High-dose acetylsalicylic acid after cerebral infarction. A Swedish Cooperative Study

The Canadian American Ticlopidine Study (CATS) in thromboembolic stroke

The Canadian American Ticlopidine Study (CATS) is a randomised, double-blind, placebo-controlled trial to assess the effect of ticlopidine (250 mg twice daily) in reducing the rate of subsequent occurrence of stroke, myocardial infarction, or vascular death in patients who have had a recent thromboembolic stroke. Twenty-five centres entered 1072 patients into the study between 1 week and 4 months after their qualifying stroke. The patients were treated and followed for up to 3 years (mean 24 months). In the efficacy analysis, the event rate per year for stroke, myocardial infarction or vascular death, considered together, was 15.3% in the placebo group and 10.8% in the ticlopidine group, representing a relative risk reduction with ticlopidine of 30.2% (95% confidence interval 7.5-48.3%; p = 0.006). Ticlopidine was beneficial for both men and women (relative risk reductions 28.1%, p = 0.037, and 34.2%, p = 0.045, respectively). Analysis by intention-to-treat gave a smaller estimate of risk reduction (23.3%, p = 0.020) for stroke, myocardial infarction, or vascular death. Adverse experiences associated with ticlopidine included neutropenia (severe in about 1% of cases) and skin rash and diarrhoea (severe in 2% of cases each); all were reversible. This study provides evidence of a beneficial effect of ticlopidine in both men and women with a recent thromboembolic stroke.

Randomized clinical trial of daily aspirin therapy in multi-infarct dementia. A pilot study

Seventy multi-infarct dementia patients were randomized into an aspirin-treated group and an untreated control group for an exploratory investigation to determine any effects of 325 mg aspirin daily on cognitive performance. The control group did not receive placebo but evaluations were carried out in a blinded manner. The index group (N = 37, mean age 67.1 years) received 325 mg of aspirin by mouth once daily while the control group (N = 33, mean age 67.6 years) was followed and treated in a similar manner except that they received no aspirin. Both groups had comparable risk factors for stroke, which were treated similarly, as well as comparable initial cerebral blood flow values, as measured by the 133xenon inhalation method, and initial scores on Cognitive Capacity Screening Examination testing. Patients were evaluated at intervals of one year. Significant improvements were demonstrated for cerebral perfusion values (P less than .0001) and cognitive performance scores (P less than .0001) among aspirin-treated patients compared to untreated controls at each of three annual follow-up evaluations. Both men and women benefited from aspirin therapy and their quality of life and independence appeared to be improved, which was not apparent in the control group. Daily aspirin appears to improve or stabilize declines in cerebral perfusion and cognition among patients with multi-infarct dementia.

Whole blood platelet function in acute ischemic stroke. Importance of dense body secretion and effects of antithrombotic agents

We studied platelet function in whole blood, a situation that better reflects the in vivo state, from 85 patients with acute ischemic stroke and from 19 healthy controls. Patients receiving no antithrombotic drugs demonstrated increased platelet dense body secretion without an associated increase in platelet aggregation, thus raising the possibility that dense body secretion may be of separate importance in cerebral infarction. Our results also suggest that dense body secretion may occur independently of aggregation. Heparin and heparin plus warfarin were ineffective in reducing the high level of dense body secretion seen in acute cerebral infarction, whereas treatment with aspirin plus dipyridamole inhibited both dense body secretion and platelet aggregation. It seems worthwhile to investigate the usefulness of antiplatelet drugs in the treatment of acute ischemic stroke wherein clinical outcome is correlated with the extent of suppression of platelet dense body secretion.

Danish very-low-dose aspirin after carotid endarterectomy trial

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.

The Canadian American Ticlopidine Study (CATS) in thromboembolic stroke. Design, organization, and baseline results

The Canadian American Ticlopidine Study is a randomized, placebo-controlled, double-blind, multicenter study to assess the efficacy and safety of ticlopidine hydrochloride in patients who have suffered a thromboembolic stroke no less than 1 week and no more than 4 months before entry into the study. The primary assessment of efficacy will be based on the cluster of outcome events recurrent stroke, myocardial infarction, or vascular death. Twenty-five clinical centers, 12 in Canada and 13 in the United States, entered a total of 1,072 patients during a 3-year recruitment period; these patients were randomly allocated to receive either 250 mg ticlopidine or identical-appearing placebo tablets twice daily for up to 3 years. Patient recruitment was completed in December 1986. Patients were followed for a maximum of 3 years or until the close of the study in December 1987; at that time an average follow-up of 25 months had been achieved. We summarize the protocol and organization of the study and document the methods of execution and analysis, with corresponding criteria, before disclosure of the treatment code to any of the study investigators. We also provide a clinical description of the patients at entry into the study.

Antiplatelet agents in the secondary prevention of stroke: meta-analysis of the randomized control trials

Randomized control trials of antiplatelet agents in the prevention of stroke following transient ischemic attacks have had conflicting results. The decision to employ aspirin instead of placebo as the control regimen in trials testing newer antiplatelet agents emphasizes the need for an accurate estimate of the efficacy of older drugs. A meta-analysis of seven randomized control trials comparing aspirin and/or sulfinpyrazone or dipyridamole with placebo was performed. For aspirin compared with placebo, a nonsignificant reduction in stroke of 15% (odds ratio 0.85, 95% confidence interval 0.60-1.19; chi 2 = 0.78, p greater than 0.30) was found. For aspirin combined with sulfinpyrazone or dipyridamole compared with placebo, a 39% reduction in stroke was observed (odds ratio 0.61, 95% confidence interval 0.39-0.95; chi 2 = 4.22, p less than 0.05); at the same time a 350% increase in gastrointestinal hemorrhage or peptic ulcer was noted (odds ratio 3.5, 95% confidence interval 1.26-9.75; chi 2 = 4.61, p less than 0.05). A trend in reduction of strokes for men was observed (odds ratio 0.58, 95% confidence interval 0.32-1.07; chi 2 = 2.52, p less than 0.15) for any regimen containing aspirin. The significant benefit of aspirin-combination therapy on stroke must be interpreted cautiously because of a number of possible biases. It is still conceivable that aspirin alone may decrease the incidence of stroke by as much as 40%, but a sample of greater than 13,000 patients would be needed to confirm the benefit observed in our analysis.