Michael V. Mazya

Karolinska University Hospital | Karolinska · Department of Neurology

Symptomatic intracerebral hemorrhage (SICH) is a serious complication in patients with acute ischemic stroke treated with intravenous thrombolysis. We aimed to develop a clinical score that can easily be applied to predict the risk of SICH. We analyzed data from 31 627 patients treated with intravenous alteplase enrolled in the Safe Implementation...

Objective: Controversy surrounds the safety of intravenous (IV) tissue plasminogen activator (tPA) in ischemic stroke patients treated with warfarin. The European tPA license precludes its use in anticoagulated patients altogether. American guidelines accept IV tPA use with an international normalized ratio (INR) ≤ 1.7. The influence of warfarin o...

Background and Purpose Patients with stroke mimics, conditions with stroke‐like symptoms, may risk harm if treated with intravenous thrombolysis (IVT). Current guidelines state low risk of intracranial hemorrhage (ICH) based on studies comprising a total of <400 stroke mimic cases. We aimed to compare safety and outcomes following IVT between patie...

Importance To our knowledge, it is unknown whether a prehospital stroke triage system combining symptom severity and teleconsultation could accurately select patients for primary stroke center bypass and hasten delivery of endovascular thrombectomy (EVT) without delaying intravenous thrombolysis (IVT). Objective To evaluate the predictive performa...

Background and Purpose: We aimed to determine whether dual-energy CT (DECT) follow-up can differentiate contrast staining (CS) from intracranial hemorrhage (ICH) in stroke patients treated with intravenous thrombolysis (IVT), who had undergone acute stroke imaging using CT angiography (CTA), and CT perfusion (CTP). Materials and Methods: Between No...

Background and aims: The best reperfusion treatment for patients with mild acute ischemic stroke (AIS) harboring proximal anterior circulation large vessel occlusion (LVO) is unknown. We aimed to compare the safety and efficacy of intravenous thrombolysis (IVT) plus endovascular thrombectomy (EVT) vs IVT alone in LVO patients with mild symptoms....

Purpose We review key design elements of positive randomized controlled trials (RCTs) in acute ischemic stroke (AIS) treatment and summarize their main characteristics. Method We searched Medline, Pubmed and Cochrane databases for positive RCTs in AIS treatment. Trials were included if (1) they had a randomized controlled design, with (at least pa...

Ultrasonographic parameters such as the common carotid artery (CCA) pulsatility index (PI) and CCA intima-media thickness (IMT) have been associated with an increased mortality and risk of recurrent stroke, respectively. We hypothesized that these ultrasonographic parameters may be useful for monitoring diabetic patients after an acute stroke. We a...

Background and objectives: Declines in stroke admission, intravenous thrombolysis, and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought...

Introduction In 2017, Stockholm implemented a new prehospital stroke triage system (SSTS) directing patients with a likely indication for thrombectomy to the regional comprehensive stroke center (CSC) based on symptom severity and teleconsultation with a physician. In Stockholm, 44% of patients with prehospital code stroke have stroke mimics. Inadv...

Background Intracranial arterial stenosis (ICAS) is a non-marginal cause of stroke/transient ischemic attacks (TIAs) and is associated with high stroke recurrence rate. Some studies have investigated the best secondary prevention ranging from antithrombotic therapy to endovascular treatment (ET). However, no direct comparison between all the possib...

Introduction The Stockholm Stroke Triage System (SSTS) is a prehospital triage system for detection of patients eligible for endovascular thrombectomy (EVT). Assessment of hemiparesis combined with ambulance-hospital teleconsultation is used to route patients directly to the thrombectomy centre. Some patients are not identified and require secondar...

Background: Reperfusion treatment in patients presenting with large vessel occlusion (LVO) and minor neurological deficits is still a matter of debate. We aimed to compare minor stroke patients treated with endovascular thrombectomy (EVT) and intravenous thrombolysis (IVT) or IVT alone. Methods: Patients enrolled in the German Stroke Registry-En...

Objectives: We aimed to determine whether there are sex differences in prehospital accuracy of the Stockholm Stroke Triage System (SSTS) to predict large artery occlusion (LAO) stroke, and endovascular thrombectomy (EVT), and whether clinical characteristics differ between men and women undergoing “code stroke” ambulance transport. Materials and Me...

Introduction: Starting reperfusion therapies as early as possible in acute ischemic strokes are of utmost importance to improve outcomes. The Comprehensive Stroke Centers (CSCs) can use surveys, shadowing personnel or perform journal analysis to improve logistics, which can be labor intensive, lack accuracy, and disturb the staff by requiring manua...

Importance Some patients have poor outcomes despite small infarcts after endovascular therapy (EVT), while others with large infarcts do well. Understanding why these discrepancies occur may help to optimize EVT outcomes. Objective To validate exploratory findings from the Endovascular Treatment for Small Core and Anterior Circulation Proximal Occ...

Background and Purpose The Stockholm Stroke Triage System (SSTS) is a prehospital algorithm for detection of endovascular thrombectomy (EVT)-eligible patients, combining symptom severity assessment and ambulance-to-hospital teleconsultation, leading to a decision on primary stroke center bypass. In the Stockholm Region (6 primary stroke centers, 1...

Objective To test the hypothesis that intravenous thrombolysis (IVT) treatment prior to endovascular thrombectomy (EVT) is associated with better outcomes in patients with anterior circulation large artery occlusion (LAO) stroke, we examined a large real-world database, the SITS-International Stroke Thrombectomy Register (SITS-ISTR). Methods We id...

Background and objective We aimed to evaluate the safety and outcomes of thrombectomy in anterior circulation acute ischaemic stroke recorded in the SITS–International Stroke Thrombectomy Register (SITS‐ISTR) and compare them with pooled randomized controlled trials (RCTs) and two national registry studies. Methods We identified centres recording...

Background Fast multi‐contrast echo planar MRI (EPIMix) has comparable diagnostic performance to standard MRI for detecting brain pathology but its performance in detecting acute cerebral infarctions has not been determined. Purpose To assess the diagnostic performance of EPIMix for the detection of acute cerebral infarctions. Study Type Retrospe...

Background and purpose: The Stockholm Stroke Triage System, implemented in 2017, identifies patients with high likelihood of large vessel occlusion (LVO) stroke. A previous report has shown Stockholm Stroke Triage System notably reduced time to endovascular thrombectomy (EVT). As the indication for EVT now includes patients up to 24 hours, we aime...

Background and purpose Dual energy CT is increasingly available and used in the standard diagnostic setting of ischemic stroke patients. We aimed to evaluate how different dual energy CT virtual monoenergetic energy levels impact identification of early ischemic changes, compared to conventional polyenergetic CT images. Materials and methods This...

Recent case-series of small size implied a pathophysiological association between coronavirus disease 2019 (COVID-19) and severe large-vessel acute ischemic stroke. Given that severe strokes are typically associated with poor prognosis and can be very efficiently treated with recanalization techniques, confirmation of this putative association is u...

Background and objective The optimal timing for initiation of dabigatran after acute ischaemic stroke (AIS) is not established. We aimed to evaluate initiation timing and clinical outcomes of dabigatran in AIS patients with non-valvular atrial fibrillation (NVAF). Design Retrospective study based on prospectively collected data in SITS (Safe Imple...

Background: Clinical suspicion of cerebral venous sinus thrombosis (CVST) is imprecise due to non-specific symptoms such as headache. The aim was to retrospectively assess the diagnostic value of nonenhanced CT (neCT) in patients with nontraumatic headache and clinically suspected CVST. Methods: A retrospective consecutive series of patients ref...

Background and Purpose— Posterior circulation stroke (PCS) accounts for 5% to 19% of patients with acute stroke receiving intravenous thrombolysis. We aimed to compare safety and outcomes following intravenous thrombolysis between patients with PCS and anterior circulation stroke (ACS) and incorporate the results in a meta-analysis. Methods— We in...

Background and Purpose— The optimal level for blood pressure after endovascular thrombectomy in acute ischemic stroke is not well established. We sought to evaluate the association of post-endovascular thrombectomy systolic blood pressure (SBP) levels with clinical outcomes. Methods— We included endovascular thrombectomy–treated patients registere...

Abstract Background and methods: Intravenous thrombolysis for acute ischemic stroke in the Middle-East and North African (MENA) countries is still confined to the main urban and university hospitals. This was a prospective observational study to examine outcomes of intravenous thrombolysis-treated stroke patients in the MENA region compared to the...

The purpose of the European Stroke Organisation–Karolinska Stroke Update Conference is to provide updates on recent stroke therapy research and to give an opportunity for the participants to discuss how these results may be implemented into clinical routine. The meeting started 22 years ago as Karolinska Stroke Update, but since 2014 it is a joint...

Objective: To determine whether dual energy CT with a combined approach (cDECT) using a plain noncontrast monochromatic CT (pCT), a water-weighted image after iodine removal, and an iodine-weighted image changes the diagnosis and classification of intracranial hemorrhage (ICH) after endovascular thrombectomy (EVT) in acute ischemic stroke compared...

Background and Purpose—Standardized registries may provide valuable data to further improve stroke care. Our aim was to obtain updated information about characteristics of stroke patients and management of stroke across the Ibero-American countries, using a common in-hospital registry (Safe Implementation of Treatments in Stroke–Sociedad Iberoameri...

Background and Purpose— There are limited data on intravenous thrombolysis treatment in patients with ischemic stroke who have received prophylactic doses of low molecular weight heparins (LMWHs). We aimed to evaluate the safety and outcomes of intravenous thrombolysis treatment in stroke patients taking thromboprophylactic doses of LMWH. Methods—...

Background and methods: Stroke incidence and mortality are reported to have increased in the Middle-East and North African (MENA) countries during the last decade. This was a prospective observational study to examine the baseline characteristics of stroke patients in the MENA region and to compare the MENA vs. the non-MENA stroke cohort in the Sa...

Background and Methods Intravenous thrombolysis (IVT) treatment for acute stroke in the Middle-East and North African (MENA) countries is still confined to the main urban and university hospitals. This was a prospective observational study to examine baseline characteristics and outcomes of IVT-treated stroke patients in the MENA region compared to...

Background and purpose Triage tools to identify candidates for thrombectomy are of utmost importance in acute stroke. No prognostic tool has yet gained any widespread use. We compared the predictive value of various models based on National Institutes of Health Stroke Scale (NIHSS) subitems, ranging from simple to more complex models, for predictin...

Background and purpose: Diagnostic transcranial Doppler ultrasound (TCD) is commonly used in patients with acute stroke before or during treatment with intravenous thrombolysis (IVT). We aimed to assess how much TCD delays IVT initiation and whether TCD influences outcomes. Methods: We analyzed data from the SITS-ISTR (Safe Implementation of Thr...

Epidemiology of Stroke in the MENA region

Introduction: Thrombolysis usage in ischaemic stroke varies across sites. Divergent advice from professional guidelines and product labels may contribute. Patients and methods: We analysed SITS-International registry patients enrolled January 2010 through June 2016. We grouped sites into organisational tertiles by number of patients arriving ≤2....

Purpose: Beyond intravenous thrombolysis, evidence is lacking on acute treatment of minor stroke caused by large artery occlusion. To identify candidates for additional endovascular therapy, we aimed to determine the frequency of non-haemorrhagic early neurological deterioration in patients with intravenous thrombolysis-treated minor stroke caused...

Background Interoperability standards intend to standardise health information, clinical practice guidelines intend to standardise care procedures, and patient data registries are vital for monitoring quality of care and for clinical research. This study combines all three: it uses interoperability specifications to model guideline knowledge and ap...

Background and purpose: ASTRAL (Acute Stroke Registry and Analysis of Lausanne) and DRAGON (includes dense middle cerebral artery sign, prestroke modified Rankin Scale score, age, glucose, onset to treatment, National Institutes of Health Stroke Scale score) are 2 recently developed scores for predicting functional outcome after acute stroke in un...

Background and Objective Introduction Patients with diabetes may develop early cerebrovascular disease manifesting as a higher burden of atherosclerosis Hypothesis In an acute stroke population, we hypothesise significantly different neurosonological precerebral vessel characteristics between diabetics and non-diabetics. Methods We retrospectively...

Introduction: Current stroke guidelines suggest performing carotid endarterectomy (CEA) within 2 weeks after an ischemic stroke or TIA caused by severe carotid stenosis. However, early carotid revascularization in patients in unstable neurological condition after acute stroke (“stroke in evolution”, SIE) is controversial because of the risk of new...

Objective: To study the safety of off-label IV thrombolysis in patients with very severe stroke (NIH Stroke Scale [NIHSS] scores >25) compared with severe stroke (NIHSS scores 15-25), where treatment is within European regulations. Methods: Data were analyzed from 57,247 patients with acute ischemic stroke receiving IV tissue plasminogen activat...

Background and purpose: This study aimed to assess the evidence on the periprocedural (<30 days) risks of carotid intervention in relation to timing of procedure in patients with recently symptomatic carotid stenosis. Methods: A systematic literature review of studies published in the past 8 years reporting periprocedural stroke/death after caro...

Background— Intravenous thrombolysis (IVT) for acute ischemic stroke is subject to label and guideline contraindications. Updated European guidelines in 2008/2009 recommended IVT in selected patients aged >80 years and stroke onset-to-treatment time 3 to 4.5 hours, which the label still prohibited. Our aim was to compare contraindication nonadheren...

Intracranial hemorrhage is an important safety end point in clinical trials.1–6 Yet, not each intracranial hemorrhage detected by computed tomography (CT) or magnetic resonance imaging (MRI) worsens neurological symptoms and impairs outcomes. Consequently, intracranial hemorrhages after ischemic stroke and reperfusion therapy are classified by both...

Psychogenic non-epileptic seizures (PNES) are commonly encountered in neurological practice and emergency medicine services. Patients with PNES are often erroneously diagnosed with having epilepsy, receiving anti-epileptic drugs and admitted to intensive care units for treatment of seizures mistaken for status epilepticus. In light of recently publ...

Intracerebral hemorrhage after treatment with intravenous recombinant tissue-type plasminogen activator for ischemic stroke can occur in local relation to the infarct, as well as in brain areas remote from infarcted tissue. We aimed to describe risk factors, 3-month mortality, and functional outcome in patients with the poorly understood complicati...

Background and purpose: The SEDAN score is a prediction rule for assessment of the risk of symptomatic intracerebral hemorrhage (SICH) per the European Cooperative Acute Stroke Study (ECASS) II definition in patients with acute ischemic stroke treated with intravenous thrombolysis. We assessed the performance of the score in predicting SICH per th...