What is the role of thrombectomy in treating distal and medium vessel (cerebral vessel) occlusions?

From the Guidelines

Thrombectomy is a reasonable treatment option for carefully selected patients with acute ischemic stroke (AIS) due to distal and medium vessel occlusions, particularly those with M2 or M3 occlusions, when treatment can be initiated within 6 hours of symptom onset.

Key Considerations

• The benefits of thrombectomy for distal and medium vessel occlusions are uncertain, but it may be reasonable for patients with AIS in whom treatment can be initiated within 6 hours of symptom onset and who have causative occlusion of the MCA segment 2 (M2) or MCA segment 3 (M3) portion of the MCAs 1.
• The use of mechanical thrombectomy with stent retrievers may be beneficial for patients with M2 occlusions, but the adjusted common OR was not significant (1.28; 95% CI, 0.51–3.21) 1.
• The direction of treatment effect for mechanical thrombectomy over standard care was favorable in M2 occlusions, but the OR and 95% CI were not significant in patient-level data pooled from trials in which the Solitaire was the only or the predominant device used 1.
• Reperfusion was associated with excellent functional outcomes (mRS score 0–1; OR, 2.2; 95% CI, 1.0–4.7) among patients with M2 occlusions 1.
• The use of mechanical thrombectomy with stent retrievers may be reasonable for carefully selected patients with AIS in whom treatment can be initiated within 6 hours of symptom onset and who have causative occlusion of the anterior cerebral arteries, vertebral arteries, basilar artery, or posterior cerebral arteries 1.

Thrombectomy Devices and Techniques

• Stent retrievers remain the first choice for mechanical thrombectomy, but the use of other devices, such as contact aspiration, may be reasonable in some circumstances 1.
• The concomitant use of distal-access suction catheters during stent retriever mechanical thrombectomy has been described in retrospective case series and may provide rapid, effective, and safe recanalization 1.

Anesthetic Techniques

• Conscious sedation and general anesthesia are the two most frequently used anesthetic approaches for patients with AIS receiving endovascular therapy, but no dedicated randomized, controlled, clinical trials have addressed this issue 1.
• Either method of procedural sedation is reasonable, but further randomized trial data are needed to determine the optimal anesthetic technique 1.

From the Research

Role of Thrombectomy in Treating Distal and Medium Vessel Occlusions

• Thrombectomy is a treatment option for distal and medium vessel occlusions, with studies showing its safety and efficacy in improving clinical outcomes 2, 3, 4.
• Mechanical thrombectomy (MT) has been shown to be effective in recanalizing distal medium vessel occlusions (DMVOs) with high success rates (>90%) and low complication rates 2, 3.
• The use of MT in DMVOs has been associated with significant improvements in clinical severity and disability at discharge, with favorable outcomes more frequent in the DMVO group compared to the M1 group 2.
• Suction thrombectomy using a microcatheter is a viable alternative treatment for tortuous DMVOs, with case series showing good results 5.
• The utility of additional imaging (CTP) in patients with medium vessel occlusions (MeVOs) who received thrombolysis at a spoke hospital and were transferred to the hub is still being evaluated, with studies showing no significant difference in long-term outcomes between the CTP and non-CTP groups 6.

Clinical Outcomes and Complications

• Studies have shown that MT is safe and effective for DMVOs, with low rates of symptomatic intracranial hemorrhage (ICH) and mortality 2, 3, 4.
• The rate of procedural complications, such as vessel perforations, is rare and comparable to MT for M1-segment occlusions 2.
• Multivariate analysis has identified younger age and lower NIHSS scores as predictors of favorable outcomes in distal occlusions 2.
• Successful recanalization has been associated with clinical improvement in patients with DMVOs 3.

Treatment Considerations

• Careful patient selection and individualized treatment remain critical in the management of DMVOs, given the typically less severe presentations and similar risk profiles to MT for M1-segment occlusions 2.
• Mechanical thrombectomy should be considered in stroke patients with confirmed medium vessel occlusions who receive thrombolysis, with CTP utilization potentially leading to lower angiography utilization and longer door-to-procedure times 6.