Carotid Intima-Media Thickness and Silent Brain Infarctions in a Biracial Cohort: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Both hypertensive and atherosclerotic processes contribute to common carotid artery intima-media thickness (CCA-IMT). Elevated CCA-IMT may be indicative of subclinical cerebrovascular disease; however, its role in the absence of concomitant carotid artery plaque is uncertain, and few studies have examined associations in Black populations.

MATERIALS AND METHODS

At cohort visit 3 (1993-1995) a subset of stroke-free participants (641 Blacks and 702 Whites, mean age 63) from the Atherosclerosis Risk in Communities (ARIC) study was imaged by brain MRI and carotid ultrasound. A CCA-IMT >0.9 mm was considered elevated. Asymptomatic brain lesions ≥3 mm were considered silent brain infarctions (SBI). Subcortical SBI measuring 3 to <20 mm were considered lacunes. Associations between elevated CCA-IMT and SBI were analyzed with Poisson regression.

RESULTS

Elevated CCA-IMT was identified in 168 participants (16% of Blacks, 10% of Whites), and SBI were observed in 156 (15% of Blacks, 8% of Whites). Elevated CCA-IMT was strongly related to anterior circulation SBI, posterior circulation SBI, and lacunes. After adjustments, elevated CCA-IMT remained associated with greater number of lacunes in Blacks ([prevalence ratio, PR] = 1.60; 95% confidence interval [CI]: 1.02-2.51), but not Whites (PR = 0.85; 95% CI: 0.35-2.04); P value for interaction = 0.12. Among Black participants without concomitant carotid plaque, elevated CCA-IMT was associated with twice the number of lacunes (PR = 2.00; 95% CI: 1.05-3.82).

CONCLUSIONS

In older Black adults, elevated CCA-IMT is independently associated with lipohyalinosis of the cerebral small vessels, irrespective of concomitant carotid plaque and vascular risk factors.

ACE I/D polymorphism in Korean patients with ischemic stroke and silent brain infarction

OBJECTIVES

Angiotensin-converting enzyme (ACE) polymorphism may play a role in stroke and silent brain infarction (SBI) susceptibility, but the results among the populations studied to date have not been consistent. Thus, we investigated the association between ACE genotypes and ischemic stroke and SBI in Korean patients.

SUBJECTS AND METHODS

DNA samples from 237 stroke patients, 264 SBI patients and 234 age-matched controls were amplified using polymerase chain reaction to detect the ACE ins/del (I/D) polymorphism. Genotype was determined by the presence of a 490-bp band (I allele) or a 190-bp band (D allele) in agarose gel electrophoresis.

RESULTS

Odds ratios of the I/D and D/D genotypes and the overall (I/D + D/D) for the I/I genotype were significantly different between stroke patients and normal controls. However, there was no significant difference between patients with SBI and controls.

CONCLUSIONS

This study is the first report of a significant association between ACE polymorphism and ischemic stroke in the Asian population. Although no consistent associations have been found between ACE polymorphism and stroke in the populations studied to date, the ACE polymorphism may be a genetic determinant of ischemic stroke, at least in Korean patients.

Angiotensinogen gene polymorphism as a risk factor for ischemic stroke

While gene polymorphism for angiotensinogen (AGT) is reported to contribute to the regulation of blood pressure and salt sensitivity, its effect on the risk of ischemic stroke remains controversial. We hypothesized that polymorphism of the AGT gene could be a risk factor for ischemic stroke. Major clinical risk factors and the AGT gene M235T polymorphism were examined in 147 consecutive stroke patients and 133 healthy age-matched controls. All patients were categorized into four stroke types (single lacuna, multiple lacunae, large-artery atherosclerosis and branch atheromatous disease in brainstem) and two vascular groups (large and perforating arterial lesions). The AGT gene M allele significantly increased the risk of single lacuna, multiple lacunae and small arterial lesions, in male patients (p=0.029, 0.031 and 0.026, respectively). Synergistic effects of the AGT gene polymorphism and clinical risks were not observed. In conclusion, AGT M allele may present a risk of lacunar infarctions in Japanese men, independent of hypertension.

Prevalence and determinants of subclinical brain infarction: the Northern Manhattan Study

OBJECTIVE

Risk factors for subclinical brain infarcts (SBI) have not been well studied, especially in Hispanic and black populations who may be at higher risk for vascular disease. We examined the prevalence and determinants of SBI in a multiethnic community cohort.

METHODS

The Northern Manhattan Study (NOMAS) includes 892 stroke-free participants who underwent brain MRI. Baseline demographic and vascular risk factor data were collected. The presence of SBI was determined from the size, location, and imaging characteristics of the lesion based on fluid attenuated inversion recovery (FLAIR) T1 and T2, and proton density MRI sequences. We calculated the prevalence of SBI and cross-sectional associations with sociodemographic and vascular risk factors, using logistic regression to adjust for relevant covariates.

RESULTS

Among 892 subjects (mean age 71.3 years), 158 (17.7%) had SBI (13.5% had 1 lesion, 4.3% had >1 lesion). Of the total 216 infarcts, most were small (<1 cm, 82.4%) and subcortical (82.9%). SBI prevalence increased with age (<65: 9.7%; 65 to 75: 16.4%; >75: 26.1%), was increased among men (21.3% vs 15.2% in women), and was increased among blacks (24.0% vs 18.1% in whites and 15.8% in Hispanics). The presence of SBI was independently associated with older age (per year: OR 1.06, 95% CI 1.04 to 1.09), male sex (OR 1.79, 95% CI 1.22 to 2.61), and hypertension (OR 2.08, 95% CI 1.35 to 3.22) adjusting for age, sex, race-ethnicity, and vascular risk factors. A significant interaction (p = 0.002) between race and age was observed such that younger black subjects had greater odds of having SBI.

CONCLUSIONS

SBI were detected in nearly 18% of subjects in a multiethnic community-based cohort. Age, male sex, and hypertension were independently associated with SBI. Subclinical cerebral infarcts are more prevalent than symptomatic infarcts and may increase the true public health burden of stroke.

Intracranial large artery disease among OCSP subtypes in ethnic South Asian ischemic stroke patients

The site of vascular stenosis correlates well with the Oxfordshire Community Stroke Project (OCSP) classification among Caucasians, but not among ethnic Chinese patients. We prospectively studied 205 consecutive ethnic South Asian ischemic stroke patients to investigate the prevalence of intracranial large artery disease determined by transcranial color-coded doppler and magnetic resonance angiography among OCSP subtypes. The distribution of OCSP subtypes was 7% total anterior circulation infarction (TACI), 17% partial anterior circulation infarction (PACI), 14% posterior circulation infarction (POCI) and 62% lacunar infarction (LACI). Significant intracranial large artery disease was common among all OCSP subtypes; 79% with TACI, 47% PACI, 65% POCI and 44% LACI. This is similar to ethnic Chinese data and is likely due to the predominance of intracranial disease over extracranial disease. Clinical axioms using OSCP subtypes based on Caucasian data may be misleading if applied to ethnic South Asians.

Ischemic stroke subtype incidence among whites, blacks, and Hispanics: the Northern Manhattan Study

BACKGROUND

Stroke incidence is greater in blacks than in whites; data on Hispanics are limited. Comparing subtype-specific ischemic stroke incidence rates may help to explain race-ethnic differences in stroke risk. The aim of this population-based study was to determine ischemic stroke subtype incidence rates for whites, blacks, and Hispanics living in one community.

METHODS AND RESULTS

A comprehensive stroke surveillance system incorporating multiple overlapping strategies was used to identify all cases of first ischemic stroke occurring between July 1, 1993, and June 30, 1997, in northern Manhattan. Ischemic stroke subtypes were determined according to a modified NINDS scheme, and age-adjusted, race-specific incidence rates calculated. The annual age-adjusted incidence of first ischemic stroke per 100,000 was 88 (95% CI, 75 to 101) in whites, 149 (95% CI, 132 to 165) in Hispanics, and 191 (95% CI, 160 to 221) in blacks. Among blacks compared with whites, the relative rate of intracranial atherosclerotic stroke was 5.85 (95% CI, 1.82 to 18.73); extracranial atherosclerotic stroke, 3.18 (95% CI, 1.42 to 7.13); lacunar stroke, 3.09 (95% CI, 1.86 to 5.11); and cardioembolic stroke, 1.58 (95% CI, 0.99 to 2.52). Among Hispanics compared with whites, the relative rate of intracranial atherosclerotic stroke was 5.00 (95% CI, 1.69 to 14.76); extracranial atherosclerotic stroke, 1.71 (95% CI, 0.80 to 3.63); lacunar stroke, 2.32 (95% CI, 1.48 to 3.63); and cardioembolic stroke, 1.42 (95% CI, 0.97 to 2.09).

CONCLUSIONS

The high ischemic stroke incidence among blacks and Hispanics compared with whites is due to higher rates of all ischemic stroke subtypes.

[Study on T13254C polymorphism of the platelet membrane glycoprotein VI in Chinese Han population]

OBJECTIVE

To investigate the T13254C polymorphism frequency in GPVI gene among Chinese Han population and its relevance to the arterial thrombotic diseases.

METHODS

The enrolled population in this study consisted of 314 healthy subjects and 274 patients with myocardial or cerebral infarctions. GPVI T13254C genotypes were determined by PCR amplification of a 355 bp fragment encompassing exon 5 of GPVI gene, followed by Msp I digestion of the product. The digested products were analyzed in 15% polyacrylamide gel electrophoresis (PAGE).

RESULTS

The frequencies of the T allele and C allele in the T13254C polymorphism were 0.9809 and 0.0191, respectively, with a frequency of heterozygous of 0.0319, which were significantly different from those reported in western population (P < 0.01). As compared with controls, no significant difference in T13254C genotype distribution was found in the arterial thrombotic diseases group.

CONCLUSION

The GPVI T13254C polymorphism appears in a low frequency in Chinese Han population. No relationship is found between T13254C polymorphism and the risk for thrombotic diseases.

[Non-valvular atrial fibrillation and completed stroke: factors determining mortality, recurrence and prognosis after a first event in the Mexican population]

AIMS

Non-valvular atrial fibrillation (NVAF) accounts for 25% of completed strokes (CS) of a cardioembolic origin in patients over 60 years old. Our aim was to define the predictors of a good and poor prognosis after a CS secondary to an NVAF in our milieu.

PATIENTS AND METHODS

We evaluated the risk factors (RF) and severity of CS in relation to death, functionality and recurrence at 5 years. 81 patients between the ages of 49 and 88 were followed up consecutively for 1 to 90 months; 38 (46.9%) of them were males. Multivariate analysis was performed with the following independent variables: age, gender, smoking, hypertension, heart disease, diabetes mellitus and characteristics of the stroke. The severity of the CS was assessed by means of the modified Rankin scale, which was dichotomised into a good prognosis (0-2) and a poor prognosis (> or = 3), both basal and at the end of the clinical control. We also evaluated the secondary preventive treatment used and its relation with recurrence, prognosis, death and complications.

RESULTS

No RF was linked to a poor prognosis or recurrence; 88% had a poor prognosis. Antiplatelet drugs were used in 42% of cases and 39% received anticoagulants. A good final progression was observed in 9.5% of the patients treated with antiplatelet drugs versus 35% of those receiving anticoagulation therapy (p = 0.004). Severity of the CS on admission was worse in the aspirin group, with no differences in recurrence and mortality. A better prognosis was observed in patients from urban areas.

CONCLUSIONS

Use of antiplatelet drugs, living in a rural area and a Rankin score of > or = 3 on admission are factors suggesting a poor prognosis in the clinical control at 5 years.

Relationship Between Abdominal Visceral Fat and Lacunar Infarcts in Japanese Men

BACKGROUND

The relationship between abdominal visceral fat accumulation and lacunar infarcts has not been previously investigated in Japanese men.

METHODS AND RESULTS

The subjects were 637 middle-aged (40-64 years) and 222 elderly (65-79 years) men who participated in a health checkup program from 1999 to 2003. The association between lacunar infarcts identified by magnetic resonance imaging and cardiovascular risk factors, including abdominal visceral fat accumulation evaluated by computed tomography, was examined. The prevalence of lacunar infarcts was 4.9%. Hypertension was associated with lacunar infarcts among both the middle-aged men [age-adjusted odds ratio (OR)=2.9 (95% confidence interval (CI): 1.1-7.8)] and the elderly men [OR=5.1 (95%CI: 1.4-19.0)]. Abdominal visceral fat accumulation was slightly associated with lacunar infarcts among middle-aged men, but not among elderly men: OR in the highest (>or=117 cm(2)) vs lowest (<or=83 cm(2)) tertiles of fat area was 2.6 (95%CI: 0.9-7.6) for middle-aged men. Extreme accumulation of visceral fat (>or=143 cm(2)) was still slightly associated with lacunar infarcts after adjustment for age, hypertension, drinking and smoking among middle-aged men [OR=2.7 (95%CI: 0.8-9.1)].

CONCLUSIONS

This cross-sectional study suggests that abdominal visceral fat accumulation is a possible risk factor of lacunar infarcts, in addition to hypertension, in middle-aged Japanese men.