Cavitary lung disease

Trends in Usage of Alternative Antiplatelet Therapy After Stroke and Transient Ischemic Attack

Background and Purpose— The effects of alternative antiplatelet agents such as clopidogrel and dipyridamole have been studied in clinical trials and heavily marketed. Because public data on their usage are limited, we examined trends in their prescription after stroke and transient ischemic attack to assess the impact of marketing and trial results.

Methods— Between 2001 and 2005, 85 US hospitals prospectively enrolled all patients admitted with ischemic stroke or transient ischemic attack into a registry designed for quality improvement (Ethos). Data on rates of antiplatelet medication usage at discharge were examined over time, and trends were evaluated by the Mantel-Haenszel test.

Results— Among 18 020 patients included during the 4-year period, 89% were discharged on antithrombotic medication. Between the first quarter of 2001 and the first quarter of 2004, prescription of clopidogrel-aspirin doubled ( P <0.0001 for trend), coincident with publication of results from CURE and CREDO showing efficacy in patients with acute coronary syndromes. Monotherapy with aspirin or clopidogrel decreased concomitantly, and use of dipyridamole-aspirin remained constant. After an increased bleeding risk was reported in the clopidogrel-aspirin arm of the MATCH trial, use of the combination decreased sharply from 31.5% in the first quarter of 2004 to 12.8% in the first quarter of 2005 ( P <0.0001), while an increase was seen in the use of clopidogrel alone (7.6% to 12.8%, P =0.03) and dipyridamole-aspirin (7.4% to 20.2%, P <0.0001).

Conclusions— Clopidogrel and dipyridamole-aspirin are used frequently after stroke or transient ischemic attack. Use of clopidogrel-aspirin was common in patients with recent ischemic stroke before the publication of MATCH, after which rates dramatically declined and use of dipyridamole-aspirin and clopidogrel alone increased.

Veterans Affairs/Department of Defense Clinical Practice Guideline for the Management of Adult Stroke Rehabilitation Care: executive summary

BACKGROUND

A panel of experts developed stroke rehabilitation guidelines for the Veterans Health Administration and Department of Defense Medical Systems.

METHODS

Starting from previously established guidelines, the panel evaluated published literature through 2002, using criteria developed by the US Preventive Services Task Force. Recommendations were based on evidence from randomized clinical trials, uncontrolled studies, or consensus expert opinion if definitive data were lacking.

RESULTS

Recommendations with Level I evidence include the delivery of poststroke care in a multidisciplinary rehabilitation setting or stroke unit, early patient assessment via the NIH Stroke Scale, early initiation of rehabilitation therapies, swallow screening testing for dysphagia, an active secondary stroke prevention program, and proactive prevention of venous thrombi. Standardized assessment tools should be used to develop a comprehensive treatment plan appropriate to each patient's deficits and needs. Medical therapy for depression or emotional lability is strongly recommended. A speech and language pathologist should evaluate communication and related cognitive disorders and provide treatment when indicated. The patient, caregiver, and family are essential members of the rehabilitation team and should be involved in all phases of the rehabilitation process. These recommendations are available in their entirety at http://stroke.ahajournals.org/cgi/content/full/36/9/e100. Evidence tables for each of the recommendations are also in the full document.

CONCLUSIONS

These recommendations should be equally applicable to stroke patients receiving rehabilitation in all medical system settings and are not based on clinical problems or resources unique to the Federal Medical System.

Therapy implications of transthoracic echocardiography in acute ischemic stroke patients

BACKGROUND AND PURPOSE

Stroke is the third leading cause of death in most Western countries. Cardioembolism might be responsible for 15% to 20% of ischemic strokes. Although atrial fibrillation can be diagnosed by electrocardiography, the remaining causes of cardioembolic stroke are diagnosed by echocardiography. Recent recommendations on the management of acute ischemic stroke fail to consider echocardiography as an essential test in all patients.

METHODS

We conducted a prospective observational study, performing transthoracic echocardiography on all patients admitted in our hospital with ischemic stroke, in sinus rhythm, from January 7, 2002, to October 16, 2003. Findings compatible with heart diseases that would indicate anticoagulation as beneficial were identified.

RESULTS

Of the 853 patients admitted with ischemic stroke, transthoracic echocardiography was performed on 846 (99.2%). Of the 435 patients with ischemic stroke, in sinus rhythm, 37.2% had findings indicating anticoagulation as beneficial: dilated cardiopathy (19.1%), previous anterior wall myocardial infarction (6.2%), left ventricular systolic dysfunction with an ejection fraction <35% (3.7%), mitral valve stenosis with enlarged left atria (1.6%), intracardiac masses (0.5%), valvular prosthesis (0.2%), and >1 abnormality (5.5%).

CONCLUSIONS

In our study, transthoracic echocardiography had therapy implications in 37.2% of ischemic stroke patients in sinus rhythm. Transthoracic echocardiography should be considered an essential test in all ischemic stroke patients in sinus rhythm.

Costs of stroke care according to handicap levels and stroke subtypes

BACKGROUND

If new advances in stroke management are to be put into practice, crucial information about their costs needs to be considered in relation to clinically pertinent variables (e.g. handicap level and stroke subtypes). Details of costs throughout the entire period of stroke care are essential in the political decision-making process, in order to avoid other budget-balancing approaches, which are not always satisfactory. Our aim was to perform an in-depth evaluation of the direct medical cost of stroke care in a large cohort.

METHODS

We included 435 consecutive patients with brain infarction in 12 primary-care and referral neurology departments. Information on acute care was prospectively collected. Information on postacute care was collected by research nurses' visits to the patient's or a relative's home 18-40 months after the stroke onset. We thus collected detailed information on handicap levels, stroke subtypes, acute hospitalization costs, rehabilitation, nursing care and ambulatory costs. This enabled us to calculate costs over an 18-month period after the initial acute hospital discharge.

RESULTS

By the 12th month after discharge, the costs amounted to 17,799 euros (16,440-19,158) per patient; the initial hospitalization accounted for 42% of this cost, rehabilitation for 29% and ambulatory care for 8%. These costs were mostly concentrated within the first 3- to 6-month period. After 46 months without recurrence, the cost of ambulatory care outweighed the cost of the first 6 months. Handicap levels explained 43% of the variance of costs (p < 0.0001) and, according to the Rankin scale divided into 3 classes (0-2, 3 and 4-5), cumulative costs over time differed considerably. Stroke subtypes were not discriminating variables except for lacunar strokes, which were significantly less costly than the other groups.

CONCLUSIONS

By providing a fairly comprehensive figure for the details of direct costs of stroke care over time, our study gives some clues about the economic burden of stroke care which is mostly driven by a high handicap level. This suggests that any early intervention aimed at reducing the handicap level will probably dramatically reduce this burden.

Recent clinical trial results with antiplatelet therapy: implications in stroke prevention

Dual antiplatelet therapy that inhibits more than one pathway of platelet activation is appealing and biologically rational. The CURE study evaluated the efficacy and safety of clopidogrel on top of acetylsalicylic acid (ASA) versus standard therapy (including ASA) in over 12,000 patients with unstable angina or non-ST-segment elevation myocardial infarction (MI). Clopidogrel in combination with ASA reduced the relative risk of the combined atherothrombotic endpoint of cardiovascular death, MI or stroke by 20% (95% CI 0.72-0.90; p < 0.001) and the absolute risk of this composite endpoint by 2.1%. While the study was not powered or designed to demonstrate a reduction in stroke, there was a 14% reduction in stroke risk (p > 0.05). Dual antiplatelet therapy was associated with an acceptable 1% increase in the incidence of major bleeding events (p = 0.001). PCI-CURE, a prespecified substudy of patients who underwent percutaneous coronary intervention (PCI) during CURE, confirmed the early and sustained benefits of clopidogrel therapy seen in the overall CURE study. CREDO was a randomized, double-blind, placebo-controlled trial in more than 2,100 patients that evaluated the continuation of clopidogrel on top of standard therapy including ASA for 12 months after PCI, and the benefit of a preprocedural clopidogrel loading dose. The long-term results at 1 year showed that there was a 27% reduction in the risk of stroke, MI or death with long-term clopidogrel therapy (p = 0.02). There was a consistent benefit of extended clopidogrel therapy for each component of the composite endpoint, with a 25.1% relative risk reduction for all-cause stroke. In patients who received clopidogrel > or =6 h before PCI, there was a 39% reduction in the risk of death, MI or urgent target-vessel revascularization at 28 days (p = 0.051). These data suggest important implications in the future for the use of an early loading dose of clopidogrel in patients undergoing carotid stenting and, if proven in current or future trials, the use of a loading dose followed by long-term continuation of clopidogrel in other high-risk atherothrombotic patients such as those with transient ischaemic attack or ischaemic stroke.

The unstable plaque

Ischaemic strokes and transient ischaemic attacks are commonly caused by cerebral embolism originating from formation of a platelet-rich thrombus superimposed on an atherosclerotic plaque or by atherothrombotic plaque rupture in a carotid or intracranial artery. Despite advances made through ultrasound imaging in our understanding of atherosclerotic plaque progression and regression, the issue of whether differences in plaque structure alone can distinguish between lesions that become symptomatic and others that remain clinically silent continues to be debated. Recent biochemical and imaging studies have identified characteristics that may reflect a high risk of vulnerability, such as outward, abluminal plaque remodelling, the presence of intra-plaque haemorrhage, inflammation, severe flow disturbances around the encroaching lesion, plaque cap thinning and ulceration, and abnormal plaque motion. Plaque stability may be improved through management of traditional cardiovascular risk factors or with biological or pharmacological agents that target pathways involved in plaque pathophysiology. Unstable plaques place patients at risk of unpredictable ischaemic events and in patients with such lesions, specific preventive treatment beyond long-term antiplatelet therapy can be used to prevent new or recurrent events.

Attrition and non-compliance in secondary stroke prevention trials

BACKGROUND

Attrition and non-compliance of subjects in secondary stroke prevention trials due to study drug-induced adverse events and loss to follow-up could lead to bias and loss of information, thus affecting the analysis of study results.

METHODS

We reviewed results from ten antiplatelet stroke prevention clinical trials: CAN TIA, DUTCH TIA, SWED ASA, SALT, UK TIA, CATS, TASS, ESPS, ESPS-2, and CAPRIE to tabulate the frequencies for total subject discontinuation, voluntary withdrawal, and loss to follow-up.

RESULTS

Forty thousand seven hundred and thirty (40,730) subjects participated in the aforementioned secondary stroke prevention trials. The range of outcomes was 11.8-52.0% for subjects discontinued for any reason (n = 9 trials); 3.0-20.9% for study drug-induced adverse events (n = 9 trials), and 4.2-7.8% for voluntary withdrawal (n = 10 trials).

CONCLUSION

There is a substantial discrepancy (up to 20%) between the frequencies of total subject discontinuation for any reason and the sum of study drug-induced adverse events, voluntary withdrawal and loss to follow-up. Underestimation of these important outcomes may limit the ability of clinicians to translate results from clinical trials into medical practice.

Usefulness of anticoagulants in the prevention of ischemic stroke

Oral anticoagulants are drugs commonly used in the prevention of vascular diseases, especially in embolic-type processes. Although several studies have assessed the possibility of using them in arterial processes, the experience has not been satisfactory so far. Heart diseases with major emboligenic flow are still the main indication, while the prevention of other low-risk heart diseases and treatment of large- or small-artery disease can be based on antiaggregant treatment. Other groups study the problem in large series.

Tissue Plasminogen Activator for Acute Ischemic Stroke in Clinical Practice

Background and Purpose— Concerns persist regarding the safety of tissue plasminogen activator (tPA) therapy for acute ischemic stroke. Numerous case series of clinical experience with tPA have been published that provide additional data on the safety of thrombolytic therapy.

Methods— This is a meta-analysis of 15 published, open-label studies that broadly followed approved indications and guidelines for tPA use in nonselective patient populations.

Results— In 2639 treated patients, the symptomatic intracerebral hemorrhage rate was 5.2% (95% confidence interval, 4.3 to 6.0), slightly lower than the 6.4% rate in the treated group of the randomized, placebo-controlled National Institute of Neurological Disorders and Stroke (NINDS) trial. The mean total death rate (13.4%) and proportion of subjects achieving a very favorable outcome (37.1%) were comparable to the NINDS trial results. Protocol deviations were reported in 19.8%. Comparing across studies showed that the mortality rate was correlated with the percentage of protocol violations ( r =0.67, P =0.018).

Conclusions— Postapproval data support the safety of intravenous thrombolytic therapy with tPA for acute ischemic stroke, especially when established treatment guidelines are followed.

Racial disparities in receipt of secondary stroke prevention agents among US nursing home residents

BACKGROUND AND PURPOSE

Although medications can significantly reduce the risk of recurrent stroke, little is known about the extent to which such therapies are given to nursing home residents. We sought to evaluate the extent to which people of color were less likely to receive pharmacological agents in the treatment of recurrent stroke while living in US nursing homes.

METHODS

We identified 19 051 residents with a recent hospitalization and primary discharge diagnosis of 434 or 436 in 5 states from 1992 to 1996; of these, 7053 had concomitant conditions indicating anticoagulant therapy. We considered aspirin, dipyridamole, ticlopidine, or warfarin alone or in combination as secondary drug prevention. Generalized linear models provided estimates of the absolute difference in prevalence estimates of the receipt of agents used for the prevention of recurrent stroke between each race-ethnicity group adjusted for potential confounders.

RESULTS

Variability in use of any treatment was observed by race-ethnicity ranging from 58% of American Indians receiving therapy to only 39% of Asian/Pacific Islanders. Among residents with an indication for anticoagulant therapy, the absolute estimated crude differences indicated that residents of color were less likely than non-Hispanic whites to receive warfarin. After controlling for confounding, Asian/Pacific Islanders, blacks, and Hispanics eligible for anticoagulant therapy received warfarin less often than non-Hispanic white residents.

CONCLUSIONS

Overall, only half of our elderly population received any pharmacological agent for secondary prevention of stroke. Interventions designed to improve the pharmacological management of recurrent stroke regardless of race are needed in the nursing home setting.

Cochrane review: dipyridamole for preventing major vascular events in patients with vascular disease

BACKGROUND

Patients enrolled in clinical trials after nondisabling cerebral ischemia have an annual risk of vascular events (death from all vascular causes, nonfatal stroke, or nonfatal myocardial infarction) of 4% to 11%. Aspirin reduces the incidence by 13%. Many trials in patients presenting with vascular disease investigated the efficacy of (addition of) dipyridamole in secondary prevention. We systematically compared the efficacy and safety of dipyridamole versus control in the presence and absence of other antiplatelet drugs in clinical trials on the secondary prevention of vascular events in patients with vascular disease.

SUMMARY OF REVIEW

Randomized trials with concealed treatment allocation in patients with a nonembolic arterial vascular disease were selected. Therapy consisted of dipyridamole in the presence or absence of other antiplatelet drugs compared with no drug or an antiplatelet drug(s) other than dipyridamole. Twenty-six trials were included, with a total of 19 842 patients. Dipyridamole was not more efficacious in the prevention of vascular death (relative risk [RR], 1.02; 95% CI, 0.90 to 1.17). It appeared more efficacious in the prevention of vascular events (RR, 0.90; 95% CI, 0.83 to 0.98), but this result only reached statistical significance because of 1 large trial in patients presenting with cerebral ischemia. Combination treatment of dipyridamole and aspirin compared with aspirin had an RR of 1.03 (95% CI, 0.87 to 1.22) for vascular death and an RR of 0.90 (95% CI, 0.80 to 1.00) for vascular events.

CONCLUSIONS

For patients who presented with arterial vascular disease, there was no evidence that dipyridamole, in the presence or absence of another antiplatelet drug (chiefly aspirin), reduced the risk of vascular death, although it may reduce the risk of further vascular events. However, this benefit was found only in a single large trial and only in patients presenting after cerebral ischemia. There was no evidence that dipyridamole alone was more efficacious than aspirin. Further trials comparing the effects of the combination of dipyridamole plus aspirin with aspirin alone are justified.

Evidence with antiplatelet therapy and ADP-receptor antagonists

Antiplatelet drugs have been shown to prevent a range of atherothrombotic events, including transient ischaemic attack (TIA) and ischaemic stroke. Clopidogrel and ticlopidine are adenosine diphosphate (ADP)-receptor antagonists that inhibit ADP-induced fibrinogen binding to platelets, a necessary step in the platelet aggregation process. The Antithrombotic Trialists' Collaboration recently published a major meta-analysis that assessed the effect of antiplatelet therapy in patients with various manifestations of atherosclerosis. In total, this analysis included 135,000 patients in comparisons of antiplatelet agents versus control and 77,000 patients in comparisons of different antiplatelet regimens. This meta-analysis found that overall, antiplatelet therapy reduces the combined odds of stroke, myocardial infarction (MI) or vascular death by 22%, and that antiplatelet agents reduce the odds of a non-fatal stroke by 25% over a wide range of patients with or without a history of cerebrovascular disease. In the CAPRIE trial of clopidogrel versus acetylsalicylic acid (ASA), there was a 10% odds reduction for stroke, MI or vascular death in favour of clopidogrel (p = 0.03). In a meta-analysis performed by the Cochrane Stroke Group, ADP-receptor antagonist therapy significantly reduced the odds of a serious vascular event (stroke, MI or vascular death) by 9% (2p = 0.01) and of any stroke by 12%. The safety/tolerability profile of clopidogrel was superior to that of ticlopidine, and at least as good as that of ASA. In CURE, a long-term benefit was observed with the use of clopidogrel on top of standard therapy (including ASA in all patients), with a 20% relative risk reduction for the primary endpoint of cardiovascular death, MI or stroke (p < 0.001) in patients with unstable angina and non-Q-wave MI. A consistent benefit was seen across all patient subgroups, including patients with a previous history of stroke. More recently, CREDO has demonstrated the incremental benefit of prolonged use of clopidogrel on top of ASA in patients undergoing elective PCI, with a 27% reduction in the combined risk of death, MI or stroke after 12 months of therapy (p = 0.02) and a 25% reduction in stroke over the same time period. The MATCH trial is currently being conducted to test the hypothesis that long-term administration of clopidogrel on top of ASA is superior to clopidogrel alone for the reduction of major ischaemic events in patients with recent TIA or ischaemic stroke who are at high risk of atherothrombotic recurrence. Further trials of clopidogrel on top of standard therapy (including ASA) are planned in neurology; these include SPS3, in patients with small subcortical strokes, and ATARI, in patients who have recently recovered from a TIA.

Thrombolytic therapy with recombinant tissue plasminogen activator for acute ischemic stroke: where do we go from here? A cumulative meta-analysis

BACKGROUND AND PURPOSE

Recombinant tissue plasminogen activator (rtPA; Actilyse) is not as widely used in clinical practice as it could be. Have new data since 1995 strengthened the evidence sufficiently to justify more widespread use of rtPA?

METHODS

We performed a sequential year-to-year cumulative meta-analysis of randomized controlled trials of rtPA in acute ischemic stroke.

RESULTS

Although the amount of data has doubled since 1995, effect estimates for key outcomes remain imprecise, and significant between-trial heterogeneity persists. In the most recent analysis, rtPA up to 6 hours after stroke yielded 55 fewer dead or dependent people per 1000 treated (95% CI, 18 to 92) despite some risk (nonsignificant excess of 19 deaths per 1000 patients treated; 95% CI, 6 fewer to 48 more). Severity of stroke, patient age, and aspirin use were possible sources of heterogeneity.

CONCLUSIONS

Despite doubling of the data since 1995, the magnitude of risks and benefits with rtPA remains imprecise. This gap in knowledge may be hindering clinical use of rtPA and can be filled only by new trials designed to address these specific issues.

Acute stroke trials: the problems of local investigators?

During stroke trials local investigators have to face many practical problems and time consuming procedures (filling in huge case report forms, performing repeat blood sample drawings for pharmacokinetic studies etc.) which, however, simply require organizational structures which is understood to be necessary to be able to conduct such kind of studies. Other, and most worrisome problems, are indeed to be solved when a sponsored research may rise potential ethical issues, or when academic research proposals clash with the interest of pharmaceutical companies or find difficulties in being funded by public institutions. It is just a greater involvement of these latter, possibly free from bureaucratic laces, which might help a balance to be struck between academic and industrial aims.

Comparison of triflusal and aspirin for prevention of vascular events in patients after cerebral infarction: the TACIP Study: a randomized, double-blind, multicenter trial

BACKGROUND AND PURPOSE

The efficacy of the antiplatelet agent triflusal for prevention of vascular events after stroke has been reported in a pilot study. However, there is a need to confirm those results in a larger study.

METHODS

We performed a randomized, double-blind, multicenter study to test the efficacy of triflusal (600 mg/d) versus aspirin (325 mg/d) for prevention of vascular events in patients with stroke or transient ischemic attack (Triflusal versus Aspirin in Cerebral Infarction Prevention [TACIP]). We assessed a combined end point (incidence of nonfatal ischemic stroke, nonfatal acute myocardial infarction, or vascular death) as well as the incidence of these events separately and the incidence of major hemorrhage.

RESULTS

Of 2113 patients, 1058 received triflusal and 1055 aspirin. The mean follow-up period was 30.1 months. The incidence of combined end point (13.1% for triflusal, 12.4% for aspirin) as well the survival analysis (hazard ratio [HR] for triflusal versus aspirin, 1.09; 95% CI, 0.85 to 1.38) showed no differences between groups. The incidence of nonfatal stroke (HR, 1.09; 95% CI, 0.82 to 1.44), nonfatal acute myocardial infarction (HR, 0.95; 95% CI, 0.46 to 1.98,) and vascular death (HR, 1.22; 95% CI, 0.75 to 1.96) was also similar. A significantly higher incidence of major hemorrhages in the aspirin group was recorded (HR, 0.48; 95% CI, 0.28 to 0.82). The overall incidence of hemorrhage was significantly lower in the triflusal group (16.7% versus 25.2%) (odds ratio, 0.76; 95% CI, 0.67 to 0.86; P<0.001).

CONCLUSIONS

This study failed to show significantly superior efficacy of triflusal over aspirin in the long-term prevention of vascular events after stroke, but triflusal was associated with a significantly lower rate of hemorrhagic complications.

Neuroprotective effect of SolCD39, a novel platelet aggregation inhibitor, on transient middle cerebral artery occlusion in rats

BACKGROUND AND PURPOSE

SolCD39 is a soluble form of recombinant human ecto-ATP/ADPase (NTPDase1) and represents a new class of antithrombotic agents. SolCD39 blocks and reverses platelet activation, preventing recruitment of additional platelets into a growing thrombus. The purpose of this study was to examine the effect of solCD39 on neurological deficit, infarct size, and extent of edema after transient middle cerebral artery occlusion (MCAO) in rats.

METHODS

Physiologically controlled Sprague-Dawley rats underwent 2-hour MCAO by retrograde insertion of an intraluminal suture coated with poly-l-lysine. The agent (solCD39) was administered intravenously before MCAO or at 1-hour or 3-hour recirculation. Other groups received vehicle (Tris-buffered saline) or human albumin (as a "positive" neuroprotective control; 25%, 0.5% of body weight) at 1-hour recirculation. Neurological status was evaluated during occlusion (at 60 minutes) and daily for 3 days after MCAO. Brains were perfusion-fixed at 72 hours, and infarct volumes and brain swelling were determined.

RESULTS

Pretreatment with solCD39 significantly improved the neurological score at 72 hours compared with the vehicle group (4.4+/-0.6 versus 7.6+/-0.6, respectively; P=0.008). Cortical infarct areas were significantly reduced at multiple levels by pretreatment with solCD39. Total striatal infarct area was also significantly reduced compared with vehicle by both solCD39 pretreatment (48% mean reduction) and solCD39 treatment at 3-hour recirculation (51% mean reduction). Treatment with SolCD39 significantly reduced total infarct volume (corrected for brain swelling) by an average of 71% to 72% when administered either before ischemia or at 3 hours of recirculation compared with vehicle. Treatment with albumin significantly reduced neurological score and total, cortical, and subcortical infarction at multiple levels, as expected.

CONCLUSIONS

Treatment with SolCD39, administered either before or at 3 hours after MCAO, improves neurological score and reduces infarct size compared with vehicle. A pharmacological agent of this type appears to have potential for the treatment of focal ischemic stroke.

Effect of increasing doses of aspirin on platelet aggregation among stroke patients

BACKGROUND AND PURPOSE

Aspirin has been shown to reduce the risk of myocardial infarction and stroke. Some investigators believe that low-dose aspirin inhibits platelet aggregation to the same degree as high-dose aspirin. Our study aimed to assess the effect of increasing doses of aspirin on the degree of platelet aggregation induced by collagen and adenosine diphosphate (ADP) among stroke patients.

METHODS

Sixteen poststroke patients were prescribed aspirin at daily doses of 40, 80, 160, 325, 650, and 1,300 mg, each dose to be taken for 14 days (total duration 12 weeks). Platelet aggregation studies using 2 microgram/ml collagen and 2 microM ADP were performed on platelet-rich plasma at baseline and on the 14th day of each dose.

RESULTS

Platelet aggregation studies using 2 microgram/ml collagen at the start of treatment and at the 14th day of each dose revealed dose-dependent inhibition by aspirin starting at 40 mg/day, but was optimal at 80- 160 mg/day. ADP-induced platelet aggregation inhibition appears to be dose dependent up to 1,300 mg/day.

CONCLUSION

Inhibition of collagen-induced platelet aggregation by aspirin appears to be optimal at 80-160 mg/day, while ADP-induced platelet aggregation inhibition by aspirin appears to be dose dependent up to 1,300 mg/day in our poststroke patients, albeit to a less remarkable degree at higher doses.

Thrombolytic treatment of clot embolism in rat: comparison of intra-arterial and intravenous application of recombinant tissue plasminogen activator

BACKGROUND AND PURPOSE

We sought to test the hypothesis that intra-arterial recombinant tissue plasminogen activator (rtPA) treatment of thromboembolic stroke is more efficient than intravenous application.

METHODS

Rats were embolized by intracarotid injection of autologous fibrin-rich blood clots. One hour later rtPA (10 mg/kg) was infused either intravenously (n=8) or intra-arterially (n=8). Control rats (n=8) received intra-arterial infusion of saline. Treatment was monitored by MR perfusion-weighted imaging and apparent diffusion coefficient (ADC) imaging, and outcome was evaluated by comparing incidence of hemorrhages and lesion volumes of ATP and pH.

RESULTS

Clot embolism led to a decline of perfusion-weighted imaging signal intensity in the middle cerebral artery territory to <40% of control. Both intra-arterial and intravenous treatment significantly improved blood flow in cerebral cortex but not in caudate putamen. In untreated animals, ATP and pH lesion volumes were 510.3+/-94.5 and 438.6+/-39.2 mm(3) at 7 hours after clot embolism, respectively. Both intravenous and intra-arterial rtPA treatment produced hemorrhagic complications but reduced ATP lesion size to 296.2+/-136.1 and 370.3+/-103.7 mm(3) and reduced pH lesion size to 263.3+/-114.6 and 303.3+/-103.0 mm(3), respectively (P<0.05 for untreated versus treated rats; no difference between intravenous and intra-arterial treatment). ADC imaging revealed that lesion reduction was due to inhibition of infarct growth but not to reversal of primary injury.

CONCLUSIONS

This study documents reduction of injury by rtPA treatment but does not reveal a difference between intra-arterial and intravenous application. Our data do not support an advantage of intra-arterial thrombolysis.

Emergent use of anticoagulation for treatment of patients with ischemic stroke

BACKGROUND

Several clinical trials have tested the potential utility of emergent anticoagulation for acute ischemic stroke.

SUMMARY OF REVIEW

Rather than performing a meta-analysis that combines the data from several trials, this review focuses on individual studies. Although these trials do have inherent limitations, they demonstrate that emergent use of an anticoagulant is associated with a modest but significantly increased risk of hemorrhagic transformation of the ischemic stroke or serious nonneurological bleeding. The trials do not demonstrate a benefit from emergent anticoagulation in improving outcome, reducing mortality, and preventing early recurrent stroke.

CONCLUSIONS

These results suggest that most patients with acute stroke should not be treated with unfractionated heparin or other rapidly acting anticoagulants after stroke. Prevention of deep vein thrombosis and pulmonary embolism among bedridden patients is the only established indication for early anticoagulation after acute ischemic stroke.