Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment.

BACKGROUND: The management of unruptured intracranial aneurysms is controversial. Investigators from the International Study of Unruptured Intracranial Aneurysms aimed to assess the natural history of unruptured intracranial aneurysms and to measure the risk associated with their repair. METHODS: Centres in the USA, Canada, and Europe enrolled patients for prospective assessment of unruptured aneurysms. Investigators recorded the natural history in patients who did not have surgery, and assessed morbidity and mortality associated with repair of unruptured aneurysms by either open surgery or endovascular procedures. FINDINGS: 4060 patients were assessed-1692 did not have aneurysmal repair, 1917 had open surgery, and 451 had endovascular procedures. 5-year cumulative rupture rates for patients who did not have a history of subarachnoid haemorrhage with aneurysms located in internal carotid artery, anterior communicating or anterior cerebral artery, or middle cerebral artery were 0%, 2. 6%, 14 5%, and 40% for aneurysms less than 7 mm, 7-12 mm, 13-24 mm, and 25 mm or greater, respectively, compared with rates of 2 5%, 14 5%, 18 4%, and 50%, respectively, for the same size categories involving posterior circulation and posterior communicating artery aneurysms. These rates were often equalled or exceeded by the risks associated with surgical or endovascular repair of comparable lesions. Patients' age was a strong predictor of surgical outcome, and the size and location of an aneurysm predict both surgical and endovascular outcomes. INTERPRETATION: Many factors are involved in management of patients with unruptured intracranial aneurysms. Site, size, and group specific risks of the natural history should be compared with site, size, and age-specific risks of repair for each patient.

Effect of time since onset of risk factors on the occurrence of ischemic stroke.

OBJECTIVE: To determine the effect of time since onset of risk factors on the modeling of risk factors for ischemic stroke. METHODS: The resources of the Rochester Epidemiology Project allowed identification of the 1,397 incident cases of ischemic stroke and age- and sex-matched control subjects from the population for 1970 through 1989. These cases and controls permitted the development of a multiple conditional logistic regression model to estimate the odds ratios of ischemic stroke for various risk factors. The time since onset variables for each risk factor were then added to the model to determine which were significant and to assess their impact on variables in the model. RESULTS: The time since onset variables for congestive heart failure and TIA were the only variables of this type included in the resultant model. Each showed the highest risk for stroke soon after the onset of the risk factor. In addition, the influence of congestive heart failure was higher at younger ages. Hypertension (with or without left ventricular hypertrophy) increases the risk for stroke but has a diminishing influence with increasing age. In addition, persons with left ventricular hypertrophy are at a higher risk than those with hypertension alone, although this difference also decreases with age. The time since onset variables pertaining to systolic hypertension at 140 to 159 mm Hg, 160 to 179 mm Hg, and > or =180 mm Hg were not significant in any analysis. CONCLUSIONS: TIA and congestive heart failure were the only risk factors for stroke for which time since onset was significant in the model for predicting ischemic stroke.

Aortic valve sclerosis and aortic atherosclerosis: different manifestations of the same disease? Insights from a population-based study.

OBJECTIVES: The aim of this study was to examine the association between atherosclerosis risk factors, aortic atherosclerosis and aortic valve abnormalities in the general population. BACKGROUND: Clinical and experimental studies suggest that aortic valve sclerosis (AVS) is a manifestation of the atherosclerotic process. METHODS: Three hundred eighty-one subjects, a sample of the Olmsted County (Minnesota) population, were examined by transthoracic and transesophageal echocardiography. The presence of AVS (thickened valve leaflets), elevated transaortic flow velocities and aortic regurgitation (AR) was determined. The associations between atherosclerosis risk factors, aortic atherosclerosis (imaged by transesophageal echocardiography) and aortic valve abnormalities were examined. RESULTS: Age, male gender, body mass index (odds ratio [OR]: 1.07 per kg/m(2); 95% confidence interval [CI]: 1.02 to 1.12), antihypertensive treatment (OR: 1.93; CI: 1.12 to 3.32) and plasma homocysteine levels (OR: 1.89 per twofold increase; CI: 0.99 to 3.61) were independently associated with an increased risk of AVS. Age, body mass index and pulse pressure (OR: 1.21 per 10 mm Hg; CI: 1.00 to 1.46) were associated with elevated (upper quintile) transaortic velocities, whereas only age was independently associated with AR. Sinotubular junction sclerosis (p = 0.001) and atherosclerosis of the ascending aorta (p = 0.03) were independently associated with AVS and elevated transaortic velocities, respectively. CONCLUSIONS: Atherosclerosis risk factors and proximal aortic atherosclerosis are independently associated with aortic valve abnormalities in the general population. These observations suggest that AVS is an atherosclerosis-like process involving the aortic valve.

The impact of stroke on the cost and level of care in nursing homes: a retrospective population-based study.

OBJECTIVE: To estimate the impact of incident stroke on nursing home (NH) costs and level of care. SUBJECTS AND METHODS: This retrospective population-based cohort study is part of a larger study that identified all Rochester, Minn, residents with a confirmed first stroke occurring between January 1, 1988, and December 31, 1989. One Rochester resident who had not had a stroke was matched to each person with stroke. Persons with and without stroke were followed up in provider-linked medical records and NH files from baseline (i.e., date of stroke) through December 31, 1994, for evidence of NH use. This study characterized the NH activity of those individuals with any NH activity after baseline (58 persons with major stroke, 36 persons with minor stroke, and 63 persons without stroke) as to NH case mix at first assessment, number of NH days, and per diem Medicaid reimbursement. RESULTS: Characteristics at first NH assessment after baseline revealed that NH residents with major stroke were younger and more disabled and required more services than residents without stroke. Over the full period of follow-up, the mean number of NH days was similar for NH residents with major stroke and those without stroke, yet per diem Medicaid reimbursement was 11% higher for residents with major stroke compared with residents without stroke. Nursing home residents with minor stroke appeared similar to those without stroke with respect to time to admission, characteristics at first assessment, number of NH days, and per diem Medicaid reimbursement. CONCLUSION: Lower incidence and severity of stroke may contribute to lower care needs and per diem cost, but no fewer NH days.

Association of atrial fibrillation and aortic atherosclerosis: a population-based study.

OBJECTIVE: To examine the association between atrial fibrillation (AF) and aortic atherosclerosis in the general population. SUBJECTS AND METHODS: Transesophageal echocardiography was performed in 581 subjects, a random sample of the adult Olmsted County, Minnesota, population (45 years of age or older) participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. The frequency of aortic atherosclerosis was determined in 42 subjects with AF and compared with that in 539 subjects without AF (non-AF group). RESULTS: Subjects with AF were significantly older than non-AF subjects (mean +/- SD age, 82+/-10 vs 66+/-13 years, respectively; P<.001) and more commonly had hypertension (28 [66.7%] vs 288 [53.4%], respectively; P=.10). The 2 groups were similar in sex and frequency of diabetes mellitus, hyperlipidemia, or smoking history (P>.10). The odds of aortic atherosclerosis (of any degree) were 2.87 times greater (95% confidence interval [CI], 1.41-5.83; P=.004) and the odds of complex atherosclerosis (protruding atheroma >4 mm thick, mobile debris, or plaque ulceration) were 2.71 times greater (CI, 1.13-6.53; P=.03) in the AF group than in the non-AF group. Age was a significant predictor of aortic atherosclerosis (P<.001). After adjusting for age, the odds of atherosclerosis and complex atherosclerosis were not significantly different between the 2 groups (P=.13 and P=.75, respectively). CONCLUSIONS: In the general population, AF is associated with aortic atherosclerosis, including complex atherosclerosis. This association is related to age since both AF and aortic atherosclerosis are more frequent in the elderly population.

Long-Term fracture risk following ischemic stroke: a population-based study.

The overall risk of fracture following stroke has not been well quantified. We addressed this issue in a population-based retrospective cohort study among the 387 Rochester, Minnesota residents who survived for 90 days following their first cerebral infarction during the 10-year period, 1960-69. Cases were matched by age and sex to controls from the general population of Rochester, and subsequent fractures were assessed through review of each subject's complete (inpatient and outpatient) medical records in the community. With comparable follow-up, the 128 fractures observed among cases were little more than the 118 seen among controls, and the cumulative incidence of any fracture after 25 years was not significantly different (71% versus 66%; p=0.464). Using stratified Cox analysis, there was no increase in the risk of fractures generally (hazard ratio (HR), 1.1; 95% CI, 0.8-1.6) or hip fractures specifically (HR, 1.1; 95% CI, 0.6-2.1) compared with controls. Among the stroke patients with hemiparesis or hemiplegia, the majority of fractures occurred on the impaired side. In a multivariate analysis, fracture risk increased with age (HR per 10 years, 1.6; 95% CI, 1.4-2.0), with hospitalization at onset of stroke (HR, 2.0; 95% CI, 1.3-3.2) and with moderate functional impairment (HR, 1.6; 95% CI, 1.02-2.5) but not severe disability (HR, 0.8; 95% CI, 0.4-1.6). No other characteristic of the stroke or its treatment was an independent predictor of overall fracture risk. Patients and their caretakers need to be aware of the risk of fracture from falls, particularly when moderate impairment permits the patient to be independently mobile.

IV immunoglobulin does not reverse established weakness in MS.

BACKGROUND: Immunoglobulin (Ig) administration induces remyelination in the Theiler's virus model of MS. METHODS: A randomized, double-blinded, placebo-controlled trial of IV immunoglobulin (IVIg) was performed in patients with MS who had persistent muscle weakness that had been stable for between 4 and 18 months to determine whether this would improve muscle strength (primary outcome: isometric muscle strength). Patients received either IVIg (0.4 g/kg) or placebo daily for 5 days, then single infusions every 2 weeks for 3 months (total, 11 infusions). Muscle groups identified by clinical measures to have unchanging significant weakness were the major targets for therapeutic response (targeted neurologic deficit [TND]). RESULTS: IVIg was well tolerated. An interim analysis after 67 patients were enrolled indicated no difference in the degree of change in strength between treatment groups in either the TND or non-TND muscle groups at 6 months, and the trial was terminated. There was no apparent benefit in relapse behavior or impairment measures during the 6-month observation period. Nor was there apparent benefit in either patients who remained clinically stable or in those with evidence of disease activity. Patients with active MS during the trial worsened in both TND and non-TND muscle groups. This worsening was seen regardless of whether the clinical manifestations of disease activity involved the TND muscle groups. CONCLUSIONS: IVIg does not reverse established weakness in MS. Measurements of isometric muscle strength were reliable (reproducible) indices of strength and may be sensitive, objective methods to document functional changes in impairment in future MS trials.

Predictors of cerebrovascular events and death among patients with valvular heart disease: A population-based study.

BACKGROUND AND PURPOSE: There is little population-based information on cerebrovascular events and survival among valvular heart disease patients. We used the Kaplan-Meier product-limit method and the Cox proportional hazards model to determine rates and predictors of cerebrovascular events and death among valve disease patients. METHODS: This population-based historical cohort study in Olmsted County, Minnesota, reviewed residents with a first echocardiographic diagnosis of mitral stenosis (n=19), mitral regurgitation (n=528), aortic stenosis (n=140), and aortic regurgitation (n=106) between 1985 and 1992. RESULTS: During 2694 person-years of follow-up, 98 patients developed cerebrovascular events and 356 died. Compared with expected numbers, these observations are significantly elevated, with standardized morbidity ratio of 3.2 (95% CI, 2.6 to 3.8) and 2. 5 (95% CI, 2.2 to 2.7), respectively. Independent predictors of cerebrovascular events were age, atrial fibrillation, and severe aortic stenosis. The risk ratio of severe aortic stenosis was 3.5 (95% CI, 1.4 to 8.6), with atrial fibrillation conferring greater risk at younger age. Predictors of death were age, sex, cerebrovascular events, ischemic heart disease, and congestive heart failure, the greatest risk being among those with both congestive heart failure and cerebrovascular events (risk ratio=8.8; 95% CI, 5. 8 to 13.4). Valve disease type and severity were not independent determinants of death. CONCLUSIONS: The risk of cerebrovascular events and death among patients with valve disease remains high. Age, atrial fibrillation, and severe aortic stenosis are independent predictors of cerebrovascular events, and age, sex, cerebrovascular events, congestive heart failure, and ischemic heart disease are independent predictors of death in these patients.

Left atrial appendage flow velocities in subjects with normal left ventricular function.

The objectives of this study were to establish reference values and define the determinants of left atrial appendage (LAA) flow velocities in the general population. LAA flow velocities (contraction and filling velocities) were assessed by transesophageal echocardiography in 310 subjects aged > or = 45 years, sampled from the population-based Stroke Prevention: Assessment of Risk in a Community study. All subjects were in sinus rhythm, with preserved left ventricular systolic function (ejection fraction > or = 50%), and without valvular disease. Values of LAA contraction and filling velocities were established for various age groups in the population. Age was negatively associated with LAA contraction and filling velocities, which decreased by 4.1 cm/s (p < 0.001) and 2.0 cm/s (p < 0.01) for every 10 years of age, respectively. Contraction velocities were 5 cm/s higher in men than in women (p < 0.05). After adjusting for age and sex, heart rate was independently associated with LAA contraction velocities (p < 0.001; nonlinear association). Body surface area, left atrial size, left ventricular mass index, and a history of previous cardiac disease or hypertension showed no significant association with LAA flow velocities (p > 0.05). Furthermore, detailed analysis of 24-hour ambulatory blood pressure data (available in 253 subjects) showed no association between various blood pressure parameters (systolic and diastolic blood pressure, out-of-bed and in-bed measurements) and LAA flow velocities (all p > 0.05). In summary, the present study establishes the reference values for LAA flow velocities in a large sample of the general population. LAA flow velocities progressively decline with age in subjects with preserved left ventricular systolic function.

Independent association of high blood pressure and aortic atherosclerosis: A population-based study.

BACKGROUND: Atherosclerosis of the thoracic aorta is associated with stroke. The association between hypertension, a major risk factor for stroke, and aortic atherosclerosis has not been determined in the general population. METHODS AND RESULTS: Transesophageal echocardiography was performed in 581 subjects, a random sample of the Olmsted County (Minnesota) population aged >/=45 years participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. Blood pressure was assessed by multiple office measurements and 24-hour ambulatory blood pressure monitoring. The association between blood pressure variables and aortic atherosclerosis was evaluated by multiple logistic regression, adjusting for other associated variables. Among subjects with atherosclerosis, blood pressure variables associated with complex aortic atherosclerosis (protruding plaques >/=4 mm thick, mobile debris, or ulceration) were determined. Age and smoking history were independently associated with aortic atherosclerosis of any degree (P:

Ischemic stroke subtypes : a population-based study of functional outcome, survival, and recurrence.

BACKGROUND AND PURPOSE: There is scant population-based information on functional outcome, survival, and recurrence for ischemic stroke subtypes. METHODS: We identified all residents of Rochester, Minnesota, with a first ischemic stroke from 1985 through 1989 using the resources of the Rochester Epidemiology Project medical records linkage system. After reviewing medical records and imaging studies, we assigned patients to 4 major ischemic stroke categories based on National Institute of Neurological Diseases and Stroke Data Bank criteria: large-vessel cervical or intracranial atherosclerosis with stenosis (ATH, n=74), cardioembolic (CE, n=132), lacunar (LAC, n=72), and infarct of uncertain cause (IUC, n=164). We used the Rankin disability score to assess functional outcome and the Kaplan-Meier product-limit method and Cox proportional hazards regression analysis with bootstrap validation to estimate rates and identify predictors of survival and recurrent stroke among these patients. RESULTS: Rankin disabilities were different across stroke subtypes at the time of stroke and 3 months and 1 year later (P=0.001). LAC was associated with milder deficits compared with other subtypes. Mean follow-up among the 442 patients in the cohort was 3.2 years. Estimated rates of recurrent stroke at 30 days were significantly different (P<0.001): ATH, 18.5% (95% CI 9.4% to 27.5%); CE, 5.3% (95% CI 1.2% to 9.6%); LAC, 1.4% (95% CI 0.0% to 4.1%); and IUC, 3. 3% (95% CI 0.4% to 6.2%). After adjusting for age, sex, and stroke severity, infarct subtype was an independent determinant of recurrent stroke within 30 days (P=0.0006; eg, risk ratio for ATH compared with CE=3.3, 95% CI 1.2 to 9.3) but not long term (P=0.07). Four of 25 recurrent strokes within 30 days were procedure-related, each in patients with ATH. Five-year death rates were significantly different (P<0.001): ATH, 32.2% (95% CI 21.1% to 43.2%); CE, 80.4% (95% CI 73.1% to 87.6%); LAC, 35.1% (95% CI 23.6% to 46.0%); and IUC, 48.6% (95% CI 40.5% to 56.7%). With adjustment for age, sex, cardiac comorbidity, and stroke severity, the subtype of ischemic stroke was an independent determinant of long-term (P=0.018; eg, risk ratio for ATH compared with cardioembolic=0.47, 95% CI 0.29 to 0.77) but not 30-day survival (P=0.2). CONCLUSIONS: Early recurrence rates for ischemic stroke caused by ATH are higher than those for other subtypes and higher than previous non-population-based studies have reported. Some of the increased risk of early recurrence among patients with ATH may be iatrogenic. Patients with LAC have better poststroke functional status than those with other subtypes. Survival is poorest among those with ischemic stroke with a cardiac source of embolism.

Racial variation in treatment for transient ischemic attacks: impact of participation by neurologists.

OBJECTIVE: This study evaluates the role of neurologists in explaining African American-white differences in the use of diagnostic and therapeutic services for cerebrovascular disease. DATA SOURCES/STUDY SETTING: Medicare inpatient hospital records were used to identify a random 20 percent sample of patients age 65 and over hospitalized with a principal diagnosis of TIA between January 1, 1991 and November 30, 1991 (n = 17,437). STUDY DESIGN: Medicare administrative data were used to identify five outcome measures: noninvasive cerebrovascular tests, cerebral angiography, carotid endarterectomy, anticoagulant therapy (as proxied by outpatient prothrombin time tests), and the specialty of the attending physician (neurologist versus other specialist). DATA COLLECTION/EXTRACTION METHODS: All Medicare claims were extracted for a 30-day period beginning with the date of admission. PRINCIPAL FINDINGS: Even after adjusting for patient demographics, comorbidity, ability to pay, and provider characteristics, African American patients were significantly less likely to receive noninvasive cerebrovascular testing, cerebral angiography, or carotid endarterectomy, compared with white patients, and to have a neurologist as their attending physician. At the same time, patients treated by neurologists were more likely to undergo diagnostic testing and less likely to undergo carotid endarterectomy. CONCLUSIONS: The findings suggest that African American patients with TIA may have less access to services for cerebrovascular disease and that at least some of this may be attributed to less access to neurologists. More research is needed on how patients at risk for stroke are referred to specialists.

Risk of surgery and anesthesia for ischemic stroke.

BACKGROUND: The goal of this study was to determine if the combination of surgery and anesthesia is an independent risk factor for the development of incident (first-time) ischemic stroke. METHODS: All residents of Rochester, MN, with incident ischemic stroke from 1960 through 1984 (1,455 cases and 1,455 age- and gender-matched controls) were used to identify risk factors associated with ischemic stroke. Cases and controls undergoing surgery involving general anesthesia or central neuroaxis blockade before their stroke/index date of diagnosis were identified. A conditional logistic regression model was used to estimate the odds ratio of surgery and anesthesia for ischemic stroke while adjusting for other known risk factors. RESULTS: There were 59 cases and 17 controls having surgery within 30 days before their stroke/index date. After adjusting for previously identified risk factors, surgery within 30 days before the stroke/index date (perioperative period) was found to be an independent risk factor for stroke (P<0.001; odds ratio, 3.9; 95% confidence interval, 2.1-7.4). In an analysis that excluded matched pairs where the case and/or control underwent surgery considered "high risk" for stroke (cardiac, neurologic, or vascular procedures), "non-high-risk surgery" was also found to be an independent risk factor for perioperative stroke (P = 0.002; odds ratio, 2.9; 95% confidence interval, 1.5-5.7). CONCLUSION: Our results suggest that there is an increased risk of ischemic stroke in the 30 days after surgery and anesthesia. This risk remains elevated even after excluding surgeries (cardiac, neurologic, and vascular surgeries) considered to be high risk for ischemic stroke.

Ischemic stroke subtypes: a population-based study of incidence and risk factors.

BACKGROUND AND PURPOSE: There is scant population-based information on incidence and risk factors for ischemic stroke subtypes. METHODS: We identified all 454 residents of Rochester, Minn, with a first ischemic stroke between 1985 and 1989 from the Rochester Epidemiology Project medical records linkage system. We used Stroke Data Bank criteria to assign infarct subtypes after reviewing medical records and brain imaging. We adjusted average annual incidence rates by age and sex to the US 1990 population and compared the age-adjusted frequency of stroke risk factors across ischemic stroke subtypes. RESULTS: Age- and sex-adjusted incidence rates (per 100 000 population) were as follows: large-vessel cervical or intracranial atherosclerosis with >50% stenosis, 27; cardioembolic, 40; lacuna, 25; uncertain cause, 52; other or uncommon cause, 4. Sex differences in incidence rates were detected only for atherosclerosis with stenosis (47 [95% CI, 34 to 61] for men; 12 [95% CI, 7 to 17] for women). There was no difference in prior transient ischemic attack and hypertension among subtypes, and diabetes was not more common among patients with lacunar infarction than other common subtypes. CONCLUSIONS: The age-adjusted incidence rate of stroke due to stenosis of the large cervicocephalic vessels is nearly 4 times higher for men than for women. There is no association between preceding transient ischemic attack and stroke mechanism. Diabetes and hypertension are not more common among patients with lacunae. Age- and sex-adjusted incidence rates for ischemic stroke subtypes in this population can be compared with similarly determined rates from other populations.

Prevalence of potential risk factors for stroke assessed by transesophageal echocardiography and carotid ultrasonography: the SPARC study. Stroke Prevention: Assessment of Risk in a Community.

OBJECTIVE: The SPARC (Stroke Prevention: Assessment of Risk in a Community) study was designed to identify risk factors for stroke and cardiovascular disease using transesophageal echocardiography and carotid ultrasonography. This protocol was undertaken to establish a cohort in which putative risk factors for stroke were identified so that subsequent follow-up could discern the roles these risk factors play in stroke incidence. SUBJECTS AND METHODS: This was a prospective, population-based study. A randomly selected cohort comprised 1475 Olmsted County, Minnesota, residents aged 45 years or older, of whom 588 agreed to participate. Transesophageal echocardiography and carotid ultrasonography were used for evaluation of the subjects. Prevalences of various cardiovascular and cerebrovascular conditions were determined. RESULTS: Transesophageal echocardiography was successfully completed in 581 subjects. The prevalence (+/-SE) of patent foramen ovale was 25.6% (+/-1.9%), and that of atrial septal aneurysm was 2.2% (+/-0.6%). The prevalence of aortic atherosclerosis increased with age and was most common in the descending aorta, particularly in subjects 75 to 84 years old. The prevalence of strands on native valve was 46.4% (+/-2.2%). Carotid ultrasonography data for 567 participants revealed minimal atherosclerotic disease. Most subjects had minimal or mild carotid occlusive disease. The prevalence of moderate (50%-79%) and severe (80%-99%) stenosis was 7.7% (+/-1.1%) and 0.3% (+/-0.2 %), respectively. CONCLUSIONS: This prospective study defines the prevalence of multiple potential cardiovascular and cerebrovascular risk factors, providing population-based data for ongoing follow-up of the risk of stroke.

Detection and control of high blood pressure in the community : Do we need a wake-up call?

At the community level, the effect of national programs in increasing hypertension awareness, prevention, treatment, and control is unclear. This study evaluated the degree of detection and control of high blood pressure in a random population-based sample of Olmsted County, Minnesota, residents >/=45 years old, of whom 636 subjects among 1245 eligible residents agreed to participate. Home interview and home and office measurements of blood pressure were used to estimate awareness, treatment, and control rates for hypertension in the community. Mean blood pressures (+/-SD) were 138/80+/-20/12 mm Hg for men and 137/76+/-23/11 mm Hg for women. The overall prevalence of hypertension was 53%. The percentage of subjects with treated and controlled hypertension was 16.6%. Thirty-nine percent of subjects were unaware of their hypertension. Despite clinical trial evidence of reduced morbidity and mortality with antihypertensive therapy, recently reported national data suggest a leveling-off trend for treatment and control of hypertension. This population-based study supports these observations and suggests that at a community level, hypertension awareness and blood pressure control rates are suboptimal, presumably because of decreased attention to the detection and control of hypertension.

Comparison of population-based models of risk factors for TIA and ischemic stroke.

OBJECTIVE: To determine whether there is a difference in the risk factors for ischemic stroke and for TIA. BACKGROUND: TIA is associated with a high risk for ischemic stroke, but some have considered TIA as mild ischemic stroke. Prevention of disabling stroke is sufficient reason to label TIA as a precursor for stroke, but some risk factors may be more or less associated with TIA than with ischemic stroke, suggesting differences in mechanism. METHODS: The medical records linkage system for the Rochester Epidemiology Project provided the means of identifying first episodes of TIA in the Rochester, MN population among those who had not had ischemic stroke. Control subjects were selected from an enumeration of the population through the medical records. The exposure to various risk factors was ascertained. The conditional likelihood approach to estimate the parameters of a multiple logistic model permitted estimation of the OR for TIA for each risk factor while adjusting for confounding variables. RESULTS: The multivariable logistic regression model for TIA shows that the estimates of the ORs for ischemic heart disease, hypertension, persistent atrial fibrillation, diabetes mellitus, and cigarette smoking are similar to the ORs for those variables in the ischemic stroke model. However, the OR for mitral valve disease in the TIA model is 0.4, suggesting that mitral valve disease is unlikely to be associated with cerebral ischemic episodes that are brief enough to be called TIA.

Lone atrial fibrillation in elderly persons: a marker for cardiovascular risk.

BACKGROUND: The risk of stroke in persons aged 60 years and younger with lone atrial fibrillation (LAF) is no greater than in the general population. The effect of older age on the risk of stroke in persons with LAF is less well established. PARTICIPANTS AND METHODS: The risk of stroke in persons with LAF and without substantial comorbidities was examined in a population-based study at a single institution in Olmsted County, Minnesota, and compared with that in an age- and sex-matched population. The mean age was 74 years (range, 61-97 years). The median duration of follow-up was 9.6 years until death or last follow-up. RESULTS: Of 55 patients, 26 had 31 cardiovascular events during follow-up, occurring a median of 5.1 years after diagnosis (range, 0.7-18 years). Of 11 cerebrovascular events, 6 were transient ischemic attacks and 5 were strokes. The event rates (percentage per person-year) were 0.9% for stroke, 1.1% for transient cerebral ischemia, and 2.6% for myocardial infarction, for a total cardiovascular event rate of 5.0% per person-year. The corresponding rates for the age- and sex-matched control group were 0.2%, 0%, and 1.1%, for a total of 1.3% per person-year. The incidence of total cardiovascular events was significantly greater (P< .01) in those with LAF, although there was no difference in survival. CONCLUSION: Lone atrial fibrillation occurring after age 60 years is a risk marker for a substantial increase in cardiovascular events that warrants consideration for antithrombotic therapy.