Thrombectomy Outcomes in the 6-24 Hour Window

Patient Selection and Technical Goals

For anterior circulation strokes presenting 6-24 hours after last known well, thrombectomy is indicated when imaging demonstrates salvageable tissue, according to the American Heart Association guidelines 1
The American Heart Association recommends CT perfusion or diffusion-weighted MRI with perfusion imaging to demonstrate salvageable tissue for patients beyond 6 hours 1
The angiographic target should be modified TICI 2b/3 reperfusion to maximize functional outcomes, as suggested by clinical guidelines 1, 2

For basilar artery occlusion, thrombectomy is indicated from 0-12 hours (Class I, Level B-R) and reasonable from 12-24 hours (Class IIa, Level B-R), according to guidelines 3
Beyond 24 hours, thrombectomy may be reasonable on a case-by-case basis (Class IIb, Level C-EO), though outcomes are generally poor and benefit uncertain 3

The American College of Cardiology and other guideline societies imply that delaying thrombectomy for unnecessary testing should be avoided, with only blood glucose measurement required before treatment 1
The American Heart Association suggests not waiting to assess IV thrombolysis response before proceeding to angiography if thrombectomy is being considered, as stated in clinical guidelines 4
Thrombectomy should not be attempted without perfusion imaging in the 6-24 hour window, as tissue selection is mandatory for benefit, according to the American Heart Association 1

The American Heart Association recommends thrombectomy for basilar artery occlusion from 0-12 hours (Class I, Level B-R) based on the ATTENTION trial 5
Thrombectomy is reasonable (Class IIa, Level B-R) from 12-24 hours for basilar artery occlusion based on the BAOCHE trial 5
The BAOCHE trial demonstrated 46% of patients achieved favorable outcomes (mRS 0-3) versus 24% with medical therapy alone 6
The ATTENTION trial showed 46% achieved good functional outcome (mRS 0-3) versus 23% with medical therapy (absolute risk reduction 2.06) 6
Mortality at 90 days was significantly lower with thrombectomy: 31-37% versus 42-55% with medical therapy 6
Symptomatic intracranial hemorrhage remained low at 5-6%, not significantly different from medical therapy 6
Patients must have PC-ASPECTS ≥6 for posterior circulation strokes 5

Thrombectomy beyond 24 hours may be reasonable on a case-by-case basis (Class IIb, Level C-EO) for basilar artery occlusion 5
Functional outcomes beyond 24 hours remain poor when recanalization is achieved >9 hours after onset in patients with low NIHSS scores (≤6) 5

The American Heart Association/American Stroke Association recommends CT perfusion or diffusion-weighted MRI with perfusion imaging for patients presenting 6-24 hours after last known well with suspected large vessel occlusion to identify salvageable brain tissue 7, 8

For patients presenting within 6 hours who meet standard thrombectomy criteria, perfusion imaging is not required, and thrombectomy can be proceeded with based on non-contrast CT and CTA alone, as recommended by the American Heart Association/American Stroke Association 7, 8
Within the 6-24 hour window, perfusion imaging is mandatory to demonstrate salvageable tissue using either CT perfusion or diffusion-weighted MRI with perfusion imaging, according to the American Heart Association/American Stroke Association 7, 8
The American Heart Association/American Stroke Association suggests applying strict eligibility criteria from landmark trials, including DAWN criteria and DEFUSE-3 criteria, to select patients for thrombectomy 7, 8

For patients developing stroke after cardiac surgery, urgent CTA and perfusion imaging is indicated, and they should be strongly considered for extended window thrombectomy based on individualized perfusion imaging data, as suggested by the Journal of Neurointerventional Surgery 9
For posterior circulation strokes, non-contrast CT with PC-ASPECTS ≥6 and CTA confirming basilar occlusion is sufficient for treatment decisions, and thrombectomy is indicated 0-12 hours (Class I) and reasonable 12-24 hours (Class IIa) based on clinical criteria alone, according to the Journal of Neurointerventional Surgery 10

The current AHA/ASA guidelines (Class I, Level A) mandate perfusion imaging for 6-24 hour patient selection, and the DEFUSE-3 and DAWN trials provide the highest quality evidence (Level A) supporting perfusion-based selection, with a number needed to treat below 3 for positive outcome shift 7, 8