Association between intraprocedural drops in blood pressure and infarct growth rate patterns after acute large-vessel occlusions

BACKGROUND

Infarct growth rate (IGR) differs among patients with acute ischemic stroke due to large vessel occlusion (LVO-AIS), and this variability has critical clinical repercussions. We explored IGR patterns and their association with blood pressure during endovascular therapy (EVT).

METHODS

This is a two-center cohort observational study that included consecutive anterior circulation LVO-AIS patients who underwent EVT and achieved modified Thrombolysis in Cerebral Infarction (mTICI) 2 c-3. Initial and final infarct volumes (FIV) were defined using admission computed tomography perfusion (CTP) defined as relative cerebral blood flow (rCBF) <30%, and diffusion-weighted imaging-magnetic resonance imaging (DWI-MRI) at 24 hours post-EVT. We categorized IGR patterns as exponential (ExpIGR) and Non-exponential (NonExp) based on their growth curves. We then dichotomized ExpIGR clinical significance based on the association of infarct growth with 90-day Modified Rankin Score (mRS) as ExpIGR-A (>13 mL) and ExpIGR-B (<13 mL). Intraprocedural blood pressure (BP) drops were calculated as the difference between median arterial pressure (MAP) at admission and the lowest intraprocedural MAP reading before recanalization, and the area between admission MAP threshold and all lower measurements of intraprocedural MAP. Logistic and linear regression were used to investigate associations between variables of interest.

RESULTS

Of 159 modified Thrombolysis in Cerebral Infarction (mTICI) 2 c-3 patients, we found that 36% demonstrated ExpIGR-A, 31% ExpIGR-B, and 32.7% NonExp patterns. The Exp-A and Exp-B groups differed significantly in National Institutes of Health Stroke Scale (NIHSS) score, Alberta Stroke Program Early CT Score (ASPECTS), glucose, and FIV. The Exp-A and NonExp groups differed in rCBF <30% vol, and time of stroke onset (SO) to admission CTP; and the Exp-B and NonExp groups in NIHSS, rCBF <30%, Tmax <6 s volume, collateral flow measured by hypoperfusion intensity ratio (HIR), and FIV. Hypotensive MAP area (HMA) was independently associated with an ExpIGR-A pattern. Infarct volume increased by 1 mL per 100 units of hypotensive area and 4.2 mL per 0.1 units of HIR, with a significant interaction between both variables.

CONCLUSION

After an LVO-AIS, the IGR can be differentiated into two distinct exponential and non-exponential patterns. A subgroup of patients with the exponential pattern experienced clinically meaningful infarct growth rates between CTP acquisition and reperfusion and seem to be highly vulnerable to episodes of sustained intraprocedural BP drops during EVT.

A Comprehensive Approach to Sample Preparation for Electron Microscopy and the Assessment of Mitochondrial Morphology in Tissue and Cultured Cells

Mitochondria respond to metabolic demands of the cell and to incremental damage, in part, through dynamic structural changes that include fission (fragmentation), fusion (merging of distinct mitochondria), autophagic degradation (mitophagy), and biogenic interactions with the endoplasmic reticulum (ER). High resolution study of mitochondrial structural and functional relationships requires rapid preservation of specimens to reduce technical artifacts coupled with quantitative assessment of mitochondrial architecture. A practical approach for assessing mitochondrial fine structure using two dimensional and three dimensional high-resolution electron microscopy is presented, and a systematic approach to measure mitochondrial architecture, including volume, length, hyperbranching, cristae morphology, and the number and extent of interaction with the ER is described. These methods are used to assess mitochondrial architecture in cells and tissue with high energy demand, including skeletal muscle cells, mouse brain tissue, and Drosophila muscles. The accuracy of assessment is validated in cells and tissue with deletion of genes involved in mitochondrial dynamics.

Safety and efficacy of the surpass streamline for intracranial aneurysms (SESSIA): A multi-center US experience pooled analysis

BACKGROUND AND PURPOSE

Flow diversion has established as standard treatment for intracranial aneurysms, the Surpass Streamline is the only FDA-approved braided cobalt/chromium alloy implant with 72-96 wires. We aimed to determine the safety and efficacy of the Surpass in a post-marketing large United States cohort.

MATERIALS AND METHODS

This is a retrospective multicenter study of consecutive patients treated with the Surpass for intracranial aneurysms between 2018 and 2021. Baseline demographics, comorbidities, and aneurysm characteristics were collected. Efficacy endpoint included aneurysm occlusion on radiographic follow-up. Safety endpoints were major ipsilateral ischemic stroke or treatment-related death.

RESULTS

A total of 277 patients with 314 aneurysms were included. Median age was 60 years, 202 (73%) patients were females. Hypertension was the most common comorbidity in 156 (56%) patients. The most common location of the aneurysms was the anterior circulation in 89% (279/314). Mean aneurysm dome width was 5.77 ± 4.75 mm, neck width was 4.22 ± 3.83 mm, and dome/neck ratio was 1.63 ± 1.26. Small-sized aneurysms were 185 (59%). Single device was used in 94% of the patients, mean number of devices per patient was 1.06. At final follow-up, complete obliteration rate was 81% (194/239). Major stroke and death were encountered in 7 (3%) and 6 (2%) cases, respectively.

CONCLUSION

This is the largest cohort study using a 72-96 wire flow diverter. The Surpass Streamline demonstrated a favorable safety and efficacy profile, making it a valuable option for treating not only large but also wide-necked small and medium-sized intracranial aneurysms.

Direct to angiosuite strategy versus standard workflow triage for endovascular therapy: systematic review and meta-analysis

BACKGROUND

Reducing stroke workflow times when performing endovascular thrombectomy is associated with improvement in clinical outcomes. We compared outcomes among large vessel occlusion (LVO) stroke patients following the direct to angiosuite (DTAS) strategy versus standard workflow (SW) when undergoing endovascular therapy.

METHODS

We conducted a systematic review and meta-analysis to compare rates of functional outcomes, reperfusion, symptomatic intracranial hemorrhage (sICH) and stroke workflow metrics. We included observational studies and clinical trials that compared the DTAS strategy versus SW, and at least one outcome of interest was assessed. Clinical, methodological and statistical heterogeneity were measured, and a random-effects model was used.

RESULTS

12 studies were included in the systematic review and 8 in the meta-analysis (n=2890). The DTAS strategy was associated with significant higher odds of good functional outcome at 90 days (47.3% vs 34.9%; OR 1.58, 95% CI 1.16 to 2.14) and a significant average reduction of door-to-puncture (mean differences (MD) -35.09, 95% CI -49.76 to -20.41) and door-to-reperfusion times (MD -32.88, 95% CI -50.75 to -15.01). We found no differences in sICH (OR 0.80, 95% CI 0.53 to 1.20), mortality (OR 1.00, 95% CI 0.60 to 1.67) or successful reperfusion rates (OR 1.37, 95% CI 0.82 to 2.29). Moreover, the DTAS strategy was associated with greater odds of dramatic clinical improvement at 24 hours (OR 1.79, 95% CI 1.15 to 2.79).

CONCLUSION

Patients undergoing the DTAS strategy had a significant reduction in door-to-puncture and door-to-reperfusion times. This resulted in an increased rate of early neurological and 90-day functional recovery without compromising safety in LVO patients undergoing endovascular thrombectomy.

Functional and Safety Outcomes of Carotid Artery Stenting and Mechanical Thrombectomy for Large Vessel Occlusion Ischemic Stroke With Tandem Lesions

Importance

Approximately 10% to 20% of large vessel occlusion (LVO) strokes involve tandem lesions (TLs), defined as concomitant intracranial LVO and stenosis or occlusion of the cervical internal carotid artery. Mechanical thrombectomy (MT) may benefit patients with TLs; however, optimal management and procedural strategy of the cervical lesion remain unclear.

Objective

To evaluate the association of carotid artery stenting (CAS) vs no stenting and medical management with functional and safety outcomes among patients with TL-LVOs.

Design, Setting, and Participants

This cross-sectional study included consecutive patients with acute anterior circulation TLs admitted across 17 stroke centers in the US and Spain between January 1, 2015, and December 31, 2020. Data analysis was performed from August 2021 to February 2022. Inclusion criteria were age of 18 years or older, endovascular therapy for intracranial occlusion, and presence of extracranial internal carotid artery stenosis (>50%) demonstrated on pre-MT computed tomography angiography, magnetic resonance angiography, or digital subtraction angiography.

Exposures

Patients with TLs were divided into CAS vs nonstenting groups.

Main Outcomes and Measures

Primary clinical and safety outcomes were 90-day functional independence measured by a modified Rankin Scale (mRS) score of 0 to 2 and symptomatic intracranial hemorrhage (sICH), respectively. Secondary outcomes were successful reperfusion (modified Thrombolysis in Cerebral Infarction score ≥2b), discharge mRS score, ordinal mRS score, and mortality at 90 days.

Results

Of 685 patients, 623 (mean [SD] age, 67 [12.2] years; 406 [65.2%] male) were included in the analysis, of whom 363 (58.4%) were in the CAS group and 260 (41.6%) were in the nonstenting group. The CAS group had a lower proportion of patients with atrial fibrillation (38 [10.6%] vs 49 [19.2%], P = .002), a higher proportion of preprocedural degree of cervical stenosis on digital subtraction angiography (90%-99%: 107 [32.2%] vs 42 [20.5%], P < .001) and atherosclerotic disease (296 [82.0%] vs 194 [74.6%], P = .003), a lower median (IQR) National Institutes of Health Stroke Scale score (15 [10-19] vs 17 [13-21], P < .001), and similar rates of intravenous thrombolysis and stroke time metrics when compared with the nonstenting group. After adjustment for confounders, the odds of favorable functional outcome (adjusted odds ratio [aOR], 1.67; 95% CI, 1.20-2.40; P = .007), favorable shift in mRS scores (aOR, 1.46; 95% CI, 1.02-2.10; P = .04), and successful reperfusion (aOR, 1.70; 95% CI, 1.02-3.60; P = .002) were significantly higher for the CAS group compared with the nonstenting group. Both groups had similar odds of sICH (aOR, 0.90; 95% CI, 0.46-2.40; P = .87) and 90-day mortality (aOR, 0.78; 95% CI, 0.50-1.20; P = .27). No heterogeneity was noted for 90-day functional outcome and sICH in prespecified subgroups.

Conclusions and Relevance

In this multicenter, international cross-sectional study, CAS of the cervical lesion during MT was associated with improvement in functional outcomes and reperfusion rates without an increased risk of sICH and mortality in patients with TLs.

Hyperacute immune responses associate with immediate neuropathology and motor dysfunction in large vessel occlusions

OBJECTIVE

Despite successful endovascular therapy, a proportion of stroke patients exhibit long-term functional decline, regardless of the cortical reperfusion. Our objective was to evaluate the early activation of the adaptive immune response and its impact on neurological recovery in patients with large vessel occlusion (LVO).

METHODS

Nineteen (13 females, 6 males) patients with acute LVO were enrolled in a single-arm prospective cohort study. During endovascular therapy (EVT), blood samples were collected from pre and post-occlusion, distal femoral artery, and median cubital vein (controls). Cytokines, chemokines, cellular and functional profiles were evaluated with immediate and follow-up clinical and radiographic parameters, including cognitive performance and functional recovery.

RESULTS

In the hyperacute phase (within hours), adaptive immune activation was observed in the post-occlusion intra-arterial environment (post). Ischemic vascular tissue had a significant increase in T-cell-related cytokines, including IFN-γ and MMP-9, while GM-CSF, IL-17, TNF-α, IL-6, MIP-1a, and MIP-1b were decreased. Cellularity analysis revealed an increase in inflammatory IL-17+ and GM-CSF+ helper T-cells, while natural killer (NK), monocytes and B-cells were decreased. A correlation was observed between hypoperfused tissue, infarct volume, inflammatory helper, and cytotoxic T-cells. Moreover, helper and cytotoxic T-cells were also significantly increased in patients with improved motor function at 3 months.

INTERPRETATION

We provide evidence of the activation of the inflammatory adaptive immune response during the hyperacute phase and the association of pro-inflammatory cytokines with greater ischemic tissue and worsening recovery after successful reperfusion. Further characterization of these immune pathways is warranted to test selective immunomodulators during the early stages of stroke rehabilitation.

Probabilistic Pairwise Model Comparisons Based on Bootstrap Estimators of the Kullback-Leibler Discrepancy

When choosing between two candidate models, classical hypothesis testing presents two main limitations: first, the models being tested have to be nested, and second, one of the candidate models must subsume the structure of the true data-generating model. Discrepancy measures have been used as an alternative method to select models without the need to rely upon the aforementioned assumptions. In this paper, we utilize a bootstrap approximation of the Kullback-Leibler discrepancy (BD) to estimate the probability that the fitted null model is closer to the underlying generating model than the fitted alternative model. We propose correcting for the bias of the BD estimator either by adding a bootstrap-based correction or by adding the number of parameters in the candidate model. We exemplify the effect of these corrections on the estimator of the discrepancy probability and explore their behavior in different model comparison settings.

Abstract WP165: Clinical And Radiological Characteristics Of Exponential And Non-exponential Infarct Growth Patterns In Anterior Circulation Large Vessel Occlusion Stroke

Introduction: Infarct evolution is a highly dynamic process that varies among individuals. This study aimed to identify clinical and radiological features associated with an exponential infarct growth rate (IGR) pattern in stroke patients with large vessel occlusion (LVO).

Methods: This is a retrospective cohort study of anterior LVO stroke patients who underwent mechanical thrombectomy (MT) and achieved complete recanalization (mTICI 2c-3). Infarct volumes were calculated at two time points, pre-MT: CT perfusion (CTP) using Rapid software to estimate the CBF<30% volume; and post-MT: using DWI-MRI. Early IGR was defined as CBF<30% (ml) / Time from stroke onset to CTP (hours); and late IGR as [DWI-MRI - CBF<30%] (ml) / Time from CTP to reperfusion (hours). Exponential IGR pattern was established when late IGR was at least three times its respective early IGR. Patients who did not meet this criterion were considered to have a non-exponential IGR. Hypoperfusion intensity ratio 0.4 identified patients with poor collateral status. Good functional outcome was defined as 90-day modified Rankin scale (mRS) 0-2.

Results: Of the 159 patients (median age 71 [6-82], 45% male, median NIHSS 14 [9-18]) included in the analysis, 91 (57%) patients had an exponential IGR pattern. These patients had higher CT ASPECTS (9[7-10] vs 8[7-9], p=0.038), higher glucose levels (126[114-150] vs 117[106-135], p=0.022), lower Tmax<6.0s (88[55-129] vs 113[81-173, p=0.014]), and higher rate of poor collaterals (31% vs 68%, p<0.001) when compared to patients with a non-exponential IGR pattern. Patients with exponential IGR pattern had lower rates of mTICI 3 (82% vs 96%, p=0.008) but no significant differences in mRS 0-2 at 90 days.

Conclusions: Parameters associated with exponential infarct growth might help to stratify the most time sensitive vulnerable LVO population in which newer therapeutic and triage strategies should be prioritized.

Fig. Infarct Growth Rate Plots and Collateral Status . A shows IGR with an exponential pattern . B shows IGR with a non-exponential pattern.

Acute Carotid Artery Stenting Versus Balloon Angioplasty for Tandem Occlusions: A Systematic Review and Meta-Analysis

Background Despite thrombectomy having become the standard of care for large-vessel occlusion strokes, acute endovascular management in tandem occlusions, especially of the cervical internal carotid artery lesion, remains uncertain. We aimed to compare efficacy and safety of acute carotid artery stenting to balloon angioplasty alone on treating the cervical lesion in tandem occlusions. Similarly, we aimed to explore those outcomes' associations with technique approaches and use of thrombolysis. Methods and Results We performed a systematic review and meta-analysis to compare functional outcomes (modified Rankin Scale), reperfusion, and symptomatic intracranial hemorrhage and 3-month mortality. We explored the association of first approach (anterograde/retrograde) and use of thrombolysis with those outcomes as well. Two independent reviewers performed the screening, data extraction, and quality assessment. A random-effects model was used for analysis. Thirty-four studies were included in our systematic review and 9 in the meta-analysis. Acute carotid artery stenting was associated with higher odds of modified Rankin Scale score ≤2 (odds ratio [OR], 1.95 [95% CI, 1.24-3.05]) and successful reperfusion (OR, 1.89 [95% CI, 1.26-2.83]), with no differences in mortality or symptomatic intracranial hemorrhage rates. Moreover, a retrograde approach was significantly associated with modified Rankin Scale score ≤2 (OR, 1.72 [95% CI, 1.05-2.83]), and no differences were found on thrombolysis status. Conclusions Carotid artery stenting and a retrograde approach had higher odds of successful reperfusion and good functional outcomes at 3 months than balloon angioplasty and an anterograde approach, respectively, in patients with tandem occlusions. A randomized controlled trial comparing these techniques with structured antithrombotic regimens and safety outcomes will offer definitive guidance in the optimal management of this complex disease.

Safety and Feasibility of Symptomatic Carotid Artery Stent-Assisted Revascularization within 48 Hours after Symptoms Onset

OBJECTIVE

We aimed to evaluate the safety and feasibility of carotid artery stenting (CAS) performed in the hyperacute period.

METHODS

We analyzed a retrospective database of CAS patients from our center. We included patients with symptomatic isolated ipsilateral extracranial carotid stenosis and acute tandem occlusions who underwent CAS. Hyperacute CAS (HCAS) and acute CAS (ACAS) groups were defined as CAS within 48 hours and >48 hours to 14 days from symptoms onset, respectively. The primary outcome was a composite of any stroke, myocardial infarction, or death at 3 months of follow-up. Secondary outcomes were periprocedural complications and restenosis or occlusion rates.

RESULTS

We included 97 patients, 39 with HCAS and 58 with ACAS. There was no significant difference between groups for the primary outcome (HCAS 3.3% vs. ACAS 6.1%; p = 1). There were no differences in the rate of perioperative complications between groups although a trend was observed (HCAS 15.3% vs. ACAS 3.4%; p = .057). The rate of restenosis or occlusion between groups (HCAS 8.1% vs. ACAS 9,1%; log-rank test p = .8) was similar with a median time of follow-up of 13.7 months.

CONCLUSION

Based on this study, CAS may be feasible in the hyperacute period. However, there are potential higher rates of perioperative complications in the hyperacute group, primarily occurring in MT patients with acute tandem occlusion. A larger multicenter study may be needed to further corroborate our findings.

Abstract P512: Immune Correlates of Functional Outcome in Acute Ischemic Stroke (AIS) Patients

Introduction: Acute Ischemic Stroke (AIS) is one of the leading causes of disability and death in US. Although Endovascular Therapy (EVT) remains the mainstay therapy during acute phase for large vessel occlusions (LVOs), functional outcome varies among the treated patients. This ischemic injury results in an inflammatory response which plays an important role in the functional and neurological outcomes. We hypothesize that the early changes in the inflammatory response near the site of occlusion can be used as predictor of long-term neurofunctional decline

Methods: AIS-LVO patients presenting to an academic comprehensive stroke center (CSC) within 24 hours from their last known well and undergoing EVT were included. Blood was collected proximal and distal to the thrombus during thrombectomy. Control samples were collected from the femoral artery and median cubital vein. Cytokine analysis and deep immune profiling was performed using a 20-parameter bead array and 13-parameter flow cytometer. Least Absolute Shrinkage and Selection Operator (LASSO) models were used for cell selection and correlation was evaluated for outcomes including mRS, NIHSS, MOCA and mortality, using R-software.

Results: With 19 patients meeting the inclusion criteria, cytokine analysis revealed a significant increase in MMP and IFN-g, and decrease in GM-CSF, IL17, TNF-α, IL6, MIP-1a, and MIP-1b distal to clot. Flow cytometry analysis revealed a significant decrease in NK-T-cells, and CD8 T-cells counts and a relative increase in GM-CSF+ and IL17+ CD4 T-cells distal to clot. Immunological and neurological analysis revealed a correlation with CD4 + IFN-γ - IL10 + (r=0.7) & CD8 + IFN-γ - GMCSF + (0.6) with mRS, and CD4 + IFN-γ - IL10 + (r=0.7), CD4+ IFN-γ - IL17 + (r= -0.6), & CD8 + IFN-γ + IL17 + (r=0.7) cells with mortality.

Conclusion: Our results indicate that local ischemia results in a hyperacute adaptive immune response at the site of occlusion. This immune response is predictive of functional outcome among AIS patients and is impactful in multiple ways, including the use of supportive therapy for patients with a poor functional trajectory and the use of immune-modulators at the site of ischemic injury.

Abstract P520: Infarct Growth Rate is an Independent Predictor of Poor Outcome and Mortality After Mechanical Thrombectomy With Successful Reperfusion

Introduction: Despite treatment with mechanical thrombectomy (MT), some patients fail to regain functional independence at 90 days. The growth of the ischemic core varies across patients, and likely reflects differences in collateral flow and ischemic tolerance. In this study, we sought establish the optimal infarct growth rate (IGR) threshold to differentiate between slow and fast progressors and assess its ability to predict poor outcome.

Methods: We retrospectively identified patients with anterior large-vessel occlusion (LVO) stroke with successful MT (mTICI ≥ 2b) at two comprehensive stroke centers. Final infarct volume (FIV) was calculated from post-MT Diffusion-weighted MRI. Assuming relative stability of the FIV after successful reperfusion, we defined IGR as [FIV (ml)] / [Time from stroke onset to reperfusion (hours)]. Good clinical outcome was defined as a modified Rankin scale score (mRS) ≤2. We used Receiver Operating Characteristics (ROC) analysis to calculate the optimal IGR threshold with high specificity for predicting a poor outcome. Multivariate logistic regression analysis was performed to evaluate the association of fast progressors (IGR ≥ 7.14 ml/h) on the poor functional outcome and mortality.

Results: Of the 212 patients (age 68 ± 15, 51% female, NIHSS 15 ± 7) included, 110 (51.8%) patients had a poor outcome. The median IGR was significantly higher in patients with poor compared to good outcome (7 ml/h vs. 3.1 ml/h, p<0.001). An IGR ≥ 7.14 ml/h showed a sensitivity of 0.49 and a specificity of 0.7 to predict a poor outcome with an area under the ROC curve of 0.65 (95% CI, 0.58-0.73). IGR ≥ 7.14 ml/h was an independent predictor of poor outcome (OR 2.2, 95% CI 1.1-4.6, p=0.036) and mortality (OR 4.2, 95% CI 1.8-10.6, p=0.001) after adjusting for age, sex, atrial fibrillation, NIHSS and ASPECTS. Ordinal regression showed that the odds of having better outcomes decrease 60% in fast progressors (OR 0.40, 95% CI: 0.22-0.70, p=0.001) after adjusting for age, sex, atrial fibrillation, NIHSS, and ASPECTS.

Conclusions: IGR is an independent predictor of poor outcome and mortality in patients with successful MT. Early identification of this population might help to institute therapeutic strategies of accelerating reperfusion and slowing the IGR.

Abstract P546: Emergent Carotid Artery Stenting and Intracranial Thrombectomy for Acute Stroke With Tandem Occlusion

Introduction: Safety of emergent carotid artery stenting (CAS) during endovascular thrombectomy (EVT) for acute strokes with intracranial large vessel and cervical internal carotid artery tandem occlusion is still unclear. Given the potential risk of symptomatic intracranial hemorrhage (ICH) with anti-thrombotic medications required in the setting of CAS, the decision between CAS versus carotid artery angioplasty (CAA) alone remains controversial. In this study, we aimed to identify the optimal endovascular carotid revascularization approach in this patient population, using a large, nationally representative dataset.

Methods: We utilized the Nationwide Readmissions Database 2016-2017 to identify patients admitted due to acute ischemic stroke who underwent anterior circulation EVT as well as CAS or CAA on the same day. Survey design methods were used to generate national estimates. Logistic regression analysis was used to compare the in-hospital outcomes between patients who underwent CAS versus CAA. Survival analysis was used to estimate the 30-day readmissions.

Results: We identified 2,042 hospitalizations meeting the study inclusion criteria (mean±SD age: 66.0±12.5 years, female 31.3%). Of these, 1,391 (68.1%) had undergone CAS and 651 (31.9%) CAA alone. Baseline characteristics between the two groups were similar except patients with CAS were more likely to be on anti-thrombotics and were less likely to have received intravenous thrombolysis (tPA) as compared to those with CAA. There was no significant difference in the clinical outcomes including ICH, in-hospital mortality, gastrostomy tube placement, prolonged mechanical ventilation, length of stay, and hospital charges between the two groups in unadjusted analysis and after adjustment for the demographics and tPA use. All-cause 30-day readmission rate was similar between the two groups [hazards ratio (HR) 0.98, 95% confidence interval (CI) 0.64-1.51, p-value 0.924]. Patients with CAS had more readmissions due to ICH (HR 2.72, 95% CI 0.30-24.74) and less readmissions due to ischemic events (HR 0.78, 95% CI 0.12-5.08), although the difference was not statistically significant.

Conclusion: Emergent CAS-EVT approach appears to be safe with no adverse outcomes compared to CAA alone.

Abstract P553: Outcomes of Acute Endovascular Cervical Carotid Revascularization in Anterior Circulation Tandem Occlusions During Mechanical Thrombectomy

Introduction: Acute ischemic strokes with intracranial large vessel occlusion (LVO) and cervical internal carotid artery (ICA) tandem occlusion have traditionally been known to have a poor prognosis. Recent evidence suggests favorable functional outcomes in patients undergoing emergent carotid artery stenting (CAS) following intracranial mechanical thrombectomy (MT). We aimed to evaluate the outcomes of endovascular carotid revascularization (CR) performed acutely after emergent intracranial MT.

Methods: We used the Nationwide Readmissions Database 2016-2017 to identify patients admitted with anterior circulation LVO treated with MT. Patients who underwent CAS or carotid artery angioplasty (CAA) during the same hospitalization were also identified. Propensity scores were used to match patients with and without CR in a 1:1 ratio by demographics, comorbidities, use of intravenous thrombolysis and hospital-level characteristics. Logistic regression and survival analyses were used to compare the outcomes.

Results: We identified 15,137 hospitalizations meeting the study inclusion criteria (mean±SD age:70.1±14.6, female 51.1%). Of these, 1,214 (8.0%) underwent CAS or CAA during the same hospitalization. After propensity score matching, we obtained 1,063 well matched pairs of patients with and without CR. In the matched cohort, patients who underwent CR had higher odds of hemorrhagic transformation (OR 1.34, 95% CI 1.07-1.69, p 0.011) and higher total hospital cost (mean difference $6,232, 95% CI 3,606-8,858, p 0.001) but other clinical outcomes including gastrostomy tube placement, decompressive craniectomy, prolonged mechanical ventilation, in-hospital mortality, length of stay, and discharge disposition did not differ between the two groups. Patients with CR were less likely to have an unplanned 30-day readmission (HR 0.67, 95% CI 0.51-0.87, p 0.004). Further, they had more readmissions due to ICH (HR 1.06, 95% CI 0.41-2.71) and less readmissions due to ischemic events (HR 0.39, 95% CI 0.14-1.08), although the difference was not statistically significant.

Conclusion: If indicated, early endovascular CR for anterior circulation tandem occlusions seems to be safe with clinical outcomes comparable to patients undergoing MT alone.

Abstract P472: Characterization of Infarct Growth Rate Patterns in Patients With Large-Vessel Occlusion Stroke Undergoing Mechanical Thrombectomy

Introduction: Infarct growth is affected by the collateral blood supply and ischemic tolerance and thus unlikely linear. This study aimed to better characterize infarct growth rates (IGR) after large-vessel occlusion (LVO) stroke.

Methods: We retrospectively identified patients with anterior LVO stroke who underwent mechanical thrombectomy (MT) at two comprehensive stroke centers. Core infarct volumes at presentation (CBF<30%) were estimated using RAPID software. Final infarct volume (FIV) was measured on post-MT MRI. We estimated IGR during two intervals: IGR 1 defined as CBF<30% (ml) / Time from onset to CTP (hours); and IGR 2 as [FIV - CBF<30% (ml)] / Time from CTP to reperfusion (hours). To calculate IGR 2, we only analyzed patients with successful MT (mTICI ≥ 2b) assuming no significant infarct growth after reperfusion. Functional outcome was assessed using the modified Rankin scale (mRS) at 90 days. We performed the Receiver-operating characteristic (ROC) analysis for each interval to best classify patients into slow and fast progressors.

Results: Of the 361 patients (age 68 ± 15, 55% female, NIHSS 14 ± 6) included in the analysis, 282 (78.1%) had successful reperfusion, and 150 (41.6%) achieved a good outcome (mRS ≤2). IGR showed an exponential growth pattern (Figure 1). There was no significant difference in the median IGR 1 between the poor and good outcome groups (2.3 vs. 1 ml, p=0.061). The median IGR 2 in patients with poor outcome was significantly higher when compared to those in the good outcome group (IGR 14.1ml/h vs. 4.62ml/h, p<0.0001). IGR 2 ≥ 12.2ml/h had a sensitivity of 0.56 and a specificity of 0.77 (AUC 0.67) for predicting poor outcome.

Conclusions: We identified an exponential infarct growth pattern after LVO stroke that differs in relation to outcome. High IGR in the interval from CTP to reperfusion is associated with worse outcomes, emphasizing the importance of future research into therapeutic approaches to slow down infarct progression.

Safety and efficacy of symptomatic carotid artery stenting performed in an emergency setting

INTRODUCTION

Carotid artery stenting (CAS) has increasingly emerged as an alternative strategy to carotid endarterectomy in the treatment of patients with symptomatic carotid stenosis. Optimal timing for CAS after symptoms onset remains unclear. We aimed to evaluate the safety and efficacy of CAS when performed in an emergency setting.

PATIENTS AND METHODS

We performed a retrospective analysis of CAS patients admitted to our CSC with symptomatic extracranial carotid occlusion or significant stenosis from January 2014-September 2019. Emergency CAS was defined as CAS performed during the same hospitalization from TIA/stroke onset, whereas elective CAS as CAS performed on a subsequent admission. The primary outcome was defined as the occurrence of any stroke, myocardial infarction, or death related to the procedure at 3 months of follow-up. Secondary outcomes included periprocedural complications and the rate of restenosis/occlusion at follow-up. Logistic regression and survival analyses were used to compare outcomes and restenosis at follow-up.

RESULTS

We identified 75 emergency and 104 elective CAS patients. Emergency CAS patients had significantly higher rates of ipsilateral carotid occlusion (17% vs. 2%, p < 0.001) and use of general anesthesia (19% vs. 4%, p = 0.001) than elective CAS. There were no significant differences between emergency and elective CAS in the primary (5.7% vs. 1%, p = 0.161) and secondary (9% vs. 4.8%, p = 0.232) outcomes. We did not find differences in the rate of restenosis/occlusion (7% vs. 11.6%; log-rank test p = 0.3) at a median of 13 months follow-up.

CONCLUSION

In our study, emergency CAS in symptomatic patients might have a similar safety and efficacy profile to elective CAS at 3 months and long-term follow-up.

Abstract TP59: Atherosclerosis and Unsuccessful Recanalization in Acute Stroke Patients

Unsuccessful recanalization rates in acute ischemic stroke patients range between 8-18%. Currently, there are no models to predict thrombectomy reperfusion success with current thrombectomy techniques. We aimed to describe the clinical and radiological features of patients with unsuccessful thrombectomy (UT) and its association with intracranial atherosclerosis (ICAD). A cohort of 413 consecutive, adult, thrombectomy patients admitted to two comprehensive stroke centers were reviewed from 2014 to 2017. Patients with anterior circulation large vessel occlusions (LVOs) and a thrombolysis in cerebral infarction (TICI) score of ≤2a were selected. Demographics, clinical and imaging data were obtained from electronic medical records. Head CT, CT angiography and digital subtraction angiography (DSA) images were reviewed by one independent investigator to evaluate ASPECTS score, vessel calcifications, clot burden score and CTA and DSA collateral score. Proposed causes of UT were categorized based on angiography evaluation by two independent neurointerventionalists. Analysis was performed using descriptive frequency analysis and univariate logistic regression models. A total of 87 low TICI score (≤2a) patients from 413 procedures were included. The median age was 74 years (IQR 58.5-84) and 58% were female. The most common comorbidity was hypertension (73.5%), followed by hyperlipidemia (46%). TICI score of 0 was found in 23% (N=20), 1 in 9.2% (N=8), and 2a in 67.8% (N=59). The inpatient mortality rate was 19.5% (17/87). Out of the remaining 70 patients, 78.5% (N=55) had a 3-month follow up modified Rankin Scale (mRS) of 3-6. The most common proposed cause of poor revascularization in our study was presence of ICAD [29.9% (n=32) of patients]. In our cohort of UT patients with ICAD, 68.8% (N=22) had TICI 2a score with majority (96.8%) having a 3 months mRS of 3-6. Patients with ICAD had 7.3% increased odds of having angiographic collateral score of 5 (p=0.035) and 15.2% increased odds of having an absence of hyperdense MCA in noncontrast CT scan (p=0.003). ICAD is frequently found in patients that undergo UT. Identification of radiological predictors of ICAD may be helpful to consider alternative revascularization strategies for LVOs.

Exercise Increases Glucose Transporter-4 Levels on Peripheral Blood Mononuclear Cells

PURPOSE

Glucose transporter 4 (GLUT4) plays a key role in the pathophysiology of type 2 diabetes. Glucose transporter 4 is upregulated in response to exercise, enhancing cellular glucose transport in skeletal muscle tissue. This mechanism appears to remain intact in individuals with insulin resistance. Details of the mechanism are poorly understood and are challenging to study due to the invasive nature of muscle biopsy. Peripheral blood mononuclear cells (PBMC) have documented insulin-sensitive GLUT4 activity and may serve as a proxy tissue for studying skeletal muscle GLUT4. The purpose of this study was to investigate whether GLUT4 in PBMC is affected by conditioning.

METHODS

We recruited 16 student athletes from the cross-country running and skiing teams and fifteen sedentary students matched for age and sex from the University of Alaska Fairbanks. Peripheral blood mononuclear cells were collected with mononuclear cell separation tubes. The GLUT4 concentrations were measured using a commercially available enzyme linked immunosorbent assay. Additionally, correlations between PBMC GLUT4 and common indicators of insulin resistance were examined.

RESULTS

Results indicate significantly higher PBMC GLUT4 levels in conditioned athletes than in their sedentary counterparts, similar to what has been documented in myocytes. Females were observed to have higher PBMC GLUT4 levels than males. Correlations were not detected between PBMC GLUT4 and hemoglobin A1c, glucose, insulin, homeostatic model assessment of insulin resistance, body mass index, or body fat.

CONCLUSIONS

This study provides evidence to support exploration of PBMC as a proxy tissue for studying GLUT4 response to exercise or other noninsulin factors.