Cerebral infarction verified by cranial computed tomography and prognosis for survival following transient ischemic attack

Prognosis and Management in the First Few Days after a Transient Ischemic Attack or Minor Ischaemic Stroke

The risk of recurrent stroke during the first few days after a transient ischaemic attack (TIA) or minor stroke is very much higher than previously estimated. However, there is considerable international variation in how patients with suspected TIA or minor stroke are managed in the acute phase, some healthcare systems providing immediate emergency inpatient care and others providing non-emergency outpatient clinic assessment. This review considers what is known about the early prognosis after TIA and minor ischaemic stroke, what factors identify individuals at particularly high early risk of stroke, and what evidence there is that urgent preventive treatment is likely to be effective in reducing the early risk of stroke.

Factors Associated with Cognitive Decline in Transient Ischemic Attack Patients

Chronic cerebrovascular disease and large ischemic stroke are both associated with cognitive impairment. Much less is known about the acute cognitive sequelae of transient ischemic attack (TIA). Although often overlooked, there is increasing evidence that cognitive impairment does occur following TIA. In some patients, cognitive changes persist after resolution of focal neurological deficits, but the temporal profile of these symptoms is unknown. In addition, clinical and imaging correlates of cognitive impairment after TIA have not been systematically studied. This under-studied and recognized problem has significant implications for TIA patient management. In this review, we summarize the evidence currently available and identify future research priorities.

The need for emergency treatment of transient ischemic attack and minor stroke

The risk of recurrent stroke following transient ischemic attack or minor stroke has recently been shown to be 5-10% at 1 week and 10-20% at 3 months, depending on study population and methods. This is considerably higher than previously estimated and current clinical guidelines reflect the need for rapid assessment although a wide variation in practice exists. Effective management of patients with transient ischemic attack or minor stroke, therefore, requires identification of individuals at the highest (and lowest) risk and initiation of appropriate secondary prevention. Risk can be stratified at initial presentation by the presence or absence of simple clinical features and following subsequent investigation. For transient ischemic attack patients, older age, diabetes, longer duration of symptoms and weakness or speech disturbance identify patients at highest risk, as does the presence of large artery atherosclerosis (mainly internal carotid artery stenosis) and lesions on diffusion-weighted magnetic resonance imaging. Strong evidence exists for the benefit of some early interventions (carotid endarterectomy and antiplatelet agents), but is circumstantial or awaited for others (statins and antihypertensives). In order for the public health challenge posed by transient ischemic attack and minor stroke to be met, considerable change is required in both public education (to ensure correct recognition of symptoms and swift presentation to medical attention) and the provision of clinical services to ensure the timely initiation of effective treatment.

Prediction and prevention of stroke after transient ischemic attack in the short and long term

Over the last 5 years, a number of studies have shown the early risk of stroke following transient ischemic attack (TIA) to be of the order of 5-10% at 1 week and 10-20% at 3 months, considerably higher than previously estimated. Because these studies have been carried out in a variety of different clinical settings, their findings are likely to be generalizable. Various independent prognostic factors for this early risk of stroke have been identified and models, based on clinical features at presentation, have been derived and validated to predict risk of stroke within 7 and 90 days after TIA. At the same time, diffusion-weighted magnetic resonance imaging and carotid imaging provide prognostic information and are likely to refine risk prediction further, although no unified model combining clinical and imaging data currently exists. Uncertainty continues surrounding the most effective secondary prevention in the hyperacute phase after TIA, especially in the choice of antiplatelet agents, although clinical trials to address this question are ongoing. However, the need for carotid endarterectomy in patients with symptomatic carotid stenosis is well established. The risk of vascular disease in the medium term (1-5 years) following TIA has been more widely studied, and predictive models for this are available. Recent data on the long-term (10 years and beyond) vascular risk after TIA demonstrate ongoing mortality from both cerebrovascular and cardiovascular causes, highlighting the need for continued secondary prevention.

European Stroke Prevention Study 2: A study of low-dose acetylsalicylic acid and of high dose dipyridamole in secondary prevention of cerebro-vascular accidents

In spite of some data being added to our knowledge of the effect of antiplatelets in secondary prevention of brain ischemic lesion in recent years, the main reasons to perform a second European Stroke Prevention Study (ESPS 2), which started in 1987-1988, were: (a) clarify the relative roles of aspirin (ASA) and dipyridamole (DP) alone or in combination; (b) confirm the efficacy of small doses of ASA and, so doing, decrease the number of drop-outs due to ASA side effects; (c) join information to the effect of antiplatelets in complete stroke. General characteristics of the sample of 6602 patients are presented and compared with other major trials and series. The patients in the four treatment arms (aspirin, dipyridamole, aspirin + dipyridamole and placebo) are compared. The more relevant features and risk factors known to influence long term prognosis are described and discussed. The small proportion of patients included with TIA (23.7%) and the comparability among treatment groups are stressed. No relevant differences have been found, among groups, on the sex or age distribution, prevalence of hypertension, diabetes, previous vascular events or atrial fibrillation, nor in the characteristics of the accident leading to the inclusion in trial.

Temporary is not always benign: similarities and differences between transient ischemic attack and angina

The introduction of the tissue-based definition of transient ischemic attack (TIA), according to which TIA may be diagnosed only in the absence of an infarction on brain neuroimaging, prompts reflections about similarities and differences between TIA and angina. Both share transitory symptoms in the absence of tissue damage, whereas stroke and myocardial infarction are associated with tissue necrosis. Apart from this, TIA and angina are widely different with respect to pathophysiology, natural history, prognosis, and response to specific medical treatments. In general terms, it could be argued that TIA differs from angina as the brain differs from the heart in structure, physiology, metabolism, and performance. Most importantly, in TIA and angina, the reversible nature of symptoms cannot be assumed as a favorable prognostic indicator. In fact, reversibility of stable angina denotes a low-risk condition, whereas in TIA and unstable angina reversibility may suggest plaque instability and relevant risk of ischemic recurrences.

Use of cranial CT to identify a new infarct in patients with a transient ischemic attack

Research on infarct detection by noncontrast cranial computed tomography (CCT) in patients with transient ischemic attack (TIA) is sparse. However, the aims of this study are to determine the frequency of new infarcts in patients with TIA, to evaluate the independent predictors of infarct detection, and to investigate the association between a new infarct and early short-term risk of stroke during hospitalization. We prospectively evaluated 1533 consecutive patients (mean age, 75.3 ± 11 years; 54% female; mean National Institutes of Health Stroke Scale [NIHSS] score, 1.7 ± 2.9) with TIA who were admitted to hospital within 48 h of symptom onset. A new infarct was detected by CCT in 47 (3.1%) of the 1533 patients. During hospitalization, 17 patients suffered a stroke. Multivariate logistic regression analysis revealed the following independent predictors for infarct detection: NIHSS score ≥10 (odds ratio [OR], 4.8), time to CCT assessment >6 h (OR 2.2), and diabetes (OR 2.3). The evidence of a new infarct was not associated with the risk of stroke after TIA. The frequency of a new infarct in patients with TIA using CCT is low. The use of the CCT tool to predict the stroke risk during hospitalization in patients with TIA is found to be inappropriate. The estimated clinical predictors are easy to use and may help clinicians in the TIA work up.

Brain imaging in patients with transient ischemic attack: a comparison of computed tomography and magnetic resonance imaging

BACKGROUND

Brain imaging in stroke aims at the detection of the relevant ischemic tissue pathology. Cranial computed tomography (CT) is frequently used in patients with transient ischemic attack (TIA) but no data is available on how it directly compares to magnetic resonance imaging (MRI).

METHODS

We compared detection of acute ischemic lesions on CT and MRI in 215 consecutive TIA patients who underwent brain imaging with either CT (n = 161) or MRI (n = 54). An MRI was performed within 24 h in all patients who had CT initially.

RESULTS

An initial assessment with CT revealed no acute pathology in 154 (95.7%) and possible acute infarction in 7 (4.3%) patients. The acute infarct on CT was confirmed by diffusion-weighted imaging (DWI) in only 2 cases (28.6%). DWI detected an acute infarct in 50 of the 154 patients with normal baseline CT (32.5%). Among 54 patients without baseline CT, DWI showed acute ischemic lesions in 19 (35.2%). The ischemic lesions had a median volume of 0.87 cm(3) (range: 0.08-15.61), and the lesion pattern provided clues to the underlying etiology in 13.7%.

CONCLUSION

Acute MRI is advantageous over CT to confirm the probable ischemic nature and to identify the etiology in TIA patients.

Tissue factor expression in the symptomatic carotid plaque

Background

The aims of this study were to identify that the differences in the natural history of patients with symptomatic and asymptomatic carotid stenosis may be reflected in differences in the expression of procoagulant protein factors.

Methods

Carotid artery plaques were obtained from 33 symptomatic and 4 asymptomatic patients with internal carotid artery stenosis of greater than 70%. These plaques were stained with monoclonal antibody against human tissue factor. Areas of staining for the cap and core were analysed using the analySIS computer programme.

Results

There were 37 patients, of whom 27 were male with a mean age 69.3 years and a range of 53 to 83 years. Statistical analysis using non-parametric tests revealed a significant increase in the area of positive staining for tissue factor in plaques taken from symptomatic patients when compared to those who were asymptomatic (P = 0001). Within the symptomatic patients group there was significantly increased tissue factor in the plaque core of those who were the most recently symptomatic (P = 0.003).

Conclusions

The unstable carotid artery plaque is associated with significantly increased tissue factor expression in the cap and core. Plaques from the most recently symptomatic patients have significantly more tissue factor in the core and this may represent part of the mechanism responsible for plaque destabilisation. More research is needed in this important area.

Keywords

Tissue Factor; Carotid stenosis; Stroke; Plaque stability

Current management of transient ischemic attack

Transient ischemic attack (TIA) is a precursor to ischemic stroke. At least half of patients with TIA have a new, small ischemic lesion demonstrable on magnetic resonance imaging using a diffusion weighted sequence. The risk of subsequent major stroke is 10-20% in the next 3 months with much of that risk front-loaded in the first week. Strategies to identify and treat high-risk patients need to be defined. The optimal treatment approach and the timing of interventions, both medical and surgical, remains unknown. In general, aspirin is the first line of treatment to prevent further stroke. Other antiplatelet agents such as clopidogrel alone or in combination with aspirin and the combination aspirin/extended-release dipyridamole may be administered. Endarterectomy or carotid stenting is of great benefit to patients with TIA secondary to stenosis in the extracranial carotid artery.

Recent advances in management of transient ischaemic attacks and minor ischaemic strokes

The risk of recurrent stroke during the first few days after a transient ischaemic attack or minor stroke is much higher than previously estimated. However, there is substantial variation worldwide in how patients with suspected transient ischaemic attack or minor stroke are investigated and treated in the acute phase: some health-care systems provide immediate emergency inpatient care and others provide non-emergency outpatient clinical assessment. This review considers what is known about the early prognosis after transient ischaemic attack and minor ischaemic stroke, what factors identify individuals at particularly high early risk of stroke, and what evidence there is that urgent preventive treatment is likely to be effective in reducing the early risk of stroke.

Delayed transient worsening of neurological deficits after ischaemic stroke

BACKGROUND

Although the causes of stroke recurrence are well known, no particular study deals with the specific issue of late-onset transient worsening of the neurological deficit (TWND) after an ischaemic stroke.

PATIENTS AND METHODS

In this retrospective study the aetiology of the TWNDs in 101 patients was compared to the causes of transient ischaemic attacks (TIAs) in 115 patients. All patients had a full cardiovascular and neuroimaging examination according to current guidelines. An electroencephalogram (EEG) was performed when necessary. The diagnosis of inhibitory seizures was retained when the EEG showed periodic lateralized epileptiform discharges or intermittent rhythmic delta activities, or when the patient developed typical seizures afterwards.

RESULTS

Arterial hypertension and diabetes were more prevalent vascular risk factors in TWND patients. Small-vessel disease and inhibitory seizures were a more frequent cause of TWNDs than of TIAs. Extracranial large-vessel disease predominates in TIA patients. The global prevalence of cardiac diseases as cause of TIAs and TWNDs was the same, although severe ulcerous plaques of the aortic arch and patent foramen ovale with atrial septum aneurysm occurred more frequently in TWND patients.

CONCLUSIONS

The most frequent causes of late-onset TWNDs were different from those of TIAs. Apart from repeated neuroimaging of the brain, exhaustive cardiac investigations and EEG are mandatory in TWND patients.

Diffusion-weighted MR imaging in transient ischaemic attacks

The purpose of this study was to determine frequency and the characteristics of diffusion-weighted imaging (DWI) abnormalities in patients with transient ischaemic attack (TIA). We analysed data of 98 consecutive patients (mean age: 60.6+/-15.4 years, 56 men) admitted between January 2003 and April 2004 for TIA. Age, gender, symptom type and duration, delay from onset to magnetic resonance imaging (MRI), probable or possible TIA and cause of TIA were compared in patients with (DWI+) and without (DWI-) lesions on DWI. Volume and apparent diffusion coefficient (ADC) values of DWI lesions were computed. DWI revealed ischaemic lesions in 34 patients (34.7%). Lesions were small (mean volume: 1.9 cm(3)+/-3.3), and ADC was moderately decreased (mean ADC ratio: 79.5%). The diagnosis of TIA was considered as probable in all DWI+ patients. A multiple logistic regression model demonstrated that TIA duration greater than or equal to 60 min (OR, 7.6; 95% CI, 2.3-25.7), aphasia (OR, 9.2; 95% CI, 2.7-31.4) and motor deficit (OR, 5.1; 95% CI, 1.5-17.8) were independent predictors of DWI lesions. Prolonged TIA duration, aphasia and motor deficits are associated with DWI lesions. More than half of TIA patients with symptoms lasting more than 60 min have DWI lesions.

Diffusion-weighted MRI in evaluation of transient ischemic attack

Diffusion-weighted magnetic resonance imaging (DWI) is a sensitive diagnostic tool for detecting recent ischemic lesions in patients with transient ischemic attacks (TIAs), but the interpretation of the presence or absence of DWI abnormalities in TIA patients still remains controversial. To elucidate the pathophysiology underlying those lesions, we analyzed DWI abnormalities in patients with recent TIAs. Based on 45 consecutive patients with TIAs who underwent DWI within 10 days of onset, demographic data and clinical manifestations were analyzed in relation to the DWI abnormalities. According to the method utilized in the Oxfordshire Community Stroke Study, clinical manifestations were classified into classical lacunar syndrome and non-lacunar symptoms. Based on the vascular distributions of ischemic lesions, the DWI abnormalities were classified into small-vessel and large-vessel lesions. DWI abnormalities were detected in 14 (31%) of 45 TIA patients. Seven (50%) of 14 DWI-positive patients had occlusive vascular lesions on intracranial magnetic resonance angiography, while only 5 (16%) of 31 DWI-negative patients had occlusive lesions (P < .05). No other demographic or clinical features, including risk factor and presence of cardiac disease, differed significantly between the DWI-positive and DWI-negative patient groups. Four (46%) of 9 DWI-positive patients who had a classical lacunar syndrome also showed small-vessel lesions on DWI, whereas all 5 patients who had non-lacunar symptoms showed large-vessel lesions. We concluded that although DWI abnormalities were detected in only one third of our TIA patients, DWI abnormalities were closely related to intracranial vascular occlusive lesions. The combination of DWI and MRA was useful for detecting large-artery lesions in patients displaying a classical lacunar syndrome.

Brain CT-scan in acute stroke patients: silent infarcts and relation to outcome

Silent infarcts (SIs) are common findings in stroke patients, but their clinical significance remains controversial. Aim of this study was to evaluate the prevalence of SI in consecutive stroke patients, characteristics, associated factors, and influence on in-hospital mortality. The population consisted of 191 patients, consecutively admitted for an acute stroke. Of 191 patients, 74 had SI on CT-scan. Silent infarcts were often multiple, right sided, lacunar. We found SI more frequently in older patients, smokers, with an ischemic stroke having small vessel disease as presumed cause. In our study SI were associated with ageing, smoke habit and lacunar stroke. Silent infarcts size influenced the rate of in-hospital mortality.

Computer analysis of ultrasonic plaque echolucency in identifying high risk carotid bifurcation lesions

OBJECTIVES

to confirm that plaque echogenicity evaluated by computer analysis, as suggested by preliminary studies, can identify plaques associated with a high incidence of strokes.

MATERIALS AND METHODS

a series of 96 patients with carotid stenosis in the range of 50-99% were studied retrospectively (41 with TIAs and 55 asymptomatic). Carotid plaque echogenicity was evaluated using a computerised measurement of the median grey scale value (GSM). All patients had a CT brain scan to determine the presence of infarction in the carotid territory.

RESULTS

the incidence of ipsilateral brain CT infarctions was 16% in the asymptomatic and 32% in the symptomatic plaques (p =0.076). It was 20% for <70% stenosis and 25% for >70% stenosis (p =0.52). It was 9% for plaques which had a GSM >50 and 40% in those with GSM <50 (p <0.001) with a relative risk of 4.6 (95% CI 1.8 to 11.6).

CONCLUSIONS

the results confirm that computer analysis of plaque echogenicity is better than the degree of stenosis in identifying plaques associated with an increased incidence of CT brain-scan infarction and consequently useful for identifying individuals at high risk of stroke. What is required is a form of image standardisation in order to apply this method to natural history studies with stroke as the endpoint.

Cerebral tomographic findings in patients undergoing carotid endarterectomy for asymptomatic carotid stenosis: short-term and long-term implications

PURPOSE

Preoperative cerebral imaging has been considered not to be cost-effective in carotid endarterectomy (CEA) for asymptomatic carotid stenosis. Yet, silent brain infarction (SBI) has been associated with the embolization potential of a severe carotid stenosis. Thus the presence of SBI may represent an additional indication for CEA in asymptomatic patients. We examined the predictive value of preoperatively detected silent cerebral lesions on early and late outcomes in patients undergoing CEA for asymptomatic carotid stenosis.

METHODS

Preoperative cerebral tomographic (CT) scans performed on 301 asymptomatic patients undergoing 346 CEAs from 1986 to 1995 were reviewed by a single neuroradiologist blinded to patients' records. Mean follow-up was 67. 3 months (range, 24-130 months). The degree of internal carotid lumen reduction was measured bilaterally in all patients (602 carotid arteries); carotid stenosis of 60% or more was found in 399 carotid arteries.

RESULTS

Of the 103 (34%) CT scans positive for cerebral lesions, 58% were lacunar. No significant association was observed between the side of the cerebral lesion on CT scan and the severity of the corresponding carotid stenosis; 38 silent lesions were detected in the 203 hemispheres ipsilateral to carotid stenoses that were less than 60% versus 95 SBIs in the 399 hemispheres ipsilateral to carotid stenoses that were 60% or more (19% vs 24%; P =.2). There were no significant differences in the perioperative stroke/death rate in patients with or without cerebral CT lesions (2% vs 1%; odds ratio, 1.94; P =.6). Mortality rate during follow-up was 22% in patients with preoperative SBI and 15% in patients without SBI (P =.1). However, actuarial survival at 10 years was shorter (P =.02) in patients with SBI. Late stroke occurred in 11% of patients with preoperative SBI and in 3% of patients without preoperative SBI (P =.006). Cox regression analysis showed that both preoperative lacunar and nonlacunar infarctions were independent predictors of late stroke (hazard ratio, 3.6; P =.04; and hazard ratio, 7.1; P =.001; respectively).

CONCLUSION

In our experience, preoperative SBI did not occur more frequently in the hemisphere ipsilateral to asymptomatic severe carotid stenosis. Although our study lacks a medically treated control group, our data show that SBI is predictive of poor neurologic outcome in asymptomatic patients undergoing CEA. We conclude that CT before CEA, selectively applied, provides information on long-term neurologic prognosis and that a less aggressive attitude towards CEA in asymptomatic patients with SBI may be justified.

Computerised tomography findings as a risk factor in carotid endarterectomy: early and late results

OBJECTIVES

To evaluate whether preoperative CT evidence of brain infarction is associated with an increased risk of early and late stroke and death in patients undergoing CEA.

DESIGN

Retrospective clinical study.

MATERIALS AND METHODS

We evaluated 844 CT scanning records from 893 patients undergoing CEA from 1986-1994: 43% (367) CT positive for cerebral infarction and 57% (477) negative. Univariate and multivariate analysis was performed for risk factors and preoperative symptoms in patients with positive and negative CT scans, and Kaplan Meier survival curves for late events.

RESULTS

A positive CT was significantly more frequent in males vs. females (p < 0.0001; O.R. 2.52; C.I. 1.73-3.73), diabetics vs. non-diabetics (p = 0.03; O.R. 1.52; C.I. 1.03-2.26), symptomatics vs. asymptomatics (p < 0.001; O.R. 2; C.I. 1.93-3.53) and contralateral occlusion vs. patency (p < 0.001; O.R. 2; C.I. 1.30-3.10). The perioperative disabling stroke/ death rate was higher in patients with a positive CT (p = 0.002; O.R. 6.27; C.I. 1.73-34.20); in asymptomatic patients this difference was striking (5 patients vs. O, p = 0.0002). Multiple logistic regression analysis for risk factors, CT findings, symptoms preceding surgery, and congruity of brain infarction confirmed a significantly higher incidence of perioperative stroke/death rate (p = 0.003; O.R. 6.37; C.I. 5.12-7.63) and early and late stroke (p = 0.02; O.R. 1.95; C.I. 1.38-2.53) and death (p = 0.0005; O.R. 2.38; C.I. 1.89-2.88) in patients with brain lesions. After 7 years, the survival rate (p = 0.0009) and stroke-free interval (p = 0.003) were lower in patients with a positive CT. After 5 years, in asymptomatic patients the survival rate (p = 0.003) and stroke-free interval (p = 0.01) were lower in the positive CT group.

CONCLUSIONS

A positive CT finding, regardless of congruity of the lesion, should be regarded as an indicator of an increased risk of stroke and death in patients scheduled for carotid surgery, especially in those with asymptomatic stenosis.

The identification of the high risk carotid plaque

OBJECTIVE

To determine the influence of carotid plaque morphology and severity of stenosis on symptoms of cerebrovascular disease and cerebral infarction.

PATIENTS AND METHODS

One hundred and ninety patients with 329 carotid plaques producing 50-99% stenosis were studied. Carotid plaque echogenicity on ultrasonography was evaluated using computerised measurement of the median of the overall grey scale content (GSM). Heterogeneity was evaluated as the difference between the GSMs of the most echogenic and the most echolucent areas within each plaque and expressed as the heterogeneity index (HI). All patients had a CT brain scan and the presence of ipsilateral cerebral infarction noted.

RESULTS

Cerebral infarction was more common in symptomatic than asymptomatic plaques (42% vs. 29%, p<0.02) and in echolucent than echogenic plaques (mean GSM of 37.8 vs. 29.7, p<0.01). Plaques with GSM below or equal to 32 were associated with a higher incidence of cerebral infarction as compared to those above this level, this was significant in both symptomatic and asymptomatic plaques. Symptomatic carotid plaque were less heterogenous than asymptomatic plaques. Plaques associated with cerebral infarction were less heterogenous than those not associated with infarction.

CONCLUSION

This study has shown that the identification of the high risk carotid plaques, i.e. those associated with a high incidence of cerebral infarction is possible both in symptomatic and asymptomatic patients. The potential of such analysis in the identification of patients with asymptomatic carotid stenosis with high and low risk of stroke should be explored in a natural history study.

Computer-assisted carotid plaque characterisation

OBJECTIVE

To determine the relationship between plaque echogenicity as measured by computer and the incidence of cerebral brain infarction.

PATIENTS AND METHODS

Eighty-seven patients with 148 plaques producing more than 50% internal carotid artery stenosis were studied. Sixty-nine plaques were in asymptomatic patients, 35 were associated with amaurosis fugax, 19 with transient ischaemic attacks and 25 with stroke. All patients had a CT brain scan and the presence of ipsilateral cerebral infarction was noted. Images of the plaques obtained with an ATL Ultramark-4 Duplex scanner (7.5 MHz high resolution probe) were transferred to a computer. Using an image analysis program a histogram for each plaque was obtained with the number of pixels plotted against the grey scale (0-225). The median of the grey scale was used as a measure of echogenicity.

RESULTS

Fifty-three (36%) of the 148 plaques were associated with ipsilateral CT brain infarction. Plaques with a grey scale median more than 32 (echogenic) were associated with an incidence of 11% (7/64) CT infarction. In contrast, plaques with grey scale median below or equal to 32 (echolucent) were associated with 55% (46/84) incidence of CT infarction (chi 2 = 30.35, p < 0.001, relative risk = 22, 95% confidence interval from 4.7 to 108).

CONCLUSION

This study indicates that computer analysis of carotid plaque can identify high-risk carotid plaques. The potential of such analysis in the identification of asymptomatic high-risk patients should be explored in further studies.

Factors affecting survival and occurrence of stroke in patients with transient ischemic attacks

OBJECTIVE

To assess the predictive value of a series of demographic and clinical variables for stroke and survival in a population after a first transient ischemic attack (TIA).

DESIGN

Cox proportional hazards regression analysis was used to determine the association of various demographic and clinical factors with survival and stroke in 330 residents of Rochester, Minnesota, who had an initial TIA with first medical attention within 120 days during the period 1955 through 1979.

MATERIAL AND METHODS

We investigated several demographic, diagnostic, and treatment variables, including initial clinical manifestations (pure sensory TIA and unilateral carotid hemispheric TIA), to estimate the significant (P < or = 0.01) predictors of survival and of stroke. Follow-up was limited to 10 years.

RESULTS

Relative survival for patients with a first TIA was 94% at 1 year and 87% at 5 years after first medical attention. Three interactions were significant predictors of survival: (1) age at TIA and gender (young women had the best survival and older women had the worst survival), (2) systolic blood pressure and congestive heart failure (patients with low systolic blood pressure and congestive heart failure had the worst survival), and (3) calendar year of onset and diabetes mellitus (survival was worst for patients with diabetes during the early years of the study). Only age was a significant independent predictor of stroke after TIA (hazards ratio, 1.45 per 10 years).

CONCLUSIONS

Estimating risks of stroke and death after TIA on the basis of demographic and clinical variables without reference to the mechanism of TIA is of limited clinical utility. Age is the most significant such predictor. Interactions that reflect comorbidity, such as diabetes, blood pressure abnormalities, or heart disease, may affect survival but not the risk for occurrence of stroke.

Transient ischaemic attacks: which patients are at high (and low) risk of serious vascular events?

The aims of this study were to determine the important prognostic factors at presentation which identify patients with transient ischaemic attacks (TIA) who are at high risk (and low risk) of serious vascular events and to derive a prediction model (equation) for each of the major vascular outcome events. A cohort of 469 TIA patients referred to a University hospital, without prior stroke, were evaluated prospectively and followed up over a mean period of 4.1 years (range 1-10 years). The major outcome events of interest were 1) stroke 2) coronary event and 3) stroke, myocardial infarction or vascular death (whichever occurred first). Prognostic factors and their hazard ratios were identified by means of the Cox proportional hazards multiple regression analysis. The significant adverse prognostic factors (in order of strength of association) for stroke were an increasing number of TIAs in the three months before presentation, increasing age, peripheral vascular disease, left ventricular hypertrophy and TIAs of the brain (compared with the eye); the prognostic factors for coronary event were increasing age, ischaemic heart disease, male sex, and a combination of carotid and vertebrobasilar TIAs at presentation; and for stroke, myocardial infarction or vascular death they were increasing age, peripheral vascular disease, increasing number of TIAs in the three months before presentation, male sex, a combination of carotid and vertebrobasilar TIAs at presentation, TIAs of the brain (compared with the eye), left ventricular hypertrophy and the eye), left ventricular hypertrophy and the eye), left ventricular hypertrophy and the presence of residual neurological signs after the TIA. Prediction models (equations) of both the relative risk and absolute risk of each of the major outcome events were produced, based on the presence or level of the significant prognostic factors and their hazard. Before it can be concluded that our equations accurately predict prognosis and can be generalised to other populations, their predictive power needs to be validated in other, independent samples of TIA patients (which we are currently doing).