Kallmes, David F.

Background Mechanical thrombectomy for ischemic stroke has traditionally been performed via transfemoral access (TFA). However, newer literature on the subject suggests that transradial access (TRA) may be equally efficacious. Methods Online databases (including PubMed, Google Scholar, Embase, and Cochrane) were queried from inception until May 2024. Abstracts and full texts were screened according to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Risk of bias assessment was performed using standardized screening tools. All dichotomous outcomes were reported as odds ratio (OR) with 95% confidence interval (CI). RevMan was used to perform the statistical analysis. Results Thirteen observational studies and one randomized clinical trial (RCT) were included in this meta-analysis. The total sample size was 4973, 4074 patients (81.2%) were in the TFA group, and 899 (18.8%) were in the TRA group. No significant differences were observed between the two groups in terms of successful recanalization (OR = 0.92; 95% CI 0.66–1.27; p = 0.60), first-pass recanalization (OR = 0.84; 95% CI 0.69–1.01, p = 0.06), access to reperfusion time (mean difference −2.99 min; 95% CI −8.33 to 2.44, p = 0.27), and favorable functional outcome. Mortality and rates of intracranial hemorrhage were comparable between the two groups, but access site complications were significantly lower in the TRA group (OR = 0.57; 95% CI 0.37–0.88; p = 0.01). Conclusion TRA for thrombectomy in large vessel ischemic strokes is comparable to TFA in terms of efficacy and has a lower incidence of access site complications. RCT data comparison of the two techniques is limited, underscoring the importance of conducting trials.

We have developed a cost-effective method to study the fate of stents, particularly flow diverter stents placed in the abdominal aorta, in a rat model. This technique utilizes (caudal) tail artery access,1–5 thereby avoiding the need for surgical exposure of the femoral or carotid arteries and reducing procedural invasiveness,6 7 aligning with the principles of refinement and reduction in animal research.7 This approach may be particularly beneficial for studies requiring multiple or iterative vascular access. The use of ultrasound guidance further reduces costs and infrastructure requirements by eliminating the need for specialized angiography suites.8 This makes this technique accessible to a broader range of research settings, promoting wider adoption and collaboration in the field of endovascular research. A detailed demonstration of this method is provided in the accompanying educational video (video 1). Video 1 -Technical video describing the tail artery access and flow diverter deployment using ultrasound guidance.

Brain arteriovenous malformations (bAVMs) are a notable cause of intracranial hemorrhage, strongly associated with severe morbidity and mortality. Contemporary treatment options include surgery, stereotactic radiosurgery, and endovascular embolization, each of which has limitations. Hence, development of pharmacological interventions is urgently needed. The recent discovery of the presence of activating Kirsten rat sarcoma ( KRAS ) viral oncogene homologue mutations in most sporadic bAVMs has opened the door for a more comprehensive understanding of the pathogenesis of bAVMs and has pointed to entirely novel possible therapeutic targets. Herein, we review the status quo of genetics, animal models, and therapeutic approaches in bAVMs.

Background The hypoperfusion intensity ratio (HIR) has emerged as a vital measure of tissue-level collateral blood flow, helping to identify patients who are likely to benefit from mechanical thrombectomy (MT). We aimed to assess the HIR’s predictive accuracy for clinical outcomes following MT in patients with acute ischemic stroke. Methods PubMed, Embase, and Scopus were searched to identify studies comparing good versus poor HIR groups based on studies’ reported cut-offs. We pooled binary outcomes to calculate odds ratios (OR) and continuous outcomes to calculate mean differences (MD) with 95% confidence intervals (95% CI) using random-effects models. PROSPERO registration code: CRD42024609185. Results 14 studies with 2987 patients, 1553 with good HIR and 1434 with poor HIR, were included in this meta-analysis. Patients with poor HIR exhibited a significantly higher baseline infarct volume compared with those with good HIR (MD 30.6 mL, 95% CI 20.8 mL to 40.3 mL, P<0.01), though baseline National Institutes of Health Stroke Scale (NIHSS) (P=0.12) and Alberta Stroke Program Early CT Score (ASPECTS) (P=0.35) were comparable between groups. The rates of infarct growth (MD 22.4 mL, 95% CI 6.7 mL to 38.0 mL, P<0.01) and 3-month mortality (OR 2.18, 95% CI 1.04 to 4.58, P=0.04) were higher among the poor HIR group and good functional recovery (modified Rankin Scale 0–2 at 3 months) was lower (OR 0.58, 95% CI 0.42 to 0.80, P<0.01). The rates of symptomatic intracranial hemorrhage (P=0.37) and successful reperfusion (P=0.47) were comparable among groups. Conclusion This meta-analysis highlights the significant negative impact of poor HIR on patient outcomes. These findings emphasize the need for personalized treatment strategies for patients with poor HIR.

Background: Variability in recanalization success during endovascular treatment for acute ischemic stroke (AIS) has led to increased interests in thrombus composition and associated cellular materials. While evidence suggests that bacteria may influence thrombus characteristics, limited data exist on microbiological profiles of thrombi in stroke patients. Objectives: Characterization of bacterial communities present in thrombi of AIS patients undergoing mechanical thrombectomy, providing insights into microbial contributions to stroke pathogenesis and treatment outcomes. Methods: Thrombi were collected from 20 AIS patients. After extracting metagenome, 16S rDNA sequencing was performed. Bioinformatic analysis included taxonomy and diversity assessments. The presence of bacterial DNA and viable bacteria in thrombi was validated using polymerase chain reaction (PCR) and bacterial culturing followed by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) analysis, respectively. Results: 16S rDNA was amplified in 19/20 thrombi (95%). Analysis identified a diverse microbial community, with Corynebacterium spp. as the most prevalent genus, followed by Staphylococcus spp., Bifidobacterium spp., Methylobacterium spp., and Anaerococcus spp. Alpha diversity analyses (Shannon index: 4.0–6.0 and Simpson index: 0.8–1.0) revealed moderate to high microbial diversity across samples; beta diversity demonstrated distinct clustering, indicating inter-patient variability in microbial profiles. PCR confirmed the presence of DNA specific to dominant bacterial taxa identified through sequencing. Culturing showed the presence of Staphylococcus epidermidis and Enterococcus faecalis in some clots as identified through MALDI analysis. Conclusions: This study shows bacterial communities present in AIS patients’ thrombi, suggesting a potential link between microbial signatures and thrombus characteristics.

Background Carotid artery tortuosity (CAT) may complicate mechanical thrombectomy (MT), potentially causing delays or preventing recanalization. However, the relationship between CAT and MT outcomes remains largely unexplored. This systematic review aims to evaluate the existing evidence regarding the impact of CAT on MT outcomes. Methods Following PRISMA guidelines, a systematic literature search was conducted using MEDLINE, EMBASE, Web of Science, Cochrane, and Scopus databases. Studies providing data for MT outcomes based on CAT status were included. Outcomes of interest included successful recanalization, first-pass efficacy (FPE), procedure time, functional independence, and procedure-related complications. Results Our search identified nine studies with 2737 patients. Three studies employed DSA to assess tortuosity, whereas the remaining six studies preferred CTA. In seven studies, CAT was associated with prolonged procedure times. In five studies, successful recanalization rates were significantly lower in CAT patients as compared to patients with non-tortuous arteries. Two studies showed that CAT could alter FPE or successful recanalization rates of first-line MT techniques. No study found statistically significant relationships between CAT and functional independence. Three studies examined the association between CAT and safety outcomes, and only one study found increased intracranial hemorrhage rates in patients with CAT. All nine studies employed different CAT criteria. Conclusions Despite the vast MT literature, the number of studies reporting CAT status remains low. CAT may affect procedure time and technical outcomes of MT. Therefore, employing a uniform CAT definition and reporting CAT more frequently can provide insights into management of patients with acute large vessel occlusions.

Background: Identifying optimal candidates for endovascular treatment (EVT) remains an ongoing priority to maximize treatment efficacy. The recent large core trials have called into question the use of infarct volume alone for selecting patients. This study aimed at exploring the feasibility of using routinely acquired Computed Tomography Perfusion (CTP) to capture how lesion location impacts brain connectivity and how this in turn affects the ability to benefit from EVT. Methods: Consecutive patients from a multi-centric stroke imaging registry were included in this study if they had a proven anterior circulation large vessel occlusion (LVO) and available baseline CTP data. Hypoperfusion (Tmax >6 seconds) and ischemic core (relative cerebral blood flow <30%) maps were automatically generated using e-CTP (Brainomix, UK) and used to derive disconnection maps via a DTI template. A voxel-based, multivariate method (Sparse Canonical-Correlation-Analysis – LESYMAPS) was used to explore associations between disconnection maps and NIHSS subitems in recanalized patients. The mismatch between Tmax and core disconnection volumes (disconnection mismatch volume) (Figure 1) was used to predict modified Rankin Scale (mRS) at 3-months using an ordinal shift regression adjusted for age, recanalization status and infarct volume. Results: One-hundred and seventy-one patients were included. The median NIHSS was 16 (11.5 to 22). The total NIHSS was associated with disconnection predominantly within the left basal ganglia, brainstem and corpus callosum. Upper and lower limb deficits (NIHSS 5a, 5b, 6a, 6b) were associated with corticospinal tract disconnection, with negative correlations within the contralateral tracts (Figure 2). Language deficits were associated with left hemisphere tract disconnection, also showing negative correlations within the contralateral tracts. The disconnection mismatch volume was an independent predictor of functional outcome at 3-months (Table 1). Conclusion: The results from this study showed that it is possible to use routinely acquired CTP to capture the effects of stroke lesion on brain connectivity and its impact on functional outcome following recanalization treatment. Such an approach could enable more nuanced treatment selection for patients based on specific neurological deficits.

Background: Acute stroke lesions become more hypodense on non-contrast CT as the ischemic injury matures. Lesions transition to established infarcts at which time recanalization treatment is thought to be futile, if not harmful. As it is not possible to directly quantify the degree of injury progression, eligibility for treatment is determined using temporal criteria. In this study we used an AI approach to segment and quantify the degree of hypoattenuation of acute stroke lesions on baseline CTs, and explored its impact on clinical outcome following mechanical thrombectomy. Methods: Imaging was collected from a multicentric registry (across 4 US and 5 EU sites) of consecutive large vessel occlusion (LVO) stroke patients who underwent mechanical thrombectomy. Baseline NCCT scans were processed using Brainomix 360 to automatically segment the ischemic core. Lesion hypoattenuation was then quantified by in-house software using the mean Net-Water-Uptake (NWU). Multivariate models were used to explore the association between NWU and clinical outcome (3-month modified Rankin scale–mRS), controlling for e-ASPECTS scores, age, and recanalization status. Interaction models were also used to examine the relationship between NWU e-ASPECTS scores. Results: Of the 1363 patients included (age: median 70, IQR: 50-79; 571 females), successful recanalization (mTICI 2b-3) was achieved for 1119 patients. Multivariate analysis found NWU (p=<.001, t=4.62; Fig1) to remain an independent predictor of outcome. There was a significant interaction effect between and ASPECTS score (p=0.029, Fig 2), suggesting that degree of hypoattenuation played a larger role in patients with lower aspects value. In subgroup analysis, NWU was not a significant predictor of outcome in patients that did not achieve successful recanalizion (mTICI 0-2a). Conclusions: These findings suggest that stroke lesion hypodensity measured using NWU might help identify patients at risk of futile recanalization, and that incorporating this information might be more relevant in patients with lower ASPECTS. The ability to determine treatment eligibility using information extracted from routine imaging would allow safe extension of treatment to patients with unclear onset time, and would account for differences in rates of infarct progression.