Evaluation of direct-to-angiography suite (DTAS) and conventional clinical pathways in stroke care: a simulation study

BackgroundRapid time to reperfusion is essential to minimize morbidity and mortality in acute ischemic stroke due to large vessel occlusion (LVO). We aimed to evaluate the workflow times when utilizing a direct-to-angiography suite (DTAS) pathway for patients with suspected stroke presenting at a comprehensive stroke center compared with a conventional CT pathway.MethodsWe developed a discrete-event simulation (DES) model to evaluate DTAS workflow timelines compared with a conventional CT pathway, varying the admission NIHSS score treatment eligibility criteria. Model parameters were estimated based on 2 year observational data from our institution. Sensitivity analyses of simulation parameters were performed to assess the impact of patient volume and baseline utilization of angiography suites on workflow times utilizing DTAS.ResultsSimulation modeling of stroke patients (SimStroke) demonstrated door-to-reperfusion time savings of 0.2–3.5 min (p=0.05) for a range of DTAS eligibility criteria (ie, last known well to arrival <6 hours and National Institutes of Health Stroke Scale ≥6–11), when compared with the conventional stroke care pathway. Sensitivity analyses revealed that DTAS time savings is highly dependent on baseline utilization of angiography suites.ConclusionsThe results of the SimStroke model showed comparable time intervals for door-to-reperfusion for DTAS compared with a conventional stroke care pathway. However, the DTAS pathway was very sensitive to baseline angiography suite utilization, with even a 10% increase eliminating the advantages of DTAS compared with the conventional pathway. Given the minimal time savings modeled here, further investigation of implementing the DTAS pathway in clinical care is warranted.

Imaging as a Selection Tool for Thrombectomy in Acute Ischemic Stroke

Large vessel occlusion (LVO) stroke represents a stroke subset associated with the highest morbidity and mortality. Multiple prospective randomized trials have shown that thrombectomy, alone or in conjunction with IV thrombolysis, is highly effective in reestablishing cerebral perfusion and improving clinical outcomes. In unselected patients and especially in patients with poor collaterals, the benefit of reperfusion therapy is exquisitely time sensitive; the earlier thrombectomy is started, the lower the likelihood of disability or death. Understanding both the pathophysiologic underpinnings and the modifying factors of this strong time-to-treatment effect demonstrated in numerous randomized clinical trials is important for implementation of intrahospital workflow measures to maximize time efficiency of thrombectomy. Reducing delays in reperfusion therapy initiation has become a priority in acute stroke care, and therefore a thorough understanding of the main systems-based factors responsible for these delays is critical. Because the time spent evaluating the patient in the emergency department, which typically includes neuroimaging studies performed in scanners remote from the angiography suite, represents the main source of delays in thrombectomy initiation, the direct to angiography (DTA) model has emerged as a means to substantially reduce treatment times and is being instituted at an increasing number of thrombectomy centers across the world. The aim of this report is to introduce DTA as an emerging stroke care paradigm for patients with suspicion of LVO stroke, review results from studies evaluating its feasibility and impact on outcomes, describe current barriers to its more widespread adoption, and propose potential solutions to overcoming these barriers.

Direct Transfer to Angiosuite in Acute Stroke

Time to reperfusion is one of the strongest predictors of functional outcome in acute stroke due to a large vessel occlusion (LVO). Direct transfer to angiography suite (DTAS) protocols have shown encouraging results in reducing in-hospital delays. DTAS allows bypassing of conventional imaging in the emergency room by ruling out an intracranial hemorrhage or a large established infarct with imaging performed before transfer to the thrombectomy-capable center in the angiography suite using flat-panel CT (FP-CT). The rate of patients with stroke code primarily admitted to a comprehensive stroke center with a large ischemic established lesion is <10% within 6 hours from onset and remains <20% among patients with LVO or transferred from a primary stroke center. At the same time, stroke severity is an acceptable predictor of LVO. Therefore, ideal DTAS candidates are patients admitted in the early window with severe symptoms. The main difference between protocols adopted in different centers is the inclusion of FP-CT angiography to confirm an LVO before femoral puncture. While some centers advocate for FP-CT angiography, others favor additional time saving by directly assessing the presence of LVO with an angiogram. The latter, however, leads to unnecessary arterial punctures in patients with no LVO (3%–22% depending on selection criteria). Independently of these different imaging protocols, DTAS has been shown to be effective and safe in improving in-hospital workflow, achieving a reduction of door-to-puncture time as low as 16 minutes without safety concerns. The impact of DTAS on long-term functional outcomes varies between published studies, and randomized controlled trials are warranted to examine the benefit of DTAS.

Abstract 1122‐000223: Direct to Angiography Suite versus Conventional Imaging in Suspected Large Vessel Occlusion Strokes: A Meta‐Analysis

Introduction : Direct transfer to angiography suite (DTAS) for patients with suspected large vessel occlusion strokes potentially requiring mechanical thrombectomy has been shown to shorten treatment times and improve outcomes compared to conventional imaging (CI) selection. This meta‐analysis compares both approaches to build more concrete evidence. Methods : The potentially relevant studies that were published in four electronic databases/search engines (PubMed, Web of Science, Cochrane Library, and Scopus) till August 2021 were reviewed. Eligible studies were included if they enrolled >10 patients in both groups, were published in English and reported baseline and procedural characteristics and 90‐day outcomes. Relevant data were then extracted and analyzed. Results : Among 4514 searched studies, six qualified for the analysis. Time from door to puncture (MD = ‐26.76minutes, 95 % CI [‐39.48, ‐14.03], P< 0.0001) as well as door to reperfusion (MD = ‐27.21 minutes,95% CI [‐47.42, ‐7.01], P = 0.008) were significantly shorter and the rates of functional independence(mRS0‐2: RR = 1.28, 95% CI [1.03, 1.60], P = 0.03) at 90‐days were significantly higher in the DTAS versus the CI approach. There was no statistically significant difference between DTAS and CI groups in terms of successful reperfusion (modified Thrombolysis In Cerebral Infraction [mTICI] score2B‐3: RR = 0.99, 95% CI [0.93, 1.06], P = 0.86), near complete/ full reperfusion (mTICI 2C‐3: RR = 0.84,95% CI [0.68, 1.04], P = 0.11), or fair outcomes at 90‐days (mRS 0–3: RR = 1.05, 95% CI [0.67, 1.64],P = 0.84). Moreover, there was no difference between groups regarding symptomatic intracranial hemorrhage (RR = 0.81, 95% CI [0.55, 1.17], P = 0.26) or 90 day‐mortality (RR = 0.85, 95% CI [0.59, 1.24],P = 0.41). Conclusions : Our meta‐analysis showed that DTAS significantly improves time metrics and functional outcome with comparable safety to the CI approach. Multicenter randomized clinical trials are ongoing to confirm these results.

Abstract 1122‐000065: Hospital Cost of DTAS Compared to ED Transfers for LVOs Undergoing Mechanical Thrombectomy

Introduction : Direct‐to‐angiography‐suite (DTAS) transfer for patients with large vessel occlusions (LVOs) undergoing mechanical thrombectomy is associated with decreased workflow times and improved neurological outcomes. Herein, we sought to demonstrate a decrease in hospital cost associated with DTAS compared to emergency department (ED) transfers for patient undergoing mechanical thrombectomy for an LVO. Methods : A retrospective analysis was performed on all patients who underwent mechanical thrombectomy for an LVO at a single comprehensive stroke center between January 1st, 2017, and March 31st, 2021. All patients who were either transferred DTAS or ED were included and compared. Total hospital cost (sum of overhead, professional, diagnostic, and room charges throughout the entire index patient admission) was obtained from the hospital financial department for the index treatment admission. A propensity adjusted (matched for age, sex, vessel occluded, co‐morbidities, BMI, admission NIHSS, access site, and use of a stent retriever) was implemented. Mean difference in hospital cost following adjustment was the primary outcome. Results : During the study period, 341 patients underwent mechanical thrombectomy for an LVO. Of these patients, 140 (41%) were transferred DTAS and 96 (28%) to the ED. There were no significant differences between cohorts in terms of age, sex, vessel occluded, admission NIHSS, co‐morbidities, number of passes, TICI score, access site, stent retriever, major complications, or in‐hospital mortality. The DTAS cohort ($33,061, sD $17,258) had a significantly lower hospital cost compared to ED transferred patients ($38,030, sD $18,572) (p = 0.04). There was no significant difference between the ED (12.2, sD 11.8) and DTAS (11.6, sD 11.1) cohorts in discharge NIHSS. Following propensity score adjustment, linear regression analysis found DTAS (compared to ED transfer) to be significantly associated with a decrease in hospital cost ($‐6,344; 95% CI: $‐11,067 to $‐1,623; p = 0.009). Conclusions : DTAS transfer for patients undergoing an acute mechanical thrombectomy for a LVO was associated with a greater than $6,000 decrease total hospital cost compared to patients first transferred to the ED. The present study further supports DTAS transfer for patients undergoing mechanical thrombectomy for LVO.

Abstract 1122‐000154: Effect of Intravenous Thrombolysis on Early Clot Lysis in Large Vessel Occlusion Strokes Undergoing Thrombectomy

Introduction : Intravenous thrombolysis (IVT) and endovascular thrombectomy (EVT) are both standard of care treatments for acute ischemic stroke patients with large vessel occlusion (LVO) who are eligible for one or both treatments. IVT may result in early recanalization in some patients with LVO. The objective of this study is to analyze whether IVT influences pre‐thrombectomy clot lysis in LVO acute ischemic strokes. Methods : We reviewed prospectively collected data for all patients with LVO ischemic strokes who were transferred to the angiography suite with intention to perform EVT at a single comprehensive stroke center between January 2016 to December 2018. We identified subjects who showed partial or complete clot lysis vs no lysis based on the first angiographic picture of the occluded territory at the time of the initial vessel selection. Descriptive statistics were used to summarize demographic and clinical characteristics. We compared key predictor variables between lysis and no lysis groups including baseline variables, effect of IVT, time from IVT to groin puncture, LVO location, final modified treatment in cerebral ischemia (mTICI) score and discharge Modified Rankin Scale (mRS). t‐test or Kruskal‐Wallis test for continuous variables and chi square test or Fisher’s Exact test for categorical variables. Results : Two hundred and fifty‐nine patients were included. Among these patients, 10.8% (28/259) showed partial or complete lysis of the clot vs 89.2% (231/259) with no lysis. Among these patients who showed clot lysis, 16/28 (57.1%) received IVT. The use of IVT did not show differences between both groups (p = 0.18). There were no differences in the baseline characteristics except for gender, which was the only variable significantly associated with clot lysis. Men had 2‐fold higher odds of spontaneous lysis compared to females (OR [95%CI]: 2.39 [1.01, 5.65], p = 0.04). There was significant difference in the final mTICI between both groups (p <0.001). Conclusions : Our study showed that IVT in a modern practice was not associated with pre‐thrombectomy lysis. Some patients had pre‐thrombectomy lysis despite not receiving IVT.

P.064 Physician Approaches to Imaging and Revascularization for Acutely Symptomatic Carotid Stenosis: Insights from the Hot Carotid Qualitative Study

Background: Evidence informing the choice between endarterectomy and stenting for acutely symptomatic carotid stenosis (“hot carotid”) is dated, and uncertainties remain regarding the optimal imaging modality. We sought to explore the thoughts of stroke physicians regarding the perioperative management of patients with acute symptomatic carotid stenosis. Methods: We conducted semi-structured interviews regarding “hot carotid” management with purposive sampling of 20 stroke physicians from 14 centres in North America, Europe, Asia, and Australia. We identified key themes using conventional qualitative content analysis. Results: Timely imaging availability, breadth of information gained, and surgeon/interventionalist preference emerged as important themes informing the choice of imaging modality. Multidisciplinary decision making, operating room/angiography suite availability, and implications of patient age and infarct size were important themes related to the choice of revascularization. Areas of uncertainty included utility of carotid plaque imaging, timing of revascularization, and the role of intervention with borderline stenosis or intraluminal thrombus. Conclusions: Our qualitative analysis revealed themes that were important to stroke experts. Teams designing international trials will have to accommodate identified variations in practice patterns and take into consideration areas of uncertainty, such as timing of revascularization, imaging of carotid plaque and non-stenotic features of carotid disease (intraluminal thrombus, plaque morphology).

Mathematical Models for Blood Flow Quantification in Dialysis Access Using Angiography: A Comparative Study

Blood flow rate in dialysis (vascular) access is the key parameter to examine patency and to evaluate the outcomes of various endovascular interve7ntions. While angiography is extensively used for dialysis access–salvage procedures, to date, there is no image-based blood flow measurement application commercially available in the angiography suite. We aim to calculate the blood flow rate in the dialysis access based on cine-angiographic and fluoroscopic image sequences. In this study, we discuss image-based methods to quantify access blood flow in a flow phantom model. Digital subtraction angiography (DSA) and fluoroscopy were used to acquire images at various sampling rates (DSA—3 and 6 frames/s, fluoroscopy—4 and 10 pulses/s). Flow rates were computed based on two bolus tracking algorithms, peak-to-peak and cross-correlation, and modeled with three curve-fitting functions, gamma variate, lagged normal, and polynomial, to correct errors with transit time measurement. Dye propagation distance and the cross-sectional area were calculated by analyzing the contrast enhancement in the vessel. The calculated flow rates were correlated versus an in-line flow sensor measurement. The cross-correlation algorithm with gamma-variate curve fitting had the best accuracy and least variability in both imaging modes. The absolute percent error (mean ± SEM) of flow quantification in the DSA mode at 6 frames/s was 21.4 ± 1.9%, and in the fluoroscopic mode at 10 pulses/s was 37.4 ± 3.6%. The radiation dose varied linearly with the sampling rate in both imaging modes and was substantially low to invoke any tissue reactions or stochastic effects. The cross-correlation algorithm and gamma-variate curve fitting for DSA acquisition at 6 frames/s had the best correlation with the flow sensor measurements. These findings will be helpful to develop a software-based vascular access flow measurement tool for the angiography suite and to optimize the imaging protocol amenable for computational flow applications.

Augmented reality enhanced tele-proctoring platform to intraoperatively support a neuro-endovascular surgery fellow

Background Remote tele-proctoring has been conducted in neuro-endovascular surgery, however, evidence to support its use in the fellowship training is limited. We demonstrate a novel augmented reality tele-proctoring platform to enable a remote attending to guide a fellow. Methods A consecutive series of neuro-endovascular cases were performed by a neuro-endovascular fellow with remote guidance from an attending surgeon. The fellow and attending were connected using a commercially available cloud-based platform designed to capture and stream up to four live video feeds from a clinical environment to a remote user. In this setting, two video streams were obtained directly from the anteroposterior and lateral cameras on the biplane. Additional video of the operator from a telescopic camera was streamed live to the remote attending surgeon. The attending could provide immediate vocal feedback and also deploy the platform's augmented reality tools to communicate with the fellow in the angiography suite. Results A total of 10 cases were performed on eight patients utilizing the cloud-based tele-proctoring platform to facilitate instruction. The series included diagnostic angiograms and interventions such as intracranial balloon angioplasty, carotid stenting, and intracranial stenting. All cases were a technical success. No complications or deaths occurred. When compared to similar cohort of 10 cases prior to these which utilized a traditional instruction paradigm; we saw no differences in contrast use ( p = 0.38), fluoroscopy time ( p = 0.85), or technical success. Conclusions This study demonstrates successful use of an augmented reality tele-proctoring platform to guide a neuro-endovascular fellow through complex neuro-interventional procedures from a remote setting.