Independent Predictor Of Stroke Risk Research Articles

Incidence of fatal stroke 24 years after acute coronary syndrome: the value of baseline albuminuria and hypertension. The ABC study on acute coronary syndrome

Abstract Background Albuminuria and hypertension are known independent predictors of stroke risk. Purpose To investigate the additive effect of baseline albuminuria and hypertension on the very long-term risk prediction of fatal stroke (FS) in patients with acute coronary syndrome (ACS). Methods The present analysis includes 589 patients admitted with ACS to 3 Italian hospitals and discharged alive. Patients were followed prospectively for 24 years or until death. Baseline clinical and laboratory data were recorded within the first 7 days of hospitalization. Results All but three patients completed the follow-up representing 7065 person-years and 44 patients (7%) developed FS. They shared most of the baseline clinical characteristics with the patients who did not have FS, except for being significantly older (mean age was 72±8 vs. 66±12 years, p=0.0008). Patients with FS also had albuminuria more frequently (66% vs. 49%, p=0.03) with significantly higher values of 3rd-day albumin–creatinine ratio (ACR), (p=0.009). At Cox regression analysis; patients who had hypertension or albuminuria had a higher risk of developing FS, hazard ratios were (HR=1.8; 95%CI=1.0–3.2; p=0.05 and HR=2.9; 95%CI=1.5–5.3; p=0.001 respectively. Patients with both hypertension and albuminuria showed an independent risk association for developing FS than patients with neither HR=4.2; 95%CI=1.8–9.7; p=0.001. Results kept true with a model adjusted for age, gender and presence of atrial fibrillation. The same results were obtained with the competing risk analysis (HR=2.6; 95%CI=1.1–6.0, p=0.02). Conclusions the results showed that the combination of hypertension and albuminuria is associated with an independent greater risk of developing a fatal stroke long after ACS.

A comprehensive contribution of genetic variations of the insulin-like growth factor 1 signalling pathway to stroke susceptibility

Background and aimsThe insulin-like growth factor (IGF)-1 signalling pathway has been implicated in the pathogenesis of atherosclerosis; however, the mechanism underlying its role in stroke remains unexplained. Herein, we aimed to explore the effects of genetic polymorphisms in the IGF1 pathway on stroke in the Chinese Han population. MethodsTwenty-six single-nucleotide polymorphisms (SNPs) in IGF1 pathway genes were genotyped in a case-control study consisting of 2070 stroke cases and 2243 controls. Main genetic effects and gene-gene interactive effects of the IGF1 pathway were evaluated. Weighted genetic risk scores (wGRS) were computed, and the associations between wGRS and gene expression were analysed. ResultsThe variants at GHRH rs6032470 were significantly associated with high risk of hemorrhagic stroke (HS), and the adjusted OR (95%CI) was 1.368 (1.136–1.647). Significant additive interaction between rs6032470 and gender was detected for HS and ischemic stroke (IS). The association of rs6032470 and stroke was stronger in males than in females. Additionally, a significant gene-gene interaction of rs6032470-rs1874479 (IGFBP1) in relation to HS risk was identified (p < 0.05). IGF1 mRNA expression was significantly upregulated in IS, while it was linearly downregulated across rs6214 genotypes. In addition, IGFBP3 transcript variant 2 mRNA level was negatively correlated with wGRS (r = -0.285, p = 0.005). ConclusionsOur findings indicated that the IGF1 signalling pathway genes potentiated the risk of stroke through both main effects and gene-gene interactions. The genetic effect of GHRH rs6032470 on stroke was gender dependent. The wGRS of IGF1 pathway genes may be an independent predictor of stroke risk.

Abstract WP171: Hemodynamic Compromise Identified by Oxygen Extraction Fraction Response (OEFR) to Acetazolamide in Stroke Patients With Large Vessel Occlusion

Hemodynamic compromise identified by cerebrovascular reserve (CVR) and oxygen extraction fraction (OEF) in stroke patients with large artery occlusion is an independent predictor of stroke risk ranging from 27 to 57%. However, comparison of both methods indicates that the sensitivity of CVR is substantially greater than OEF in detecting hemodynamic compromise which may be because CVR includes a vasodilator challenge with acetazolamide as opposed to OEF made in the resting state. We hypothesized that the response of OEF (OEFR) to an acetazolamide challenge would better correlate with CVR than OEF. We examined the correlation between CVR and OEFR to acetazolamide in stroke patients with large artery occlusion. Methods: Stroke patients with large artery occlusion (internal carotid or middle cerebral artery) were studied by positron emission tomography (PET) using H2 15O2 (water) for cerebral blood flow (CBF) and 15O2 (gas) for cerebral metabolic rate for oxygen before and after acetazolamide. CVR was calculated as: CVR (%) = [(CBFa- CBFb)/CBFb] X 100; where: CBFb = CBF before acetazolamide, CBFa = CBF after acetazolamide. OEF response (OEFR) was similarly calculated as: OEFR (%) = [(OEFa-OEFb)/OEFb]X100; for the entire middle cerebral artery territory of each hemisphere. Results: There was a highly significant (P=0.0001) negative linear correlation between CVR and OEFR indicating increasing ischemic stress (Figure). Hemispheres from three patients showed a positive OEFR. Discussion: A positive OEFR in response to a cerebrovascular challenge definitively indicates hemodynamic compromise and eliminates the problem of deciding on the absolute threshold for OEF to signify hemodynamic compromise. A negative OEFR reflects sufficient cerebrovascular reserve relative to oxygen demand.

Dietary Sodium to Potassium Ratio and Risk of Stroke in a Multiethnic Urban Population: The Northern Manhattan Study.

There is growing evidence that increased dietary sodium (Na) intake increases the risk of vascular diseases, including stroke, at least in part via an increase in blood pressure. Higher dietary potassium (K), seen with increased intake of fruits and vegetables, is associated with lower blood pressure. The goal of this study was to determine the association of a dietary Na:K with risk of stroke in a multiethnic urban population. Stroke-free participants from the Northern Manhattan Study, a population-based cohort study of stroke incidence, were followed-up for incident stroke. Baseline food frequency questionnaires were analyzed for Na and K intake. We estimated the hazard ratios and 95% confidence intervals for the association of Na:K with incident total stroke using multivariable Cox proportional hazards models. Among 2570 participants with dietary data (mean age, 69±10 years; 64% women; 21% white; 55% Hispanic; 24% black), the mean Na:K ratio was 1.22±0.43. Over a mean follow-up of 12 years, there were 274 strokes. In adjusted models, a higher Na:K ratio was associated with increased risk for stroke (hazard ratio, 1.6; 95% confidence interval, 1.2-2.1) and specifically ischemic stroke (hazard ratio, 1.6; 95% confidence interval, 1.2-2.1). Na:K intake is an independent predictor of stroke risk. Further studies are required to understand the joint effect of Na and K intake on risk of cardiovascular disease.

A rabbit model of cerebral microembolic signals for translational research: preclinical validation for aspirin and clopidogrel

Essentials Microembolic signal (MES) is an independent predictor of stroke risk in patients. A rabbit model of cerebral microembolic signals was established. Therapeutic efficacy was demonstrated for aspirin and clopidogrel on microembolic signals. Potential translational value of this preclinical model of MES was demonstrated. Objectives Cerebral microembolic signals (MESs) detected by transcranial Doppler (TCD) ultrasound constitute an independent predictor of stroke risk and prognosis. The aim of this study was to develop a novel preclinical model of MESs to facilitate translational research. Methods A clinical TCD ultrasound machine was used to detect MESs in the cerebral circulation of New Zealand White rabbits. Technical feasibility was assessed for the measurement of MESs in the middle cerebral artery (MCA) by TCD. FeCl3 -induced carotid arterial thrombosis was optimized for the generation of endogenous microemboli. Ascending doses of two antithrombotic agents (aspirin and clopidogrel) were evaluated individually and in combination for their effects on both arterial thrombosis and MESs in a 30% FeCl3 -induced carotid arterial thrombosis model, along with ex vivo functional assays. Results Dose-dependent FeCl3 -induced arterial thrombosis studies showed that 30% FeCl3 resulted in the most consistent and reproducible MESs in the MCA (3.3 ± 0.7 MESs h(-1) ). Ascending-dose studies showed that the effective doses for 50% inhibition (ED50 ) of thrombus formation, based on integrated blood flow and thrombus weight, respectively, were 3.1 mg kg(-1) and 4.2 mg kg(-1) orally for aspirin, and 0.3 mg kg(-1) and 0.28 mg kg(-1) orally for clopidogrel. The ED50 values for MES incidence were 12.7 mg kg(-1) orally for aspirin, and 0.25 mg kg(-1) orally for clopidogrel. Dual treatment with aspirin (5 mg kg(-1) ) and clopidogel (0.3 mg kg(-1) ) resulted in significant reductions in cerebral MESs (P < 0.05) as compared with monotherapy with either agent. Conclusions Our study demonstrated the successful establishment of the MES model in rabbits, and it may provide translational value for MESs and ischemic stroke research.

Apixaban Inhibits Cerebral Microembolic Signals Derived from Carotid Arterial Thrombosis in Rabbits.

Cerebral microembolic signal (MES) is an independent predictor of stroke risk and prognosis. The objective of this study is to assess the effects of apixaban, as a representative of the novel oral anticoagulant class, on a rabbit model of cerebral MES. A clinical transcranial Doppler ultrasound instrument was used to assess MESs in the middle cerebral artery in a 30% FeCl3-induced carotid arterial thrombosis model in male New Zealand White rabbits. Ascending doses of apixaban were evaluated as monotherapy and in combination with aspirin on both arterial thrombosis and MES. Pharmacokinetic and pharmacodynamic responses were also evaluated. The effective dose for 50% inhibition (ED50) of thrombus formation for monotherapy was 0.04 mg/kg per hour apixaban, i.v. (0.03 μM plasma exposure) for the integrated blood flow, 0.13 mg/kg per hour apixaban (0.10 μM plasma exposure) for thrombus weight, and 0.03 mg/kg per hour apixaban (0.02 μM plasma exposure) for MES. Dual treatment with aspirin (5 mg/kg, PO) and apixaban (0.015 mg/kg per hour, i.v.) resulted in a significant reduction in cerebral MES (P < 0.05) compared with monotherapy with either agent. Pharmacokinetic analysis of apixaban and pharmacodynamic assays using activated partial thromboplastin time (aPTT) and prothrombin time (PT) for apixaban- and arachidonic acid-induced platelet aggregation for aspirin were used to confirm the exposure-response relationships. In summary, our study demonstrates that apixaban in a concentration-dependent manner inhibits both arterial thrombosis and MES, suggesting a potential association between factor Xa (FXa) blockade and the reduction in MES in patients at risk of ischemic stroke.

In older men, higher plasma testosterone or dihydrotestosterone is an independent predictor for reduced incidence of stroke but not myocardial infarction.

Older men have lower T levels, but whether differences in circulating T or its metabolites dihydrotestosterone (DHT) or estradiol (E2) contribute to cardiovascular disease remains controversial. We tested the hypothesis that plasma T, DHT, and E2 are differentially associated with the incidence of myocardial infarction (MI) and stroke in older men. Plasma total T, DHT, and E2 were assayed using liquid chromatography-mass spectrometry in early-morning samples from 3690 community-dwelling men aged 70-89 years. Outcomes of the first hospital admission or death due to MI or stroke were ascertained by data linkage. Mean follow-up was 6.6 years. Incident MI occurred in 344, stroke in 300, and neither in 3046 men. In a multivariate analysis adjusting for age and other risk factors, T, DHT, and E2 were not associated with incident MI [fully adjusted hazard ratio (HR) for T in quartile (Q) 4 vs Q1: 0.92, 95% confidence interval (CI) 0.66-1.28; DHT: 0.83, 95% CI 0.59-1.15; E2: 0.84, 95% CI 0.62-1.15]. Higher T or DHT was associated with a lower incidence of stroke (T: Q4: Q1 fully adjusted HR 0.56, 95% CI 0.39-0.81, P = .002; DHT: 0.57, 95% CI 0.40-0.81, P = .002). E2 was not associated with stroke (HR 0.76, 95% CI 0.54-1.08, P = .123). Higher plasma T or DHT is a biomarker for reduced risk of stroke but not MI. Androgen exposure may influence outcomes after rather than the incidence of MI, whereas androgens but not E2 are independent predictors of stroke risk. Randomized clinical trials are needed to clarify the impact of modifying T or DHT on the risk of stroke in aging men.

Risk of ischaemic stroke according to pattern of atrial fibrillation: analysis of 6563 aspirin-treated patients in ACTIVE-A and AVERROES.

The pattern of atrial fibrillation (AF) occurrence-paroxysmal, persistent, or permanent-is associated with progressive stages of atrial dysfunction and structural changes and may therefore be associated with progressively higher stroke risk. However, previous studies have not consistently shown AF pattern to predict stroke but have been hampered by methodological shortcomings of low power, variable event ascertainment, and variable anticoagulant use. We analysed the rates of stroke and systemic embolism in 6563 aspirin-treated patients with AF from the ACTIVE-A/AVERROES databases. There was thorough searching for events and adjudication. Multivariable analyses were performed with the adjustment for known risk factors for stroke. Mean age of patients with paroxysmal, persistent, and permanent AF was 69.0 ± 9.9, 68.6 ± 10.2, and 71.9 ± 9.8 years (P < 0.001). The CHA2DS2-VASc score was similar in patients with paroxysmal and persistent AF (3.1 ± 1.4), but was higher in patients with permanent AF (3.6 ± 1.5, P < 0.001). Yearly ischaemic stroke rates were 2.1, 3.0, and 4.2% for paroxysmal, persistent, and permanent AF, respectively, with adjusted hazard ratio of 1.83 (P < 0.001) for permanent vs. paroxysmal and 1.44 (P = 0.02) for persistent vs. paroxysmal. Multivariable analysis identified age ≥ 75 year, sex, history of stroke or TIA, and AF pattern as independent predictors of stroke, with AF pattern being the second strongest predictor after prior stroke or TIA. In a large population of non-anticoagulated AF patients, pattern of AF was a strong independent predictor of stroke risk and may be helpful to assess the risk/benefit for anticoagulant therapy, especially in lower risk patients.

Abstract 115: Snapshot MR-OEF for Simultaneous Imaging of Tissue Oxygenation and CVR in 90 Seconds

Introduction: Asymmetric hemispheric cerebral Oxygen Extraction Fraction (OEF) has been shown to be an independent predictor of stroke risk. Furthermore, the NIH/NINDS Progress Review Group has recently named tissue oxygenation imaging as a primary research goal in its August 2013 review. We have developed a novel method of imaging OEF with MRI. We present an analysis of MR-OEF images using breath-hold and cardiac-gating as inducers of physiologic stress. Methods: We acquire a 2D k-space volume using a novel rosette trajectory in 65 ms for simultaneous imaging of OEF and vascular reserve. Subjects were tested under 2 transient stress conditions: breath-hold and cardiac-gated. Breath-hold: 20 susceptibility weighted measurements were taken (Δt = 3 secs) with an induced 15 second breath-hold. Cardiac-gated: Because of the speed of PARSE (65 ms) we are able to see the transient hemodynamic fluctuations induced from the cardiac cycle. Images were acquired in 25 ms intervals from the R-wave trigger. Results: Measured mean OEF in normal brain parenchyma of 36.87 ± 6.6% and regions in symptomatic patients reaching 84.05 ± 4.54% correlate well with literature. OEF images taken during the first 125 ms of the cardiac cycle in a symptomatic patient with a right ICA stenosis are shown in Figure 1. Asymmetric hemispheric OEF (right hemispheric 13.06% elevation) is clearly visible. We also see a non-uniform flush in of de-oxygenated hemoglobin with a subsequent uneven outflow, unseen in healthy volunteers, suggesting regions of compromised cerebral vascular reserve. Discussion/Conclusion: Our novel acquisition allows us to simultaneously image single slice OEF and vascular reserve in 65 ms (with total scan time less than 90 seconds). Move over, because of its unprecedented speed, we for the first time, have the temporal resolution to examine the cerebral hemodynamic fluctuations caused by the pressure waveforms induced by the cardiac cycle.

Stroke Prevention in Patients with Non-valvular Atrial Fibrillation: New Insight in Selection of Rhythm or Rate Control Therapy and Impact of Mean Platelet Volume

The aim of this study was to determine the impact of mean platelet volume (MPV) on the strategy for treatment of atrial fibrillation (AF) with respect to stroke prevention. MPV was analyzed in 265 patients with AF who were undergoing treatment using rhythm or rate control. The primary endpoint was ischemic stroke or a transient ischemic attack (TIA) event. Kaplan-Meier analysis revealed a significantly higher stroke rate in the rate control group compared to the rhythm control group. A significantly higher stroke rate was observed in the higher tertile MPV group (≥7.9 fL) compared to the lower tertile MPV group (<7.3 fL). When the MPV cut-off level was set to 7.85 fL using the receiver operating characteristic curve, the sensitivity was 80.0% and the specificity was 70.4% for differentiating between the group with stroke and the group without stroke. In the Cox proportional hazard analysis, after adjusting for sex, treatment strategy for AF, high MPV level, antithrombotic treatment, and high CHADS2 score, higher MPV, rate control strategy for treatment of AF, and high CHADS2 score were found to be independent predictors of stroke risk. In addition, patients with AF who were treated using rate control had high stroke risk with an MPV over 7.85 fL and high CHADS2 score. The results of this study demonstrate that the MPV and the rate control strategy for treatment of AF were predictive markers for stroke; its predictive power for stroke was independent of female sex and high CHADS2 score in patients with AF.

Stroke prediction using mean platelet volume in patients with atrial fibrillation

Platelet size, measured as mean platelet volume (MPV), is associated with platelet reactivity. MPV has been identified as an independent risk factor for future stroke and myocardial infarction. The aim of this study was to determine the association of MPV with the development of stoke in patients with atrial fibrillation (AF). MPV, N-terminal pro B-type natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hsCRP) were analysed in 200 patients with AF (mean age 69 years; 56% male). The primary endpoint was ischaemic stroke event. The mean MPV was 8.5 ± 1.0 fL and the median NT-proBNP was 1916.5 (IQR 810–4427) pg/mL. The median hsCRP was 0.47 (IQR 0.32–2.46) mg/dL. There were 14 stroke events during a mean of 15.1 months of follow up. Kaplan-Meier analysis revealed that the higher tertile MPV group (≥8.9 fL) had a significantly higher stroke rate compared to the lower tertile MPV group (<8.0 fL) (14.7% vs. 3.1%, log-rank: P = 0.01). A higher MPV was an independent predictor of stroke risk after adjusting for age, gender, and other CHADS2 (congestive heart failure, hypertension, diabetes, and previous stroke or transient ischemic attack (TIA) history) score components (hazard ratio: 5.03, 95% CI 1.05–24.05, P = 0.043) in Cox proportional hazard analysis. When the MPV cut-off level was set to 8.85 fL using the receiver operating characteristic curve, the sensitivity was 71% and the specificity was 69% for differentiating between the group with stroke and the group without stroke. This value was more useful in patients with a low to intermediate traditional thromboembolic risk (CHADS2 score <2). Furthermore, AF patients with an MPV over 8.85 fL had high stroke risk without anticoagulation, especially in the low thromboembolic risk group (Log-Rank <0.0001). The results of this study show that MPV was a predictive marker for stroke; its predictive power for stroke was independent of age, gender, and other CHADS2 score components in patients with AF. These findings suggest that anticoagulation may be needed in patients with a high MPV, even if they have low to intermediate traditional thromboembolic risk (CHADS2 score <2).

The Link between Atrial Fibrillation and Stroke in Women

Atrial fibrillation (AF) is the most common clinically significant cardiac arrhythmia. The most serious complication of AF is thromboembolic stroke. The individual risk of stroke in the setting of AF varies. Several clinical factors have been identified as independent predictors of stroke in AF, including prior stroke, age, hypertension and diabetes. The bulk of available data identifies female gender as another independent predictor of stroke risk in AF. In this article, we review the link between AF and an elevated stroke risk in women, explore the potential pathophysiologic basis for this association and examine the data regarding the effectiveness of anticoagulation in reducing this risk.

Association between White Matter Ischaemia and Carotid Plaque Morphology as Defined by High-resolution In Vivo MRI

Both carotid plaque morphology and severity of white matter ischaemia (WMI) have been shown to be independent predictors of stroke risk. This study tests the hypothesis that there is an association between carotid plaque morphology as determined by high-resolution carotid MRI and WMI. Forty patients (80 arteries) with at least 40% stenosis on screening Doppler ultrasound were recruited and underwent high-resolution axial carotid MRI at 1.5 T. In a blinded manner, plaque characteristics such as lipid core, fibrous cap, intraplaque haemorrhage, lumen area, plaque area, and American Heart Association (AHA) classification were qualitatively and quantitatively evaluated. The severity of WMI was independently quantified using a modified Scheltens score based on standard brain Fluid-Attenuated Inversion Recovery. Linear mixed effect models were used to test if carotid plaque characteristics could independently predict severity of WMI. Hypertension (p=0.005) and previous a history of transient ischaemic attack or stroke (p=0.038) were found to be significant predictors of severity of WMI. After accounting for confounding variables, no significant association was found between the modified Scheltens score and lipid core size (p=0.122), fibrous cap status (p=0.991), intraplaque haemorrhage (p=0.708), plaque area (0.835), lumen area (0.371) or an AHA Type VI complex plaque (p=0.195). Carotid plaque morphology as defined by MRI does not independently predict severity of WMI.

C linical- and I maging-Based P rediction of Stroke Risk After Transient Ischemic Attack

Background and Purpose— Predictive instruments based on clinical features for early stroke risk after transient ischemic attack suffer from limited specificity. We sought to combine imaging and clinical features to improve predictions for 7-day stroke risk after transient ischemic attack. Methods— We studied 601 consecutive patients with transient ischemic attack who had MRI within 24 hours of symptom onset. A logistic regression model was developed using stroke within 7 days as the response criterion and diffusion-weighted imaging findings and dichotomized ABCD 2 score (ABCD 2 ≥4) as covariates. Results— Subsequent stroke occurred in 25 patients (5.2%). Dichotomized ABCD 2 score and acute infarct on diffusion-weighted imaging were each independent predictors of stroke risk. The 7-day risk was 0.0% with no predictor, 2.0% with ABCD 2 score ≥4 alone, 4.9% with acute infarct on diffusion-weighted imaging alone, and 14.9% with both predictors (an automated calculator is available at http://cip.martinos.org). Adding imaging increased the area under the receiver operating characteristic curve from 0.66 (95% CI, 0.57 to 0.76) using the ABCD 2 score to 0.81 (95% CI, 0.74 to 0.88; P =0.003). The sensitivity of 80% on the receiver operating characteristic curve corresponded to a specificity of 73% for the CIP model and 47% for the ABCD 2 score. Conclusions— Combining acute imaging findings with clinical transient ischemic attack features causes a dramatic boost in the accuracy of predictions with clinical features alone for early risk of stroke after transient ischemic attack. If validated in relevant clinical settings, risk stratification by the CIP model may assist in early implementation of therapeutic measures and effective use of hospital resources.

Prognostic Impact of 24-Hour Mean Blood Pressure and Pulse Pressure on Stroke

To the Editor: Using 4.7 years of follow-up data on 2311 Western, hypertensive subjects, Verdecchia and colleagues1 reported that 24-hour ambulatory mean blood pressure (BP), not pulse pressure (PP), was an independent predictor of stroke risk. Because the association between BP and stroke risk has been reported to be much steeper in Eastern populations than in Western populations,2 the prognostic impact of 24-hour mean BP and PP on stroke could be different between these populations. Therefore, we investigated the association between 24-hour mean BP and PP and stroke using data …

The role of carotid screening before coronary artery bypass

Five hundred thirty-nine patients with no symptoms of cerebral ischemia undergoing coronary artery bypass were preoperatively evaluated for presence of carotid stenosis by noninvasive methods (duplex scanning and ocular pneumoplethysmography-Gee). Overall prevalence of carotid stenosis greater than 75% was higher (8.7%) than that generally reported. Age greater than 60 years was significantly related to presence of carotid stenosis greater than 75% (11.3% vs 3.8%, p = 0.003). Risk factors such as hypercholesterolemia, hypertension, diabetes mellitus, and smoking were not predictive for carotid stenosis, postoperative stroke, or death. Carotid stenosis greater than 75% (odds ratio 9.87, p less than 0.005) and coronary artery bypass redo (odds ratio 5.26, p less than 0.05) were both independent predictors of stroke risk. Patients were divided into four groups: group 1, minimal or mild degree of carotid stenosis (less than 50%), not submitted to prophylactic carotid endarterectomy (432 patients, 80.1%); group 2, moderate degree of stenosis (50% to 75%), no prophylactic carotid endarterectomy (60 patients, 11.2%); group 3, severe carotid stenosis; (greater than 75%), submitted to prophylactic carotid endarterectomy (19 patients, 3.5%), group 4, severe carotid stenosis (greater than 75%) no prophylactic carotid endarterectomy (28 patients, 5.2%). Patients in group 4 had significantly higher stroke rate (14.3%) compared to the other three groups (1.1%) (p = 0.0019). The finding of carotid stenosis greater than 75% in patients over 60 years of age was associated with occurrence of stroke in 15% of cases. Carotid screening is helpful to determine patients at increased risk of stroke and should be performed in patients greater than 60 years.(ABSTRACT TRUNCATED AT 250 WORDS)