The International Stroke Conference 2008 New Orleans, Louisiana February 20-22, 2008

Current guideline statements for primary and secondary prevention of cardiovascular disease (CVD) rely on estimates of absolute risk of coronary events. For example, the American Heart Association guidelines on primary prevention state that persons with ≥10% risk over 10 years of myocardial infarction (MI) or coronary death should be considered for antiplatelet therapy with aspirin.1 Similarly, the National Cholesterol Education Program Adult Treatment Panel III (ATP III) guidelines2 state that target low-density lipoprotein level should be based on projected absolute risk of future coronary events rather than on presence or absence of specific risk factors. These guidelines state that patients at high risk of MI and coronary death, defined as an absolute 10-year risk of ≥20%, should have a target low-density lipoprotein level <100 mg/dL and should receive statin therapy if needed to achieve this goal. Stroke, however, is not included as one of the outcomes contributing to these absolute risk levels. Included in the group of patients with elevated risk, moreover, are those who already have ischemic heart disease, as well as patients deemed to be “coronary heart disease (CHD) risk equivalents,” indicating those at the same elevated risk as patients with ischemic heart disease. CHD risk equivalents include patients with diabetes mellitus, those with multiple risk factors that put them at elevated risk based on calculation of their Framingham Score, and patients with “other forms of symptomatic atherosclerotic disease.” The latter group is further defined to include those with peripheral arterial disease (PAD), abdominal aortic aneurysm (AAA), and carotid artery disease. The category of “risk equivalents” in the ATP III guidelines, however, does not include the vast majority (≈80%3) of ischemic stroke patients without carotid artery disease as cause of their stroke. Ischemic stroke is therefore notably excluded from the list of outcomes contributing to …

Marc Fisher MD Kennedy Lees MD Section Editors: Hypertension is the most important modifiable risk factor for stroke.1,2 It is estimated that 25% or more of strokes may be attributable to hypertension. Because many patients with stroke have mild hypertension or prehypertension, we have shifted our focus and now think of stroke on a continuum of risk based on blood pressure (BP) level rather than on a threshold effect.3 Because high BP may not exist in isolation, a wider definition of hypertension has been proposed that also takes into account the absolute risk of cardiovascular events and associated metabolic factors or early disease markers.3 Lowering BP reduces the risk of stroke. Epidemiological studies have shown that for each 10 mm Hg lower systolic blood pressure (SBP), there is a decrease in risk of stroke of approximately one third in persons aged 60 to 79 years. This association is continuous down to levels of at least 115/75 mm Hg and is consistent across sexes, regions, stroke subtypes, and for fatal and nonfatal events.4 Lowering diastolic blood pressure (DBP) was once the main target to achieve stroke and other cardiovascular event reduction, but SBP has now become the target.3 As recently shown, even the elderly with sustained SBP elevation may gain from BP reduction in relation to less fatal or nonfatal stroke, death, and heart failure.5 Although the role of longer-term BP control to improve outcomes in patients with stroke is undisputed, BP management immediately after a stroke remains controversial. In an effort to resolve this controversy, several pilot clinical trials have been initiated. In this review, we discuss the results of some of these trials and available evidence-based guidelines for BP control in the settings of acute ischemic and hemorrhagic stroke (excluding subarachnoid hemorrhage) and …

Should We Be Treating Blood Pressure More Aggressively and Earlier After Acute Stroke?

Specogna, AV; Patten, SB; Hill, MD; University of Calgary, Calgary, AB Background: Previous studies have examined predictors of treatment costs after Spontaneous Intracerebral Hemorrhage (ICH) in various countries and healthcare systems. Currently however, there is no clear understanding of which factors are associated with cost in any Canadian setting and thus no way of understanding how to plan ICH healthcare spending. Methods: We used a retrospective case series study design and adjusted linear regression to investigate if an association existed between the total cost of ICH hospital care in a Canadian health centre and age (years), gender (female vs. male), Charlson Comorbidity Index (0 vs. ≥1), in-hospital mortality (alive vs. dead), and having surgery (no vs. yes). Economic, treatment, and patient data were obtained from administrative sources. Total inflation-adjusted hospital cost per discharge was estimated in Canadian Dollars and log transformed for all analyses. Results: Analyses were performed using 987 consecutive ICH discharges from 1999 to 2008. The total cost of ICH hospital care was highly variable (mean cost per discharge=$25,613.96±$36,116.33; min $446.81 to max $326,275.10). Older age (β=–0.0057; 95% CI: –0.0103 to –0.0011) and death in hospital (β=–0.4859; 95% CI: –0.6357 to –0.3342) were significantly associated with lower total hospital cost per discharge. Whereas Charlson Comorbidity Index of ≥1 (β=0.6489; 95% CI: 0.5063 to 0.7916) and having surgery (β=1.3552; 95% CI: 1.1893 to 1.5210) were significantly associated with higher total hospital cost per discharge. Gender was not significantly associated with cost (β=0.0727; 95% CI: –0.0679 to 0.2134). Conclusions: To our knowledge this is the first study to examine predictors of ICH treatment costs in Canada. In a Canadian health centre, ICH treatment costs were significantly associated with patient age, level of comorbidity, in-hospital mortality, and surgical treatment. This study provides evidence that it may be reasonable to consider …

Case presentation : During cardiac catheterization, a 65-year-old man suddenly complained of nuchal pain, vertigo, and nausea and rapidly became unconscious, presumably from a stroke. The operator was unsure what type of imaging and management should be undertaken in this infrequent clinical setting. He paged the neurologist, asking him to urgently provide a strategy for diagnosis and management. Although the overall rate of stroke after left heart catheterization or percutaneous coronary intervention (PCI) is low, ranging from 0.2% to 0.4% (Tables 1 and 2⇓),1–5 it is the most debilitating complication from the patient’s perspective, associated with a high rate of morbidity and mortality (Figure 1).1–8 In 20 679 consecutive patients who underwent PCI in a large-volume center, stroke occurred in 0.44%.4 Multivariate analysis has shown that the occurrence of stroke was more frequently associated with diabetes mellitus, hypertension, prior stroke, or renal failure and was independently associated with in-hospital death. Patients who suffered a stroke had previously undergone longer cardiac catheterization procedures, using more contrast, were more likely to have had the procedure for urgent reasons, and to have had intraaortic balloon counterpulsation, a procedure that is itself known to increase the risk of stroke.9 Possible explanations for this latter characteristic include the greater propensity for hemodynamic compromise in these patients, which may increase the risk of ischemic stroke, and less meticulous care in advancing the catheter through the aorta during urgent PCI, which increases the risk of embolization by scraping of aortic plaques with subsequent embolization of debris to the brain. Indeed, scraping of aortic plaques occurs in >50% of PCI cases and more frequently with large than with small catheters.10 Cerebral microembolism is thought to be the main mechanism of periprocedural ischemic stroke occurring with PCI. This finding is supported …

Age-adjusted stroke incidence has decreased over the past 50 years, likely as a result of changes in the prevalence and impact of various stroke risk factors. An updated version of the Framingham Stroke Risk Profile (FSRP) might better predict current risks in the FHS (Framingham Heart Study) and other cohorts. We compared the accuracy of the standard (old) and of a revised (new) version of the FSRP in predicting the risk of all-stroke and ischemic stroke and validated this new FSRP in 2 external cohorts, the 3C (3 Cities) and REGARDS (Reasons for Geographic and Racial Differences in Stroke) studies. We computed the old FSRP as originally described and a new model that used the most recent epoch-specific risk factor prevalence and hazard ratios for individuals ≥55 years of age and for the subsample ≥65 years of age (to match the age range in REGARDS and 3C studies, respectively) and compared the efficacy of these models in predicting 5- and 10-year stroke risks. The new FSRP was a better predictor of current stroke risks in all 3 samples than the old FSRP (calibration χ2 of new/old FSRP: in men: 64.0/12.1, 59.4/30.6, and 20.7/12.5; in women: 42.5/4.1, 115.4/90.3, and 9.8/6.5 in FHS, REGARDS, and 3C, respectively). In the REGARDS, the new FSRP was a better predictor among whites compared with blacks. A more contemporaneous, new FSRP better predicts current risks in 3 large community samples and could serve as the basis for examining geographic and racial differences in stroke risk and the incremental diagnostic utility of novel stroke risk factors.

Establishing new approaches for the prevention and treatment of stroke relies on identifying modifiable risk factors that contribute to the development of this complex disease. Mendelian randomization (MR) studies, analogous to naturally occurring randomized trials, can assess causality of potentially modifiable biomarkers and offer new insights into biological pathways. Stroke is the second leading cause of death worldwide and the chief determinant of long-term disability. Stroke is a heterogeneous disease arising from several distinct underlying pathologies and is typically classified as ischemic or hemorrhagic, and further subclassified using imaging data. Ischemic stroke (IS), including its 3 main subtypes: small vessel disease, large vessel disease, and cardioembolic stroke, accounts for ≈80% of stroke and is the result of an interrupted blood supply, leading to localized areas of ischemia in the brain. Small vessel disease may be a consequence of nonatherosclerotic, as well as atherosclerotic, mechanisms that result in an occlusion of the small perforating arteries, whereas large vessel disease results from occlusions or emboli from plaque rupture in larger vessels, such as a carotid artery. Cardioembolic stroke arises typically from emboli from the heart. By contrast, hemorrhagic stroke is a consequence of intracerebral hemorrhage (bleeding into the brain) or subarachnoid hemorrhage (bleeding into the subarachnoid space). These diverse stroke subtypes have distinct underlying pathologies reflecting different risk factor distributions. MR studies, using genetic variants as instrumental variables, afford a powerful approach to assessing causality of risk factors and avoid biases inherent in observational studies, including confounding and reverse causation. This review considers the contribution of MR studies to stroke epidemiology and their relevance to understanding risk factors and new therapeutic targets for stroke. Meta-analyses of large prospective studies have enhanced our knowledge of classical and emerging risk factors for stroke.1–4 Classical risk factors for stroke include nonmodifiable characteristics, …

APOL1 renal risk variants are strongly associated with chronic kidney disease in Black adults, but reported associations with cardiovascular disease (CVD) have been conflicting. We examined associations of APOL1 with incident coronary heart disease (n=323), ischemic stroke (n=331), and the composite CVD outcome (n=500) in 10 605 Black participants of the REGARDS study (Reasons for Geographic and Racial Differences in Stroke). Primary analyses compared individuals with APOL1 high-risk genotypes to APOL1 low-risk genotypes in Cox proportional hazards models adjusted for CVD risk factors and African ancestry. APOL1 high-risk participants were younger and more likely to have albuminuria at baseline than APOL1 low-risk participants. The risk of incident stroke, coronary heart disease, or composite CVD end point did not significantly differ by APOL1 genotype status in multivariable models. The association of APOL1 genotype with incident composite CVD differed by diabetes mellitus status (Pinteraction=0.004). In those without diabetes mellitus, APOL1 high-risk genotypes associated with greater risk of incident composite CVD (hazard ratio, 1.67; 95% confidence interval, 1.12-2.47) compared with those with APOL1 low-risk genotypes in multivariable adjusted models. This latter association was driven by ischemic strokes (hazard ratio, 2.32; 95% confidence interval, 1.33-4.07), in particular, those related to small vessel disease (hazard ratio, 5.10; 95% confidence interval, 1.55-16.56). There was no statistically significant association of APOL1 genotypes with incident CVD in subjects with diabetes mellitus. The APOL1 high-risk genotype was associated with higher stroke risk in individuals without but not those with chronic kidney disease in fully adjusted models. APOL1 high-risk status is associated with CVD events in community-dwelling Black adults without diabetes mellitus.

Proponents of cholesterol as a risk factor for stroke usually support their argument by citing evidence from clinical trials of the beneficial effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (“statins”) in reducing stroke risk among people with prior cardiovascular disease. Although such studies may provide some supportive evidence, causation can really only be established between a risk factor and a disease when certain criteria are met.1 These include the criteria that the association between the risk factor and the disease must be temporal and biologically plausible. Although there may be little or no debate about whether cholesterol is a biologically plausible risk factor for stroke or that high cholesterol levels precede (rather than follow) stroke, some of the other criteria are more ambiguous. These other “guidelines for causation” are discussed below: There have been numerous major prospective epidemiological studies of cholesterol and the risk of stroke. However, at best, the …

Emerging Therapies for Cerebrovascular Disorders

Brammås et al investigated the association between the mortality rate associated with ischemic stroke during the first year after acute myocardial infarction (AMI) in the Swedish Web-system for Enhancement and Development of Evidence-based Care in Heart Disease Evaluated According to Recommended Therapies registry (SWEDEHEART).This represents a large, national quality register of all patients admitted to a coronary care unit in Swedish hospitals.A total of 173 233 patients were recorded from 1998 to 2008, at the time of their index AMI.Of these, 7185 (4.1%) had an ischemic stroke within 1 year of AMI.The primary end point, death within 1 year from the index AMI, occurred in 2624 (36.5%) of patients with ischemic stroke.Conversely, mortality rate was 18.3% in patients who did not experience an ischemic stroke in the year after AMI.Patients who died during the first year after AMI, as well as those with ischemic stroke were older, had more comorbidities, and were less often taking evidence-based medication.Overall, women had higher mortality rates than men.Importantly, analysis of time trends indicated that during the observation period, mortality rates decreased from 1998 to 2008 by ≈10% in patients with stroke.These rates were similar for men and women.Expectedly, the strongest predictors of 1-year mortality were advancing age, heart failure, renal disease, peripheral arterial disease, diabetes mellitus, and less use of evidence-based treatments (including percutaneous coronary intervention, statins, angiotensinconverting enzyme inhibitors, antiplatelets, and anticoagulants).Interestingly, the use of diuretics was associated with an increased risk for mortality.However, without further analysis it remains unclear whether this association was because of worse comorbidities in treated patients.Nevertheless, this study clearly highlights that despite the beneficial effect of evidence-based treatments and overall improved outcome during the past decade, mortality in this patient population remains high, and further research is required to elucidate this issue.For example, this study did not inform on stroke subtype that might allow for further risk stratification.Also, the cause of death remained unknown, which could provide important clues for improving secondary prevention measures in affected patients.See p 3050.

Should Tenecteplase be Given in Clinical Practice for Acute Ischemic Stroke Thrombolysis?

Introduction: The neuropeptide neurotensin (NT) has been linked to cardiovascular and metabolic disease risk. Through measurement of its stable equimolar precursor, pro-neurotensin/neuromedin N (pro-NT/NMN), hyperactivity of NT has been associated with aggregate cardiovascular outcomes that include stroke. However, the exclusive association of pro-NT/NMN with incident ischemic or hemorrhagic stroke has not been studied. Hypothesis: Higher serum pro-NT/NMN is associated with incident ischemic and hemorrhagic stroke. Methods: Prospective case-cohort study in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. From 2003-2007, REGARDS enrolled 30,239 White or Black adults aged ≥45. Pro-NT/NMN was measured by immunoassay in 464 ischemic stroke cases, 49 hemorrhagic stroke cases, and 800 non-cases from a random cohort. Cox proportional-hazards models were used to calculate hazard ratios (HR) of stroke by pro-NT/NMN quartiles and per standard deviation (SD) of log pro-NT/NMN. Model 1 (both stroke types) included demographic factors as covariates, Model 2A (ischemic only) added ischemic stroke risk factors, and Model 2B (hemorrhagic only) added hemorrhagic stroke risk factors. Results: The table shows an increased HR of ischemic stroke for those in the 4th vs 1st-quartile pro-NT/NMN in Model 1 with a trend of increased risk across quartiles; this was attenuated in Model 2A. Prebaseline diabetes and coronary artery disease were the largest confounders of ischemic stroke risk, with each accounting for 19% of the association observed in Model 1. There was no association of pro-NT/NMN with hemorrhagic stroke in either model. There were no interactions of race or sex with log pro-NT/NMN. Conclusions: Higher pro-NT/NMN is associated with increased risk of ischemic stroke after adjusting for demographics, but this was not independent of stroke risk factors. No significant association with hemorrhagic stroke was observed; this analysis was limited by a small number of events.

Major Ongoing Stroke Trials

Stroke is a complex disease, with both genetic and environmental factors having a role in its pathogenesis. A review of past studies shows some evidence of genetic influences in the development of stroke. This is supported by studies of cardiovascular disease, which indicate major genetic influences at several levels including the development of risk factors. New approaches to phenotypic classifications, patient ascertainment, and genetic analysis will stimulate research into the role of genetics in cerebrovascular disease.