Vertebral Artery Dominance in Patients with Embolic Basilar Artery Occlusion: Insights Toward Embolus Trajectory

Vertebral Artery Dominance in Patients with Embolic Basilar Artery Occlusion: Insights Toward Embolus Trajectory | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Vertebral Artery Dominance in Patients with Embolic Basilar Artery Occlusion: Insights Toward Embolus Trajectory Daryl Goldman, Emery Monnig, Amol Mehta, Christopher Kellner, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6490223/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: Embolic basilar artery occlusion (eBAO) is less common than anterior circulation stroke. The anatomic basis for this discrepancy is not understood. Vertebral artery dominance (VAD) correlates with blood flow to the basilar artery. We hypothesized that left VAD is less common in eBAO, as the right vertebral artery is the more proximal to the heart in typical aortic arch anatomy. Methods: This retrospective single-center, case-control study identified cases of eBAO. Right, left, and co-dominant (RVAD, LVAD, and CVAD) prevalence was calculated in standardized fashion by CTA. To estimate the VAD prevalence in asymptomatic patients, a systematic review and metanalysis was performed. The pooled estimate of VAD prevalence in the asymptomatic group was compared to the eBAO cohort using χ 2 test. Results: In total, 72 eBAO were identified in the institutional cohort, and prevalence of LVAD, RVAD, and CVAD was 23.6%, 33.3%, and 43.1% respectively. Systematic review included eight studies and 1813 asymptomatic patients. Mean VAD prevalence in the asymptomatic population was LVAD 47.0% (39.0-55.1%), RVAD 26.9% (22.7–31.5%), and CVAD 25.9% (18.8–34.7%). VAD proportions differed significantly in the eBAO group (p < .001), with lower proportion of LVAD (OR 0.37, CI 0.20–0.67, p < .001), higher proportion of CVAD (OR 1.89, CI 1.13–3.13, p = .01) but no difference in RVAD (1.39, CI 0.81–2.35, p = .22). Conclusion: LVAD is significantly less common in patients with eBAO compared to asymptomatic patients. Non-LVAD anatomy (RVAD and CVAD) may represent a novel anatomic risk factor for eBAO. This finding could influence techniques for endovascular thrombectomy. Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Basilar artery occlusion (BAO) is a devastating form of large vessel occlusive (LVO) ischemic stroke. Compared with anterior circulation LVO, BAO carries a worse prognosis, with mortality exceeding 20%, with significant disability among survivors. 1 BAO can arise from different mechanisms, with in-situ atherosclerosis, dissection, and cardiogenic emboli being the most well-described. Among these, embolic BAO (eBAO) is associated with more severe clinical deficit at presentation, but better functional outcomes with successful endovascular treatment (EVT). 2 Recent trials showing superior outcomes with EVT over medical management in BAO have renewed interest in identifying anatomical and physiological risk factors that predispose patients to BAO. 3,4 Notably, eBAO comprises fewer than 10% of all LVO 5 despite the basilar artery receiving 20% of total cerebral blood flow. 9 In-silico models suggest that embolus trajectory is influenced by embolus volume 6 , aortic arch geometry 7 , and relative vessel flow rates, and cardiac rhythm. 8 Vertebral artery dominance (VAD), defined as functional asymmetry in vertebral artery caliber and flow, is a common anatomic variant, found in over 60% of the population. Prior work has shown that VA flow correlates with vessel cross-sectional area, suggesting that the dominant artery could be a more likely conduit for emboli. 10 The right VA, a tributary of the brachiocephalic trunk (BCT) of the aorta, may be a preferential trajectory for central arterial emboli, as recent in-silico work has shown higher emboli rates in the BCT (12%) than either the left common carotid (9%) or left subclavian arteries (7%). However, most studies report left vertebral artery dominance (LVAD) as more prevalent in the general population. 11–13 The purpose of this study was to investigate the association of VAD to eBAO in patients undergoing EVT. We hypothesized that anatomic configurations favoring greater right VA flow (non-left LVAD) would be more common in patients with eBAO. Methods Study Design: This was a retrospective, case-control study comparing VAD patterns among three groups: 1) patients with eBAO, 2) patients with BAO with non-embolic etiology and 3) asymptomatic individuals from a systematic review and meta-analysis of the literature. This study was approved by the local institutional review board (IRB) and informed consent was waived. All data collection and analysis performed in the study involving human participants was in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. No funding was provided for this study. Institutional Case Series: Data Collection and Patient Selection Consecutive patients undergoing EVT for posterior circulation LVO were identified from a prospectively maintained single-center databasePatients with confirmed or suspected cardioembolic etiology based on TOAST criteria were included in the eBAO group. 14 Patients with definite or possible arterial dissection or atherosclerotic etiology ( e.g. artery-artery embolus or flow limitation) were included in the non-eBAO group. A flow chart of patient selection is included in Fig. 1 . Vertebral Artery Dominance Assessment VAD was assessed using pre-treatment CTA or procedural DSA when CTA was unavailable. VAD was defined using the criteria of Jeng et al. 15 : Arterial caliber difference of ≥ 0.3mm between VAs at the C4 and C5 transverse foramina defined the dominant VA. Patients not meeting this threshold were classified as having co-vertebral artery dominance (CVAD). All images were reviewed by a neuroendovascular surgery fellow or fellowship trained neuroradiologist. Systematic Review and Metanalysis: To estimate the prevalence of VAD proportion in asymptomatic populations, we performed a PRISMA-guided systematic review of GoogleScholar and MEDLINE. The inclusion criteria were: 1) absence of known vertebrobasilar symptoms or vascular pathology, 2) VAD defined using the Jeng criteria. 15 Pooled prevalence and confidence intervals (CI) were estimated using random-effects models with logit transformation and inverse variance weighting. Heterogeneity was assessed using I² and τ² statistics (DerSimonian-Laird method and CI calculated using Jackson method) and tested using Q statistic. Statistical Analysis: In the asymptomatic group, we compared observed VAD distributions with a null hypothesis of equal prevalence (33.3% each for LVAD, RVAD, and CVAD). Odds ratios and 95% confidence intervals were calculated. Differences between eBAO and the non-eBAO and asymptomatic groups were calculated using Pearson's χ² test with Yates’ correction. All data analysis was performed using R v 4.11 ( R Foundation for Statistical Computing, Vienna, Austria ). using the meta and metafor packages. For all statistical testing, p < .05 was considered significant. Results Institutional Case Series Of 126 BAO were treated during the study period, 123 had complete angiographic and clinical data. Among these, stroke etiology was embolic in 72 (65%, eBAO cohort), of which 61/72 (84.7%) were cardioembolic and 11/72 (15/3%) were embolic stroke of undetermined source (ESUS). Fifty one patients (41.5%) had a non-embolic stroke mechanism including symptomatic atherosclerosis in 25/51 (49.0%), symptomatic stenosis with likely underlying dissection in 13/51 (25.5%) and dissection with artery-to-artery embolus in 13/51 (25.5%). Clinical characteristics of the two groups (eBAO and non-eBAO) are summarized in Table 1 . Patients with eBAO were older (68.4 vs. 61.9, p = .02), had higher rates of atrial fibrillation (44.4% vs. 21.5%, p = .01) and had lower left ventricular ejection fraction (49.9% vs. 57.4%, p = .006). Prevalence of VAD in Posterior Circulation Stroke Patients In the eBAO group, VAD distribution was: LVAD 23.6%, RVAD 33.3%, and CVAD 28.5%. The prevalence of VAD in the non-eBAO group (n = 51) had non-significantly higher fraction of LVAD (37.2%, p = .11) and lower fraction of RVAD(19.6%, p = .10) and identical fraction of CVAD 43.1% (p = 1.0). Estimation of VAD Prevalence in Asymptomatic Populations: Systematic Review and Metanalysis Initial screening identified 29 studies, of which 8 met inclusion criteria for further analysis (n = 1813 patients). 15–22 The pooled estimated VAD prevalence of asymptomatic patiens was: LVAD 47.0% (95%CI 39.0-55.1%, I 2 = 91.0%, τ 2 = 0.19, p < .001 ), RVAD 26.9% (95% CI 22.7–31.5%, I 2 = 76.5%, τ 2 = 0.077, p < .001) , and CVAD 25.9% (95% CI 18.8–34.7%, I 2 = 92.2%, τ 2 = 0.29, p < .001 ). The weighting, distribution, and inter-study heterogeneity are described in forests plots Fig. 2 . Compared to the hypothesis of equal VAD distribution, LVAD was overrepresented (OR 1.74, 95%CI 1.24–2.42, I 2 = 82.2%, τ 2 = 0.19 p < .001), while RVAD (OR 0.72, 95%CI 0.57–0.90, I 2 = 56.5%, τ 2 = 0.06 , p = .027) and CVAD (OR 0.75, 95%CI 0.48–1.19, I 2 = 88.9%, τ 2 = 0.33 , p < .001) were underrepresented. The observed versus hypothetical VAD distributions are summarized in forest plots in Fig. 3 . Differences in VAD Prevalence in BAO groups and Asymptomatic Patients Overall, the distribution of VAD profiles differed significantly in the eBAO group compared to the asymptomatic population estimate (p < .001). Patients with eBAO had significantly lower LVAD prevalence (23.6% vs. 47.0%, OR 0.37, CI 0.20–0.67, p < .001). Conversely, eBAO patients had higher prevalence of CVAD (43.1% vs. 25.9%, OR 1.89, CI 1.13–3.13, p = .01). The prevalence of RVAD was also higher in the eBAO group but this was not statistically significant (33.3% vs. 26.9%, OR 1.39, CI 0.81–2.35, p = .22). Prevalence differences are summarized in Fig. 4 . In the non-eBAO group, the overall distribution of VAD prevalence was not statistically significant from the asymptomatic population estimate (p = .09). There was a higher prevalence of CVAD (43.1% vs. 25.9%, OR 1.9, CI 1.03–3.46, p = .03) but no significant difference in prevalence of LVAD (37.2% vs. 47.0%, OR 0.72, CI 0.38–1.32, p = .32) nor RVAD (19.6% vs. 26.9%, OR 0.68, CI 0.30–1.39, p = .33). Discussion This study identifies a distinct pattern of VAD in patients with eBAO, characterized by lower prevalence of LVAD and relatively higher prevalence of RVAD and CVAD. Notably LVAD was approximately ½ as common in eBAO as in asymptomatic patients (23.6% vs. 47.0%). These findings suggest that relatively greater blood flow to the right vertebral artery may increase risk of embolic stroke in the posterior circulation. Conversely, higher prevalence of LVAD in asymptomatic populations could account for the observation that posterior circulation LVO is less frequent than expected based on total cerebral blood flow. Few studies have focused on VAD in the contemporary era of EVT and these findings have implications for stroke interventionalists. Recent randomized control trials showing benefit of EVT in BAO have underscored the importance of rapid recanalization in this population. 3,4 Whereas transfemoral access is widely used as a first line approach, the right vertebral artery offers a more direct conduit to the basilar artery from a radial artery approach 23 and radial access for EVT has proved effective and safe in published series. 24,25 The observation that ≥ 75% of patients with eBAO have either CVAD or RVAD implies that a right radial artery access may be an appropriate first line technique for a substantial fraction of patients this population. Beyond the implications for EVT, the finding that VAD patterns differ in eBAO raises important questions about the physiology of embolus trajectory. The basilar artery receives 20% of cerebral blood flow 9 , but accounts for fewer than 10% of LVOs. 5,26 In conventional three-vessel aortic arch anatomy, the innominate artery is the first great vessel encountered by systolic blood flow. Aortic arch geometry influences downstream trajectory of emboli, but most studies of embolus trajectory to date are limited to the anterior circulation. 6,7 In-silica computational flow models show that the innominate artery (which gives rise to the right VA in most patients) receives the largest fraction of cardiac output, and that emboli tend to travel proportionally to outlet flow rates. 8 Taken together, these models suggest that vessel geometry and flow are the principle drivers of embolus trajectory. Our finding that CVAD and RVAD are overrepresented in patients with eBAO is consistent with these models, suggesting that greater right vertebral artery flow may increase the probability of embolus flow to the posterior circulation. It has long been debated whether VAD or symmetrical vertebral artery anatomy is the most common anatomic configuration. Prior analyses have been limited by small sample sizes and varying definitions of VAD. We present a pooled analysis of eight studies using consistent criteria showing that LVAD is the most common configuration in asymptomatic populations (47%). This is consistent with earlier studies of VA diameter or flow, without specifically classifying VAD. 11,13,21,27–30 VA blood flow is tightly correlated to vessel caliber 29,29,32 , thus the tendency toward LVAD in the general population implies lower blood flow fraction to the right VA. 13 The left VA arises from the left subclavian artery in 96% of patients and is the most distal and circuitous path from the heart to the intracranial circulation for a central embolus . 33 The prevalence of LVAD anatomy may therefore account for the low frequency of eBAO relative to anterior circulation LVO, owing to lower probability of embolus to the LVA relative to the carotid arteries. Prior studies of VAD have focused on non-embolic stroke mechanisms 34 including arterial dissection, atherosclerosis, and dolichoectasia. 3517,36 This is among the first studies to consider VAD as a risk factor for embolic posterior circulation stroke. In the non-eBAO cohort, we found no difference in VAD distribution relative to asymptomatic patients. The observed difference in CVAD is potentially attributable to weighting of the metanalysis, which includes one study that did not differentiate CVAD as distinct from unilateral VAD. 17 The relative portions of RVAD and LVAD showed a symmetric decrease in prevalence in the non-eBAO group. Overall, these data suggest that accounting for taxonomic differences, the VAD profile of non-eBAO is similar to asymptomatic patients. Limitations: There are several important limitations of this study. First, the patient population (eBAO) was drawn from an endovascular database thus patients who did not undergo EVT are underrepresented. During the study period (2015–2024) several trials questioned the effect of EVT in BAO therefore evolving practices with EVT could result in selection bias. Next, the use of VAD defined by CTA is an imperfect proxy of true vertebral artery flow and results in an dichotomization of a continuous variable. While ultrasound Doppler is the gold standard in flow assessment, this is not feasible in acutely ill patients. Nonetheless, VAD classification is a practical substitute and easily applied in clinical practice. A related limitation is the amorphous definition of VAD used in the literature. The selected VAD criteria are based on the spatial resolution of CDUS and have been applied in numerous studies, though inter-reader agreement has not been rigorously tested. 15 Conclusion Patients with eBAO have significantly lower rates of LVAD compared to asymptomatic controls. This finding suggests that vertebral artery anatomy influences risk of posterior circulation embolic stroke. Specifically, right or co-dominant VA blood flow may predispose to eBAO. This has implications for stroke risk stratification and procedural planning in EVT. Declarations The author(s) declare that they had full access to all the data in this study and the authors take complete responsibility for the integrity of the data and the accuracy of the data analysis. Funding/ Support: None Acknowledgements : None Conflicts of Interest/Competing Interests: The authors declare no conflicts of interest Ethics Approval: This study was approved by institutional review board (IRB). Informed consent was waived. Ethical Statement: All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent : Informed consent was waived by the institutional review board (IRB) for all individual participants included in the study. Author Contribution D.G. and M.T.C. designed the study concept and wrote the manuscript. D. 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A Preliminary Study of Anti‐TNFα Therapy for Symptomatic Dolichoectatic Vertebrobasilar Aneurysms. Stroke: Vascular and Interventional Neurology . 2024;4:e000890. Table 1 Table 1 Characteristics of patients with embolic (eBAO) vs. non-embolic (non-eBAO) posterior circulation stroke from single-center retrospective review Embolic Basilar Artery Occlusion Non-embolic Basilar artery occlusion p-value Age (years) 69.4 ± 14.6 61.9 ± 18.6 .02 Sex (% women) 25/72 (34.7%) 20/51 39.3% .70 Atrial Fibrillation 32/72 (44.4%) 11/51 21.5% .01* LV Ejection Fraction 49.9 ± 16.0% 57.5 ± 14.1% .006** Aortic Arch Type Type 1 62/72 (86.1%) 45/51 (88.2%) .79 Type 2 7/72 (9.7%) 6/51 (11.8%) .77 Other 3/72 (4.2%) n/a --- Vertebral Artery Dominance LVAD 17/72 (23.6%) 19/51 (37.2%) .11 RVAD 24/72 (33.3% 10/51 (19.6% .10 CVAD 31/72 (43.1%) 22/51 (43.1%) 1.0 Additional Declarations No competing interests reported. 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Travis Caton","email":"data:image/png;base64,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","orcid":"","institution":"Mount Sinai Health System","correspondingAuthor":true,"prefix":"","firstName":"M.","middleName":"Travis","lastName":"Caton","suffix":""}],"badges":[],"createdAt":"2025-04-20 15:53:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6490223/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6490223/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82279602,"identity":"1b5d5d90-456c-4163-8f6a-6141087566d3","added_by":"auto","created_at":"2025-05-08 15:05:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":54079,"visible":true,"origin":"","legend":"\u003cp\u003eInstitutional case series selection flow diagram.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6490223/v1/78fa97c6a58ab8ca21b3107b.png"},{"id":82279604,"identity":"dda2a5aa-7f5f-486a-b024-9c66ea4b8423","added_by":"auto","created_at":"2025-05-08 15:05:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":101298,"visible":true,"origin":"","legend":"\u003cp\u003eForest Plot of random-effects metanalysis showing pooled mean prevalence of vertebral artery dominance patterns and associated confidence intervals, including right vertebral artery dominance (RVAD), left vertebral artery dominance (LVAD), and co-dominant vertebral arteries (CVAD) in asymptomatic patients using discriminating threshold of ≥ 3mm\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6490223/v1/7929ef7ca5d46d4e82b22754.png"},{"id":82278802,"identity":"6f68ee8f-0ac9-4a1c-9d2b-04d94ecf3387","added_by":"auto","created_at":"2025-05-08 14:57:34","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":35130,"visible":true,"origin":"","legend":"\u003cp\u003eMetanalysis of vertebral artery dominance prevalence reported as odds ratios assuming a null hypothesis of equal distribution in right vertebral artery dominance (RVAD), left vertebral artery dominance (LVAD) and co-dominant vertebral arteries (CVAD).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6490223/v1/56fd39db65c3feb3bb55ed3a.png"},{"id":82280986,"identity":"013f1a30-ffac-4b4c-8abf-13d8a17cb629","added_by":"auto","created_at":"2025-05-08 15:13:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":30797,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of prevalence of vertebral artery dominance (VAD) patterns in embolic basilar artery occlusion (eBAO) with the pooled mean estimate from the metanalysis of asymptomatic patients showed a significant difference in VAD pattern (p\u0026lt;.001)(A) . Comparison of non-embolic basilar artery occlusion (non-eBAO) showed no significant difference with the pooled estimate from asymptomatic patients (p=.09).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6490223/v1/cd07e967cdb1a64ca153c420.png"},{"id":82428939,"identity":"f87419d7-a435-4c46-a4f4-5717196a0fe0","added_by":"auto","created_at":"2025-05-10 15:16:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1026956,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6490223/v1/5ba99ce7-0724-442d-8fd2-9c0e052efb0c.pdf"},{"id":82278806,"identity":"76f5b787-27fd-4f5f-a515-da13bbc6be17","added_by":"auto","created_at":"2025-05-08 14:57:35","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":40941,"visible":true,"origin":"","legend":"","description":"","filename":"SuppFig.docx","url":"https://assets-eu.researchsquare.com/files/rs-6490223/v1/24ed3e8da410bb9ebbc5ea84.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Vertebral Artery Dominance in Patients with Embolic Basilar Artery Occlusion: Insights Toward Embolus Trajectory","fulltext":[{"header":"Background","content":"\u003cp\u003eBasilar artery occlusion (BAO) is a devastating form of large vessel occlusive (LVO) ischemic stroke. Compared with anterior circulation LVO, BAO carries a worse prognosis, with mortality exceeding 20%, with significant disability among survivors.\u003csup\u003e1\u003c/sup\u003e BAO can arise from different mechanisms, with in-situ atherosclerosis, dissection, and cardiogenic emboli being the most well-described. Among these, embolic BAO (eBAO) is associated with more severe clinical deficit at presentation, but better functional outcomes with successful endovascular treatment (EVT).\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eRecent trials showing superior outcomes with EVT over medical management in BAO have renewed interest in identifying anatomical and physiological risk factors that predispose patients to BAO.\u003csup\u003e3,4\u003c/sup\u003e Notably, eBAO comprises fewer than 10% of all LVO \u003csup\u003e5\u003c/sup\u003e despite the basilar artery receiving 20% of total cerebral blood flow. \u003csup\u003e9\u003c/sup\u003e In-silico models suggest that embolus trajectory is influenced by embolus volume\u003csup\u003e6\u003c/sup\u003e, aortic arch geometry\u003csup\u003e7\u003c/sup\u003e, and relative vessel flow rates, and cardiac rhythm.\u003csup\u003e8\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eVertebral artery dominance (VAD), defined as functional asymmetry in vertebral artery caliber and flow, is a common anatomic variant, found in over 60% of the population. Prior work has shown that VA flow correlates with vessel cross-sectional area, suggesting that the dominant artery could be a more likely conduit for emboli.\u003csup\u003e10\u003c/sup\u003e The right VA, a tributary of the brachiocephalic trunk (BCT) of the aorta, may be a preferential trajectory for central arterial emboli, as recent in-silico work has shown higher emboli rates in the BCT (12%) than either the left common carotid (9%) or left subclavian arteries (7%). However, most studies report left vertebral artery dominance (LVAD) as more prevalent in the general population.\u003csup\u003e11\u0026ndash;13\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe purpose of this study was to investigate the association of VAD to eBAO in patients undergoing EVT. We hypothesized that anatomic configurations favoring greater right VA flow (non-left LVAD) would be more common in patients with eBAO.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design:\u003c/h2\u003e \u003cp\u003eThis was a retrospective, case-control study comparing VAD patterns among three groups: 1) patients with eBAO, 2) patients with BAO with non-embolic etiology and 3) asymptomatic individuals from a systematic review and meta-analysis of the literature. This study was approved by the local institutional review board (IRB) and informed consent was waived. All data collection and analysis performed in the study involving human participants was in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. No funding was provided for this study.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eInstitutional Case Series: Data Collection and Patient Selection\u003c/h3\u003e\n\u003cp\u003eConsecutive patients undergoing EVT for posterior circulation LVO were identified from a prospectively maintained single-center databasePatients with confirmed or suspected cardioembolic etiology based on TOAST criteria were included in the eBAO group.\u003csup\u003e14\u003c/sup\u003e Patients with definite or possible arterial dissection or atherosclerotic etiology ( e.g. artery-artery embolus or flow limitation) were included in the non-eBAO group. A flow chart of patient selection is included in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003ch3\u003eVertebral Artery Dominance Assessment\u003c/h3\u003e\n\u003cp\u003eVAD was assessed using pre-treatment CTA or procedural DSA when CTA was unavailable. VAD was defined using the criteria of Jeng et al.\u003csup\u003e15\u003c/sup\u003e: Arterial caliber difference of \u0026ge;\u0026thinsp;0.3mm between VAs at the C4 and C5 transverse foramina defined the dominant VA. Patients not meeting this threshold were classified as having co-vertebral artery dominance (CVAD). All images were reviewed by a neuroendovascular surgery fellow or fellowship trained neuroradiologist.\u003c/p\u003e\n\u003ch3\u003eSystematic Review and Metanalysis:\u003c/h3\u003e\n\u003cp\u003eTo estimate the prevalence of VAD proportion in asymptomatic populations, we performed a PRISMA-guided systematic review of GoogleScholar and MEDLINE. The inclusion criteria were: 1) absence of known vertebrobasilar symptoms or vascular pathology, 2) VAD defined using the Jeng criteria.\u003csup\u003e15\u003c/sup\u003e Pooled prevalence and confidence intervals (CI) were estimated using random-effects models with logit transformation and inverse variance weighting. Heterogeneity was assessed using I\u0026sup2; and τ\u0026sup2; statistics \u003cem\u003e(DerSimonian-Laird method and CI calculated using Jackson method)\u003c/em\u003e and tested using \u003cem\u003eQ\u003c/em\u003e statistic.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis:\u003c/h2\u003e \u003cp\u003eIn the asymptomatic group, we compared observed VAD distributions with a null hypothesis of equal prevalence (33.3% each for LVAD, RVAD, and CVAD). Odds ratios and 95% confidence intervals were calculated. Differences between eBAO and the non-eBAO and asymptomatic groups were calculated using Pearson's χ\u0026sup2; test with Yates\u0026rsquo; correction. All data analysis was performed using R v 4.11 (\u003cem\u003eR Foundation for Statistical Computing, Vienna, Austria\u003c/em\u003e). using the \u003cem\u003emeta\u003c/em\u003e and \u003cem\u003emetafor\u003c/em\u003e packages. For all statistical testing, p\u0026thinsp;\u0026lt;\u0026thinsp;.05 was considered significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eInstitutional Case Series\u003c/h2\u003e \u003cp\u003eOf 126 BAO were treated during the study period, 123 had complete angiographic and clinical data. Among these, stroke etiology was embolic in 72 (65%, eBAO cohort), of which 61/72 (84.7%) were cardioembolic and 11/72 (15/3%) were embolic stroke of undetermined source (ESUS). Fifty one patients (41.5%) had a non-embolic stroke mechanism including symptomatic atherosclerosis in 25/51 (49.0%), symptomatic stenosis with likely underlying dissection in 13/51 (25.5%) and dissection with artery-to-artery embolus in 13/51 (25.5%).\u003c/p\u003e \u003cp\u003eClinical characteristics of the two groups (eBAO and non-eBAO) are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Patients with eBAO were older (68.4 vs. 61.9, p\u0026thinsp;=\u0026thinsp;.02), had higher rates of atrial fibrillation (44.4% vs. 21.5%, p\u0026thinsp;=\u0026thinsp;.01) and had lower left ventricular ejection fraction (49.9% vs. 57.4%, p\u0026thinsp;=\u0026thinsp;.006).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePrevalence of VAD in Posterior Circulation Stroke Patients\u003c/h3\u003e\n\u003cp\u003eIn the eBAO group, VAD distribution was: LVAD 23.6%, RVAD 33.3%, and CVAD 28.5%. The prevalence of VAD in the non-eBAO group (n\u0026thinsp;=\u0026thinsp;51) had non-significantly higher fraction of LVAD (37.2%, p\u0026thinsp;=\u0026thinsp;.11) and lower fraction of RVAD(19.6%, p\u0026thinsp;=\u0026thinsp;.10) and identical fraction of CVAD 43.1% (p\u0026thinsp;=\u0026thinsp;1.0).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eEstimation of VAD Prevalence in Asymptomatic Populations: Systematic Review and Metanalysis\u003c/h2\u003e \u003cp\u003eInitial screening identified 29 studies, of which 8 met inclusion criteria for further analysis (n\u0026thinsp;=\u0026thinsp;1813 patients).\u003csup\u003e15\u0026ndash;22\u003c/sup\u003e The pooled estimated VAD prevalence of asymptomatic patiens was: LVAD 47.0% (95%CI 39.0-55.1%, \u003cem\u003eI\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;91.0%,\u003cem\u003eτ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u0026thinsp;0.19, p\u0026thinsp;\u0026lt;\u0026thinsp;.001\u003c/em\u003e), RVAD 26.9% (95% CI 22.7\u0026ndash;31.5%, \u003cem\u003eI\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;76.5%,\u003cem\u003eτ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u0026thinsp;0.077, p\u0026thinsp;\u0026lt;\u0026thinsp;.001)\u003c/em\u003e, and CVAD 25.9% (95% CI 18.8\u0026ndash;34.7%, \u003cem\u003eI\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;92.2%,\u003cem\u003eτ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u0026thinsp;0.29, p\u0026thinsp;\u0026lt;\u0026thinsp;.001\u003c/em\u003e). The weighting, distribution, and inter-study heterogeneity are described in forests plots Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Compared to the hypothesis of equal VAD distribution, LVAD was overrepresented (OR 1.74, 95%CI 1.24\u0026ndash;2.42, \u003cem\u003eI\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;82.2%,\u003cem\u003eτ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u0026thinsp;0.19\u003c/em\u003e p\u0026thinsp;\u0026lt;\u0026thinsp;.001), while RVAD (OR 0.72, 95%CI 0.57\u0026ndash;0.90, \u003cem\u003eI\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;56.5%,\u003cem\u003eτ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u0026thinsp;0.06\u003c/em\u003e, p\u0026thinsp;=\u0026thinsp;.027) and CVAD (OR 0.75, 95%CI 0.48\u0026ndash;1.19, \u003cem\u003eI\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;88.9%,\u003cem\u003eτ\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e\u0026thinsp;\u003cem\u003e=\u0026thinsp;0.33\u003c/em\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;.001) were underrepresented. The observed versus hypothetical VAD distributions are summarized in forest plots in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eDifferences in VAD Prevalence in BAO groups and Asymptomatic Patients\u003c/h2\u003e \u003cp\u003eOverall, the distribution of VAD profiles differed significantly in the eBAO group compared to the asymptomatic population estimate (p\u0026thinsp;\u0026lt;\u0026thinsp;.001). Patients with eBAO had significantly lower LVAD prevalence (23.6% vs. 47.0%, OR 0.37, CI 0.20\u0026ndash;0.67, p\u0026thinsp;\u0026lt;\u0026thinsp;.001). Conversely, eBAO patients had higher prevalence of CVAD (43.1% vs. 25.9%, OR 1.89, CI 1.13\u0026ndash;3.13, p\u0026thinsp;=\u0026thinsp;.01). The prevalence of RVAD was also higher in the eBAO group but this was not statistically significant (33.3% vs. 26.9%, OR 1.39, CI 0.81\u0026ndash;2.35, p\u0026thinsp;=\u0026thinsp;.22). Prevalence differences are summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eIn the non-eBAO group, the overall distribution of VAD prevalence was not statistically significant from the asymptomatic population estimate (p\u0026thinsp;=\u0026thinsp;.09). There was a higher prevalence of CVAD (43.1% vs. 25.9%, OR 1.9, CI 1.03\u0026ndash;3.46, p\u0026thinsp;=\u0026thinsp;.03) but no significant difference in prevalence of LVAD (37.2% vs. 47.0%, OR 0.72, CI 0.38\u0026ndash;1.32, p\u0026thinsp;=\u0026thinsp;.32) nor RVAD (19.6% vs. 26.9%, OR 0.68, CI 0.30\u0026ndash;1.39, p\u0026thinsp;=\u0026thinsp;.33).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study identifies a distinct pattern of VAD in patients with eBAO, characterized by lower prevalence of LVAD and relatively higher prevalence of RVAD and CVAD. Notably LVAD was approximately \u0026frac12; as common in eBAO as in asymptomatic patients (23.6% vs. 47.0%). These findings suggest that relatively greater blood flow to the right vertebral artery may increase risk of embolic stroke in the posterior circulation. Conversely, higher prevalence of LVAD in asymptomatic populations could account for the observation that posterior circulation LVO is less frequent than expected based on total cerebral blood flow.\u003c/p\u003e \u003cp\u003eFew studies have focused on VAD in the contemporary era of EVT and these findings have implications for stroke interventionalists. Recent randomized control trials showing benefit of EVT in BAO have underscored the importance of rapid recanalization in this population.\u003csup\u003e3,4\u003c/sup\u003e Whereas transfemoral access is widely used as a first line approach, the right vertebral artery offers a more direct conduit to the basilar artery from a radial artery approach\u003csup\u003e23\u003c/sup\u003e and radial access for EVT has proved effective and safe in published series.\u003csup\u003e24,25\u003c/sup\u003e The observation that \u0026ge;\u0026thinsp;75% of patients with eBAO have either CVAD or RVAD implies that a right radial artery access may be an appropriate first line technique for a substantial fraction of patients this population.\u003c/p\u003e \u003cp\u003eBeyond the implications for EVT, the finding that VAD patterns differ in eBAO raises important questions about the physiology of embolus trajectory. The basilar artery receives 20% of cerebral blood flow\u003csup\u003e9\u003c/sup\u003e, but accounts for fewer than 10% of LVOs.\u003csup\u003e5,26\u003c/sup\u003e In conventional three-vessel aortic arch anatomy, the innominate artery is the first great vessel encountered by systolic blood flow. Aortic arch geometry influences downstream trajectory of emboli, but most studies of embolus trajectory to date are limited to the anterior circulation.\u003csup\u003e6,7\u003c/sup\u003e In-silica computational flow models show that the innominate artery (which gives rise to the right VA in most patients) receives the largest fraction of cardiac output, and that emboli tend to travel proportionally to outlet flow rates.\u003csup\u003e8\u003c/sup\u003e Taken together, these models suggest that vessel geometry and flow are the principle drivers of embolus trajectory. Our finding that CVAD and RVAD are overrepresented in patients with eBAO is consistent with these models, suggesting that greater right vertebral artery flow may increase the probability of embolus flow to the posterior circulation.\u003c/p\u003e \u003cp\u003eIt has long been debated whether VAD or symmetrical vertebral artery anatomy is the most common anatomic configuration. Prior analyses have been limited by small sample sizes and varying definitions of VAD. We present a pooled analysis of eight studies using consistent criteria showing that LVAD is the most common configuration in asymptomatic populations (47%). This is consistent with earlier studies of VA diameter or flow, without specifically classifying VAD.\u003csup\u003e11,13,21,27\u0026ndash;30\u003c/sup\u003e VA blood flow is tightly correlated to vessel caliber \u003csup\u003e29,29,32\u003c/sup\u003e, thus the tendency toward LVAD in the general population implies lower blood flow fraction to the right VA.\u003csup\u003e13\u003c/sup\u003e The left VA arises from the left subclavian artery in 96% of patients and is the most distal and circuitous path from the heart to the intracranial circulation for a central embolus .\u003csup\u003e33\u003c/sup\u003e The prevalence of LVAD anatomy may therefore account for the low frequency of eBAO relative to anterior circulation LVO, owing to lower probability of embolus to the LVA relative to the carotid arteries.\u003c/p\u003e \u003cp\u003ePrior studies of VAD have focused on non-embolic stroke mechanisms\u003csup\u003e34\u003c/sup\u003e including arterial dissection, atherosclerosis, and dolichoectasia.\u003csup\u003e3517,36\u003c/sup\u003e This is among the first studies to consider VAD as a risk factor for embolic posterior circulation stroke. In the non-eBAO cohort, we found no difference in VAD distribution relative to asymptomatic patients. The observed difference in CVAD is potentially attributable to weighting of the metanalysis, which includes one study that did not differentiate CVAD as distinct from unilateral VAD.\u003csup\u003e17\u003c/sup\u003e The relative portions of RVAD and LVAD showed a symmetric decrease in prevalence in the non-eBAO group. Overall, these data suggest that accounting for taxonomic differences, the VAD profile of non-eBAO is similar to asymptomatic patients.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eLimitations:\u003c/h2\u003e \u003cp\u003eThere are several important limitations of this study. First, the patient population (eBAO) was drawn from an endovascular database thus patients who did not undergo EVT are underrepresented. During the study period (2015\u0026ndash;2024) several trials questioned the effect of EVT in BAO therefore evolving practices with EVT could result in selection bias. Next, the use of VAD defined by CTA is an imperfect proxy of true vertebral artery flow and results in an dichotomization of a continuous variable. While ultrasound Doppler is the gold standard in flow assessment, this is not feasible in acutely ill patients. Nonetheless, VAD classification is a practical substitute and easily applied in clinical practice. A related limitation is the amorphous definition of VAD used in the literature. The selected VAD criteria are based on the spatial resolution of CDUS and have been applied in numerous studies, though inter-reader agreement has not been rigorously tested.\u003csup\u003e15\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePatients with eBAO have significantly lower rates of LVAD compared to asymptomatic controls. This finding suggests that vertebral artery anatomy influences risk of posterior circulation embolic stroke. Specifically, right or co-dominant VA blood flow may predispose to eBAO. This has implications for stroke risk stratification and procedural planning in EVT.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe author(s) declare that they had full access to all the data in this study and the authors take complete responsibility for the integrity of the data and the accuracy of the data analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding/ Support:\u003c/strong\u003e None\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e: None\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest/Competing Interests:\u0026nbsp;\u003c/strong\u003eThe authors declare \u003cu\u003eno\u003c/u\u003e conflicts of interest\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval:\u003c/strong\u003e This study was approved by institutional review board (IRB). Informed consent was waived.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Statement:\u003c/strong\u003e All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent\u003c/strong\u003e: Informed consent was waived by the institutional review board (IRB) for all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eD.G. and M.T.C. designed the study concept and wrote the manuscript. D. G., E.M., A.M. and M.T.C. collected the data, performed analysis, and designed figures. All other authors participated in contributing data and reviewing the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eVergouwen MDI, Algra A, Pfefferkorn T, Weimar C, Rueckert CM, Thijs V, Kappelle LJ, Schonewille WJ, null null. Time is Brain(stem) in Basilar Artery Occlusion. \u003cem\u003eStroke\u003c/em\u003e. 2012;43:3003\u0026ndash;3006. \u003c/li\u003e\n\u003cli\u003eLiu H, Zeng G, Zeng H, Yu Y, Yue F, Ke Y, Yan Z, Pu J, Zhang J, Wei W, et al. Endovascular treatment for acute basilar artery occlusion due to different stroke etiologies of large artery atherosclerosis and cardioembolism. \u003cem\u003eEuropean Stroke Journal\u003c/em\u003e. 2022;7:238\u0026ndash;247. \u003c/li\u003e\n\u003cli\u003eJovin TG, Li C, Wu L, Wu C, Chen J, Jiang C, Shi Z, Gao Z, Song C, Chen W, et al. 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The Clinical Research Progress of Vertebral Artery Dominance and Posterior Circulation Ischemic Stroke. \u003cem\u003eCerebrovascular Diseases\u003c/em\u003e. 2022;51:553\u0026ndash;556. \u003c/li\u003e\n\u003cli\u003eZhou M, Zheng H, Gong S, Guo J, Chen N, Zhou D, Yang R, Zhu C, He L. Vertebral artery hypoplasia and vertebral artery dissection. \u003cem\u003eNeurology\u003c/em\u003e. 2015;84:818\u0026ndash;824. \u003c/li\u003e\n\u003cli\u003eCaton MT, Narsinh K, Han W, Chaganti R, Graf J, Halabi C, Winkler E, Cooke DL. A Preliminary Study of Anti‐TNF\u0026alpha; Therapy for Symptomatic Dolichoectatic Vertebrobasilar Aneurysms. \u003cem\u003eStroke: Vascular and Interventional Neurology\u003c/em\u003e. 2024;4:e000890. \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table 1","content":"\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab1\" border=\"1\" class=\"fr-table-selection-hover\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCharacteristics of patients with embolic (eBAO) vs. non-embolic (non-eBAO) posterior circulation stroke from single-center retrospective review\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eEmbolic Basilar Artery Occlusion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNon-embolic Basilar artery occlusion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e69.4\u0026thinsp;\u0026plusmn;\u0026thinsp;14.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e61.9\u0026thinsp;\u0026plusmn;\u0026thinsp;18.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex (% women)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25/72 (34.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20/51 39.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAtrial Fibrillation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32/72 (44.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11/51 21.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.01*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eLV Ejection Fraction\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e49.9\u0026thinsp;\u0026plusmn;\u0026thinsp;16.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e57.5\u0026thinsp;\u0026plusmn;\u0026thinsp;14.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.006**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAortic Arch Type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eType 1\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e62/72 (86.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45/51 (88.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eType 2\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7/72 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6/51 (11.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.77\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eOther\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3/72 (4.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003en/a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e---\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVertebral Artery Dominance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eLVAD\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17/72 (23.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19/51 (37.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eRVAD\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24/72 (33.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10/51 (19.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eCVAD\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31/72 (43.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e22/51 (43.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6490223/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6490223/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose:\u003c/h2\u003e \u003cp\u003eEmbolic basilar artery occlusion (eBAO) is less common than anterior circulation stroke. The anatomic basis for this discrepancy is not understood. Vertebral artery dominance (VAD) correlates with blood flow to the basilar artery. We hypothesized that left VAD is less common in eBAO, as the right vertebral artery is the more proximal to the heart in typical aortic arch anatomy.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eThis retrospective single-center, case-control study identified cases of eBAO. Right, left, and co-dominant (RVAD, LVAD, and CVAD) prevalence was calculated in standardized fashion by CTA. To estimate the VAD prevalence in asymptomatic patients, a systematic review and metanalysis was performed. The pooled estimate of VAD prevalence in the asymptomatic group was compared to the eBAO cohort using χ\u003csup\u003e2\u003c/sup\u003e test.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eIn total, 72 eBAO were identified in the institutional cohort, and prevalence of LVAD, RVAD, and CVAD was 23.6%, 33.3%, and 43.1% respectively. Systematic review included eight studies and 1813 asymptomatic patients. Mean VAD prevalence in the asymptomatic population was LVAD 47.0% (39.0-55.1%), RVAD 26.9% (22.7\u0026ndash;31.5%), and CVAD 25.9% (18.8\u0026ndash;34.7%). VAD proportions differed significantly in the eBAO group (p\u0026thinsp;\u0026lt;\u0026thinsp;.001), with lower proportion of LVAD (OR 0.37, CI 0.20\u0026ndash;0.67, p\u0026thinsp;\u0026lt;\u0026thinsp;.001), higher proportion of CVAD (OR 1.89, CI 1.13\u0026ndash;3.13, p\u0026thinsp;=\u0026thinsp;.01) but no difference in RVAD (1.39, CI 0.81\u0026ndash;2.35, p\u0026thinsp;=\u0026thinsp;.22).\u003c/p\u003e\u003ch2\u003eConclusion:\u003c/h2\u003e \u003cp\u003eLVAD is significantly less common in patients with eBAO compared to asymptomatic patients. Non-LVAD anatomy (RVAD and CVAD) may represent a novel anatomic risk factor for eBAO. This finding could influence techniques for endovascular thrombectomy.\u003c/p\u003e","manuscriptTitle":"Vertebral Artery Dominance in Patients with Embolic Basilar Artery Occlusion: Insights Toward Embolus Trajectory","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-08 14:57:30","doi":"10.21203/rs.3.rs-6490223/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"96e7003d-c03d-4591-8316-f575d029a352","owner":[],"postedDate":"May 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-05-10T15:08:24+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-08 14:57:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6490223","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6490223","identity":"rs-6490223","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}