American Heart Association

prevention

Interview: Professor Dr. Hans-Christoph Diener on “Dabigatran for Prevention of Stroke after Embolic Stroke of Undetermined Source”

Professor Dr. Hans-Christoph Diener

Professor Dr. Hans-Christoph Diener

A conversation with Professor Dr. Hans-Christoph Diener, Faculty of Medicine at the University of Duisburg-Essen, on the recently published randomized clinical trials assessing the safety and efficacy of non-vitamin K oral anticoagulants (NOACs) in patients with embolic strokes of undetermined source (ESUS), and on the future of anticoagulation in the secondary prevention of cryptogenic cerebral ischemia.

Interviewed by Aristeidis H. Katsanos, Research Fellow at the Department of Neurology, Ruhr University of Bochum.

They will be discussing the paper “Dabigatran for Prevention of Stroke after Embolic Stroke of Undetermined Source,” published in the May 16, 2019 issue of the New England Journal of Medicine.

Dr. Katsanos: Can you please summarize for the readers of the blog the main hypothesis and findings of the RE-SPECT ESUS trial?

Prof. Diener: Patients with ESUS (embolic stroke of undetermined source) have high risk of recurrent stroke, and the risk of recurrent stroke per year is about 5%. We assume that the majority of these recurrent strokes have an embolic source. Therefore, oral anticoagulation should be superior to antiplatelet therapy in patients with ESUS.

Defining the Optimal Duration of Dual Antiplatelet Therapy after Ischaemic Stroke or Transient Ischaemic Attack

Alan C. Cameron, MB ChB, BSc (Hons), MRCP

Rahman H, Khan SU, Nasir F, Hammad T, Meyer MA, Kaluski E. Optimal Duration of Aspirin Plus Clopidogrel After Ischemic Stroke or Transient Ischemic Attack: A Systematic Review and Meta-Analysis. Stroke. 2019;50:947–953.

Through a systemic review and meta-analysis of 10 randomised trials comparing dual antiplatelet therapy (DAPT) with aspirin plus clopidogrel versus aspirin alone in over 15,000 patients with ischaemic stroke (IS) or transient ischaemic attack (TIA), Rahman and colleagues demonstrate that £1 month of DAPT reduces the relative risk of recurrent IS by almost 50% with no increase in major bleeding. In contrast, £3 months of DAPT reduces IS by 28% but increases major bleeding, whilst >3 months of DAPT does not reduce recurrent IS and increases major bleeding. The reduction in risk of recurrent IS with £3 months of DAPT may be due to substantial early benefit within the first few days or weeks. The POINT and CHANCE trials suggest maximum benefit is achieved when DAPT is initiated within the first 24 hours after minor IS or high-risk TIA, which highlights a need for services that allow patients to be reviewed within this timeframe.

The risk of bleeding was greater in aspirin naïve patients in analysis of the EXPRESS and FASTER studies, highlighting a need to screen carefully for bleeding risk factors in this group of patients. Better blood pressure control combined with screening and management of bleeding risk factors is essential to ensure benefits from antiplatelet therapy are not offset by increased bleeding. Overall, we can be confident that DAPT is most effective and safe in the early weeks after minor IS or high-risk TIA to reduce the risk of recurrence.

A New Look at ICAS from the SAMMPRIS Data

Richard Jackson, MD

Wabnitz AM, Derdeyn CP, Fiorella DJ, Lynn MJ, Cotsonis GA, Liebeskind DS, et al. Hemodynamic Markers in the Anterior Circulation as Predictors of Recurrent Stroke in Patients With Intracranial Stenosis. Stroke. 2018;50:143–147.

Ashley M. Wabnitz MD et al. introduced the finding that despite the superiority of aggressive medical management (AMM) in intracranial atherosclerotic arterial stenosis (ICAS), 15% of patients still had primary end point of stroke during a median follow up of 32.4 years.

The study was a post-hoc analysis of 154 patients of the total 227 patients with intracranial stenosis randomized to AMM, 49 ICA and 105 MCA. Non-MCA territory infracts and stenosis were excluded, as well as 53 patients for baseline imaging not corresponding to the qualifying event. All patients included in SAMMPRIS had angiographically verified 70-99% stenosis of ICA, MCA, vertebral or basilar arteries. Infarct patterns were classified into core, perforator, internal borderzone, or cortical borderzone based on published templates from a retrospective analysis of WASID lesions. Interobserve agreement for infarct patterns was k=0.8. Evaluation of collaterals was assessed by a validated scale by the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology; however, collaterals were assessed as impaired versus not impaired despite the validated scale having 4 grades.

Carotid Endarterectomy is Safe After Intravenous Thrombolysis

Mohammad Anadani, MD

Ijäs P, Aro E, Eriksson H, Vikatmaa P, Soinne L, Venermo M. Prior Intravenous Stroke Thrombolysis Does Not Increase Complications of Carotid Endarterectomy. Stroke. 2018

The benefit of carotid endarterectomy (CEA) for symptomatic carotid stenosis is well established; however, the optimal timing of procedure after stroke is still a matter of debate. Although few studies showed an increased risk of periprocedural stroke and death with early CEA (within 48 hours), others did not. In patients who receive intravenous thrombolysis (IVT), CEA is often delayed due to a concern of increased risk of intracerebral hemorrhage (ICH). However, this delay may result in a theoretical increase in risk of recurrent stroke while waiting for CEA.

In this study, Ijäs and colleagues underwent a retrospective registry study to investigate the safety and optimal timing of CEA after IV thrombolysis (IVT).

Omega-3 Fatty Acid Biomarkers: A Potential Marker of Incident Ischemic Stroke Risk?

Mark R. Etherton, MD, PhD

Saber H, Yakoob MY, Shi P, Longstreth Jr. WT, Lemaitre RN, Siscovick D, et al. Omega-3 Fatty Acids and Incident Ischemic Stroke and Its Atherothrombotic and Cardioembolic Subtypes in 3 US Cohorts. Stroke. 2017

In this entry, I discuss a recent publication by Hamidreza Saber and colleagues regarding the relationship of circulating omega-3 fatty acids levels and incident ischemic stroke.

The authors set out to clarify the impact of omega-3 fatty acids on ischemic stroke incidence. Observational studies of self-reported omega-3 fatty acid consumption and omega-3 fatty acid supplementation trials have previously produced disparate results. As such, the authors quantified circulating omega-3 fatty acid levels in association with ischemic stroke incidence from 3 separate prospective cohort studies.

The authors used data from the Cardiovascular Health Study (CHS), Nurses’ Health Study (NHS), and Health Professionals Follow-Up Study (HPFS). Each of these three cohort studies represent distinct patient populations, which does influence the overall generalizability of these results. CHS is a prospective cohort study of adults aged 65 years and older. The NHS is a prospective cohort study of female registered nurses 30 to 55 years of age. Lastly, HPFS is a cohort study of U.S. male health professionals 40 to 75 years of age. Most participants in each study were white (88% in CHS, for example). The analysis of NHS and HPFS was based on a nested case-control study of age and vascular-risk factor matched controls. Ischemic stroke was subdivided into atherothrombotic, cardioembolic, or other. At the time of enrollment in the studies, blood samples were collected and stored for later analysis of omega-3 fatty acid levels. Of note, there were some differences in collection and storage of blood samples for fatty acid analysis between the three studies.

Author Interview: George Ntaios, MD

George Ntaios

George Ntaios

A conversation with George Ntaios, MD, MSc (ESO Stroke Medicine), PhD, Assistant Professor of Internal Medicine, Department of Medicine, University of Thessaly

Interviewed by Stephen Makin, PhD, Clinical Lecturer at Glasgow University

They will be discussing the paper, “Real-World Setting Comparison of Nonvitamin-K Antagonist Oral Anticoagulants Versus Vitamin-K Antagonists for Stroke Prevention in Atrial Fibrillation: A Systematic Review and Meta-Analysis,” being published in the September 2017 issue of Stroke.

Dr. Makin: Thank you for taking the time to talk to us.

Prof. Ntaios: Thank you for the invitation to discuss our study.

Dr. Makin: Could I begin by asking you to summarize your study and its findings?

Prof. Ntaios: We aimed to summarize all available evidence from high-quality real-world observational studies about the efficacy and safety of non-vitamin-K-oral-anticoagulants (NOACs) compared to vitamin-K-antagonists (VKAs) in patients with atrial fibrillation (AF). Based on 28 identified studies, we found that dabigatran, rivaroxaban and apixaban, as compared to VKAs, are associated with lower risk of intracranial haemorrhage and similar risk of ischemic stroke and ischemic stroke or systemic embolism; apixaban and dabigatran with lower risk of mortality; apixaban with fewer gastrointestinal and major haemorrhages; dabigatran and rivaroxaban with higher risk of gastrointestinal haemorrhage; and dabigatran and rivaroxaban with a similar rate of myocardial infarction.

Elevated Blood Pressure Significantly Associated with Risk of Vascular Dementia

Danny R. Rose, Jr., MD


Vascular dementia is the second most common cause of dementia, but many aspects of the disease are poorly understood. In particular, there is conflicting evidence regarding the relationship between blood pressure and vascular dementia. Elevated blood pressure in midlife has been found to have a positive association with future development of dementia, but several other studies have found low blood pressure in old age to be associated with an increased risk of dementia. One possible explanation of these findings is that it represents “reverse causality,” meaning vascular dementia is responsible for low blood pressure by decreasing sympathetic drive. Blood pressure medication may also play a confounding role in this association. Emdin et al. sought to further clarify this association by conducting an analysis of 4.28 million individuals without vascular disease or dementia, supplemented with an analysis of a prospective population-based cohort of patients with TIA and stroke.

The study included patients from age 30 to 90 and excluded patients with pre-existing cardiovascular disease to minimize the potential of reverse causality related to advanced age and cardiovascular disease causing reduced blood pressure, respectively. The endpoint of the primary analysis was an inclusive definition of vascular dementia based on ICD 10 coding and was inclusive of patients with co-existing Alzheimer’s disease. Secondary analysis excluded these patients and excluded patients treated with medications commonly used to treat AD. The first four years of follow-up were excluded in the primary analysis to mitigate the effect of patients with undiagnosed dementia. Cox models, stratified by practice, were used to determine hazard ratios for the association for clustering of patients by practice. The primary analysis was adjusted for age, sex, body mass index and smoking status. The Oxford Vascular Study cohort was used to confirm findings independently.

Out of a cohort of 4.28 million individuals free of vascular disease and dementia, 14,934 cases were reported to have vascular dementia. After excluding for presentations during the first four years of follow-up, 11,114 cases were included. The association between usual SBP and risk of vascular dementia followed a linear progression within the age groups of 30-50 and 51-70. The age group of 71-90 did not show a significant association. The strength of association decreased with increasing age category. Overall for individuals aged 70 years or less at baseline, 20 mm Hg higher usual SBP was associated with a 26% higher risk of vascular dementia (HR 1.26 CI 1.17, 1.34). Significant negative associations with systolic and diastolic blood pressures were observed for the age group 71-90, but after excluding for the first eight years of follow-up, no significant association was observed. Adjusting for patients in the primary care cohort that had TIA and stroke events reduced the HR to 1.18, indicating that 30% of the excess risk of vascular dementia per 20mm Hg higher SBP is mediated through risk of future stroke and TIA. The OXVASC cohort did not show a relationship between the most recent SBP or DBP in patients relative to their diagnosis of new dementia, but did show significant positive associations with DBP and SBP in 5-9 years prior to the TIA/stroke and particularly 10-20 years prior.

This study supports prior positive associations between blood pressure in mid-life and vascular dementia and also suggests that elevated blood pressure attributes a significant risk for the development of vascular dementia at least until the age of 70. The authors’ rationale for excluding confounders in the cohort appears to be sound and had the intended effect of strengthening the associations studied. The study refutes previous reports of a negative association with blood pressure and vascular dementia in the elderly, likely in part due to the aforementioned adjustments, strengthening the authors’ hypothesis of reverse causality. This study represents by far the largest analysis of the association between blood pressure and risk of vascular dementia and although it is susceptible to limitations related to the diagnosis of dementia in a primary care setting, it represents a significant advancement in our understanding of the complex pathophysiology of vascular dementia.


Limited Meta-analysis Suggests Patients with Asymptomatic Carotid Occlusion are at Low Risk of Ipsilateral Stroke, High Risk of Non-stroke Mortality

Danny R. Rose, Jr., MD

Hackam DG. Prognosis of Asymptomatic Carotid Artery Occlusion: Systematic Review and Meta-Analysis. Stroke. 2016

Although carotid artery occlusion is estimated to account for 10-15% of all ischemic strokes and transient ischemic attacks, there is little consensus regarding the long-term prognosis of asymptomatic carotid artery occlusion (ACAO), which is most often found incidentally during workup for cerebrovascular disease. Hackam sought to shed light on this issue by conducting a systematic review of studies that enrolled patients with ACAO that collected follow-up information on the occurrence of ipsilateral ischemic stroke as an outcome measure. 


A total of 13 studies were included in the meta-analysis. The studies enrolled 4406 patients, 718 of whom had ACAO (16%). The median age of patients with ACAO was 67 and 23% were female.  All but two studies used ultrasound to define ACAO diagnostically; however the use of angiography was high overall (66% of subjects). Median follow-up was 2.80 years, with an annual ipsilateral stroke rate of 1.3% (95% CI 0.4-2.1%). Two-year and 5-year rates of stroke were 2.5% and 6.3%, respectively. There was substantial heterogeneity in the base estimate (I2=53%). Annual total stroke was 2.0% (95% CI 0.9-3%; I2=40%). 

Eleven studies reported on ipsilateral TIA, with an annual rate of 1% (95% CI 0.3-1.8% I2=40%) and an annual total TIA rate of 3.0% (95% CI 1.9-4.1% I2=0).  Seven studies reported mortality, with an annual rate of death of 7.7% with marked heterogeneity (95% CI 4.3-11.2% I2=83%). Six studies reported stroke-related death, with an annual rate of 1.1% (95% CI 0.07-2.1% I2=63%). Cardiac death was more frequent at 3.3% per year (95% CI 1.2-5.4% I2=83%). In the prescribed subgroup analysis, studies published on or after the year 2000 had a statistically significantly lower aggregate ipsilateral stroke rate than studies published before 2000 (0.9% to 1.5%, p=0.003). Adjusting for publication bias suggested a revised ipsilateral stroke rate of 0.3% per year (95% CI -0.4 to 1.1%).

Although the study was limited by significant heterogeneity, it suggests that the risk from ACAO is low. With subgroup analysis of studies published after the advent of contemporary medical management of vascular disease and trim-and-fill analysis suggesting a lack of studies published to the left of the mean, the rate is likely lower than the 1.3% per year grand mean that was reported. However, the annual risk of death was quite high (7.7%), likely attributable to ACAO being a surrogate marker of systemic atherosclerosis, possibly carrying a higher risk of cardiac death. 

Further study of this population is warranted. Potential avenues for future study would include a prospective cohort of patients with medically managed carotid stenosis and occlusion with matched controls, following a variety of vascular outcomes. Perfusion or more in-depth angiographic imaging to identify a potential subset of patients at higher risk of stroke could also be of use.  

Adherence to DASH Diet Associated With Lower Stroke Risk

Neal S. Parikh, MD

The Dietary Approaches to Stop Hypertension (DASH) diet is known reduce blood pressure in hypertensive and normotensive individuals. The authors assessed whether DASH diet adherence is associated with incident stroke.
The authors performed their analyses in two large, prospective Swedish cohorts of middle-aged to older men and women free of incident stroke.  The participants answered a 350-item questionnaire on diet and vascular risk factors in the late 1990s and were followed by linkage with the National Patient Register and the Cause of Death Register.
The exposure variable was a modified DASH diet score, assessed based on a validated food-frequency questionnaire. Covariates included standard demographics and vascular risk factors (hypertension, hyperlipidemia, diabetes, atrial fibrillation, smoking history, aspirin use, family history of myocardial infarction at early age, and body mass index).  Total caloric intake was included as a covariate, but dietary sodium was not. The outcome measure was incident stroke (ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage).  Participants were classified into quartiles based on their DASH diet score. Multivariate analyses were performed to test the association between DASH adherence and incident stroke.
Participants with high adherence to the DASH diet were fairly similar to participants with low adherence. The mean age was 60 years. Approximately 50% were overweight. Approximately 20% had hypertension, 10% had hyperlipidemia, and 6% had diabetes.  Over 882,727 person-years of follow-up, there were 3,896 ischemic strokes, 560 intracerebral hemorrhages, and 176 subarachnoid hemorrhages. High adherence to the DASH diet was associated with a lower risk of ischemic stroke and a trend towards lower risk of intracerebral hemorrhage. Participants in the highest quartile had a 14% lower risk of ischemic stroke than those in the lowest quartile.
This study adds to two prior studies that suggested that adherence to a DASH diet is associated with lower risk of stroke. The two prior studies and this study are likely underpowered for intracerebral hemorrhage and subarachnoid hemorrhage. The authors note that a similar association between the Mediterranean diet and stroke risk has been identified. Features shared by the DASH and Mediterranean diets may be responsible for lower stroke risk.  
The main limitations of this study are the observational design and the outdated cohort, which likely did not benefit from contemporary vascular risk factor management. However, in the context of prior studies, this study provides compelling evidence in support of a healthy diet for the prevention of stroke.
By |April 11th, 2016|prevention|1 Comment

Risk Analysis of Unruptured Intracranial Aneurysms: Prospective 10-Year Cohort Study

Peggy Nguyen, MD

Murayama Y, Takao H, Ishibashi T, Saguchi T, Ebara M, Yuki I, et al. Risk Analysis of Unruptured Intracranial Aneurysms: Prospective 10-Year Cohort Study. Stroke. 2016

The optimal management of unruptured aneurysms, whether by clipping or coiling, has never been defined in a randomized study.  Inferences can be made from what we know about the natural course of unruptured aneurysms, which have been previously studied in the ISUIA and UCAS. In this study, the authors add to the literature with a 10-year follow up of unruptured aneurysms to define the risk factors of rupture and looked at outcomes of rupture.

A total of 2665 patients with 3434 unruptured intracranial aneurysms (UIAs) were referred to

the institution, of which 1556 patients with 1960 aneurysms were conservatively observed and 937 aneurysms were repaired (793 by coiling, 144 by surgical clipping). In the

conservatively managed group:

  • The mean follow up duration was 7388 aneurysm-years.
  • 56 aneurysms ruptured with an overall annual incidence of subarachnoid hemorrhage of 0.76% with mean duration to rupture from initial consultation being 547 days.
  • Independent risk factors for aneurysm rupture were: (1) aneurysm size, (2) specific location, (3) presence of a daughter sac, and (4) history of SAH.
  • The annual rupture rate of aneurysms < 5 mm was 0.33%, > 5 mm was 3.1%, 7-9 mm was 2.9%, 10-24 mm was 10.2%, and 25+ mm was 33.1%; a cut-off point of 5 mm was associated with a higher risk of rupture, smaller than the 7 mm size which was previously demonstrated.
  • Vertebro-basilar aneurysms demonstrated a significantly higher risk of rupture compared to other locations.
  • Of ruptured aneurysms, only 46.4% patients returned to normal life; 28.6% resulted in an mRS of 3-5, 26.8% resulted in death. 

Given the devastating effects of aneurysm rupture, as confirmed in this study, would it be prudent to coil/clip these aneurysms, even when incidental and unruptured? Unfortunately, this study does not necessarily answer the question of what the best management would be for unruptured aneurysms; it does, however, confirm the size relationship of aneurysm and rupture, at a smaller size than previously reported, which prompts additional questions on what, exactly, is the size of aneurysm which we should be concerned about.

By |March 14th, 2016|prevention|0 Comments