For this retrospective study, the investigators will collect and analyze data of patients who presented with posterior artery occlusion and underwent mechanical thrombectomy (the type of endovascular stroke treatment) and intravenous thrombolysis (the type of non-endovascular stroke treatment).

The electronic health records will be queried for the demographic, medical history, and outcomes data of all patients with posterior cerebral artery occlusion who underwent mechanical thrombectomy, intravenous thrombolysis (IVT), or medical management.

The primary aims of the research are to evaluate, in patients presenting with posterior artery occlusion (PCA), whether favorable outcome would be superior for EVT compared to Medically Management (MM), inclusive of intravenous thrombolysis (IVT), as measured by:

• 90-day modified Rankin Scale (mRS) ordinal shift or
• decrease in NIH Stroke Scale/Score (NIHSS) by two points at 24 hours or at hospital discharge

The secondary aims are to evaluate in patients presenting with PCA occlusion, other outcome and safety metrics:

• 90-day functional independence, mRS 0-2
• 90-day excellent outcome, mRS 0-1
• Visual field recovery (none, partial, complete) by 90-days
• rate of reperfusion by modified thrombolysis in cerebral infarction (TICI) scale grade
• any intracranial hemorrhage
• symptomatic intracranial hemorrhage
• mortality

In subgroup analysis, the investigators aim to identify subgroups that may confer differential treatment benefit by:

• location of occlusion on the PCA segment (P1, P2, P3)
• NIHSS strata (0-6, 7-15,>16)
• time from symptom onset to treatment (0 to <6h vs 6-24h)
• posterior circulation (PC) Acute Stroke Prognosis Early Computed Tomography Score (ASPECTS)
• visual field defect on presentation

The investigators hypothesize that greater benefit in outcomes would be seen in EVT treated patients with higher NIHSS, more proximal PCA occlusion, higher PC ASPECTS scores, and shorter time from symptom onset to treatment.

Inclusion Criteria:

• Had an ischemic stroke with isolated posterior cerebral artery occlusion (P1, P2, or P3 segments) and was medically managed or managed with EVT during the study time period.

Exclusion Criteria:

• Patient with documented basilar artery occlusion and concomitant PCA occlusion
• Patient with documented basilar artery occlusion, migration with secondary PCA occlusion

Patients identified from electronic health records who have undergone stroke medical management treatment from 1/01/2003 to 01/01/2022 and patients who have undergone EVT stroke treatment from 01/01/2015 - 01/01/2022.