Stroke Prevention in Atrial Fibrillation Study. Final results. Aspirin in the prevention of progressing stroke: a randomized controlled study. Aspirin and ticlopidine for prevention of recurrent stroke in black patients: a randomized trial. Comparison of triflusal and aspirin for prevention of vascular events in patients after cerebral infarction: the TACIP Study: a randomized, double-blind, multicenter trial. Effects of low-dose warfarin and aspirin versus no treatment on stroke in a medium-risk patient population with atrial fibrillation. Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial. Warfarin versus aspirin for prevention of thromboembolism in atrial fibrillation: Stroke Prevention in Atrial Fibrillation II Study. A comparison of warfarin and aspirin for the prevention of recurrent ischemic stroke. A randomized trial of anticoagulants versus aspirin after cerebral ischemia of presumed arterial origin. The Stroke Prevention in Reversible Ischemia Trial (SPIRIT) Study Group.
Atrial fibrillation in the absence of rheumatic valvular disease is associated with a fivefold to sevenfold increased risk of ischemic stroke.
                The Stroke Prevention in Atrial Fibrillation Study, a multicenter, randomized trial, compared 325 mg/day aspirin (double-blind) or warfarin with placebo for prevention of ischemic stroke and systemic embolism (primary events), and included 1,330 inpatients and outpatients with constant or intermittent atrial fibrillation. During a mean follow-up of 1.3 years, the rate of primary events in patients assigned to placebo was 6.3% per year and was reduced by 42% in those assigned to aspirin (3.6% per year; p = 0.02; 95% confidence interval, 9-63%). In the subgroup of warfarin-eligible patients (most less than 76 years old), warfarin dose-adjusted to prolong prothrombin time to 1.3-fold to 1.8-fold that of control reduced the risk of primary events by 67% (warfarin versus placebo, 2.3% versus 7.4% per year; p = 0.01; 95% confidence interval, 27-85%). Primary events or death were reduced 58% (p = 0.01) by warfarin and 32% (p = 0.02) by aspirin. The risk of significant bleeding was 1.5%, 1.4%, and 1.6% per year in patients assigned to warfarin, aspirin, and placebo, respectively.
                Aspirin and warfarin are both effective in reducing ischemic stroke and systemic embolism in patients with atrial fibrillation. Because warfarin-eligible patients composed a subset of all aspirin-eligible patients, the magnitude of reduction in events by warfarin versus aspirin cannot be compared. Too few events occurred in warfarin-eligible patients to directly assess the relative benefit of aspirin compared with warfarin, and the trial is continuing to address this issue. Patients with nonrheumatic atrial fibrillation who can safely take either aspirin or warfarin should receive prophylactic antithrombotic therapy to reduce the risk of stroke. 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. Blacks are disproportionately affected by stroke, and they are about 2 times more likely than most other individuals in the United States to die of or experience stroke.
                To determine the efficacy and safety of aspirin and ticlopidine to prevent recurrent stroke in black patients.
                Randomized, double-blind, investigator-initiated, multicenter trial of 1809 black men and women who recently had a noncardioembolic ischemic stroke and who were recruited between December 1992 and October 2001 from 62 academic and community hospitals in the United States and followed up for up to 2 years.
                A total of 902 patients received 500 mg/d of ticlopidine and 907 received 650 mg/d of aspirin.
                Recurrent stroke, myocardial infarction, or vascular death was the composite primary end point (according to intention-to-treat analysis). The secondary outcome was fatal or nonfatal stroke.
                The blinded phase of the study was halted after about 6.5 years when futility analyses revealed a less than 1% probability of ticlopidine being shown superior to aspirin in the prevention of the primary outcome end point. The primary outcome of recurrent stroke, myocardial infarction, or vascular death was reached by 133 (14.7%) of 902 patients assigned to ticlopidine and 112 (12.3%) of 907 patients assigned to aspirin (hazard ratio, 1.22; 95% confidence interval, 0.94-1.57). Kaplan-Meier curves for time to event for the primary outcome did not differ significantly (P =.12 by log-rank test). Kaplan-Meier curves for time to the secondary outcome of fatal or nonfatal stroke approached a statistically significant reduction favoring aspirin over ticlopidine (P =.08 by log-rank test). The frequency of laboratory-determined serious neutropenia was 3.4% for patients receiving ticlopdine vs 2.2% for patients receiving aspirin (P =.12) and 0.3% vs 0.2% for thrombocytopenia, respectively (P =.69). One ticlopidine-treated patient developed thrombocytopenia, which was thought to be a case of possible thrombotic thrombocytopenia purpura, and recovered after therapy with plasmapheresis.
                During a 2-year follow-up, we found no statistically significant difference between ticlopidine and aspirin in the prevention of recurrent stroke, myocardial infarction, or vascular death. However, there was a nonsignificant trend for reduction of fatal or nonfatal stroke among those in the aspirin group. Based on these data and the risk of serious adverse events with ticlopidine, we regard aspirin as a better treatment for aspirin-tolerant black patients with noncardioembolic ischemic stroke. 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.
                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.
                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).
                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. To assess the optimal stroke prevention treatment for patients with atrial fibrillation (AF) and a low-medium risk (< or =4%) of stroke.
                A total of 668 patients with persistent or permanent AF, without an indication for full dose and with adequate rate control on sotalol, were randomized to warfarin 1.25 mg + aspirin 75 mg daily (W/A, 334 patients) or no anticoagulation (C, 334 patients). The mean follow-up period was 33 months. The protocol intended to verify a 37% relative risk reduction provided a 4% stroke incidence in the C group.
                The stroke incidence was less in the W/A group, although the reduction was not statistically significant (W/A 9.6% versus C 12.3%). Four haemorrhagic strokes were identified, two in each group. Secondary end-points were transient ischaemic attacks (TIA) (W/A 3.3% versus C 4.5%), all cause mortality (W/A 9.3% versus C 10.8%), cardiovascular morbidity (W/A 17.7% versus C 22.2%) and the combination of stroke + TIA (W/A 11.7% versus C 16.5%). Bleedings were documented in 19 versus four patients (W/A 5.7% versus C 1.2%) (P = 0.003), although none fatal. Sinus rhythm (SR) was recorded occasionally in 68 patients (W/A 9.6% versus C 10.8%). The stroke incidence tended to be higher in those with SR than without, 16.2% versus 10.4%.
                Our results were inconclusive, but consistent with a small beneficial effect of W/A for reduction of stroke and major vascular events in AF patients at moderate risk. The low-dose regiment produced, however, a significantly increased risk of bleedings. Documented SR occasionally recorded may represent a subpopulation that warrants full dose warfarin. 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. Warfarin is an established treatment for prevention of ischaemic stroke in patients with atrial fibrillation, but the value of this agent relative to aspirin in unclear. In the first Stroke Prevention in Atrial Fibrillation (SPAF-I) study, direct comparison of warfarin with aspirin was limited by the small number of thromboembolic events. SPAF-II aims to address this issue and also to assess the differential effects of the two treatments according to age. We compared warfarin (prothrombin time ratio 1.3-1.8, international normalised ratio 2.0-4.5) with aspirin 325 mg daily for prevention of ischaemic stroke and systemic embolism (primary events) in two parallel randomised trials involving 715 patients aged 75 years or less and 385 patients older than 75; we sought reductions in the absolute rate of primary events by warfarin compared with aspirin of 2% per year and 4% per year, respectively. In the younger patients, warfarin decreased the absolute rate of primary events by 0.7% per year (95% CI-0.4 to 1.7). The primary event rate per year was 1.3% with warfarin and 1.9% with aspirin (relative risk [RR] 0.67, p = 0.24). The absolute rate of primary events in low-risk younger patients (without hypertension, recent heart failure, or previous thromboembolism) on aspirin was 0.5% per year (95% CI 0.1 to 1.9). Among older patients, warfarin decreased the absolute rate of primary events by 1.2% per year (95% CI-1.7 to 4.1). The primary event rate per year was 3.6% with warfarin and 4.8% with aspirin (RR 0.73, p = 0.39). In this older group, the rate of all stroke with residual deficit (ischaemic or haemorrhagic) was 4.3% per year with aspirin and 4.6% per year with warfarin (RR 1.1). Warfarin may be more effective than aspirin for prevention of ischaemic stroke in patients with atrial fibrillation, but the absolute reduction in stroke rate by warfarin is small. Younger patients without risk factors had a low rate of stroke when treated with aspirin. In older patients the rate of stroke (ischaemic and haemorrhagic) was substantial, irrespective of which agent was given. Patient age and the inherent risk of thromboembolism should be considered in the choice of antithrombotic prophylaxis for patients with atrial fibrillation. Despite the use of antiplatelet agents, usually aspirin, in patients who have had an ischemic stroke, there is still a substantial rate of recurrence. Therefore, we investigated whether warfarin, which is effective and superior to aspirin in the prevention of cardiogenic embolism, would also prove superior in the prevention of recurrent ischemic stroke in patients with a prior noncardioembolic ischemic stroke.
                In a multicenter, double-blind, randomized trial, we compared the effect of warfarin (at a dose adjusted to produce an international normalized ratio of 1.4 to 2.8) and that of aspirin (325 mg per day) on the combined primary end point of recurrent ischemic stroke or death from any cause within two years.
                The two randomized study groups were similar with respect to base-line risk factors. In the intention-to-treat analysis, no significant differences were found between the treatment groups in any of the outcomes measured. The primary end point of death or recurrent ischemic stroke was reached by 196 of 1103 patients assigned to warfarin (17.8 percent) and 176 of 1103 assigned to aspirin (16.0 percent; P=0.25; hazard ratio comparing warfarin with aspirin, 1.13; 95 percent confidence interval, 0.92 to 1.38). The rates of major hemorrhage were low (2.22 per 100 patient-years in the warfarin group and 1.49 per 100 patient-years in the aspirin group). Also, there were no significant treatment-related differences in the frequency of or time to the primary end point or major hemorrhage according to the cause of the initial stroke (1237 patients had had previous small-vessel or lacunar infarcts, 576 had had cryptogenic infarcts, and 259 had had infarcts designated as due to severe stenosis or occlusion of a large artery).
                Over two years, we found no difference between aspirin and warfarin in the prevention of recurrent ischemic stroke or death or in the rate of major hemorrhage. Consequently, we regard both warfarin and aspirin as reasonable therapeutic alternatives. Aspirin is only modestly effective in the secondary prevention after cerebral ischemia. Studies in other vascular disorders suggest that anticoagulant drugs in patients with cerebral ischemia of presumed arterial (noncardiac) origin might be more effective. The aim of the Stroke Prevention in Reversible Ischemia Trial (SPIRIT) therefore was to compare the efficacy and safety of 30 mg aspirin daily and oral anticoagulation (international normalized ratio [INR] 3.0-4.5). Patients referred to a neurologist in one of 58 collaborating centers because of a transient ischemic attack or minor ischemic stroke (Rankin grade < or =3) were eligible. Randomization was concealed, treatment assignment was open, and assessment of outcome events was masked. The primary measure of outcome was the composite event "death from all vascular causes, nonfatal stroke, nonfatal myocardial infarction, or nonfatal major bleeding complication." The trial was stopped at the first interim analysis. A total of 1,316 patients participated; their mean follow-up was 14 months. There was an excess of the primary outcome event in the anticoagulated group (81 of 651) versus 36 of 665 in the aspirin group (hazard ratio, 2.3; 95% confidence interval [CI], 1.6-3.5). This excess could be attributed to 53 major bleeding complications (27 intracranial; 17 fatal) during anticoagulant therapy versus 6 on aspirin (3 intracranial; 1 fatal). The bleeding incidence increased by a factor of 1.43 (95% CI, 0.96-2.13) for each 0.5 unit increase of the achieved INR. Anticoagulant therapy with an INR range of 3.0 to 4.5 in patients after cerebral ischemia of presumed arterial origin is not safe. The efficacy of a lower intensity anticoagulation regimen remains to be determined.
Aspirin appears to reduce stroke and major vascular events in patients with non-valvular AF similar to its effect in other high-risk patients (i.e. by about 25%). For primary prevention among AF patients with an average stroke rate of 4% per year, about 10 strokes would likely be prevented yearly for every 1000 AF patients given aspirin.