Publications by authors named "Peter J Mitchell"

Article Synopsis
  • The study investigates how repeat imaging for stroke patients being transferred to comprehensive stroke centers (CSCs) affects the timing of endovascular thrombectomy (EVT) and identifies factors that can predict changes in brain infarct size during transport.
  • Researchers analyzed data from patients with large vessel occlusion who underwent CT perfusion imaging at both primary and comprehensive stroke centers, focusing on changes in imaging parameters and clinical factors.
  • Results showed that growth in the perfusion core during transport was rare and primarily linked to lower initial ASPECTS scores, suggesting that initial favorable imaging may indicate whether repeat imaging is needed upon arrival at the CSC.
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Article Synopsis
  • The no-reflow phenomenon may lead to poor patient outcomes after thrombectomy, with various imaging definitions leading to inconsistent prevalence rates.
  • An analysis of 131 patients showed significant variability in no-reflow prevalence (0.8-22.1%) and poor agreement between different imaging definitions regarding patient outcomes.
  • The definition based on >15% cerebral blood volume or flow asymmetry was most effective in predicting poor clinical outcomes 90 days post-treatment.
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Purpose: For nearly half of patients who undergo Endovascular Thrombectomy following ischemic stroke, successful recanalisation does not guarantee a good outcome. Understanding the underlying tissue changes in the infarct tissue with the help of biomarkers specific to ischemic stroke could offer valuable insights for better treatment and patient management decisions. Using quantitative susceptibility mapping (QSM) MRI to measure cerebral iron concentration, this study aims to track the progression of iron within the infarct lesion after successful reperfusion.

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Background: Clinicians need simple and highly predictive prognostic scores to assist practical decision-making. We aimed to develop a simple outcome prediction score applied 24 hours after anterior circulation acute ischemic stroke treatment with endovascular thrombectomy and validate it in patients treated both with and without endovascular thrombectomy.

Methods: Using the HERMES (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) collaboration data set (n=1764), patients in the endovascular thrombectomy arm were divided randomly into a derivation cohort (n=430) and a validation cohort (n=441).

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Background: Robust collateral circulation has been linked with better reperfusion and clinical outcomes. It remains unclear how individual assessments of collateral circulation may be translated into clinical practice.

Methods: The pooled Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials (HERMES) angiography dataset was analyzed by a centralized, independent imaging core blinded to other clinical data.

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Article Synopsis
  • The PROCEED model was developed to predict persistent perfusion deficit (PPD) in patients after thrombectomy who have incomplete blood flow restoration, and this study aimed to validate its effectiveness using data from multiple centers.
  • Researchers used data from two clinical trials and a cohort from the Medical University of Graz to assess how well the model can predict PPD, analyzing metrics like discrimination and calibration accuracy.
  • Results showed the model performed well, accurately identifying PPD in 38% of 371 patients, and offering the potential to reduce unnecessary medical interventions while maintaining the identification of patients with PPD.
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Background And Objectives: Early treatment with intravenous alteplase increases the probability of lytic-induced reperfusion in large vessel occlusion (LVO) patients. The relationship of tenecteplase-induced reperfusion and the timing of thrombolytic administration has not been explored. In this study, we performed a comparative analysis of tenecteplase and alteplase reperfusion rates and assessed their relationship to the time of thrombolytic administration.

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Background: Ischemic stroke lesion volume at follow-up is an important surrogate outcome for acute stroke trials. We aimed to assess which differences in 48-hour lesion volume translate into meaningful clinical differences.

Methods: We used pooled data from 7 trials investigating the efficacy of endovascular treatment for anterior circulation large vessel occlusion in acute ischemic stroke.

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Background: A proportion of large vessel occlusion strokes demonstrate early recanalization, obviating the initial intention to proceed to endovascular thrombectomy. Neurological improvement is a possible surrogate marker for reperfusion. We aimed to determine the optimal threshold of neurological improvement, as defined by the National Institutes of Health Stroke Scale (NIHSS), which best associates with early recanalization.

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Stroke is a leading cause of paralysis, most frequently affecting the upper limbs and vocal folds. Despite recent advances in care, stroke recovery invariably reaches a plateau, after which there are permanent neurological impairments. Implantable brain-computer interface devices offer the potential to bypass permanent neurological lesions.

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Intracranial atherosclerotic disease (ICAD) is one of the most common causes of acute ischemic stroke worldwide. Patients with acute large vessel occlusion due to underlying ICAD (ICAD-LVO) often do not achieve successful recanalization when undergoing mechanical thrombectomy (MT) alone, requiring rescue treatment, including intra-arterial thrombolysis, balloon angioplasty, and stenting. Therefore, early detection of ICAD-LVO before the procedure is important to enable physicians to select the optimal treatment strategy for ICAD-LVO to improve clinical outcomes.

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Background: Functional outcomes in patients with acute ischemic stroke (AIS) with large vessel occlusion (LVO) undergoing endovascular treatment (EVT) with poor reperfusion were compared with patients with AIS-LVO treated with best medical management only.

Methods: Data are from the HERMES collaboration, a patient-level meta-analysis of seven randomized EVT trials. Baseline characteristics and functional outcomes (modified Rankin Scale (mRS) score at 90 days) were compared between patients with poor reperfusion (defined as modified Thrombolysis in Cerebral Infarction Score 0-1 on the final intracranial angiography run as assessed by the central imaging core laboratory) and patients in the control arm with multivariable logistic ordinal logistic regression adjusted for pre-specified baseline variables.

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Importance: Outcome prediction after endovascular treatment (EVT) for ischemic stroke is important to patients, family members, and physicians.

Objective: To develop and validate a model based on preprocedural and postprocedural characteristics to predict functional outcome for individual patients after EVT.

Design, Setting, And Participants: A prediction model was developed using individual patient data from 7 randomized clinical trials, performed between December 2010 and December 2014.

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Peripheral ophthalmic artery aneurysm is a rare disease entity. We review the relevant literature and report a case of fusiform aneurysm involving the entire intraorbital ophthalmic artery in association with multiple intracranial and extracranial aneurysms, diagnosed on digital subtraction angiography. The patient suffered irreversible blindness secondary to compressive optic neuropathy which did not improve after a 3-day trial of intravenous methylprednisolone.

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Background: First pass effect (FPE), defined as single-pass complete or near complete reperfusion during endovascular thrombectomy (EVT) for large vessel occlusion (LVO) strokes, is a critical performance metric. Atrial fibrillation (AF)-related strokes have different clot composition compared with non-AF strokes, which may impact thrombectomy reperfusion results. We compared FPE rates in AF and non-AF stroke patients to evaluate if AF-related strokes had higher FPE rates.

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Background: Following reperfusion treatment in ischemic stroke, computed tomography (CT) imaging at 24 h is widely used to assess radiological outcomes. Even without visible hyperattenuation, occult angiographic contrast may persist in the brain and confound Hounsfield unit-based imaging metrics, such as net water uptake (NWU).

Aims: We aimed to assess the presence and factors associated with retained contrast post-thrombectomy on 24-h imaging using dual-energy CT (DECT), and its impact on the accuracy of NWU as a measure of cerebral edema.

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Background: Current guidelines for ischaemic stroke treatment recommend a strict, but arbitrary, upper threshold of 185/110 mm Hg for blood pressure before endovascular thrombectomy. Nevertheless, whether admission blood pressure influences the effect of endovascular thrombectomy on outcome remains unknown. Our aim was to study the influence of admission systolic blood pressure (SBP) on functional outcome and on the effect of endovascular thrombectomy.

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Article Synopsis
  • - The study aimed to compare the safety and effectiveness of tenecteplase (TNK) versus alteplase in patients suffering from tandem lesion (TL) strokes, using data from the EXTEND-IA TNK trials.
  • - Results showed that TNK-treated patients had better rates of intracranial reperfusion (20%) compared to those treated with alteplase (7%), but no significant differences were found in long-term functional outcomes, mortality rates, or symptomatic intracranial hemorrhage (sICH) between the two treatments.
  • - Overall, the investigation concluded that TNK is similar to alteplase regarding functional outcomes and safety in patients with TL strokes, suggesting that TNK could be a viable treatment
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Background: Intracranial occlusion site, contrast permeability, and clot burden are thrombus characteristics that influence alteplase-associated reperfusion. In this study, we assessed the reperfusion efficacy of tenecteplase and alteplase in subgroups based on these characteristics in a pooled analysis of the EXTEND-IA TNK trial (Tenecteplase Versus Alteplase Before Endovascular Therapy for Ischemic Stroke).

Methods: Patients with large vessel occlusion were randomized to treatment with tenecteplase (0.

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Background: Time to reperfusion is an important predictor of outcome in ischaemic stroke from large vessel occlusion (LVO). For patients requiring endovascular thrombectomy (EVT), the transfer times from peripheral hospitals in metropolitan and regional Victoria, Australia to comprehensive stroke centres (CSCs) have not been studied.

Aims: To determine transfer and journey times for patients with LVO stroke being transferred for consideration of EVT.

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Importance: The role of endovascular thrombectomy is uncertain for patients presenting beyond 24 hours of the time they were last known well.

Objective: To evaluate functional and safety outcomes for endovascular thrombectomy (EVT) vs medical management in patients with large-vessel occlusion beyond 24 hours of last known well.

Design, Setting, And Participants: This retrospective observational cohort study enrolled patients between July 2012 and December 2021 at 17 centers across the United States, Spain, Australia, and New Zealand.

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Article Synopsis
  • Reperfusion therapy significantly benefits ischemic stroke patients by reducing infarct growth and cerebral edema, which may be key to improving clinical outcomes.* -
  • A study involving 542 patients found that successful reperfusion was linked to decreased infarct growth and midline shift, highlighting their role as mediators in treatment effectiveness.* -
  • Although successful reperfusion initially correlated with better functional outcomes, this link diminished when accounting for infarct growth and midline shift, indicating these factors greatly influence treatment success.*
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Background: Extensive randomized controlled clinical trials for endovascular thrombectomy in anterior circulation large vessel occlusions (internal carotid arteries and M1 segment of middle cerebral arteries) have been published over the past decade, but there have not been randomized controlled trials for distal arterial occlusions to date. Distal arterial occlusion randomized controlled trials are essential to decide on patient selection, imaging criteria, and endovascular approach to improve the outcome and reduce complications.

Summary: The definition of distal arterial occlusion is however unclear, and we believe that a uniform nomenclature of distal arterial occlusions is essential for the design of robust randomized controlled studies.

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