American Heart Association

Article Commentary: “Cerebral Blood Flow Predicts the Infarct Core”

Adeola Olowu, MD

Amukotuwa S, Straka M, Aksoy D, Fischbein N, Desmond P, Albers G, et al. Cerebral Blood Flow Predicts the Infarct Core: New Insights From Contemporaneous Diffusion and Perfusion Imaging. Stroke. 2019;50:2783–2789.

The purpose of this study was to assess if cerebral blood flow (CBF) from perfusion studies could accurately estimate infarct core size in ischemic stroke patients during acute stroke management for appropriate thrombectomy triage. Relative cerebral blood flow (rCBF) accuracy would be determined by comparing infarct size to DWI of MRI.

Imaging data was assessed from the DEFUSE 2 and SENSE 3 studies. DEFUSE 2 (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evaluation) evaluated if MRI can be used to determine which patients would most likely benefit from endovascular reperfusion. SENSE 3 (Sensitivity Encoding) compared DWI and CT perfusion to reliably detect ischemic core tissue, at risk tissue, and tissue at risk of hemorrhagic transformation. Between the two studies, 119 patients had both DWI and perfusion studies within 24 hours of symptoms onset. 

Relative CBF (rCBF) was divided into 12 thresholds (0.20-0.44), and each of those thresholds were compared to the corresponding DWI. rCBF threshold of 0.32 provided the best prediction of infarct core estimate with DWI. When applying an infarct core limit of 70 mL for thrombectomy, approximately 94% of patients were correctly triaged to the appropriate therapy.

Figure 1. Coregistered diffusion-weighted imaging (DWI) and processed perfusion-weighted imaging (PWI) images from a 66-year old man who had an acute right MCA M1 segment occlusion.
Figure 1. Coregistered diffusion-weighted imaging (DWI) and processed perfusion-weighted imaging (PWI) images from a 66-year old man who had an acute right MCA M1 segment occlusion.

Educate and Empower EMS for Expedited Acute Stroke Treatment

Rohan Arora, MD

Gu H-Q, Rao Z-Z, Yang X, Wang C-J, Zhao X-Q, Wang Y-L, et al. Use of Emergency Medical Services and Timely Treatment Among Ischemic Stroke: Findings From the China Stroke Center Alliance. Stroke. 2019;50:1013–1016.

Despite the progress in stroke treatment protocols in the United States, the rate of tPA use remains low due to the inability of ischemic stroke patients to reach the hospital within the narrow therapeutic window. EMS plays a very crucial role in acute stroke care by decreasing prehospital delay and by providing prenotification for the stroke team activation, which leads to decrease in door-to-needle time.

Gu et al. analyzed data from the Chinese Stroke Centre Alliance for patients with ischemic stroke from 2015 to 2018 to study the pattern of EMS use, factors associated and its impact on prehospital delay and the treatment. Absolute standardized difference and multivariate logistic models were used. Of 560447 patients with ischemic stroke, only 12.5% used EMS for transportation to the hospital. EMS use was significantly less in the younger population, low income group, milder stroke symptoms, HTN, DM and PVD, while its use was significantly more in patients with history of CVD. Perhaps EMS education regarding stroke in the young might still be something to continually work on. EMS transport was significantly associated with less prehospital delay, shorter onset-to-door time, shorter door-to-needle time (if prenotification is sent) and more rapid treatment. The authors concluded that a low proportion of AIS patients using EMS could be due to lack of accessibility to EMS or lack of awareness for urgent stroke treatment.

What About Stroke Primary Prevention? Article Commentary on “Hypothetical Lifestyle Strategies in Middle-Aged Women and the Long-Term Risk of Stroke”

Grace Y. Kuo, MD, MS, BA

Jain P, Suemoto C, Rexrode K, Manson J, Robins J, Hernan M, et al. Hypothetical Lifestyle Strategies in Middle-Aged Women and the Long-Term Risk of Stroke. Stroke. 2020.

We are fortunate enough to be in an era in which we have multiple validated treatments for stroke care. However, with the decrease in overall stroke incidence and mortality, we are beginning to see a gender disparity in the disease of stroke. More women, particularly in the elderly populations, suffer from stroke than men. Although it may be due to longer life expectancy for women, it is still important to look for strategies to decrease this disparity. Prospective studies have found an inverse association between healthy lifestyles and strokes. However, as the natural history of the chronic conditions that lead to strokes occurs over decades, the actual effects of lifestyle interventions for primary prevention are difficult to study in randomized trials.

The article “Hypothetical Lifestyle Strategies in Middle-Aged Women and the Long-Term Risk of Stroke” is an attempt to understand the effects of dietary and non-dietary modifications on stroke risk by using longitudinal observational data in a hypothetical analysis to estimate the possible risk reduction of the interventions. Data was obtained from the Nurse’s Health Study (NHS), a database that was started in 1976 with 121,701 participants. In 1984, the participants were sent a food frequency questionnaire (FFQ), which was used as a basis for dietary pattern. Based on this survey, 59,727 participants were deemed eligible, after exclusion criteria of having pre-existing cardiovascular events (stroke, MI, angina, history of CABG) and cancer. Incomplete surveys or surveys with implausible responses were also excluded from analysis. 1986, the first follow-up year, was set as the baseline year to allow for adjustment for pre-baseline confounders. Every two years thereafter, participants were sent follow-up questionnaires. Participants were followed until their first diagnosis of stroke, death or June 2012.

Intensive LDL Cholesterol Lowering Improves Cardiovascular Outcomes in Patients With Recent TIA or Stroke

Ravinder-Jeet Singh, MBBS, DM

Amarenco P, Kim JS, Labreuche J, Charles H, Abtan J, Béjot Y, et al; Treat Stroke to Target Investigators. A Comparison of Two LDL Cholesterol Targets after Ischemic Stroke. N Engl J Med. 2020;382:9-19.

Several observational studies have investigated the effects of serum cholesterol levels (or its subfractions) on cardiovascular health and disease. These studies have shown that increased serum cholesterol is a strong risk factor for coronary artery disease, though association with stroke is less clear.(1-3) The inconsistent association between cholesterol and stroke could partly be explained by the difference in the effects of total cholesterol levels or its subfractions (especially LDL cholesterol) on the risk of ischemic vs hemorrhagic stroke, which are often combined in many epidemiologic studies. High total cholesterol is associated with higher risk of ischemic stroke, while low total cholesterol increases hemorrhagic stroke risk, and similar observations are noted with LDL cholesterol (LDL-C) levels as well.(2-6) Nonetheless, control of serum LDL-C levels constitutes standard recommendation for primary and secondary stroke prevention.(7)

Use of high-dose statins after a recent TIA or stroke was shown to reduce the incidence of stroke and other cardiovascular events in the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) trial, despite a small increase in the incidence of hemorrhagic stroke.(8) Further, multiple clinical trials and their meta-analysis showed that more intensive LDL-C lowering is associated with greater reduction in cardiovascular events.(9) Whether intensive LDL-C lowering among patients with recent TIA/stroke lowers future stroke risk was not assessed in the previous trials. In the January issue of NEJM, Amarenco et al. reported the results of the Treat Stroke to Target (TST) trial, which compared two LDL-C targets after recent TIA and ischemic stroke.

Caveolae, a Target for Stroke Therapeutics?

Melissa Trotman-Lucas, PhD
@TrolucaM

Blochet C, Buscemi L, Clément T, Gehri S, Badaut J, Hirt L. Involvement of caveolin-1 in neurovascular unit remodeling after stroke: Effects on neovascularization and astrogliosis. JCBFM. 2020;40:163-176.

Despite the collective history of failed neuroprotective therapies aimed at treating ischemic injury, the need to discover alternative stroke therapies is still present. However, despite improvements in the detection and treatment of ischemic strokes, a significant proportion of patients are ineligible for treatment and, therefore, unable to benefit. This impacts patient outcome, leaving many individuals with lifelong disabilities. Currently, the neurovascular unit (NVU) is being considered as a viable therapeutic target. This complex combination of capillaries, endothelial cells, pericytes, astrocytes and neurons closely controls connectivity between the brain and the blood. Events in the NVU contribute to cell death and neurological dysfunction during infarction, but also certain cell types within the unit have been shown to play a role in the preservation of post-stroke brain function. Endothelial cells, for instance, are key to the dynamic process of neovascularization, whereby these cells proliferate, migrate and differentiate following ischemic injury. Neovascularization is thought to be a key process in ischemia recovery, stimulating blood flow, vascular collateralization and neuroplasticity. In addition to the role of endothelial cells post-injury, astrocytes are also understood to be prominent in post-stroke recovery, transforming in the presence of molecules released during ischemic damage such as cytokines. These transformed astrocytes termed reactive astrocytes are known to be important in the formation of a glial scar that surrounds the damaged tissue. Interestingly, for some time it has been thought that the glial scar hindered axonal growth during brain recovery; however, recent evidence suggests the opposite and indeed promotion of axon development.

Mechanical Thrombectomy in Vertebrobasilar Occlusion: Still Looking for Evidence

Elena Zapata-Arriaza, MD
@ElenaZaps

Liu X, Dai Q, Ye R, Zi W, Liu Y, Wang H, et al. Endovascular treatment versus standard medical treatment for vertebrobasilar artery occlusion (BEST): an open-label, randomised controlled trial. Lancet Neurol. 2020;19:115-122.

Efficacy and safety of endovascular treatment (EVT) in anterior circulation strokes is clearly validated; however, such evidence is still lacking in vertebrobasilar occlusions. Liu et al. aimed to demonstrate safety and efficacy of EVT in posterior circulation strokes. To achieve this goal, the authors performed a multicenter, randomized, open-label trial in patients within 8 h of vertebrobasilar occlusion (basilar or V4 segment of vertebral artery). Patients were allocated to receive either EVT plus standard medical therapy or standard medical therapy alone. Given endovascular procedure, stent-retriever was the most employed technique, but thromboaspiration, intra-arterial thrombolysis, balloon angioplasty or stenting were also permitted. Primary outcome was mRS 0-3 at 90 days, assessed on an intention-to-treat basis. Primary safety outcome was mortality at 90 days. Secondary safety endpoints included symptomatic intracranial hemorrhage, device-related complications and other severe events rates. Each participating center had to have completed at least 5 mechanical thrombectomy procedures with stent retriever devices in the preceding year. The primary data analysis was done on the intention-to-treat population. In addition, secondary prespecified analyses were performed in the per-protocol population and in the as-treated population.

Author Interview: Dr. Houman Khosravani, MD, PhD, on “Protected Code Stroke: Hyperacute Stroke Management During the Coronavirus Disease 2019 (COVID-19) Pandemic”

Houman Khosravani
Houman Khosravani

A conversation with Houman Khosravani, MD, PhD, Assistant Professor, Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Canada. Twitter: @neuroccm

Interviewed by Victor J. Del Brutto, MD, Assistant Professor, Stroke Division, Department of Neurology, University of Miami Miller School of Medicine, Florida. Twitter: @vdelbrutto

They will be discussing the paper “Protected Code Stroke: Hyperacute Stroke Management During the Coronavirus Disease 2019 (COVID-19) Pandemic,” published in Stroke.

Dr. Del Brutto: First of all, I would like to thank you and your team for putting together these thoughtful recommendations on how to evaluate patients with suspected stroke during the Coronavirus Disease 2019 (COVID-19) pandemic. As a stroke neurologist, I share the global feeling of uncertainty that this pandemic has caused and look forward to modifying my institution practices in order to maximize patients’ outcomes, their safety, and the safety of the professionals involved in their care. In your article, you mention that stroke patients are at an increased risk of suboptimal outcomes during the COVID-19 pandemic. Could you please comment on the factors that may influence patient outcomes?

Dr. Khosravani: During the COVID-19 pandemic, patients are affected at several junctions in stroke care, including during the hyperacute phase. For example, paramedics responding to a stroke call, in some jurisdictions, will begin the screening process prior to arrival and then again on scene. When screening is positive, pre-notification to the hospital should occur, and this triggers a protected code stroke (PCS). Patients being brought directly to the ED will require additional screening. The necessary use of PPE, with a Safety Lead observing, will add some delays to the front-end processes, but these are essential to keeping providers safe. It is very plausible that, for example, door-to-needle/door-to-groin puncture times will be impacted. Similarly, at the point-of-care, a COVID-19–suspected patient going to imaging will result in having special precautions used in the scanner or neuroangiography suite, which will add additional time (for cleaning as well); this impacts scenarios with back-to-back code strokes as well.

Article Commentary: “Association of Blood Pressure During Thrombectomy for Acute Ischemic Stroke With Functional Outcome”

Adeola Olowu, MD

Maïer B, Fahed R, Khoury N, Guenego A, Labreuche J, Taylor G, et al. Association of Blood Pressure During Thrombectomy for Acute Ischemic Stroke With Functional Outcome: A Systematic Review. Stroke. 2019;50:2805–2812.

Greater than 50% of patients with successful recanalization are unable to regain functional independence at 3 months. There are several factors that contribute to the functional outcomes of patients who undergo mechanical thrombectomy; however, blood pressure is a prognostic factor that can be modulated (or managed).  This article addresses blood pressure management as a critical prognostic factor for outcome in acute ischemic stroke treated with mechanical thrombectomy. 

A systematic review of peri-procedural blood pressure values during mechanical thrombectomy was performed. A total of 9 studies out of 576 were eligible for systematic review after 2012. The 9 studies were comprised of 1 multicenter trial, 4 prospective trials, and 5 retrospective trials for a total of > 1000 patients. The systematic review revealed differences in how patient hemodynamics are being measured, as well as managed.

By |March 31st, 2020|clinical|0 Comments

Meet the Blogger: Rohan Arora, MD, FAHA

Rohan Arora

Name: Rohan Arora, MD, FAHA
Hometown: New Delhi, India
Current Position: Director of Stroke Program at LIJ Forest Hills, New York; Program Director, Vascular Neurology Fellowship, Zucker School of Medicine at Hofstra, Northwell, NY        

Q: What made you interested in a career in stroke?       

A: Finding myself in a position where my knowledge and expertise can save an individual from having permanent disability due to stroke is my constant motivation to practice this field. It could be a quick phone call/a telemedicine consult or long hours of ICU care; everything counts.

Q: What has been your career path into this field?

A: My focus is providing cutting edge clinical care, especially to young stroke patients, and enrolling patients in NIH-funded clinical studies and clinical trials. I am interested in finding novel methods to encourage people for a low-stress healthy lifestyle; that is one of the most commonly encountered risk factors for stroke and cerebrovascular disease.

By |March 25th, 2020|clinical|0 Comments

Author Interview: Dr. Eric Jouvent, MD, PhD, on “Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy”

Dr. Eric Jouvent
Dr. Eric Jouvent

A conversation with Dr. Eric Jouvent, MD, PhD, Professor of Neurology at Paris University. He is involved in acute stroke care in the stroke unit in Lariboisière Hospital in Paris. He holds a PhD in image processing.

Interviewed by Dr. Stephanie Lyden, MD, BS, a vascular neurology fellow at the University of Utah.

They will be discussing the article “Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy: Lessons From Neuroimaging.” Published in the January 2020 issue of Stroke, it is part of a Focused Updates in Cerebrovascular Disease series of articles on topics related to cerebral small vessel diseases.

Dr. Lyden: First of all, thank you for taking the time to discuss this important topic. What led you to become interested in studying CADASIL?

Dr. Jouvent: It was not really a choice at first. Residency in France is different than in the United States, where we first choose a city and then we move from department to department in that city. At the end of that time period, you hope to match in a department or with a team. At the end of my cycle, I matched with a team headed by Dr. Bousser, who identified the first family with CADASIL, in part because I was not only interested in stroke, but also in cognitive and behavioral alterations and in advanced MRI techniques, which are key aspects in small vessel diseases. This was how I started to become involved in CADASIL research.