Cortical Vein Opacification for Risk Stratification in Anterior Circulation Endovascular Thrombectomy
Introduction
Endovascular thrombectomy (EVT) has been established as a standard of care for the acute ischemic stroke due to anterior circulation large vessel occlusion (ACLVO). In 2015, 5 randomized controlled trials (MR CLEAN, ESCAPE, REVASCAT, SWIFT PRIME, and EXTEND IA) showed the benefit of mechanical thrombectomy over the standard medical management.1, 2, 3, 4, 5 Pooled analysis of these trials (HERMES) found that EVT within 12 hours of symptom onset achieves a favorable neurologic outcome (modified Rankin Scale [mRS] of 0-2) in roughly 20% at 90 days.6 Imaging used to guide treatment for these trials included computed tomographic angiography (CTA) to identify an occlusion in a proximal cerebral artery, and noncontrast computed tomography (CT) to identify at-risk but noninfarcted cortex (the ischemic penumbra) via the Alberta Stroke Program Early CT Score (ASPECTS). More recent trials such as DAWN and DEFUSE 3 used perfusion imaging in conjunction with automated software to better characterize the ischemic penumbra.7, 8 They also demonstrated the efficacy of EVT up to 24 hours after symptom onset. Despite the fact that patients in the latter trials had a much longer time from symptom onset to reperfusion, a greater proportion of these patients were functionally independent at 90 days (49% and 45%, respectively).7, 8 This so-called late window paradox likely reflects the ability to select for patients with a relatively small core infarct and favorable collaterals that stall the loss of the penumbra by using perfusion imaging.9
Cortical venous opacification on CTA is another potential means to assess the tissue state and extent of collateral circulation for patients with ACLVO. Two recent studies have explored this possibility, each with its own scoring system.10, 11 The Prognostic Evaluation based on Cortical vein score difference In Stroke (PRECISE) study found that decreased opacification of the cortical veins in the affected hemisphere compared to the unaffected hemisphere was predictive of poor outcome (mRS 3-6).11 The Cortical Vein Opacification Score (COVES) study was a larger retrospective study using data from MR CLEAN. This group found that the absence of cortical venous opacification in the affected hemisphere was not only associated with poor outcomes but also a lack of benefit from EVT when compared to a control group.10
The availability of additional factors for identifying patients who are more likely to benefit from EVT is desirable. Although ASPECTS and CT perfusion provide valuable information regarding the presence of salvageable tissue, assessment of venous opacification may augment this by indicating the resistance of the microcirculatory bed in the affected vascular territory. The COVES and PRECISE scores differ both in the veins they evaluate and the manner in which they are calculated. To date, the 2 scores have not been directly compared, and their predictive abilities have only been evaluated in the studies introducing them. As a result, their use in clinical practice remains limited. Our study aimed to assess and compare the sensitivity and specificity of the PRECISE and COVES scores for predicting functional outcomes after EVT for ACLVO in our own retrospective cohort.
Section snippets
Patient Selection
After obtaining Institutional Review Board approval (#962789-4), a retrospective review was performed identifying all patients at our institution who received EVT for ACLVO between January 1, 2014 and December 25, 2017. Inclusion criteria included the availability of pre-procedural CTA and confirmation of ACLVO as defined by occlusion of the internal carotid artery or proximal middle cerebral artery (M1 or proximal M2) on digital subtraction angiography. The electronic medical record was
Demographic and Presenting Data
From 2014 to 2017 a total of 369 patients received EVT for proximal anterior circulation stroke. There were 103 patients with preprocedural CTA available to evaluate venous opacification, and these patients were included in the study. Those without CTA had imaging from an outside hospital that was not available (155), did not receive CTA due to hyperdense MCA sign on noncontrast CT (89), or had preprocedural MR angiography instead of CTA (22). Inclusion and exclusion of patients in this study
Discussion
The use of mechanical thrombectomy for large vessel stroke continues to expand as more trial data becomes available and patient selection criteria are continually refined. The 2018 American Heart Association/American Stroke Association guidelines extended the therapeutic window of EVT to 24 hours, which reflected the added value of perfusion imaging-based selection as demonstrated in the DAWN and DEFUSE 3 trials.12 One study found that ASPECTS score and an arterial collateral score could be
Conclusions
Poor cortical venous opacification, as defined by an unfavorable COVES score, was associated with unfavorable neurologic outcomes at 90 days in our retrospective cohort of patients undergoing EVT for ACLVO. Furthermore, favorable COVES scores were associated with favorable 90-day functional outcomes. We believe that this scoring system has a useful adjunctive role in patient selection for mechanical thrombectomy, particularly in the early therapeutic window. However, a prospective multicenter
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2023, Clinical Neurology and NeurosurgeryCitation Excerpt :As far as we are aware, this observation has not been previously reported. An additional prognostic value from the incorporation of MV to CV can be seen with an incremental rise in the odds ratio of COVES compared to PRECISE (CV only) and with our model (CV + MV) compared to COVES [10]. As shown in Table 1, 85 % of patients with MV asymmetry had a suboptimal clinical outcome, whereas only 50 % of patients with MV symmetry had a good clinical outcome.
The authors have no competing interests to declare.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.