Donald Frei

Donald Frei
radiology imaging associates · Director, NeuroInterventional Surgey, President - Society of NeuroInterventional Surgery

MD

About

165
Publications
29,156
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
13,181
Citations
Citations since 2017
67 Research Items
9421 Citations
201720182019202020212022202305001,0001,500
201720182019202020212022202305001,0001,500
201720182019202020212022202305001,0001,500
201720182019202020212022202305001,0001,500
Introduction
Additional affiliations
July 2001 - April 2016
radiology imaging associates
Position
  • Managing Director

Publications

Publications (165)
Article
Objectives Treatment of ischemic stroke with endovascular thrombectomy (EVT) leads to improved outcomes compared to IV tPA. The neutrophil-lymphocyte ratio (NLR), a marker of inflammation, has been proposed to predict outcomes in ischemic stroke patients and may be used to identify patients at risk for poor outcomes after EVT. Materials and Method...
Article
Full-text available
BACKGROUND Endovascular management of wide‐necked bifurcation aneurysms poses a therapeutic challenge, as coiling often requires the use of multiple adjunctive stent constructs to achieve successful embolization without compromising parent vessel integrity. The Neuroform Atlas Stent System is a novel low‐profile, intraluminal remodeling device. The...
Article
Introduction: Neutrophil-lymphocyte ratios (NLRs) can be used to assess inflammatory status, with higher NLRs indicating inflammation and physiologic stress. NLRs after ischemic stroke have been shown to predict both short- and long-term outcomes. Methods: This was a retrospective study of adult patients admitted to a high-volume stroke center in 1...
Article
Background There is conflicting evidence on the utility of intravenous (IV) alteplase in patients with emergent large vessel occlusion (ELVO) treated with mechanical thrombectomy (MT). Methods This was a post hoc analysis of the COMPASS: a trial of aspiration thrombectomy versus stent retriever thrombectomy as first-line approach for large vessel...
Article
Background Cerebral vasospasm (CV) after aneurysmal subarachnoid hemorrhage (aSAH) is linked to worse neurological outcomes. The NeVa VS is a novel cerebral dilation device based on predicate stent retrievers. We report the results of the Vesalio NeVa VS for the Treatment of Symptomatic Cerebral Vasospasm following aSAH (VITAL) Study. Methods This...
Conference Paper
Full-text available
Introduction Stent-assisted coil embolization of cerebral aneurysms can be performed using one of multiple techniques. Jailing is the ability to trap microcatheter in the aneurysm while laying a stent across the neck of the aneurysm followed by coiling the aneurysm. Crossing technique refers to placing a microcatheter through the interstices of the...
Conference Paper
Introduction Cerebral vasospasm after aneurysmal subarachnoid hemorrhage is linked to delayed cerebral ischemic and worse neurological outcomes. Pharmacological treatment with intra-arterial vasodilators allows for transient improvement in cerebral perfusion. Balloon angioplasty may provide durable luminal gain, but risks vessel rupture and thrombo...
Conference Paper
Introduction Endovascular management of wide-necked bifurcation aneurysms poses a therapeutic challenge as coiling often requires the use of multiple adjunctive stent constructs to achieve successful embolization without compromising parent vessel integrity. The Neuroform Atlas Stent System is a novel low-profile, intraluminal remodeling device. Th...
Article
BACKGROUND Heterogeneous effect of endovascular aneurysm therapy has been observed across different anatomic locations. There is a paucity of data for stent-assisted coiling of middle cerebral artery (MCA) aneurysms. OBJECTIVE To present the results of the MCA aneurysm group from the Neuroform Atlas (Stryker Neurovascular) investigational device e...
Article
Full-text available
Background It is not clear whether the COVID-19 pandemic and subsequent Society of Neurointerventional Surgery (SNIS) recommendations affected hospital stroke metrics. Methods This retrospective cohort study compared stroke patients admitted to a comprehensive stroke center during the COVID-19 pandemic April 1 2020 to June 30 2020 (COVID-19) to pa...
Article
Full-text available
Background Stent-assisted coiling of wide-necked intracranial aneurysms (IAs) using the Neuroform Atlas Stent System (Atlas) has shown promising results. Objective To present the primary efficacy and safety results of the ATLAS Investigational Device Exemption (IDE) trial in a cohort of patients with posterior circulation IAs. Methods The ATLAS t...
Article
Full-text available
Background: The COVID-19 pandemic led to profound changes in the organization of health care systems worldwide. Aims: We sought to measure the global impact of the COVID-19 pandemic on the volumes for mechanical thrombectomy (MT), stroke, and intracranial hemorrhage (ICH) hospitalizations over a 3-month period at the height of the pandemic (March 1...
Conference Paper
Full-text available
Background Imaging clot characteristics such as clot density and perviousness (the latter is defined as a difference in regional clot density values between computed tomography angiography (CTA) and non-contrast CT [NCCT]), can be used as an imaging marker characterizing red blood cell and fibrin composition of the clot serving. We aimed to examine...
Article
Background Clot density (Hounsfield units, HU) and perviousness (post-contrast increase in the HU of clot) are thought to be associated with clot composition. We evaluate whether these imaging characteristics were associated with angiographic outcomes of aspiration and stent retriever thrombectomy in COMPASS: a trial of aspiration thrombectomy vers...
Article
Full-text available
Background and Purpose Stent-assisted coil embolization using the new generation Neuroform Atlas Stent System has shown promising safety and efficacy. The primary study results of the anterior circulation aneurysm cohort of the treatment of wide-neck, saccular, intracranial, aneurysms with the Neuroform Atlas Stent System (ATLAS trial [Safety and E...
Article
Full-text available
Background Enrollment in time-sensitive endovascular stroke trials can be challenging because of an inability to consent a debilitated patient. Often the legally authorized representative is not on site. Remote consent procedures in the US are inconsistent with the majority of sites shunning these approaches. The current pandemic with visitor restr...
Article
Full-text available
Background Nerinetide, an eicosapeptide that interferes with post-synaptic density protein 95, is a neuroprotectant that is effective in preclinical stroke models of ischaemia-reperfusion. In this trial, we assessed the efficacy and safety of nerinetide in human ischaemia-reperfusion that occurs with rapid endovascular thrombectomy in patients who...
Article
Background: Nerinetide, an eicosapeptide that interferes with post-synaptic density protein 95, is a neuroprotectant that is effective in preclinical stroke models of ischaemia-reperfusion. In this trial, we assessed the efficacy and safety of nerinetide in human ischaemia-reperfusion that occurs with rapid endovascular thrombectomy in patients wh...
Article
Object: Cerebral venous thrombosis (CVT) is a rare type of stroke whose pathophysiology differs from arterial stroke. CVT is treated with systemic anticoagulant therapy even in the setting of intracerebral hemorrhage. Patients who do not respond adequately may require decompressive surgery. The study objective was to examine the timing of anticoag...
Article
Introduction: Mechanisms for the hospital identification of patients with suspected large vessel occlusions (LVO) vary widely based on referring and receiving stroke center resources. We compared processes for identifying patients with suspected LVO who may be candidates for endovascular therapy (EVT) at non-EVT hospitals and the criteria for inter...
Article
Background: To determine the clinical outcomes of perimesencephalic subarachnoid hemorrhages based on the computed tomography (CT) bleeding patterns. Methods: This retrospective cohort study included: (1) patients (≥18 years) admitted to a comprehensive stroke center (January 2015-May 2018), (2) with angiography-negative, nontraumatic subarachnoid...
Conference Paper
Full-text available
Background and purpose Stent-assisted coil embolization using the new generation Neuroform Atlas™ Stent System has shown promising technical, safety, and clinical feasibility and efficacy. Here, we present the one year angiographic and efficacy results of the anterior circulation cohort in the ATLAS Investigational Device Exemption (IDE) Trial. Me...
Article
Background: Stent retriever thrombectomy of large-vessel occlusion results in better outcomes than medical therapy alone. Alternative thrombectomy strategies, particularly a direct aspiration as first pass technique, while promising, have not been rigorously assessed for clinical efficacy in randomised trials. We designed COMPASS to assess whether...
Article
Background: Given the overwhelming evidence for the benefit of stent-retriever thrombectomy, a future trial of primary aspiration thrombectomy (PAT) against best medical therapy (BMT) alone has become unethical and impractical. Therefore, alternative approaches are needed to further investigate the impact of PAT in the outcomes in large vessel occl...
Article
The overwhelming benefit of endovascular therapy in patients with large-vessel occlusions suggests that more patients will be screened than treated. Some of those patients will be evaluated first at primary stroke centers; this type of evaluation calls for standardizing the imaging approach to minimize delays in assessing, transferring, and treatin...
Article
Full-text available
Background and objective Stent-assisted coil embolization is a well-established treatment of intracranial wide-necked aneurysms. The Neuroform Atlas Stent System is a new generation microstent designed to enhance coil support, conformability, deliverability, and improve deployment accuracy. We present the 1-year efficacy and angiographic results of...
Chapter
Cerebral venous sinus thrombosis (CVST) is an uncommon diagnosis affecting as many as 15.7 patients per million people per year. It affects females more common than males with a ratio of 3:1, and in the majority of cases, there is a predisposing hypercoagulable state or less commonly an underlying cause such as trauma or infection.
Article
Background: CT perfusion (CTP) and diffusion or perfusion MRI might assist patient selection for endovascular thrombectomy. We aimed to establish whether imaging assessments of irreversibly injured ischaemic core and potentially salvageable penumbra volumes were associated with functional outcome and whether they interacted with the treatment effe...
Article
Background: Evidence regarding whether imaging can be used effectively to select patients for endovascular thrombectomy (EVT) is scarce. We aimed to investigate the association between baseline imaging features and safety and efficacy of EVT in acute ischaemic stroke caused by anterior large-vessel occlusion. Methods: In this meta-analysis of in...
Article
Ischemic stroke is a treatable disease with alteplase, a clot-busting medical treatment, and endovascular therapy (EVT), mechanical removal of the clot through a minimally invasive procedure. The effectiveness of both treatments is time dependent, and they are usually given together. Alteplase is less effective than EVT, but is widely available at...
Article
Background and purpose The purpose of this study was to assess the initial post-market experience of the device and how it is compared with the Penumbra Pivotal trial used to support the 510k application. Methods A retrospective case review of 157 consecutive patients treated with the Penumbra system at seven international centers was performed. P...
Conference Paper
Background In order to maximize clinical outcomes in patients with acute ischemic stroke related to ELVO (Emergent Large Vessel Occlusion), safe and rapid recanalization is necessary. Our level 1 stroke center has developed a standardized protocol which has allowed us to achieve a median door-to-recanalization time of less than 60 min. In order to...
Conference Paper
Introduction Smart Coils are novel generation of embolic coils comprised of complex and WAVE shape properties with varying levels of softness to promote dense packing and durable long-term occlusion. We report results from interim analysis on utility of the Penumbra Smart Coil System in the treatment of a variety of intracranial vascular lesions, s...
Conference Paper
Introduction Wide-necked bifurcating aneurysms remain a significant challenge for endovascular treatment. Therefore, the Barrel VRD was designed to specifically address wide-neck bifurcating anatomy with a bulging center that has two ‘hinge’ segments to allow excellent apposition across the aneurysm neck. Materials and methods The Barrel IDE Study...
Article
Full-text available
Background and purpose: In the ESCAPE trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion with Emphasis on Minimizing CT to Recanalization Times), patients with large vessel occlusions and small infarct cores identified with computed tomography (CT)/CT angiography were randomized to endovascular therapy or stan...
Article
Background: Mechanical thrombectomy (MT) is the current standard of care for acute ischemic stroke (AIS) patients with emergent large-vessel occlusions (ELVO). Successful reperfusion of ELVO is traditionally defined by modified Thrombolysis in Cerebral Infarction (mTICI) grades of 2b or 3. Objective: To evaluate the comparative safety and effica...
Article
Objective: In this multicenter study, we sought to evaluate comparative safety and efficacy of combined IV thrombolysis (IVT) and mechanical thrombectomy (MT) vs direct MT in emergent large vessel occlusion (ELVO) patients. Methods: Consecutive ELVO patients treated with MT at 6 high-volume endovascular centers were evaluated. Standard safety an...
Article
Full-text available
Importance The treatment effects of individual mechanical thrombectomy devices in large-vessel acute ischemic stroke (AIS) remain unclear. Objective To determine whether the novel 3-dimensional (3-D) stent retriever used in conjunction with an aspiration-based mechanical thrombectomy device (Penumbra System; Penumbra) is noninferior to aspiration-...
Article
Full-text available
BACKGROUND AND PURPOSE: The safety and efficacy of endovascular therapy for large-artery stroke in the extended time window is not yet well-established. We performed a subgroup analysis on subjects enrolled within an extended time window in the Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE) trial. MATERIALS A...
Article
Full-text available
Background Tandem occlusions of the extracranial carotid and intracranial carotid or middle cerebral artery have a particularly poor prognosis without treatment. Several management strategies have been used with no clear consensus recommendations. We examined subjects with tandem occlusions enrolled in the ESCAPE trial and their outcomes. Methods...
Conference Paper
Background Mechanical thrombectomy (MT) for acute ischemic stroke (AIS) patients with emergent large-vessel occlusions (ELVO) has become the standard of care. Current top-tier guidelines recommend intravenous thrombolysis (IVT) administration for ELVO patients before MT if presented within recommended time window for IVT. However, it is not known w...
Conference Paper
Background Mechanical thrombectomy (MT) for acute ischemic stroke (AIS) patients with emergent large-vessel occlusions (ELVO) has become the standard of care. A recent meta-analysis of the 5 randomized trials demonstrated that 46% of patients in the intervention arm achieved mRS of 0–2 at 3 months. Considering the fact that significant numbers of p...
Conference Paper
Introduction Various thrombectomy devices promise high rates of recanalization and reduction of disability. A recent meta-analysis of the Solitaire device demonstrated its utility as safe and effective in revascularization of large vessel occlusions. The present analysis seeks to determine if good clinical outcome can similarly be achieved by the 3...
Conference Paper
Purpose It is well established that endovascular thrombectomy (EVT) benefits patients with acute ischemic stroke (AIS). Nevertheless, although ~30% of patients with large infarct volume regain functional independence at 90 days, it remains controversial whether this particular cohort should be treated. The purpose of this study was to determine pre...
Conference Paper
Introduction Endovascular therapy for cerebral aneurysms has increasingly been adopted as a viable treatment strategy for its minimally invasive but effective approach. This rising adoption has been correlated with an evolution in coil technology, including the recently FDA-cleared SMART Coil. In contrast to traditional bare metal coils, which have...
Data
Figure S1. Comparative receiver operating characteristic (ROC) curve with area under the ROC presented for the full model (Model) and the cross‐validated model (ROC1). ROC curves are presented for all patients (A, n=152) and stratified by endovascular treatment (B, n=73) or no endovascular treatment (C, n=76).
Article
Full-text available
Background and purpose: Increasing thrombus length (TL) impedes recanalization after intravenous (IV) thrombolysis. We sought to determine whether the clinical benefit of aspiration thrombectomy relative to IV r-tPA (recombinant tissue-type plasminogen activator) may be greater at longer TL. Methods: THERAPY was a randomized trial of aspiration...
Article
Full-text available
Background Cerebral venous thrombosis is a rare cause of stroke that poses diagnostic, therapeutic, and prognostic challenges. Mainstay treatment is systemic anticoagulation, but endovascular treatment is increasingly advocated. Our objectives were to describe the epidemiology, treatment, and prognosis of 152 patients with cerebral venous thrombosi...
Article
Introduction: A recent meta-analysis of five stroke endovascular therapy (EVT) randomized controlled trials (RCTs) confirmed EVT’s benefits in patients with acute ischemic stroke caused by proximal large vessel occlusion (LVO). Hypothesis: We hypothesize that treatment with the novel 3D Stent Retriever used with the Penumbra System and the Penumbra...
Article
Introduction: The relative treatment effects for a stent retriever when used as an adjunct to aspiration versus aspiration alone remain unclear. The aim of this study was to demonstrate the safety and efficacy of the Penumbra stent retriever, 3D, when used in conjunction with the Penumbra Aspiration System (3D/PS), was non-inferior to the Penumbra...
Article
Introduction: A recent meta-analysis of four randomized controlled trials (RCTs) concluded that mechanical thrombectomy using Solitaire for large vessel ischemic stroke was effective with significantly reduced disability. Hypothesis: Our hypothesis was that treatment with the Penumbra Aspiration System and the novel 3D Stent Retriever would demonst...
Article
Introduction: Despite suffering mild acute ischemic strokes (AIS, NIHSS≤7), patients have a non-zero risk of significant morbidity and mortality. Intra-arterial therapy (IAT) is clearly effective in non-mild AIS, but mild AISs have been excluded from IAT trials, limiting our understanding of their outcomes after IAT. The objective of this study was...
Article
Background: Recent recommendations for mechanical thrombectomy (MT) of acute ischemic stroke (AIS) patients with emergent large-vessel occlusions (ELVO) appropriately award top tier evidence (TTE) to the same selective criteria that were employed in recent clinical trials. We sought to evaluate the safety and efficacy of MT in AIS patients with ELV...
Article
Purpose: Mechanical thrombectomy has been demonstrated to provide benefits in the treatment of acute ischemic stroke (AIS). But whether to treat AIS patients with a large infarct core remains controversial. Although it is a common practice that patients with large infarct core are not offered endovascular treatment, previous data have consistently...
Article
Introduction: Patients with mild acute ischemic strokes (NIHSS ≤7, AISs) have been excluded from intra-arterial therapy (IAT) trials, limiting our understanding of their outcomes after IAT. Mild AIS with large vessel occlusions (LVOs) represent a fragile subset of mild AISs. Despite a low NIHSS, these patients can have a sudden failure of collatera...
Article
Background: The Colorado Stroke Advisory Board (COSAB) asked three Joint Commission (JC) comprehensive stroke centers (CSC) and one primary stroke center (PSC) to assist with determining the usefulness of the Cincinnati Pre-Hospital Stroke Severity Score (CPSSS) in predicting large vessel occlusion (LVO) in patients with acute stroke symptoms. Purp...
Article
Full-text available
Six recent trials and a patient-level meta-analysis have demonstrated the superiority of endovascular therapy (EVT) compared with standard care (including intravenous alteplase) among patients with large-artery anterior circulation strokes.1–7 The absolute benefit of EVT was substantial in these trials, and EVT now requires careful implementation a...
Article
Background: While mechanical thrombectomy (MT) has become the standard of care for patients with acute ischemic stroke (AIS) with emergent large-vessel occlusions (ELVO), recently published guidelines appropriately award top-tier evidence to the same selective criteria that were employed in completed clinical trials. We sought to evaluate the safe...
Article
Background and purpose: Infarct in a new previously unaffected territory (INT) is a potential complication of endovascular treatment. We applied a recently proposed methodology to identify and classify INTs in the ESCAPE randomized controlled trial (Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on...
Article
Background and purpose Intra-arterial therapy (IAT) is most effective when performed rapidly after ischemic stroke onset. However, there are limited performance benchmarks in IAT and there is a scarcity of information on how to structure an effective IAT protocol and its impact on time to treatment. The objective of our study was to detail a standa...
Article
Recent randomized clinical trials1–5 established the superiority of endovascular recanalization techniques, specifically mechanical embolectomy, compared with best medical therapy alone for the treatment of patients with emergent large vessel occlusion (ELVO) stroke. ELVO stroke is defined as a stroke secondary to anterior circulation large vessel...
Article
Importance: Endovascular thrombectomy with second-generation devices is beneficial for patients with ischemic stroke due to intracranial large-vessel occlusions. Delineation of the association of treatment time with outcomes would help to guide implementation. Objective: To characterize the period in which endovascular thrombectomy is associated...
Article
Introduction: Traditional platinum coils used for cerebral aneurysm embolization have a uniform degree of softness throughout an individual coil's length. Recently, SMART Coils (Penumbra Inc., Alameda, CA) have been developed, which transition in softness along the length of their coils. We report the initial clinical results with this technology....
Article
Full-text available
Background and purpose: Thrombectomy, primarily with stent retrievers with or without adjunctive aspiration, provided clinical benefit across multiple prospective randomized trials. Whether this benefit is exclusive to stent retrievers is unclear. Methods: THERAPY (The Randomized, Concurrent Controlled Trial to Assess the Penumbra System's Safet...
Article
Full-text available
Introduction Limited data exist on the efficacy of intra-arterial therapy (IAT) for ischemic stroke resulting from extended thrombi. IV-rtPA has been the staple of ischemic stroke therapy, however the efficacy of IV thrombolytics is known to diminish with increasing thrombus length, subsequently reducing the potential for successful revascularizati...
Article
Full-text available
Background Acute stroke treatment has been proven to be most effective when performed immediately. The objective of our study was to describe the steps taken to improve time metrics for patients receiving intra-arterial therapy (IAT), and compare metrics before and after implementation of interventions. Hypothesis Through streamlining the evaluati...
Article
Full-text available
Introduction There is currently no standardized criterion for a clinically defined symptomatic intracranial hemorrhages (sICH), particularly secondary to endovascular therapy of ischemic stroke. Recent randomized controlled trials evaluating the efficacy and safety of intra-arterial therapy have published results with varying complication rates bas...
Article
Full-text available
Introduction Imaging still serves as an integral tool for stroke validation and intervention. Limited data is available as to whether performing CTA immediately following non-contrast CT (NCCT) will delay overall treatment time. Centers conducting concurrent NCCT and CTA relative to those performing NCCT alone were evaluated to determine whether ha...
Article
Full-text available
Objective The safety and efficacy of intra-arterial treatment (IAT) in patients with acute ischemic stroke (AIS) due to cervical artery dissection (CeAD) has not been formally studied. The purpose of this study was twofold: first, describe a large series with CeAD treated with IAT; second, analyze outcomes with CeAD receiving IAT versus (a) CeAD no...
Article
Background—The ESCAPE trial used innovative imaging and aggressive target time metrics to demonstrate benefit of endovascular treatment in patients with acute ischemic stroke. We analyze the impact of time on clinical outcome and the effect of patient, hospital and health system characteristics on workflow within the trial. Methods and Results—Rel...
Article
Acute ischemic stroke remains a major public health concern, with low national treatment rates for the condition, demonstrating a disconnection between the evidence of treatment benefit and delivery of this treatment. Intravenous thrombolysis and endovascular thrombectomy are both strongly evidence supported and exquisitely time sensitive therapies...
Article
Acute ischemic stroke remains a major public health concern, with low national treatment rates for the condition, demonstrating a disconnection between the evidence of treatment benefit and delivery of this treatment. Intravenous thrombolysis and endovascular thrombectomy are both strongly evidence supported and exquisitely time sensitive therapies...
Article
Full-text available
Ischemic stroke is a leading cause of death and disability worldwide. Much of the long-term disability occurs in patients with Emergent Large Vessel Occlusion (ELVO). In fact, in these patients, occlusion of a major intracerebral artery results in a large area of brain injury often resulting in
Article
BACKGROUND AND PURPOSE: The goal of reperfusion therapy in acute ischemic stroke is to limit brain infarction. The objective of this study was to investigate whether the beneficial effect of endovascular treatment on functional outcome could be explained by a reduction in post-treatment infarct volume. METHODS: The Endovascular Treatment for Smal...
Article
Full-text available
The ESCAPE trial demonstrated strong morbidity benefit and mortality reduction for endovascular stroke treatment. Following the release of the main results, the ESCAPE trial investigators convened at a 2-day close-out meeting in March 2015 in Banff, Alberta, Canada. Meeting discussions focused on system implications, procedural characteristics, and...