Inflammatory Markers and Prognosis After Cerebral Thrombectomy in Large Vessel Occlusion

• Prospective Mechanical Thrombectomy Cohort (Other): Adults with acute ischemic stroke due to anterior circulation large vessel occlusion who undergo clinically indicated mechanical thrombectomy. All participants receive standard stroke care determined by the treating clinical team; no experimental intervention is assigned. Paired arterial blood samples are collected during thrombectomy from sites proximal and distal to the thrombus. A peripheral venous blood sample collected at hospital admission is used as a supportive systemic reference. Clinical, imaging, procedural, and 90-day functional outcome data are collected prospectively.

Primary outcomes

• Trans-Thrombus Interleukin-6 Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus interleukin-6 (IL-6) gradient, defined as ln \[T2b/T2a\], where T2b is the IL-6 concentration in arterial plasma collected distal to the thrombus and T2a is the IL-6 concentration in arterial plasma collected proximal to the thrombus.

Secondary outcomes

• Trans-Thrombus Interleukin-1 Beta Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus Interleukin-1β gradient, defined as ln\[T2b/T2a\], where T2b is the Interleukin-1β concentration in arterial plasma collected distal to the thrombus and T2a is the Interleukin-1β concentration in arterial plasma collected proximal to the thrombus.
• Trans-Thrombus Interleukin-17 Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus Interleukin-17 gradient, defined as ln\[T2b/T2a\], where T2b is the Interleukin-17 concentration in arterial plasma collected distal to the thrombus and T2a is the Interleukin-17 concentration in arterial plasma collected proximal to the thrombus.
• Trans-Thrombus Complement C3 Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus Complement C3 gradient, defined as ln\[T2b/T2a\], where T2b is the Complement C3 concentration in arterial plasma collected distal to the thrombus and T2a is the Complement C3 concentration in arterial plasma collected proximal to the thrombus.
• Trans-Thrombus Complement C5a Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus Complement C5a gradient, defined as ln\[T2b/T2a\], where T2b is the Complement C5a concentration in arterial plasma collected distal to the thrombus and T2a is the Complement C5a concentration in arterial plasma collected proximal to the thrombus.
• Trans-Thrombus Malondialdehyde Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus Malondialdehyde gradient, defined as ln\[T2b/T2a\], where T2b is the Malondialdehyde concentration in arterial plasma collected distal to the thrombus and T2a is the Malondialdehyde concentration in arterial plasma collected proximal to the thrombus.
• Trans-Thrombus Matrix Metalloproteinase-9 Gradient [During mechanical thrombectomy, before recanalization]: The primary outcome is the within-participant trans-thrombus Matrix Metalloproteinase-9 gradient, defined as ln\[T2b/T2a\], where T2b is the Matrix Metalloproteinase-9 concentration in arterial plasma collected distal to the thrombus and T2a is the Matrix Metalloproteinase-9 concentration in arterial plasma collected proximal to the thrombus.
• Modified Rankin Score [90 (±14) days]: The ordinal distribution of modified Rankin Scale (mRS) scores from 0 (no symptoms) to 6 (death).
• Functional independence [90 (±14) days]: The proportion of mRS score of 0-2 at 90 days.
• Good Function [90 (±14) days]: The proportion of mRS score of 0-3 at 90 days.
• Early neurological improvement [24 (±12) hours]: The proportion of NIHSS 0-1 or ≥4 points reduction at 24 (±12) hours.
• Change in stroke severity [7 (±1) days or at discharge]: The change of NIHSS score from baseline to 7 days or at discharge (whichever comes first)
• Quality of life measured by EQ-5D-5L [90 (±14) days]: EQ-5D-5L scale score at 90 days.

Other outcomes

• Symptomatic intracranial hemorrhage [24 (±12) hours]: Incidence of symptomatic intracranial hemorrhage within 36 hours from randomization (Heidelberg criteria)
• Any intracranial hemorrhage [24 (±12) hours]: Incidence of any intracranial hemorrhage within 36 hours from randomization (Heidelberg classification)
• Extracranial bleeding [24 (±12) hours]: Incidence of moderate-to-severe extracranial bleeding (GUSTO criteria) within 36 hours from randomization
• Malignant Cerebral Edema [7 (±1) days or at discharge]: Cerebral edema causing substantial mass effect, defined by neurological deterioration with imaging evidence of space-occupying cerebral swelling and/or the requirement for decompressive hemicraniectomy
• Mortality [90 days]: All cause death within 90 days.
• Modified Rankin Score [1 year]: The ordinal distribution of modified Rankin Scale (mRS) scores from 0 (no symptoms) to 6 (death).

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Age 18 years or older.
* Acute ischemic stroke caused by anterior circulation large vessel occlusion, confirmed by routine vascular imaging or digital subtraction angiography.
* Undergoing clinically indicated mechanical thrombectomy according to routine clinical practice.
* Provision of written informed consent by the participant or legally authorized representative, in accordance with local ethics requirements.

Exclusion Criteria:

* Posterior circulation large vessel occlusion.
* Mechanical thrombectomy not performed.
* Known active systemic infection, active malignancy, or chronic inflammatory/autoimmune disease requiring systemic immunosuppressive treatment, when these conditions are expected to substantially affect inflammatory biomarker measurements.
* Pregnancy or breastfeeding, if required by the local ethics committee.
* Enrollment in another interventional study that could affect inflammatory biomarker measurements or clinical outcome assessment.
* Inability to obtain informed consent, where consent from a legally authorized representative is not permitted or cannot be obtained.

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• Xingyu Chen, MD, Principal investigator, Zhongshan Hospital Xiamen University