American Heart Association

Monthly Archives: June 2014

Primary preventive potential for stroke by avoidance of major lifestyle risk factors: the EPIC-Heidelberg cohort.

Sebina Bulic, MD

Tikk K, Sookthai D, Monni S, Gross ML, Lichy C, Kloss M, and Kaaks R. Primary Preventive Potential for Stroke by Avoidance of Major Lifestyle Risk Factors: The European Prospective Investigation Into Cancer and Nutrition-Heidelberg Cohort. Stroke. 2014

Thanks to the outstanding efforts of stroke community, stroke dropped to fourth leading cause of death. Large epidemiologic studies have identified many modifiable risk factors for stroke. It has been proposed that up to 60-90 % of strokes might be preventable through lifestyle modifications. 

EPIC-Heidelberg is a prospective cohort study that is a part of a large-scale Europe-wide study, the European Prospective Investigation into Cancer and Nutrition (EPIC). Out of 23,927 persons, 551 (195 women and 356 men) had a first diagnosis of stroke during an average follow-up of 12.7 years. All patients completed a general questionnaire and a computer-guided interview about basic demographic factors, prevalent diseases and lifestyle factors. For all study participants weight, height, hip and waist circumferences were measured by trained study nurses.

Effects of general obesity (BMI) and abdominal obesity (waist circumference), smoking, alcohol consumption, diet and physical activity on ischemic, intracerebral or subarachnoid hemorrhage were assessed separately for men and women. The study had some unexpected findings such as associations of general obesity and abdominal obesity with stroke in multivariable models were no longer significant, with the exception of abdominal obesity among women. In men, the risk estimates by different levels of physical activity categories were mostly not statistically significant. No statistically significant association between average lifetime alcohol consumption levels and stroke risk was observed among women. The healthiest diet score was not inversely associated with stroke risk in women. Despite this, it was estimated that from 153 to 94 strokes per 100,000 women and from 261 to 161 strokes per 100,000 men, for the age group 60-65 is preventable. About 38% of stroke cases were estimated as preventable through adherence to a healthy lifestyle profile (never smoking, maintaining optimal body-mass-index and waist circumference, performing physical exercise, consuming a moderate quantity of alcohol and following a healthy dietary pattern). These are estimates of significant potential for stroke risk reduction considering that blood pressure, blood lipids, blood sugar were not taken into consideration.

We are in great need of continuous epidemiological surveillance and identification of modifiable risk factors in fluid stroke prevention and acute stroke management milieu. We need to continue with our efforts to conquer stroke. 

The 6 minute acute stroke MRI/MRA/DSC

Adam de Havenon, MD

Nael K, Khan R, Choudhary G, Meshksar A, Villablanca P, Tay J, et al. Six-Minute Magnetic Resonance Imaging Protocol for Evaluation of Acute Ischemic Stroke: Pushing the Boundaries. Stroke. 2014

    Noncontrast head CT is the sole imaging modality needed to triage patients for the only evidence-based treatment of acute ischemic stroke therapy – IV tPA. After a series of negative trials last year, the utility of endovascular thrombectomy is questionable, along with the utility of angiography or perfusion imaging in the acute phase of ischemic stroke. However, there are good reasons to get a CT angiogram, the most compelling being to rule out basilar artery occlusion, which will always be an endovascular emergency, but also to enroll patients in trials for new treatment options. Currently the majority of stroke centers rely on CT angiogram and CT perfusion for this imaging niche, but there are limitations to CT, the most important being the lack of diffusion-weighted imaging (DWI), but also the significant dose of ionizing radiation and contrast dye. MRI provides the entire package, but conventional DWI, MRA, FLAIR, and GRE take up to 20 minutes for even an abbreviated scan. 

    Kambiz Nael et al. describe a 6 minute acute stroke MRI protocol, that utilizes newer sequences with rapid scan times and only mild image quality degradation. The authors use this protocol on 62 patients with ischemic stroke in the last 24 hours and NIHSS ≥ 3, and then repeated it on 22 of those patients. The protocol includes a DWI, an echo-planar imaging (EPI) FLAIR, EPI-GRE, contrast-enhanced MRA neck and brain, and DSC perfusion. The EPI sequences had good correlation with conventional FLAIR and GRE; and there was excellent interobserver agreement for the scans, the vast majority of which were diagnostic.

    From an imaging perspective, the protocol is a success and it is remarkable that we can reduce the scan time for so many different sequences to only 6 minutes. It should be noted, however, that the excellent signal-to-noise ratio the authors achieve requires a 3 tesla magnet and multi-coil technology. Many comprehensive stroke centers lack this degree of imaging sophistication.

    MRI research should continue to investigate ways to reduce scan time and improve image quality, but the question is if there is a role for such innovation in acute stroke. Many stroke neurologists feel there is, even in the administration of IV tPA, but at present the data is not compelling. Ultimately, though, we may find ourselves using MRI for all acute stroke patients if widespread technology permits such rapid scan times with preserved image quality. Future research will determine the role for this 6 minute MRI, and, invariably, the 5 minute one as well.

    Five-fold difference in stroke mortality rates between Chicago neighborhoods.

    Matthew Edwardson, MD

    Hunt BR, Deot D, and Whitman S. Stroke Mortality Rates Vary in Local Communities in a Metropolitan Area:Racial and Spatial Disparities and Correlates. Stroke. 2014

    Many factors influence the stroke mortality rate. Thankfully, some of these factors are reversible, yet it remains challenging to identify the best approach to improve public health. One method is to identify vulnerable populations and target them for public health initiatives. This article by Hunt and colleagues identifies such populations in the city of Chicago. Not surprisingly, the highest mortality rates were on the South and West sides of Chicago in mostly poor and black communities.

    The authors reviewed death certificates over the span of 3 years in Chicago, documenting cause of death, race, and neighborhood of residence. They discovered that the overall stroke mortality rate was higher in Chicago than the national average (44.9 vs. 42.2 per 100,000 respectively, P < 0.001); however, the rates for each individual race were lower than the national average for each respective race with the exception of Puerto Ricans. This suggests the high stroke mortality rate overall in Chicago is driven by the large black population, who experienced higher rates than the other races (57 per 100,000).  Low socioeconomic status correlated with increased stroke rates in black neighborhoods, but not in neighborhoods predominated by other races.  Somewhat surprisingly, the stroke mortality rate among Mexicans was much lower than the rate for all other races including whites.      

    I lived in Chicago during my medical school training and can foresee how the disparities discovered by Hunt and colleagues may lead to improved public health in the city. According to the authors, residents in the neighborhood with the highest stroke mortality were 5 times more likely to die of stroke than those in the neighborhood with the lowest mortality. Improving access to care in the communities with the highest stroke mortality rates is one way to address this disparity. 

    During medical school I had the opportunity to do a rotation at the Lawndale Christian Health Center. The residents of the North Lawndale community served by this clinic were predominantly poor and black. It was amazing to witness the impact that affordable health care had on this community. Nonetheless, North Lawndale had the 5th highest stroke mortality rate in Chicago according to the authors.  While adding additional clinics to this neighborhood might have had more impact, there are clearly many factors that contribute to stroke mortality, not just access to care. Now that the authors have identified the most vulnerable populations and neighborhoods, more work can be done to tease apart the root cause of increased stroke mortality in Chicago and ultimately improve public health.

    Predicting late seizures after ICH using novel CAVE score

    Vivek Rai, MD

    Haapaniemi E, Strbian D, Rossi C, Putaala J, Sipi T, Mustanoja S, et al. The CAVE Score for Predicting Late Seizures After IntracerebralHemorrhage. Stroke. 2014

    Seizures are a common complication of acute intracerebral hemorrhage (ICH). Further, based on timing of first symptomatic event, seizures are categorized into early (occurring within first 7 days of ICH) and late seizures (occurring after first 7 days of ICH). While early seizures (ES) are thought to result from acute disruption of brain integrity and function, late seizures (LS) are believed to occur due to neuronal reorganization and formation of new epileptogenic foci. Although a number of studies have looked at the relationship between ES and LS, no tools or risk stratification systems are available to predict LS.

    Haapaniemi and colleagues analyzed data of about 1000 patients of primary ICH through Helsinki University Central Hospital, Finland, excluding patients with ICH due to tumor, trauma, subarachnoid hemorrhage (SAH) and ischemic stroke. The authors report 11% incidence of ES and 9.2% incidence of LS which is in line with other reported data. Of the several variables, cortical involvement, younger age (<65 y), larger ICH volume at baseline (>10 mL), and early seizures within 7 days of ICH were associated with development of LS, with coefficients ranging from 0.8 to 1.5 which were rounded to 1 to generate CAVE score ranging from 0-4. The corresponding risk of LS during follow-up was 0.6%, 3.6%, 9.8%, 34.8%, and 46.2% for CAVE score points 0 to 4, respectively. The scoring system was validated in a smaller PITCH cohort based in Lille, France.

    The authors have developed a novel risk stratification scoring system which is easy to remember and calculate. Further, they have provided evidence of validation of the proposed CAVE score in a smaller but unrelated cohort. The CAVE score can be of great clinical utility in identification of patients who are at high risk of developing epilepsy after ICH. I only wish that the authors had included tumor, trauma and SAH patients in their analysis to further broaden the application of this tool. Further investigations are necessary to study the use of CAVE score in making clinical decisions about treatment with anti-epileptic medications.

    Female Sex and Smoking in the Natural Course of Unruptured Intracranial Aneurysms.

    Hassanain Toma, MD

    Korja M, Lehto H, and Juvela S. Lifelong Rupture Risk of Intracranial Aneurysms Depends on RiskFactors: A Prospective Finnish Cohort Study. Stroke. 2014

    Studying the natural history of UIA is difficult because of the temptation to treat these aneurysms before they rupture. Fortuitously, in Finland, UIAs were left untreated until 1979. This provided Korja et al. a population to study the lifelong natural course of unruptured intracranial aneurysms and identify high-risk and low-risk patients for the rupture.

    They prospectively evaluated 118 patients with UIA diagnosed between 1956 and 1978. They were followed until death or subarachnoid hemorrhage (SAH). They demonstrated that the annual UIA rupture rate ranges from 0% to 6.5% (average 1.6%), depending on individual risk factors. These risk factor were found to be female sex, current smoking and aneurysm size of >7 mm in diameter.
    In their discussion, the authors focused on a very important concept. Large UIA (>7mm) are associated higher rupture rates, but they must start off as small aneurysms before they reach their critical rupture size. In their cohort 77% of small aneurysms grew to >7 mm before rupturing. That subgroup mainly involved women who are current smokers, whereas none of the non-smoking men developed aneurysmal rupture.  This finding is important because it better stratifies UIA that are at risk of rupturing.
    My neurosurgical colleagues often dismiss small aneurysms based on their size.  Although underpowered, this study highlights the importance of considering patient’s sex and smoking status to inform patients of their UIA rupture risk, and empower physicians with data to better educate their patients about the risk of smoking and aneurysmal rupture.

    Functional status and outcomes following CEA for asymptomatic stenosis

    Deepa P. Bhupali, MD

    Dayama A, Pimple P, Badrinathan B, Lee R, and Reeves JG. Activities of Daily Living Is a Critical Factor in Predicting Outcome After Carotid Endarterectomy in Asymptomatic Patients. Stroke. 2014

    Dayama et al. explore how functional status affects post-operative outcomes in patients undergoing carotid endarterectomy (CEA) for asymptomatic stenosis. They used a national dataset that included information from over 300 hospitals and looked at the effect of pre-operative functional status on post-operative outcomes including 30 day mortality following CEA in asymptomatic patients. Functional status was divided into independent, partially dependent and dependent. One of their primary findings was that patients who were partially or completely dependent for ADLs had a higher risk of 30 day mortality as compared to independent patients. 

    Their paper is based on a procedure that is hotly debated in the stroke and vascular circles: CEA for asymptomatic stenosis. This means that the results of the study are specific to a procedure that is not universally accepted or practiced.  So while this is interesting information, there might be a narrow audience to receive it.
    One of the strengths of the study is that it examined a population that is somewhat representative of the “real-world.” They used a group that likely represents many of the patients we see each day which makes the data more compelling. However, the overall conclusion, that a patient with a higher functional status does better in the post-operative period as compared to a more impaired level of functioning is not a new concept and may not immediately impact bedside care.