The goal of this clinical trial is to determine whether rescue distal mechanical thrombectomy can improve outcomes in patients with persistent distal occlusions after successful proximal mechanical thrombectomy for acute ischemic stroke.

Many patients with acute ischemic stroke caused by large vessel occlusion undergo emergency treatment with proximal mechanical thrombectomy, which removes the main clot and restores flow in a large artery. However, in some patients, one or more smaller distal arteries remain occluded after successful proximal recanalization. It is not yet known whether treating these persistent distal occlusions improves angiographic or clinical outcomes.

This study will compare two approaches:

Rescue distal mechanical thrombectomy: an additional distal mechanical thrombectomy procedure is performed during the same endovascular session.

Conservative management: no additional distal endovascular intervention is performed after successful proximal mechanical thrombectomy.

The main questions the study aims to answer are:

• Is rescue distal mechanical thrombectomy feasible in this setting?
• Is it safe?
• Does it improve angiographic and clinical outcomes?

Participants will be randomly assigned during the index endovascular procedure to one of the two study groups and will be followed with imaging and clinical assessments during hospitalization and at 90 days.

Approximately 72 participants will take part in this study at the Centre hospitalier de l'Université de Montréal (CHUM).

The 2BE3 - Phase II study is a clinical trial designed to evaluate the feasibility and safety of rescue distal mechanical thrombectomy in patients with persistent distal occlusions following successful proximal recanalization.

Endovascular thrombectomy has become the standard of care for acute ischemic stroke caused by large vessel occlusion (LVO), with substantial improvement in clinical outcomes demonstrated in multiple randomized trials. However, despite successful recanalization of the primary occlusion, a proportion of patients continue to have persistent distal occlusions or incomplete reperfusion, which may limit neurological recovery. Residual distal occlusions, particularly in medium- and distal-vessel territories, remain an important and insufficiently studied contributor to suboptimal outcomes after thrombectomy.

The optimal management of persistent distal occlusions after successful proximal thrombectomy remains uncertain. In current practice, some operators perform rescue distal mechanical thrombectomy, whereas others do not perform additional distal endovascular intervention because of concerns related to vessel injury, hemorrhagic complications, or prolonged procedure time. As a result, management remains variable and is not currently guided by high-level evidence.

This is a randomized, controlled, open-label trial with blinded outcome assessment (PROBE design). Approximately 72 adult patients with acute ischemic stroke who undergo successful proximal mechanical thrombectomy but have one or more persistent distal occlusions will be enrolled. During the index endovascular procedure, eligible participants will be randomly assigned to one of two study groups:

Rescue distal mechanical thrombectomy group: participants undergo rescue distal mechanical thrombectomy during the same endovascular session.

Conservative management group: no additional distal endovascular intervention is performed after successful proximal mechanical thrombectomy.

The primary objective of the study is to evaluate the feasibility and safety of rescue distal mechanical thrombectomy in this clinical setting. Secondary objectives include evaluating angiographic reperfusion, functional outcome at 90 days, early neurological improvement, and procedure-related safety outcomes.

Because this study is conducted in an emergency stroke setting, the consent process is adapted to the participant's clinical condition. Whenever possible, informed consent is obtained directly from the participant before inclusion. If the participant lacks decision-making capacity, consent is obtained from an authorized representative, in accordance with applicable local regulations and ethics requirements. If decision-making capacity is regained, the participant is informed about the study and continued participation is confirmed according to the protocol.

The trial is conducted at the Centre hospitalier de l'Université de Montréal (CHUM). All procedures included in the study are already used in routine clinical stroke care. Data are collected securely using the REDCap system, and imaging and clinical outcomes are assessed by independent evaluators blinded to treatment allocation.

This phase II trial is intended to generate feasibility, safety, and preliminary outcome data to inform the design of a future larger study. The results may help guide treatment decisions for patients with persistent distal occlusions after proximal thrombectomy.

Inclusion Criteria:

• Age ≥ 18 years
• Acute ischemic stroke with proximal large vessel occlusion (M1, M2, ICA, or basilar artery) treatable with mechanical thrombectomy
• Presence of one or more persistent distal occlusions (M2-M4, A1-A5, or P1-P5) after successful proximal mechanical thrombectomy
• The participant is considered suitable for either rescue distal mechanical thrombectomy or conservative management in the event of persistent distal occlusion
• Informed consent obtained from the participant or authorized representative, in accordance with the protocol and local regulations

Exclusion Criteria:

• Poor expected 3-month prognosis due to comorbid conditions
• Opposition by the participant or, in emergency inclusion circumstances, by an authorized representative

We may consider sharing de-identified individual participant data (IPD) upon reasonable request, after study completion and publication of primary results. Any data sharing will be subject to applicable ethical approvals, data use agreements, and privacy regulations.