Occurrence Of Transient Ischemic Attack Research Articles

Acetylsalicylic acid in the prevention of stroke in patients with reversible cerebral ischemic attacks. A Danish cooperative study.

Two hundred and three patients, 148 males and 55 females, who during the last month before admission had experienced at least one reversible cerebral ischemic attack of less than 72 hours duration, were randomly assigned to treatment with either acetylsalicylic acid (ASA) 1000 mg daily (101 patients) or placebo (102 patients). The average follow-up period was 25 months. The two treatment groups were comparable with respect to age, sex, associated diseases, risk factors, number and duration of cerebral ischemic attacks. No statistically significant differences were found between the treatment groups as to the primary end point: stroke or death (ASA group 20.8%, placebo group 16.7%). Occurrence of transient ischemic attacks during the treatment period was not reduced by ASA treatment, whereas there was a trend suggesting fewer myocardial infarctions in the ASA group (5.9%) than in the placebo group (13.7%). The difference, however, was not statistically significant (p = 0.10). We were thus unable to demonstrate any favorable influence of ASA 1000 mg daily in patients with reversible ischemic attacks. This study does not, of course, prove that ASA treatment is ineffective in stroke prevention.

Indium‐111 platelet scintigraphy in cerebrovascular disease

We obtained scintigraphic images of the neck from 100 patients with suspected cerebrovascular disease after injecting indium-111-labeled autologous platelets. One or more focuses of increased activity, implying local platelet accumulation, were seen along the course of the cervical carotid arteries in 52 patients. In 64 patients, there was a highly significant correlation between the results of scintigraphy and carotid arteriography (p = 10(6)). There was no significant correlation between the scintigraphic findings and the previous or subsequent occurrence of transient ischemic attack or cerebral infarction in the carotid circulation. These data suggest that factors other than the simple formation of platlet thrombi in the cervical carotid arteries are of primary importance in the pathogenesis of stroke.

Long-term follow-up of asymptomatic carotid bruits

Ninety-seven patients with asymptomatic carotid bruits were followed up 5 to 13 years or until the occurrence of transient ischemic attacks, stroke or death. In 11 percent of the patients transient ischemic attacks developed and in 19 percent, strokes. Symptoms that developed in more than half of the patients did so within 2 years and 90 percent within 6 years of detection of the bruit. Seventeen of 18 strokes occurred without antecedent transient ischemic attacks. Fifty-three of the patients underwent 94 major noncarotid operations with no postoperative strokes. Death occurred in 37 percent of the patients during the follow-up period, and 90 percent of the deaths were due to cardiac problems or stroke.

A Stochastic Model for the Occurrence of Transient Ischemic Attacks

This paper presents the development, application and evaluation of a stochastic model of the frequency of occurrence of transient ischemic attacks (TIAs). TIAs occur during periods of abnormal arterial activity. The TIAs which occur during a single period of abnormal activity are called a cluster of TIAs. Thus, the number of TIAs occurring in a time interval is determined by the number of clusters of TIAs occurring and the number of TIAs per cluster. The distribution of the number of clusters, which is a modification of the Poisson distribution, is obtained through the use of infinitesimal probabilities and the method of generating function. The number of TIAs per cluster follows the logarithmic series distribution. The distribution of the number of TIAs is then a modification of the negative binomial distribution, which allows for censoring of the data that may be related to the occurrence of the clusters of TIAs. Estimates for the parameters, based on observed frequencies, are obtained, which allow the model to be applied to data from the Aspirin in Transient Ischemic Attacks Study.

Controlled trial of aspirin in cerebral ischemia.

Adouble-blind trial of aspirin for the treatment of cerebral ischemia was begun in 1972 and continued for 37 months. This was accomplished despite difficulties in controlling a long-term study of a drug which has widespread availability and consumption. The study design, criteria for selection of patients, follow-up surveillance, and methods of data analysis are presented. We report only subjects without carotid surgery before randomization. Patients (178) who had carotid transient ischemic attacks (TIAs) were randomly allocated to aspirin or placebo and followed to determine the incidence of subsequent TIAs,death, cerebral infarction or retinal infarction. Analysis of the first six months of follow-up revealed a statistically significant differential in favar of aspirin when death or cerebral or retinal infarction and the occurrence of TIAs were grouped and considered together as end points. Significance in favor of aspirin treatment was mainly revealed in patients with a history of multiple TIAs and was most evident in those individuals having carotid lesions appropriate to the TIA symptoms. It cannot be inferred from this study that aspirin prevents stroke because when end points were restriced to death or cerebral or retinal infarction, there was no statistically significant differential between the aspirin and placebo treatments.