Danish very-low-dose aspirin after carotid endarterectomy trial. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. Low molecular-weight heparin versus aspirin in patients with acute ischaemic stroke and atrial fibrillation: a double-blind randomised study. HAEST Study Group. Heparin in Acute Embolic Stroke Trial. Combination antithrombotic therapy in unstable rest angina and non-Q-wave infarction in nonprior aspirin users. Primary end points analysis from the ATACS trial. Antithrombotic Therapy in Acute Coronary Syndromes Research Group. Aspirin in the prevention of progressing stroke: a randomized controlled study. Medium intensity oral anticoagulants versus aspirin after cerebral ischaemia of arterial origin (ESPRIT): a randomised controlled trial. Randomised controlled trial of streptokinase, aspirin, and combination of both in treatment of acute ischaemic stroke. Multicentre Acute Stroke Trial--Italy (MAST-I) Group. Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial. CAST: randomised placebo-controlled trial of early aspirin use in 20,000 patients with acute ischaemic stroke. CAST (Chinese Acute Stroke Trial) Collaborative Group.
The effect of very-low-dose aspirin as an antithrombotic agent was evaluated blindly in 301 patients who had recently undergone carotid endarterectomy. After randomization, 150 patients received aspirin and 151 received placebo. The two groups were comparable with regard to age, sex, blood pressure, previous cerebrovascular events, and smoking habits. The effect of the study medication on platelet aggregation was measured twice in each patient during the first 2 months and at each follow-up visit; the dose was individually adjusted. In 76% of the patients receiving aspirin, 50 mg/day gave satisfactory platelet inhibition, 13% needed 60 mg/day, 8% needed 70 mg/day, and 3% needed 100 mg/day. Platelet aggregation was found to be inhibited in only 1.2% of the measurements in the patients receiving placebo. Observation during treatment averaged 21 months; total intention-to-treat follow-up averaged 25 months. For the combined outcome events of transient ischemic attack, stroke, acute myocardial infarction, and vascular death, aspirin reduced risk by 11% (95% confidence limits: -38% to 48%, p greater than 0.1). Thus, there was no significant effect of very-low-dose aspirin in our trial. To determine the effects of antiplatelet therapy among patients at high risk of occlusive vascular events.
                Collaborative meta-analyses (systematic overviews).
                Randomised trials of an antiplatelet regimen versus control or of one antiplatelet regimen versus another in high risk patients (with acute or previous vascular disease or some other predisposing condition) from which results were available before September 1997. Trials had to use a method of randomisation that precluded prior knowledge of the next treatment to be allocated and comparisons had to be unconfounded-that is, have study groups that differed only in terms of antiplatelet regimen.
                287 studies involving 135 000 patients in comparisons of antiplatelet therapy versus control and 77 000 in comparisons of different antiplatelet regimens.
                "Serious vascular event": non-fatal myocardial infarction, non-fatal stroke, or vascular death.
                Overall, among these high risk patients, allocation to antiplatelet therapy reduced the combined outcome of any serious vascular event by about one quarter; non-fatal myocardial infarction was reduced by one third, non-fatal stroke by one quarter, and vascular mortality by one sixth (with no apparent adverse effect on other deaths). Absolute reductions in the risk of having a serious vascular event were 36 (SE 5) per 1000 treated for two years among patients with previous myocardial infarction; 38 (5) per 1000 patients treated for one month among patients with acute myocardial infarction; 36 (6) per 1000 treated for two years among those with previous stroke or transient ischaemic attack; 9 (3) per 1000 treated for three weeks among those with acute stroke; and 22 (3) per 1000 treated for two years among other high risk patients (with separately significant results for those with stable angina (P=0.0005), peripheral arterial disease (P=0.004), and atrial fibrillation (P=0.01)). In each of these high risk categories, the absolute benefits substantially outweighed the absolute risks of major extracranial bleeding. Aspirin was the most widely studied antiplatelet drug, with doses of 75-150 mg daily at least as effective as higher daily doses. The effects of doses lower than 75 mg daily were less certain. Clopidogrel reduced serious vascular events by 10% (4%) compared with aspirin, which was similar to the 12% (7%) reduction observed with its analogue ticlopidine. Addition of dipyridamole to aspirin produced no significant further reduction in vascular events compared with aspirin alone. Among patients at high risk of immediate coronary occlusion, short term addition of an intravenous glycoprotein IIb/IIIa antagonist to aspirin prevented a further 20 (4) vascular events per 1000 (P<0.0001) but caused 23 major (but rarely fatal) extracranial bleeds per 1000.
                Aspirin (or another oral antiplatelet drug) is protective in most types of patient at increased risk of occlusive vascular events, including those with an acute myocardial infarction or ischaemic stroke, unstable or stable angina, previous myocardial infarction, stroke or cerebral ischaemia, peripheral arterial disease, or atrial fibrillation. Low dose aspirin (75-150 mg daily) is an effective antiplatelet regimen for long term use, but in acute settings an initial loading dose of at least 150 mg aspirin may be required. Adding a second antiplatelet drug to aspirin may produce additional benefits in some clinical circumstances, but more research into this strategy is needed. Patients with acute ischaemic stroke and atrial fibrillation have an increased risk of early stroke recurrence, and anticoagulant treatment with heparins has been widely advocated, despite missing data on the balance of risk and benefit.
                Heparin in Acute Embolic Stroke Trial (HAEST) was a multicentre, randomised, double-blind, and double-dummy trial on the effect of low-molecular-weight heparin (LMWH, dalteparin 100 IU/kg subcutaneously twice a day) or aspirin (160 mg every day) for the treatment of 449 patients with acute ischaemic stroke and atrial fibrillation. The primary aim was to test whether treatment with LMWH, started within 30 h of stroke onset, is superior to aspirin for the prevention of recurrent stroke during the first 14 days.
                The frequency of recurrent ischaemic stroke during the first 14 days was 19/244 (8.5%) in dalteparin-allocated patients versus 17/225 (7.5%) in aspirin-allocated patients (odds ratio=1.13, 95% CI 0.57-2.24). The secondary events during the first 14 days also revealed no benefit of dalteparin compared with aspirin: symptomatic cerebral haemorrhage 6/224 versus 4/225; symptomatic and asymptomatic cerebral haemorrhage 26/224 versus 32/225; progression of symptoms within the first 48 hours 24/224 versus 17/225; and death 21/224 versus 16/225. There were no significant differences in functional outcome or death at 14 days or 3 months.
                The present data do not provide any evidence that LMWH is superior to aspirin for the treatment of acute ischaemic stroke in patients with atrial fibrillation. However, the study could not exclude the possibility of smaller, but still worthwhile, effects of either of the trial drugs. The purpose of this study was to compare combination antithrombotic therapy with aspirin plus anticoagulation versus aspirin alone, when added to conventional antianginal therapy in patients with unstable rest angina or non-Q-wave myocardial infarction who were nonprior aspirin users.
                Two hundred fourteen patients were randomized; 109 were randomized to receive aspirin alone (162.5 mg daily) and 105 to receive a combination of aspirin plus anticoagulation, ie, aspirin 162.5 mg daily plus heparin (activated partial thromboplastin time, two times control) followed by aspirin 162.5 mg daily plus warfarin (international normalized ratio, 2 to 3). Trial therapy was begun by 9.5 +/- 8.8 hours of qualifying pain and was continued for 12 weeks. Primary end points were recurrent angina with ECG changes, myocardial infarction, and/or death. Analysis by intention to treat of primary events at 12 weeks was performed. At 14 days, there was a significant reduction in total ischemic events in the combination group versus aspirin alone (10.5% versus 27%, P = .004). An efficacy analysis of primary events at 12 weeks also revealed a large reduction in total ischemic events in the combination group versus aspirin alone (13% versus 25%, P = .06). Bleeding complications were slightly more common with combination therapy.
                In nonprior aspirin users, combination antithrombotic therapy with aspirin plus anticoagulation significantly reduces recurrent ischemic events in the early phase of unstable angina. In acute stroke, progression has a severe impact on patient outcome and no effective treatment is known. The main objective was to evaluate the efficacy of aspirin for prevention of stroke progression thereby improving outcome.
                The trial was randomized, double-blind and placebo-controlled.
                The patients were treated in stroke units of four hospitals in Sweden.
                Patients with ischaemic stroke but not complete paresis were included. No antiplatelet drugs were allowed within the last 72 h before onset. Delay until first trial dosage was maximized to 48 h. The trial was designed to detect a 20% reduction of the rate of stroke progression, which was estimated to take place in 20% of cases. Totally, 441 patients (220 aspirin, 221 placebo) completed the trial. Baseline comparisons between the groups showed no differences.
                Aspirin (325 mg) or placebo was given once daily for five consecutive days.
                Neurological assessments were carried out three times daily during the treatment period to detect progression of at least two points in the Scandinavian Stroke Supervision Scale. Patient outcome was followed up at discharge and at 3 months.
                Aspirin treatment did not significantly reduce the frequency of stroke progression. Amongst aspirin-treated patients, stroke progression occurred in 15.9% as compared with 16.7% in the placebo group, which is less frequent than expected. The relative risk was 0.95 (95% CI 0.62-1.45) in the treatment group. As regards patient outcome at discharge and after 3 months, aspirin treatment did not show any difference.
                No positive effect of aspirin, of the expected size, could be shown on the frequency of stroke progression or patient outcome. Oral anticoagulants are better than aspirin for secondary prevention after myocardial infarction and after cerebral ischaemia in combination with non-rheumatic atrial fibrillation. The European/Australasian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT) aimed to determine whether oral anticoagulation with medium intensity is more effective than aspirin in preventing future vascular events in patients with transient ischaemic attack or minor stroke of presumed arterial origin.
                In this international, multicentre trial, patients were randomly assigned within 6 months after a transient ischaemic attack or minor stroke of presumed arterial origin either anticoagulants (target INR range 2.0-3.0; n=536) or aspirin (30-325 mg daily; n=532). The primary outcome was the composite of death from all vascular causes, non-fatal stroke, non-fatal myocardial infarction, or major bleeding complication, whichever occurred first. In a post hoc analysis anticoagulants were compared with the combination of aspirin and dipyridamole (200 mg twice daily). Treatment was open, but auditing of outcome events was blinded. Primary analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial (number ISRCTN73824458) and with ClinicalTrials.gov (NCT00161070).
                The anticoagulants versus aspirin comparison of ESPRIT was prematurely ended because ESPRIT reported previously that the combination of aspirin and dipyridamole was more effective than aspirin alone. Mean follow-up was 4.6 years (SD 2.2). The mean achieved INR was 2.57 (SD 0.86). A primary outcome event occurred in 99 (19%) patients on anticoagulants and in 98 (18%) patients on aspirin (hazard ratio [HR] 1.02, 95% CI 0.77-1.35). The HR for ischaemic events was 0.73 (0.52-1.01) and for major bleeding complications 2.56 (1.48-4.43). The HR for the primary outcome event comparing anticoagulants with the combination treatment of aspirin and dipyridamole was 1.31 (0.98-1.75).
                Oral anticoagulants (target INR range 2.0-3.0) are not more effective than aspirin for secondary prevention after transient ischaemic attack or minor stroke of arterial origin. A possible protective effect against ischaemic events is offset by increased bleeding complications. In ischaemic stroke, thrombolytic drugs speed the recanalisation of intracerebral arteries. The effects of aspirin are not known. A trial was conducted to determine whether, separately or together, streptokinase and aspirin have clinical benefits in acute ischaemic stroke similar to those in acute myocardial infarction. 622 patients with acute ischaemic stroke within 6 hours of symptom onset were randomised with a 2 x 2 factorial design to (i) a 1-hour intravenous infusion of 1.5 MU streptokinase, (ii) 300 mg/day buffered aspirin for 10 days, (iii) both active treatments, or (iv) neither. Early results raised a question whether the trial should be continued. Streptokinase (alone or with aspirin) was associated with an excess of 10-day case fatality (odds ratio 2.7; 95% confidence interval 1.7-4.3; 2p < 0.00001). Of the four groups randomised, only patients allocated to streptokinase plus aspirin had a significantly higher risk of early death than those given neither streptokinase nor aspirin (odds ratio 3.5; 95% CI 1.9-6.5; 2p < 0.00001). Streptokinase (alone or with aspirin) and aspirin (alone or with streptokinase) reduced, albeit not significantly, the incidence of combined six-month case fatality and severe disability: odds ratio for streptokinase 0.9 (95% CI 0.7-1.3) and odds ratio for aspirin 0.9 (95% CI 0.6-1.3). The risk of early death with thrombolytic treatments should be weighed against the potential benefit of a marginal reduction of severe disability after the first six months. Results of trials of aspirin and dipyridamole combined versus aspirin alone for the secondary prevention of vascular events after ischaemic stroke of presumed arterial origin are inconsistent. Our aim was to resolve this uncertainty.
                We did a randomised controlled trial in which we assigned patients to aspirin (30-325 mg daily) with (n=1363) or without (n=1376) dipyridamole (200 mg twice daily) within 6 months of a transient ischaemic attack or minor stroke of presumed arterial origin. Our primary outcome event was the composite of death from all vascular causes, non-fatal stroke, non-fatal myocardial infarction, or major bleeding complication, whichever happened first. Treatment was open, but auditing of outcome events was blinded. Primary analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial (number ISRCTN73824458) and with (NCT00161070).
                Mean follow-up was 3.5 years (SD 2.0). Median aspirin dose was 75 mg in both treatment groups (range 30-325); extended-release dipyridamole was used by 83% (n=1131) of patients on the combination regimen. Primary outcome events arose in 173 (13%) patients on aspirin and dipyridamole and in 216 (16%) on aspirin alone (hazard ratio 0.80, 95% CI 0.66-0.98; absolute risk reduction 1.0% per year, 95% CI 0.1-1.8). Addition of the ESPRIT data to the meta-analysis of previous trials resulted in an overall risk ratio for the composite of vascular death, stroke, or myocardial infarction of 0.82 (95% CI 0.74-0.91). Patients on aspirin and dipyridamole discontinued trial medication more often than those on aspirin alone (470 vs 184), mainly because of headache.
                The ESPRIT results, combined with the results of previous trials, provide sufficient evidence to prefer the combination regimen of aspirin plus dipyridamole over aspirin alone as antithrombotic therapy after cerebral ischaemia of arterial origin. Aspirin is effective in the treatment of acute myocardial infarction and in the long-term prevention of serious vascular events in survivors of stroke and myocardial infarction. There is, however, no reliable evidence on the effectiveness of early aspirin use in acute ischaemic stroke.
                The Chinese Acute Stroke Trial (CAST) was a large randomised, placebo-controlled trial of the effects in hospital of aspirin treatment (160 mg/day) started within 48 h of the onset of suspected acute ischaemic stroke and continued in hospital for up to 4 weeks. The primary endpoints were death from any cause during the 4-week treatment period and death or dependence at discharge, and the analyses were by intention to treat. 21,106 patients with acute ischaemic stroke were enrolled in 413 Chinese hospitals at a mean of 25 h after the onset of symptoms (10,554 aspirin, 10,552 placebo). 87% had a CT scan before randomisation. It was prospectively planned that the results would be analysed in parallel with those of the concurrent. International Stroke Trial (IST) of 20,000 patients with acute stroke from other countries.
                There was a significant 14% (SD 7) proportional reduction in mortality during the scheduled treatment period (343 [3.3%] deaths among aspirin-allocated patients vs 398 [3.9%] deaths among placebo-allocated patients; 2p = 0.04). There were significantly fewer recurrent ischaemic strokes in the aspirin-allocated than in the placebo-allocated group (167 [1.6%] vs 215 [2.1%]; 2p = 0.01) but slightly more haemorrhagic strokes (115 [1.1%] vs 93 [0.9%]; 2p > 0.1). For the combined in-hospital endpoint of death or non-fatal stroke at 4 weeks, there was a 12% (6) proportional risk reduction with aspirin (545 [5.3%] vs 614 [5.9%]; 2p = 0.03), an absolute difference of 6.8 (3.2) fewer cases per 1000. At discharge, 3153 (30.5%) aspirin-allocated patients and 3266 (31.6%) placebo-allocated patients were dead or dependent, corresponding to 11.4 (6.4) fewer per 1000 in favour of aspirin (2p = 0.08).
                There are two major trials of aspirin in acute ischaemic stroke. Taken together, CAST and the similarly large IST show reliably that aspirin started early in hospital produces a small but definite net benefit, with about 9 (SD 3) fewer deaths or non-fatal strokes per 1000 in the first few weeks (2p = 0.001), and with 13 (5) fewer dead or dependent per 1000 after some weeks or months of follow-up (2p < 0.01).
Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in patients who cannot swallow), and started within 48 hours of onset of presumed ischaemic stroke reduces the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications and improves long-term outcome.