Association Between the Degree of Vertebrobasilar Stenosis, Location, Infarction Pattern and QMRA Flow State

Background and Purpose The relationship between the degree and location of vertebrobasilar stenosis and QMRA distal-flow status is uncertain. Our aim was to investigate the relationship between QMRA distal-flow status with degree and location of vertebrobasilar stenosis. Methods We retrospectively reviewed patients who presented with acute ischemic stroke, had neurovascular imaging demonstrating ≥50% stenosis of extracranial or intracranial vertebral or basilar arteries, and QMRA performed within one year of stroke, between 2009 and 2021. Standardized methods were used to measure the degree of stenosis and to dichotomize vertebrobasilar distal-flow status. Patients were grouped based on the involved artery and the location and severity of disease. P-values were calculated using chi-squared analysis and Fisher exact test with statistical significance defined as p <0.05. Results Sixty-nine patients met study inclusion, consisting of 31 with low distal-flow and 38 with normal distal-flow states. Low distal-flow states were found exclusively in patients with severe stenosis or occlusion; however, severe stenosis or occlusion was poorly predictive of distal-flow status as nearly half of these patients had normal flow states (47%). Bilateral vertebral disease was significantly associated with low distal-flow states compared to patients with unilateral vertebral (70.8% versus 14.3%; p = 0.01), isolated basilar (70.8% versus 28.6%; p = 0.01), or mixed (71.4% versus 47.1%; p = 0.01) disease. Conclusions Severe stenosis of ≥70% may mark the minimal threshold required to cause hemodynamic insufficiency in the posterior circulation, but nearly half of these patients may remain hemodynamically sufficient. The presence of bilateral vertebral stenosis resulted in a five-fold increase in the probability of QMRA low distal-flow status compared to unilateral vertebral disease. Our findings may have implications for the design of future treatment trials of endovascular versus medical management that may use hemodynamic markers as inclusion criteria. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement None. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Not Applicable The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Feinstein Institute for Medical Research IRB #: 21-0006 I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Not Applicable I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Not Applicable I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Not Applicable All data is available upon request