprophylaxis may be inadequate. Future thromboprophylactic studies should focus on the patients at high risk defined in this study.

Antithrombotic Therapy in Children*

This article about antithrombotic therapy in children is part of the 7th American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh the 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 article are the following. In neonates with venous thromboembolism (VTE), we suggest treatment with either unfractionated heparin or low-molecular-weight heparin (LMWH), or radiographic monitoring and anticoagulation therapy if extension occurs (Grade 2C). We suggest that clinicians not use thrombolytic therapy for treating VTE in neonates, unless there is major vessel occlusion that is causing the critical compromise of organs or limbs (Grade 2C). For children (ie, > 2 months of age) with an initial VTE, we recommend treatment with i.v. heparin or LMWH (Grade 1C+). We suggest continuing anticoagulant therapy for idiopathic thromboembolic events (TEs) for at least 6 months using vitamin K antagonists (target international normalized ratio [INR], 2.5; INR range, 2.0 to 3.0) or alternatively LMWH (Grade 2C). We suggest that clinicians not use thrombolytic therapy routinely for VTE in children (Grade 2C). For neonates and children requiring cardiac catheterization (CC) via an artery, we recommend i.v. heparin prophylaxis (Grade 1A). We suggest the use of heparin doses of 100 to 150 U/kg as a bolus and that further doses may be required in prolonged procedures (both Grade 2 B). For prophylaxis for CC, we recommend against aspirin therapy (Grade 1B). For neonates and children with peripheral arterial catheters in situ, we recommend the administration of low-dose heparin through a catheter, preferably by continuous infusion to prolong the catheter patency (Grade 1A). For children with a peripheral arterial catheter-related TE, we suggest the immediate removal of the catheter (Grade 2C). For prevention of aortic thrombosis secondary to the use of umbilical artery catheters in neonates, we suggest low-dose heparin infusion (1 to 5 U/h) (Grade 2A). In children with Kawasaki disease, we recommend therapy with aspirin in high doses initially (80 to 100 mg/kg/d during the acute phase, for up to 14 days) and then in lower doses (3 to 5 mg/kg/d for > or = 7 weeks) [Grade 1C+], as well as therapy with i.v. gammaglobulin within 10 days of the onset of symptoms (Grade 1A).

Secondary stroke prevention: review of clinical trials

Patients who experience a stroke or transient ischemic attack (TIA) are at high risk for subsequent vascular events, most commonly stroke. This article focuses on clinical trials examining secondary prevention of stroke and reviews the various commonly used methods of stroke prevention: surgical approaches, antihypertensive treatment, lipid- and cholesterol-lowering medications, anticoagulant therapies, and antiplatelet therapies.

Critical Care Assessment and Management of Acute Ischemic Stroke

The resuscitation and treatment of patients with an acute stroke has evolved measurably during the past 2 decades. Acute ischemic stroke represents a true emergency where time is crucial and, therefore, evaluation and treatment often proceed simultaneously. Advanced imaging techniques can provide information about the state of brain perfusion, metabolism, and the cerebrovascular anatomy to help identify patients with viable brain tissue who may derive the greatest benefit from available therapies. Currently, several agents are available for rapid restoration of perfusion to ischemic brain. These include intravenous administration of recombinant tissue-type plasminogen activator (tPA), which is effective within a 3-hour period, and intraarterial thrombolytic therapy, which may be effective within 6 hours. In addition, newer agents such as ancrod and abciximab may be effective within the acute time period. Optimal care requires a multidisciplinary approach with attention to a wide variety of therapeutic issues while maintaining adequate brain perfusion to reverse or halt the ischemic process. Herein, the author examines the important therapeutic concerns in the critical care management of ischemic stroke, including the management of elevated intracranial pressure, elevated and low blood pressure, cardiac complications, and potential metabolic disturbances.

Ximelagatran compared with warfarin for prevention of thromboembolism in patients with nonvalvular atrial fibrillation: Rationale, objectives, and design of a pair of clinical studies and baseline patient characteristics (SPORTIF III and V)

BACKGROUND

Ximelagatran is a novel, oral direct thrombin inhibitor under investigation as an alternative to warfarin for prevention of thromboembolism in patients with nonvalvular atrial fibrillation (AF). Two long-term studies in patients with AF and at least one additional risk factor for stroke are underway to compare the safety and efficacy of fixed-dose ximelagatran (36 mg bid) without coagulation monitoring with dose-adjusted warfarin (international normalized ratio 2.0-3.0).

METHODS

SPORTIF III is a randomized, open-label, parallel-group study with blinded event assessment involving 3407 patients at 259 sites in 23 countries. SPORTIF V is similar, but with double-blind treatment allocation involving 3922 patients at 409 North American sites. The primary end point in each study is the incidence of all strokes and systemic embolic events, and the objective is to establish the noninferiority of ximelagatran relative to warfarin. Secondary end point constellations include (1) death, stroke, systemic embolism, and myocardial infarction; (2) ischemic stroke, transient ischemic attack, and systemic embolism; and (3) bleeding and treatment discontinuation. Blinded central committees adjudicate all end points and monitor patient safety. The studies commenced July 2000; enrollment ended in December 2001. Each study will accrue > or =4000 patient-years and > or =80 primary end points with a minimum per-patient exposure of 12 months. Combined analysis of both studies is also planned.

RESULTS

The demographics of the 2 patient populations are similar and should allow the studies to meet the objective.

CONCLUSIONS

The program, the largest conducted in this indication, will determine the safety and antithrombotic efficacy of ximelagatran as an alternative to warfarin for prevention of thromboembolism in patients with AF.

Antithrombotic drug treatment of pediatric patients with ischemic stroke

Causes of stroke in children include congenital heart malformations, sickle cell disease, infections, and metabolic disorders. Up to 80% of children with ischemic stroke have cerebrovascular disease, and case control studies demonstrate an association of ischemic stroke in children with hereditary prothrombotic risk factors. There have been no randomized, clinical trials for primary prevention, short-term treatment, or secondary prevention of pediatric ischemic stroke. Treatment recommendations are based on small case series or case reports, and have mainly been adapted from adult stroke studies. Antiplatelet agents (e.g. aspirin [acetylsalicylic acid]) and heparins (e.g. low molecular weight heparin), have been used on an individual patient basis. Warfarin is administered in children with cardioembolic stroke, arterial dissection, or persistent hypercoagulable states. Alteplase has been used in a few patients within 3 hours of the onset of symptoms. In each patient treated the benefit of anticoagulation has to be weighed up against the individual bleeding risk.

Need for Continued Use of Anticoagulants After Intracerebral Hemorrhage

One of the unsolved dilemmas in cerebrovascular disease is the ideal timing to restart anticoagulant therapy (ACT) safely in patients who have suffered an intracranial hemorrhage and have an indication to continue ACT. No randomized studies with evidence-based data are available to settle this issue. Only a few reports have been published; their shortcomings include small numbers of patients evaluated retrospectively, a broad spectrum of indications for ACT, different types of hemorrhage, and variable methods of reversing and restarting ACT. Despite this variability, most reports agree that 1) ACT has to be immediately reversed to decrease the risk of hemorrhage progression; 2) a period between 1 and 2 weeks appears sufficient to allow for management and monitoring of the hemorrhage off ACT; and 3) ACT can be safely restarted after the period off of treatment. A physician confronting a patient with intracranial hemorrhage and the need for ACT faces a situation of individually focused clinical decision making. The problem rests in balancing the risks of a worsening or recurring hemorrhage on one side, and the risk of thromboembolism on the other. From available information and personal experience, an unvalidated risk stratification can be proposed to categorize patients in low- and high-risk groups for hemorrhagic complications and embolic phenomena, assigning them to 5 or 15 days off ACT, respectively. Intermediate-risk patients can have ACT restarted in 5 to 15 days from the onset of the intracranial hemorrhage. Anticoagulation should be immediately reversed. Fresh frozen plasma is the standard treatment in most institutions. Prothrombin complex concentrate is an alternative, but issues of availability make its use impractical. The use of recombinant factor VIIa is an attractive new option.

Drug therapy of neurovascular disease

Recent advances in the prevention and pharmacotherapy of cerebrovascular disease have provided more favorable clinical outcomes. For the treatment of an acute ischemic stroke, the early use of thrombolytic agents can reduce the degree of brain damage while improving functional outcomes. However, trials evaluating various classes of other neuroprotective agents have not shown benefit to date. For the prevention of second stroke, the use of antiplatelet drugs, HMG-CoA reductase inhibitors, and angiotensin-converting enzyme inhibitors with a diuretic have shown benefit in reducing new events. In patients with underlying heart disease or atrial fibrillation, warfarin appears to be the drug of choice in preventing stroke. Early treatment of hemorrhagic stroke with calcium channel blockers can improve the functional outcome. Innovative therapies are now available for the treatment of migraine and vascular dementia. Primary prevention of stroke remains the optimal therapeutic strategy and includes treatment of systemic hypertension and hypercholesterolemia.

Acute stroke thrombolysis with intravenous tissue plasminogen activator in an Australian tertiary hospital

OBJECTIVE

To report initial experience with the use of intravenous tissue plasminogen activator (tPA) to treat acute ischaemic stroke at an Australian tertiary-care hospital.

DESIGN

Retrospective audit of computerised hospital stroke database.

PARTICIPANTS AND SETTING

All patients with acute ischaemic stroke treated with intravenous tPA between April 1999 and July 2002 at the Royal Melbourne Hospital, VIC.

MAIN OUTCOME MEASURES

Times from stroke onset to arrival at the emergency department (ED) and treatment; rates of symptomatic intracerebral haemorrhage (ICH); clinical outcome at three months; and violations of treatment protocol.

RESULTS

Of 932 patients admitted with ischaemic stroke, 30 were treated with intravenous tPA. Median time from stroke onset to tPA treatment was 2 h 48 min, and median door-to-needle time was 1 h 49 min. Door-to-needle time improved in the last 12 months of the audit, with four of 15 patients achieving the recommended 60 min. Eleven patients (37%) had excellent clinical outcomes at three-month follow-up (modified Rankin score, 0-1), and 15 (50%) were functionally independent (score, 0-2). Mortality rate was 10%, similar to that of all ischaemic stroke patients during the audit period. Two patients (7%) had symptomatic ICH. Treatment deviated from protocol in seven patients (23%), five of whom received tPA over three hours after stroke onset.

CONCLUSION

Rates of favourable outcomes and symptomatic ICH at our hospital were similar to those achieved in international phase III and IV trials in specialised centres.

Rapid platelet inhibition after a single capsule of Aggrenox: challenging a conventional full-dose aspirin antiplatelet advantage?

Aggrenox is a novel combination of 25 mg of aspirin with 200 mg of sustained release dipyridamole. In a recent large trial (ESPS-2), Aggrenox was twice as effective for secondary stroke prevention as either aspirin or dipyridamole alone, suggesting superior platelet inhibition for combination therapy. We sought to compare the time course of platelet inhibition with Aggrenox compared with escalating doses of non-enteric coated aspirin. Data from 10 healthy volunteers were analyzed. Fasting subjects sequentially ingested aspirin in the following order: 325 mg, 81 mg, 25 mg, and then one pill of Aggrenox after a 3-week interval for aspirin washout. Platelet function was assessed at baseline, 15, 30, 60, and 120 min post-medication with 5 microM epinephrine and 5 microM ADP using conventional aggregometry. Aspirin provided significant (P < 0.01) reduction of platelet aggregation at 15 min post 325 mg, 30 min post 81 mg, and unexpectedly within 60 min after taking 25 mg of aspirin. A single pill of Aggrenox also inhibited platelet aggregation within 1 hr after administration. Aspirin inhibits platelets remarkably fast. Both Aggrenox and a matching dose of aspirin (25 mg) exhibit significant antiplatelet properties within 60 min after ingestion. These findings could be relevant for the optimal balance between the reduction of vascular events via sufficient and rapid platelet inhibition and low risk of bleeding complications associated with the Aggrenox therapy.

Hemoglobinopathies

The outlook for patients with sickle cell disease has improved steadily during the last two decades. In spite of these improvements, curative therapies are currently available only to a small minority of patients. The main theme of this chapter is to describe new therapeutic options that are at different stages of development that might result in further improvements in the outlook for patients with these disorders.

Dr. Joseph DeSimone and his colleagues had previously made the important observation that the hypomethylating agent 5-azacytidine can reverse the switch from adult to fetal hemoglobin in adult baboons. Although similar activity was demonstrated in patients with sickle cell disease and β-thalassemia, concern about the toxicity of 5-azacytidine prevented its widespread use in these disorders. In Section I, Dr. DeSimone discusses the role of DNA methylation in globin gene regulation and describe recent clinical experience with decitabine (an analogue of 5-azacytidine) in patients with sickle cell disease. These encouraging studies demonstrate significant fetal hemoglobin inducing activity of decitabine in patients who fail to respond to hydroxyurea.

In Section II, Dr. George Atweh continues the same theme by describing recent progress in the study of butyrate, another inducer of fetal hemoglobin, in patients with sickle cell disease and β-thalassemia. The main focus of his section is on the use of a combination of butyrate and hydroxyurea to achieve higher levels of fetal hemoglobin that might be necessary for complete amelioration of the clinical manifestations of these disorders. Dr. Atweh also describes novel laboratory studies that shed new light on the mechanisms of fetal hemoglobin induction by butyrate.

In Section III, Dr. Ronald Nagel discusses the different available transgenic sickle mice as experimental models for human sickle cell disease. These experimental models have already had a significant impact on our understanding of the pathophysiology of sickle cell disease. Dr. Nagel describes more recent studies in which transgenic sickle mice provide the first proof of principle that globin gene transfer into hematopoietic stem cells inhibits in vivo sickling and ameliorates the severity of the disease.

Although stroke in adult patients with sickle cell disease is not as common as in children, adult hematologists, like their pediatric colleagues, need to make management decisions in adult patients with a stroke or a history of stroke. Dr. Robert Adams has led several large clinical studies that investigated the role of transfusions in the prevention of stroke in children with sickle cell disease. Much less is known, however, about the prevention of first or subsequent strokes in adult patients with sickle cell disease. In Section IV, Dr. Adams provides some general guidelines for the management of adult patients with stroke while carefully distinguishing between recommendations that are evidence-based and those that are anecdotal in nature.

Treatment and monitoring of patients with antiphospholipid antibodies and thrombotic history (Hughes syndrome)

Patients with Hughes (antiphospholipid) syndrome who develop an initial thrombosis have an increased risk of subsequent thrombotic events. Current therapy to prevent recurrent thrombosis is controversial. While it seems clear that anticoagulant treatment is a better option than anti-aggregants alone, there is no consensus regarding the duration and intensity of oral anticoagulation. The risk of bleeding, the main complication of anticoagulant treatment, and the need for frequent monitoring of the International Normalized Ratio to measure the anticoagulant effect of warfarin concern patients and physicians. In addition, there is some debate about the validity of the International Normalized Ratio in patients with lupus anticoagulant activity. The development of new therapies that target more specific pathogenic mechanisms is highly warranted.

Racial differences in the prevalence of cardiac sources of embolism in subjects with unexplained stroke or transient ischemic attack evaluated by transesophageal echocardiography

Little is known about the distribution of cardiac sources of embolism among African-Americans with cryptogenic cerebrovascular events. We compared the prevalence of potential cardiac sources of embolism between black and white patients referred to our laboratory for transesophageal echocardiographic (TEE) evaluation of unexplained stroke or transient ischemic attack. Records were reviewed to exclude subjects with high-risk cardiac or vascular disorders likely to explain the index event. Of 297 patients satisfying the inclusion criteria, 196 were white and 87 black. Potential cardioembolic sources were significantly less common in blacks than in whites (adjusted odds ratio [OR], 0.44; 95% confidence interval [CI] 0.26 to 0.75), and related largely to the difference in prevalence of interatrial communication (OR 0.40; 95% CI 0.21 to 0.74). In contrast, African-Americans had a higher prevalence of left ventricular (LV) hypertrophy (OR 3.50; 95% CI 1.97 to 6.22), and particularly, moderate or severe hypertrophy (OR 4.03; 95% CI 1.88 to 9.65) compared with whites. In conclusion, in African-Americans with unexplained cerebrovascular events, the yield of TEE for potential cardioembolic sources, and especially interatrial communication, is lower than in their white counterparts. African-Americans exhibit a substantially higher prevalence of LV hypertrophy, which may be a marker for a higher burden of subclinical cerebrovascular disease involved in the pathogenesis of cryptogenic cerebral ischemia in this population.

Weighted regularization in electrical impedance tomography with applications to acute cerebral stroke

We apply electrical impedance tomography to detect and localize brain impedance changes associated with stroke. Forward solutions are computed using the finite-element method in two dimensions. We assume that baseline conductivity values are known for the major head tissues, and focus on changes in the brain compartment only. We use singular-value decomposition (SVD) to show that different impedance measurement patterns, which are theoretically equivalent by the reciprocity theorem, have different sensitivities to the brain compartment in the presence of measurement noise. The inverse problem is solved in part by standard means, using iterated SVD, and regularizing by truncation. To improve regularization we introduce a weighting scheme which normalizes the sensitivity matrix for voxels at different depths. This increases the number of linearly independent components which contribute to the solution, and forces the different measurement patterns to have similar sensitivity. When applied to stroke, this weighted regularization improves image quality overall.

Combined central retinal arterial and venous obstruction: emergency ophthalmic arterial fibrinolysis

PURPOSE

To investigate the role of urokinase selectively perfused into the ophthalmic artery as an emergency treatment for combined central retinal arterial obstruction (CRAO) and central retinal venous obstruction (CRVO).

MATERIALS AND METHODS

Over a 6-year period, 11 consecutive patients presented with recent combined CRAO and CRVO (< or =72 hours). Urokinase (300,000 IU) was selectively perfused via the femoral artery into the ophthalmic artery for 40 minutes. Evaluation criteria were Snellen visual acuity with best correction, funduscopic results, and retinal arteriovenous transit time assessed over a mean 3.5-year follow-up. Mean vision and retinal perfusion were tested by means of repeated-measures analysis of variance. The correlation between visual improvement and retinal perfusion improvement was evaluated by means of Spearman rank correlation.

RESULTS

Substantial improvement in vision and retinal perfusion was noted in seven of the 11 patients treated. Mean vision improvement was significant (P =.009) within 24-48 hours after fibrinolysis, increased until 1 month after (P =.006), then remained stable throughout the follow-up (P >.10). Visual improvement correlated with retinal perfusion improvement during the period from before fibrinolysis to 24-48 hours after (P =.028). In all patients with improved results, retinal hemorrhages transiently increased. One patient had intravitreal hemorrhage shortly after fibrinolysis.

CONCLUSION

For this uncommon clinical entity, which typically has a poor visual outcome, these results suggest that ophthalmic arterial fibrinolysis may restore retinal perfusion, which leads to rapid substantial visual improvement in many cases of combined CRAO and CRVO, without systemic complications, but it may be responsible for intravitreal hemorrhage.

Stroke prevention therapy beyond antithrombotics: unifying mechanisms in ischemic stroke pathogenesis and implications for therapy: an invited review

BACKGROUND

It is estimated that about half of cardiovascular disease risk is explained by conventional risk factors. The realization that atherosclerosis is an inflammatory disease has led to a search for new stroke and cardiovascular disease risk factors and treatments. As such, the vulnerable atherosclerotic plaque has become the main focus for new medical strategies for plaque stabilization and stroke prevention.

SUMMARY OF REVIEW

In this invited review, I discuss inflammation as a possible risk factor for stroke, unifying mechanisms in ischemic stroke pathogenesis, and new avenues for stroke prevention---statin agents, angiotensin-converting enzyme inhibitors, and vitamins. These new stroke prevention therapies may help to reduce inflammation, serve to stabilize the atherosclerotic plaque, or act by other protective mechanisms.

CONCLUSION

Beyond the traditional antithrombotic agents, statin agents, angiotensin-converting enzyme inhibitors, and vitamins may prove to be important additions to our armamentarium for stroke prevention.

Inhibition of factor IX(a) is protective in a rat model of thromboembolic stroke

BACKGROUND AND PURPOSE

Although used clinically to prevent stroke, there are few examples of anticoagulant investigations in the treatment of acute thromboembolic stroke in animal models. The treatment of thromboembolic stroke in experimental models has been investigated almost exclusively around the use of tissue plasminogen activator (tPA). In this study, using a rat thromboembolic stroke model, we investigated the use of an inhibitory anti-factor IX(a) monoclonal antibody (SB 249417) for the treatment of thromboembolic stroke and compared its efficacy to that of tPA.

METHODS

Stroke was initiated by delivering 6 clots into the internal carotid artery. After 2, 4, or 6 hours, rats received either intravenous vehicle, 10.0 mg/kg tPA, or 1.0, 2.0, or 3.0 mg/kg SB 249417. At 24 hours after stroke, infarct volumes and neurological deficits were assessed.

RESULTS

Treatment with tPA 2, 4, or 6 hours after stroke reduced infarct volumes by 35% (P=NS), 45%, and 39%, respectively. tPA treatment did not improve neurological deficits at any time point. Treatment with SB 249417 (3.0 mg/kg) 2, 4, or 6 hours after stroke reduced infarct volumes by 44%, 50%, and 13% (P=NS), respectively. Neurological deficits were reduced by 49%, 42%, and 13% (P=NS), respectively. Neither mortality nor hemorrhage was affected by either treatment.

CONCLUSIONS

The data indicate that the inhibition of factor IX(a) within 4 hours of thromboembolic stroke produced a more favorable outcome than tPA. When treatment was initiated 6 hours after stroke, the benefits of factor IX(a) inhibition were lost, whereas tPA continued to suppress lesion development, albeit without a corresponding improvement in functional deficits. This study suggests that cerebral ischemia and the resultant perfusion deficit are exacerbated by the activation of blood coagulation and that anticoagulants like SB 249417 may find utility in the treatment of ischemic stroke.

Aging has a complex effect on a rat model of ischemic stroke

Stroke in humans is usually associated with advanced age. Nevertheless, almost all animal models of ischemic stroke are based on young animals. The present study was designed to assess the effect of age on the development of ischemic injury in a model of focal brain ischemia in rats. Two age groups of Wistar rats were used: young adult (3 months) and old (24-26 months). Under halothane anesthesia, polyethylene microspheres (50 microm in diameter) were injected into the left common carotid artery following a temporary occlusion of the external carotid artery. Sham-operated rats underwent the same procedure but were injected with an identical volume (100 microl) of saline only. Rats of both experimental groups displayed neurological impairment after surgery. However, contrary to expectation, the young rats were more affected than the old rats. Young rats displayed an abrupt 30% decrement in neurological functions in the first week and then showed a partial functional recovery into a 12% decrement from the second week on. Old rats developed the neurological impairment gradually over a 2-week period (6.3% in the first week and 11% in the second week and thereafter). One month later, rats were tested in a water maze task. Again, performance was more impaired in the young ischemic rats than in the old rats. Histological evaluation revealed more extensive neurological damage in young ischemic as compared to old rats. Thus, although increased age has a critical effect on the evolution of the neurological impairment following focal brain ischemia and stroke, its effects in the rat model were more pronounced in the young animals.

Improving delivery of acute stroke therapy: The TLL Temple Foundation Stroke Project

BACKGROUND AND PURPOSE

Only a small minority of acute stroke patients receive approved acute stroke therapy. We performed a community and professional behavioral intervention project to increase the proportion of stroke patients treated with approved acute stroke therapy.

METHODS

This study used a quasi-experimental design. Intervention and comparison communities were compared at baseline and during educational intervention. The communities were based in 5 nonurban East Texas counties. The multilevel intervention worked with hospitals and community physicians while changing the stroke identification skills, outcome expectations, and social norms of community residents. The primary goal was to increase the proportion of patients treated with intravenous recombinant tissue plasminogen activator (rTPA) from 1% to 6% of all cerebrovascular events in the intervention community.

RESULTS

We prospectively evaluated 1733 patients and validated 1189 cerebrovascular events. Intravenous rTPA treatment increased from 1.38% to 5.75% among all cerebrovascular event patients in the intervention community (P=0.01) compared with a change from 0.49% to 0.55% in the comparison community (P=1.00). Among the ischemic stroke patients, an increase from 2.21% to 8.65% was noted in the intervention community (P=0.02). The comparison group did not appreciably change (0.71% to 0.86%, P=1.00). Of eligible intravenous rTPA candidates, treatment increased in the intervention community from 14% to 52% (P=0.003) and was unchanged in the comparison community (7% to 6%, P=1.00).

CONCLUSIONS

An aggressive, multilevel stroke educational intervention program can increase delivery of acute stroke therapy. This may have important public health implications for reducing disability on a national level.

Aggrenox: an aspirin and extended-release dipyridamole combination

Stroke is one of the leading causes of death in the United States. The risk of experiencing a recurrent stroke remains elevated for several years after an initial stroke or a transient ischemic attack (TIA), therefore secondary prevention is crucial in reducing the risk of stroke and the complications and costs associated with stroke. Aggrenox, a combination of low-dose aspirin and extended-release dipyridamole, is a new agent that is effective in the secondary prevention of stroke and transient ischemia of the brain. The clinical effect of its two antiplatelet agents are additive and significantly better than either aspirin or dipyridamole alone, although it has not been shown to be more effective than aspirin alone in preventing death. Aggrenox is much more expensive than aspirin alone but has been shown to be more cost-effective. At this point, much of the pharmacologic information concerning this combination agent is based on previous data about aspirin and immediate-release dipyridamole. This combination of aspirin and extended-release dipyridamole may play a significant role in secondary stroke and TIA prevention.

Tinzaparin in acute ischaemic stroke (TAIST): a randomised aspirin-controlled trial

BACKGROUND

Low-molecular-weight heparins and heparinoids are superior to unfractionated heparin in the prevention and treatment of venous thromboembolism, but their safety and efficacy in acute ischaemic stroke are inadequately defined.

METHODS

This randomised, double-blind, aspirin-controlled trial tested the safety and efficacy of treatment with high-dose tinzaparin (175 anti-Xa IU/kg daily; 487 patients), medium-dose tinzaparin (100 anti-Xa IU/kg daily; 508 patients), or aspirin (300 mg daily; 491 patients) started within 48 h of acute ischaemic stroke and given for up to 10 days. Primary intracerebral haemorrhage was excluded by computed tomography. Outcome was assessed, with treatment allocation concealed, by the modified Rankin scale at 6 months (independence [scores 0-2] vs dependence or death [scores 3-6]).

FINDINGS

Of 1486 randomised patients, two did not receive treatment and 46 were lost to follow-up. The proportions independent at 6 months were similar in the groups assigned high-dose tinzaparin (194/468 [41.5%]), medium-dose tinzaparin (206/486 [42.4%]), or aspirin (205/482 [42.5%]). There was no difference in effect in any predefined subgroup, including patients with presumed cardioembolic stroke. Other outcome measures were similar between the treatment groups (disability, case-fatality, and neurological deterioration rates). During the in-hospital treatment period no patient assigned high-dose tinzaparin developed a symptomatic deep-vein thrombosis compared with nine assigned aspirin. Conversely, seven patients assigned high-dose tinzaparin developed symptomatic intracerebral haemorrhage compared with one in the aspirin group.

INTERPRETATION

Treatment with tinzaparin, at high or medium dose, within 48 h of acute ischaemic stroke did not improve functional outcome compared with aspirin. Although high-dose tinzaparin was superior in preventing deep-vein thrombosis, it was associated with a higher rate of symptomatic intracranial haemorrhage.

Compliance with secondary prevention of ischemic stroke: a prospective evaluation

BACKGROUND AND PURPOSE

Compliance with pharmacological therapy is essential for the efficiency of secondary prevention of ischemic stroke. Few data exist regarding patient compliance with antithrombotic and risk factor treatment outside of controlled clinical trials. The aim of the present study was to assess the rate of and predictors for compliance with secondary stroke prevention 1 year after cerebral ischemia and to identify reasons for noncompliance.

METHODS

Patients with a diagnosis of ischemic stroke or TIA and antithrombotic discharge medication were prospectively recruited. At 1 year, the proportion of patients compliant with antithrombotic treatment and with medication for risk factors (eg, hypertension, diabetes, hyperlipidemia) was evaluated through structured telephone interviews. In addition, the reasons for nontreatment with antithrombotic and risk factor medication were determined. Independent predictors for compliance were analyzed by logistic regression analyses.

RESULTS

Of 588 consecutive patients admitted to our stroke unit, 470 had a discharge diagnosis of cerebral ischemia (TIA 26.2%, cerebral infarct 73.8%) and recommendations for antithrombotic therapy. At 1 year, 63 patients (13.4%) had died and 21 (4.5%) were lost to follow-up, thus, 386 could finally be evaluated. Of the patients, 87.6% were still on antithrombotic medication, and 70.2% were treated with the same agent prescribed on discharge. Of the patients with hypertension, diabetes, and hyperlipidemia, 90.8%, 84.9%, and 70.2% were still treated for their respective risk factors. Logistic regression analyses revealed age (OR 1.03, 95% CI 1.00 to 1.06), stroke severity on admission (OR 1.09, 95% CI 1.00 to 1.20), and cardioembolic cause (OR 4.13, 95% CI 1.23 to 13.83) as independent predictors of compliance.

CONCLUSIONS

Compliance with secondary prevention in patients with ischemic stroke is rather good in the setting of our study. Higher age, a more severe neurological deficit on admission, and cardioembolic stroke cause are associated with better long-term compliance. Knowledge of these determinants may help to further improve the quality of stroke prevention.