Frequency, Determinants, and Outcomes of Emboli to Distal and New Territories Related to Mechanical Thrombectomy for Acute Ischemic Stroke

Abstract

Background and Purpose: Clot fragmentation and distal embolization during endovascular thrombectomy for acute ischemic stroke may produce emboli downstream of the target occlusion or in previously uninvolved territories. Susceptibility-weighted magnetic resonance imaging can identify both emboli to distal territories (EDT) and new territories (ENT) as new susceptibility vessel signs (SVS). Diffusion-weighted imaging (DWI) can identify infarcts in new territories (INT). Methods: We studied consecutive acute ischemic stroke patients undergoing magnetic resonance imaging before and after thrombectomy. Frequency, predictors, and outcomes of EDT and ENT detected on gradient-recalled echo imaging (EDT-SVS and ENT-SVS) and INT detected on DWI (INT-DWI) were analyzed. Results: Among 50 thrombectomy-treated acute ischemic stroke patients meeting study criteria, mean age was 70 (±16) years, 44% were women, and presenting National Institutes of Health Stroke Scale score 15 (interquartile range, 8–19). Overall, 21 of 50 (42%) patients showed periprocedural embolic events, including 10 of 50 (20%) with new EDT-SVS, 10 of 50 (20%) with INT-DWI, and 1 of 50 (2%) with both. No patient showed ENT-SVS. On multivariate analysis, model-selected predictors of EDT-SVS were lower initial diastolic blood pressure (odds ratio, 1.09 [95% CI, 1.02–1.16]), alteplase pretreatment (odds ratio, 5.54 [95% CI, 0.94–32.49]), and atrial fibrillation (odds ratio, 7.38 [95% CI, 1.02–53.32]). Classification tree analysis identified pretreatment target occlusion SVS as an additional predictor. On univariate analysis, INT-DWI was less common with internal carotid artery (5%), intermediate with middle cerebral artery (25%), and highest with vertebrobasilar (57%) target occlusions ( P =0.02). EDT-SVS was not associated with imaging/functional outcomes, but INT-DWI was associated with reduced radiological hemorrhagic transformation (0% versus 54%; P <0.01). Conclusions: Among acute ischemic stroke patients treated with thrombectomy, imaging evidence of distal emboli, including EDT-SVS beyond the target occlusion and INT-DWI in novel territories, occur in about 2 in every 5 cases. Predictors of EDT-SVS are pretreatment intravenous fibrinolysis, potentially disrupting thrombus structural integrity; atrial fibrillation, possibly reflecting larger target thrombus burden; lower diastolic blood pressure, suggestive of impaired embolic washout; and pretreatment target occlusion SVS sign, indicating erythrocyte-rich, friable target thrombus.

Development of a clot-adhesive coating to improve the performance of thrombectomy devices

“…In spite of radiological success in about 80% of territories which occurs in about 2 every 5 cases (40% of cases). 4 Lastly, Luraghi et al…”

“…21 In addition, Wong et al documented the issue regarding SE in distal or new territories which occurs in about 2 every 5 cases (40% of cases). 4 Lastly, Luraghi et al described the clot rolling phenomena during the MT resulting in the detachment of the thrombi from the device during the procedure, study ran with a variety of commercial BMS devices using an in vitro model. 22 A recent translational study suggests that thrombectomy outcome would be significantly improved by strategies aimed at increasing the incorporation of the embolus within the device and at minimizing the release of secondary emboli.…”

“…21 In addition, Wong et al documented the issue regarding SE in distal or new territories which occurs in about 2 every 5 cases (40% of cases). 4 Lastly, Luraghi et al…”

“…However, MT procedures carry the risk of iatrogenic clot fragmentation and embolism towards the distal vascular bed, defined as secondary embolism (SE). Such SE may unfavorably influence clinical outcome 4 . Various strategies have been employed to reduce SE rates including the design refinement of MT devices and the study of their effectiveness to interact with the clot [5][6][7] .…”

Distal Embolization in Relation to Radiological Thrombus Characteristics, Treatment Details, and Functional Outcome

“…Among the 48 participating centers, 23 (48%) had thin-slice NCCT and CTA available in more than 70% of their patients. We excluded cases with: (1) poor arterial opacification on baseline CTA (n=4), (2) uncorrectable coregistration errors (n=19), (3) motion or beam hardening artifacts (n=30), (4) NCCT with residual contrast in the vessels as a result of initial contrast injection at the referring site (n=45), (5) patients with no or minimal reperfusion on final DSA run (expanded Thrombolysis in Cerebral Infarction Score 0-1) and absence of emboli in new territory (ENT) at the last angiography run, as the occurrence of DE in the downstream territory cannot be reliably determined beyond an occluded and non-revascularized artery on DSA (n=20; Figure ).…”