Enteric-coated acetylsalicylic acid plus dipyridamole compared with anticoagulants in the prevention of ischemic events in patients with transient ischemic attacks

Secondary prophylactic treatment and long-term prognosis after TIA and different subtypes of stroke. A 25-year follow-up hospital-based observational study

OBJECTIVES

To assess long-term prognosis after transient ischemic attack (TIA)/subtypes of stroke relative to secondary prophylactic treatment(s) given.

MATERIALS AND METHODS

Retro/prospective follow-up of patients hospitalized in the Stroke Unit or in the Department of Neurology, Linköping, in 1986 and followed up to Feb. 2011.

RESULTS

A total of 288 men were followed up for 2254 years (mean 7.8 years) and 261 women for 1984 years (mean 7.6 years). In men, the distribution to anticoagulants (AC) (warfarin treatment) was 18%, antiplatelet therapy (APT) usually ASA 75 mg/day 54%, untreated 27%, unknown 2%. In women, the distribution to AC was 15%, APT 60%, untreated 23%, unknown 2%, respectively. Mortality rates at 1 year, 10 years, and 25 years for men were 21%, 67%, and 93%, respectively, versus the rates in women of 24%, 71%, and 90%, respectively. Survival curves showed markedly increased risk of death compared to the normal population. AC treatment was more favorable for men regarding the annual risk of stroke, compared with APT (9.4% vs. 9.8%), as well as the risks of MI, (5.6% vs. 6.7%), and death (8.1% vs. 10.3%), compared to women for stroke (11.6% vs. 8.8%) and MI (5.3% vs. 3.7%) but not for death (8.3% vs. 8.4%). The risk of fatal bleeding was 0.86% annually on AC compared to 0.17% on APT. According to Cox regression analysis included patients with TIA/ischemic stroke, first-line treatment had beneficial effects on survival: AC OR 0.67 (0.5-0.9), APT 0.67 (0.52-0.88) versus untreated.

CONCLUSIONS

Patients with a history of TIA/stroke had a higher mortality rate versus controls, providing support for both primary and secondary prophylaxis regarding vascular risk factors for death. This study also provided support for secondary prophylactic treatment with either AC or ASA (75 mg once daily) to reduce the vascular risk of death unless there are contraindications.

Vitamin K antagonists versus antiplatelet therapy after transient ischaemic attack or minor ischaemic stroke of presumed arterial origin

BACKGROUND

People who have had a transient ischaemic attack (TIA) or non-disabling ischaemic stroke have an annual risk of major vascular events of between 4% and 11%. Aspirin reduces this risk by 20% at most. Secondary prevention trials after myocardial infarction indicate that treatment with vitamin K antagonists is associated with a risk reduction approximately twice that of treatment with antiplatelet therapy.

OBJECTIVES

To compare the efficacy and safety of vitamin K antagonists and antiplatelet therapy in the secondary prevention of vascular events after cerebral ischaemia of presumed arterial origin.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 15 September 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 3), MEDLINE (2008 to September 2011) and EMBASE (2008 to September 2011). In an effort to identify further relevant trials we searched ongoing trials registers and reference lists. We also contacted authors of published trials for further information and unpublished data.

SELECTION CRITERIA

Randomised trials of oral anticoagulant therapy with vitamin K antagonists (warfarin, phenprocoumon or acenocoumarol) versus antiplatelet therapy for long-term secondary prevention after recent transient ischaemic attack or minor ischaemic stroke of presumed arterial origin.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality and extracted data.

MAIN RESULTS

We included eight trials with a total of 5762 participants. The data showed that anticoagulants (in any intensity) are not more efficacious in the prevention of vascular events than antiplatelet therapy (medium intensity anticoagulation: relative risk (RR) 0.80, 95% confidence interval (CI) 0.56 to 1.14; high intensity anticoagulation: RR 1.02, 95% CI 0.49 to 2.13). There is no evidence that treatment with low intensity anticoagulation gives a higher bleeding risk than treatment with antiplatelet agents: RR 1.27 (95% CI 0.79 to 2.03). However, it was clear that medium and high intensity anticoagulation with vitamin K antagonists, with an INR of 2.0 to 4.5, were not safe because they yielded a higher risk of major bleeding complications (medium intensity anticoagulation: RR 1.93, 95% CI 1.27 to 2.94; high intensity anticoagulation: RR 9.0, 95% CI 3.9 to 21).

AUTHORS' CONCLUSIONS

For the secondary prevention of further vascular events after TIA or minor stroke of presumed arterial origin, there is sufficient evidence to conclude that vitamin K antagonists in any dose are not more efficacious than antiplatelet therapy and that medium and high intensity anticoagulation leads to a significant increase in major bleeding complications.

Amaurosis fugax caused by heritable thrombophilia-hypofibrinolysis in cases without carotid atherosclerosis: thromboprophylaxis prevents subsequent transient monocular partial blindness

Nineteen patients (age 60 +/- 14) with amaurosis fugax associated with heritable thrombophilia-hypofibrinolysis without ipsilateral atherosclerotic carotid plaque or other causes of amaurosis fugax were studied. Our hypothesis was that case-specific thromboprophylaxis would prevent subsequent amaurosis fugax episodes. Prospective treatment data were available for 13 cases. Thrombophilic disorders included high Factors VIII and XI, G20210A prothrombin heterozygosity, low proteins C and S, MTHFR mutations, and the PL A1/A2 mutation. Hypofibrinolytic disorders included plasminogen activator inhibitor-1 4G4G, and high lipoprotein (a). Treatments included Coumadin; Lovenox, folic acid-vitamin B6-vitamin B12, discontinuation of estrogens-selective estrogen receptor modulators, Glucophage, and aspirin, as appropriate. Usually within 1 month on therapy, patients became asymptomatic and have remained asymptomatic for > or = 1 year on therapy, without adverse treatment side effects. When amaurosis fugax occurs without carotid artery atherosclerosis or other known causes, thrombophilia or hypofibrinolysis, or both are nearly universal, safely treatable, reversible pathoetiologies.

Oral anticoagulants versus antiplatelet therapy for preventing further vascular events after transient ischaemic attack or minor stroke of presumed arterial origin

BACKGROUND

Patients with limited cerebral ischaemia of arterial origin have an annual risk of major vascular events between 4% and 11%. Aspirin reduces this risk by 20% at most. Secondary prevention trials after myocardial infarction indicate that treatment with oral anticoagulants is associated with a risk reduction approximately twice that of treatment with antiplatelet therapy.

OBJECTIVES

To compare the efficacy and safety of oral anticoagulants and antiplatelet therapy in the secondary prevention of vascular events after cerebral ischaemia of presumed arterial origin.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (searched 16 September 2004). Authors of published trials were contacted for further information and unpublished data.

SELECTION CRITERIA

Randomised trials examining long-term secondary prevention after recent ischaemic stroke of presumed arterial origin were selected. The oral anticoagulant therapy had to be of specified intensity with warfarin, phenprocoumon or acenocoumarol versus antiplatelet therapy.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials for inclusion, assessed trial quality and extracted data. Subgroup analyses with treatment International Normalized Ratio (INR) 1.4 to 2.8 (low intensity), INR 2.1 to 3.6 (medium intensity) and INR 3.0 to 4.5 (high intensity) were performed.

MAIN RESULTS

Five trials, with 4076 patients were selected. The data do not allow a robust conclusion on whether anticoagulants are more or less efficacious in the prevention of vascular events than antiplatelet therapy (medium intensity anticoagulation relative risk (RR) 0.96, 95% confidence intervals (CI) 0.38 to 2.42; high intensity anticoagulation RR 1.02, 95% CI 0.49 to 2.13). There is no evidence that treatment with low or medium intensity anticoagulation gives a higher bleeding risk than treatment with antiplatelet agents. The relative risk for major bleeding complications for low intensity anticoagulation was 1.27 (95% CI 0.79 to 2.03) and for medium intensity anticoagulation 1.19 (95% CI 0.59 to 2.41). However, it was clear that high intensity oral anticoagulants with INR 3.0 to 4.5 were not safe, because they yielded a higher risk of major bleeding complications (RR 9.0, 95% CI 3.9 to 21).

AUTHORS' CONCLUSIONS

For secondary prevention of further vascular events after limited ischaemic stroke of arterial origin, there is insufficient evidence to justify the routine use of medium-intensity oral anticoagulants; such treatment should only be used as part of a clinical trial. More intense anticoagulation is not safe and should not be used in this setting. Low-intensity anticoagulation is not likely to be more or less efficacious than aspirin.

Risk of Myocardial Infarction and Vascular Death After Transient Ischemic Attack and Ischemic Stroke

Background— Whether stroke patients should be investigated for asymptomatic coronary artery disease remains matter of debate. Absolute risks of myocardial infarction (MI) and vascular death after a stroke have not been accurately assessed. We performed a systematic review and a meta-analysis to determine the risk of MI and nonstroke vascular death after transient ischemic attack (TIA) and ischemic stroke. Cohort studies of TIA or ischemic stroke patients were included if they were published between 1980 and March 2005, reported risk of MI and nonstroke vascular death, enrolled >100 patients, and had at least 1 year of follow-up. We included 39 studies in a total of 65 996 patients with mean follow-up of 3.5 years. Two reviewers independently carried out data extraction using a standardized form. Absolute annual risks were estimated through weighted meta-regressions with a random effect. To test the predictions of expected event rates derived from our analysis, we used individual patient data.

Summary of Review— The annual risks were 2.1% (CI 95%: 1.9 to 2.4) for nonstroke vascular death, 2.2% (1.7 to 2.7) for total MI, 0.9% (0.7 to 1.2) for nonfatal MI and 1.1% (0.8 to 1.5) for fatal MI. The time course of risk was linear. Estimated risks fitted well with observed risks at the individual level. There was no heterogeneity in the absolute risks according to baseline study characteristics.

Conclusions— Patients with TIA or stroke have a relatively high risk of MI and nonstroke vascular death. Additional research is needed to identify the determinants of coronary artery disease in stroke patients.

Amaurosis fugax: associations with heritable thrombophilia

The aim of this study was to prospectively assess associations between amaurosis fugax, inherited thrombophilia, and acquired thrombophilia. Thrombophilia and hypofibrinolysis were studied in 11 cases (eight women, three men; all white) with amaurosis fugax, 57 +/- 17 years old, selected by the absence of abnormal brain magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), magnetic resonance venography (MRV), ipsilateral internal carotid artery plaque, atrial fibrillation, or cardiac thrombus. Cases were compared to 78 healthy adult white controls (53 +/- 18 years old) for serologic measures, and by polymerase chain reaction to 248 healthy white controls (78 adults, 170 children) for gene mutations. All 11 cases had one or more familial thrombophilic coagulation disorder including one heterozygous for the G1691A factor V Leiden mutation, two with low free protein S, four with high factor VIII, three with resistance to activated protein C, three homozygous for the C677T methylenetetrahydrofolate reductase (MTHFR) mutation, two compound C677T-A1298C MTHFR heterozygotes, and three with hypofibrinolytic 4G4G homozygosity for the PAI-1 gene. The case with factor VIII of 160% had two other thrombophilias (compound MTHFR C677T-A1298C heterozygosity, resistance to activated protein C), and hypofibrinolytic high Lp(a). Thrombophilic C677T MTHFR homozygosity or compound C677T-A1298C heterozygosity was present in five of 10 (50%) cases vs. 30 of 248 (12%) controls, Fisher's p (p(f)) = .005. Thrombophilic factor VIII was high in four of 10 (40%) cases vs. 0 of 38 controls, p(f) = .001. Thrombophilic hyperestrogenemia in five of the eight women (four exogenous estrogen, one pregnant) may have interacted with inherited thrombophilia-hypofibrinolysis, promoting thrombus formation. In cases selected by the absence of abnormal brain magnetic resonance imaging, significant ipsilateral internal carotid artery plaque, atrial fibrillation, or cardiac thrombus, we speculate that amaurosis fugax can be caused by reversible (by anticoagulation) retinal artery thrombi associated with heritable thrombophilia and/or hypofibrinolysis, often augmented by estrogen-driven acquired thrombophilia.

Oral anticoagulants versus antiplatelet therapy for preventing further vascular events after transient ischaemic attack or minor stroke of presumed arterial origin

BACKGROUND

Patients who are entered in clinical trials after a transient ischaemic attack (TIA) or non disabling ischaemic stroke have an annual risk of important vascular events (death from all vascular causes, non-fatal stroke, or non-fatal myocardial infarction) of between 4 and 11 percent. Aspirin, in a daily dose of 30mg or more, offers only modest protection after cerebral ischaemia: it reduces the incidence of major vascular events by 20 percent at most. Secondary prevention trials after myocardial infarction indicate that treatment with oral anticoagulants is associated with a risk reduction approximately twice that of treatment with antiplatelet therapy.

OBJECTIVES

1) To compare the efficacy of oral anticoagulants and antiplatelet therapy in the secondary prevention of vascular events after cerebral ischaemia of presumed arterial origin. 2) To compare the safety of oral anticoagulants and antiplatelet therapy in the secondary prevention of vascular events after cerebral ischaemia of presumed arterial origin.

SEARCH STRATEGY

This review draws on the search strategy developed for the Stroke Group as a whole. Relevant trials were identified in the Specialised Register of Controlled Trials (last searched: June 2000). Authors of published trials were contacted for further information and unpublished data.

SELECTION CRITERIA

Randomised trials with concealed treatment allocation on long term (> 6 months) secondary prevention after recent (< 6 months) TIA or minor ischaemic stroke of presumed arterial origin were selected. The oral anticoagulant therapy was to be of specified intensity (by means of the International Normalised Ratio (INR)) with warfarin, phenprocoumon or acenocoumarol versus a single antiplatelet drug (or combination of antiplatelet agents).

DATA COLLECTION AND ANALYSIS

Two reviewers selected trials meeting the inclusion criteria and extracted details of randomisation methods, blinding of treatments and assessments, whether intention-to-treat analysis is possible from the published data, whether treatment groups are comparable with regard to major prognostic risk factors for outcomes, the number of patients who are excluded or lost to follow-up, definition of outcomes, and entry and exclusion criteria. The methodological quality of each trial was assessed by the two reviewers using these extracted data. In addition, target INR for anticoagulant treatment and dose and type of antiplatelet drug, duration of follow-up and the numbers of defined outcome events was recorded. The data were analysed according to the intention-to-treat principle. Subgroup analyses with treatment INR 2.1 - 3.6 versus INR 3.0 - 4.5 was performed. Relative and absolute risk reductions were calculated by means of the statistical software provided by the Cochrane Collaboration.

MAIN RESULTS

Four trials, with a total of 1870 patients were selected. In the prevention of ischaemic stroke after cerebral ischaemia of presumed arterial origin, the available data do not allow a robust conclusion on whether anticoagulants (in any intensity) are more efficacious than antiplatelet therapy (low intensity anticoagulation RR 0.96, 95% CI 0.38 to 2.42, high intensity anticoagulation RR 1.02, 95% CI 0.49 to 2.13). Treatment with anticoagulation INR 2.1 - 3.6 does not give an importantly higher bleeding risk than treatment with antiplatelet agents (RR 1.19, 95% CI 0.59 to 2.41). It is clear that oral anticoagulants INR 3.0 - 4.5 are not safe, because they yield a higher risk of major bleeding complications (RR 9.0, 95% CI 3.9 to 21).

REVIEWER'S CONCLUSIONS

For the secondary prevention of further vascular events after transient ischaemic attack or minor stroke of presumed arterial origin, there is insufficient evidence to justify the routine use of low intensity oral anticoagulants (INR 2.0 - 3.6). More intense anticoagulation (INR 3.0 - 4.5) is not safe and should not be used in this setting.

Collaborative overview of randomised trials of antiplatelet therapy--I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Antiplatelet Trialists' Collaboration

OBJECTIVE

To determine the effects of "prolonged" antiplatelet therapy (that is, given for one month or more) on "vascular events" (non-fatal myocardial infarctions, non-fatal strokes, or vascular deaths) in various categories of patients.

DESIGN

Overviews of 145 randomised trials of "prolonged" antiplatelet therapy versus control and 29 randomised comparisons between such antiplatelet regimens.

SETTING

Randomised trials that could have been available by March 1990.

SUBJECTS

Trials of antiplatelet therapy versus control included about 70,000 "high risk" patients (that is, with some vascular disease or other condition implying an increased risk of occlusive vascular disease) and 30,000 "low risk" subjects from the general population. Direct comparisons of different antiplatelet regimens involved about 10,000 high risk patients.

RESULTS

In each of four main high risk categories of patients antiplatelet therapy was definitely protective. The percentages of patients suffering a vascular event among those allocated antiplatelet therapy versus appropriately adjusted control percentages (and mean scheduled treatment durations and net absolute benefits) were: (a) among about 20,000 patients with acute myocardial infarction, 10% antiplatelet therapy v 14% control (one month benefit about 40 vascular events avoided per 1000 patients treated (2P < 0.00001)); (b) among about 20,000 patients with a past history of myocardial infarction, 13% antiplatelet therapy v 17% control (two year benefit about 40/1000 (2P < 0.00001)); (c) among about 10,000 patients with a past history of stroke or transient ischaemic attack, 18% antiplatelet therapy v 22% control (three year benefit about 40/1000 (2P < 0.00001)); (d) among about 20,000 patients with some other relevant medical history (unstable angina, stable angina, vascular surgery, angioplasty, atrial fibrillation, valvular disease, peripheral vascular disease, etc), 9% v 14% in 4000 patients with unstable angina (six month benefit about 50/1000 (2P < 0.00001)) and 6% v 8% in 16,000 other high risk patients (one year benefit about 20/1000 (2P < 0.00001)). Reductions in vascular events were about one quarter in each of these four main categories and were separately statistically significant in middle age and old age, in men and women, in hypertensive and normotensive patients, and in diabetic and nondiabetic patients. Taking all high risk patients together showed reductions of about one third in non-fatal myocardial infarction, about one third in non-fatal stroke, and about one third in vascular death (each 2P < 0.00001). There was no evidence that non-vascular deaths were increased, so in each of the four main high risk categories overall mortality was significantly reduced. The most widely tested antiplatelet regimen was "medium dose" (75-325 mg/day) aspirin. Doses throughout this range seemed similarly effective (although in an acute emergency it might be prudent to use an initial dose of 160-325 mg rather than about 75 mg). There was no appreciable evidence that either a higher aspirin dose or any other antiplatelet regimen was more effective than medium dose aspirin in preventing vascular events. The optimal duration of treatment for patients with a past history of myocardial infarction, stroke, or transient ischaemic attack could not be determined directly because most trials lasted only one, two, or three years (average about two years). Nevertheless, there was significant (2P < 0.0001) further benefit between the end of year 1 and the end of year 3, suggesting that longer treatment might well be more effective. Among low risk recipients of "primary prevention" a significant reduction of one third in non-fatal myocardial infarction was, however, accompanied by a non-significant increase in stroke. Furthermore, the absolute reduction in vascular events was much smaller than for high risk patients despite a much longer treatment period (4.4% antiplatelet therapy v 4.8% control; five year

Differences in the outcome of patients with TIA versus minor stroke

In the Swedish aspirin low dose trial (SALT) 101 patients were enrolled from the Department of Medicine, Falun. 42 patients had experienced TIA/amaurosis fugax, whereas 59 patients had suffered a minor stroke/retinal infarction. History of hypertension treated or known untreated occurred statistically more frequently in the minor stroke group at randomisation (P less than 0.01) and the mean diastolic blood pressure (DBP) was higher in the minor stroke group during the observation time (P less than 0.05; ANOVA). The minor stroke group had less favourable outcomes according to survival curves (stroke or death) during a mean observation time of 34 months in each group (P less than 0.05 at 29 months). The findings of the present trial suggest that hypertension and the higher mean DBP during the observation time might explain the better outcome of end points of stroke or death in patients with TIA.

A methodological appraisal of research on prognosis after transient ischemic attacks

We analyzed existing research on the prognosis of patients who have had a transient ischemic attack to identify studies that adhere to basic methodological principles and to identify underinvestigated questions. Studies were eligible for analysis if they were published in peer-reviewed journals after 1950, written in English, and included at least 50 patients with transient ischemia. Studies that included patients with stroke were included only if they reported outcome rates separately for the subgroup of patients with transient ischemia. All eligible studies were extracted by one investigator who recorded adherence to six key methodological principles. Among 60 eligible studies, 54 were observational cohort studies and six were randomized trials. Adherence to the six methodological principles was as follows: eight studies included an adequate description of diagnostic criteria and of procedures used to assure adherence to the criteria, 54 used appropriate end points, two assembled inception cohorts, 10 included an adequate description of end point surveillance, 22 adequately reported and analyzed censored patients, and 10 included a multivariate analysis for predictive variables. No study adhered to all six principles, but two adhered to the three most important ones (appropriate end points, inception cohort, and adequate reporting and analysis of censored patients). Aspects of prognosis after transient ischemia that have not been completely investigated include the severity of subsequent strokes and methods for estimating the outcome risk for individual patients. We conclude that only a few published investigations on prognosis after transient ischemia are methodologically complete. This finding helps explain why it is difficult to interpret many studies. Further research is needed and should target underinvestigated topics.