Introduction Endovascular therapy (EVT) has been shown to be superior for the treatment of acute basilar-artery occlusion compared to standard medical care. However, it is unknown if the number of retrieval attempts performed during EVT for posterior circulation stroke (PCS) influence the clinical outcome.

Aim of Study Our goal was to quantify the influence of EVT on clinical outcome depending on the number of retrievals needed for successful reperfusion in a large multi-center cohort of PCS patients.

Methods Of 6635 patients from the German Stroke Registry, patients who received EVT for posterior circulation stroke with known admission National Institutes of Health Stroke Scale (NIHSS) score, final Thrombolysis in Cerebral Infarction (TICI) score, and number of retrievals were included. Successful reperfusion was defined as a TICI score of 2b/3. The primary outcome was defined as a modified Rankin scale (mRS) of 0–3 at day 90.

Results The inclusion criteria were met by 528 patients from 21 centers. Besides the highly significant negative association with older age, higher NIHSS and positive association with iv. thrombolysis, the odds of good clinical outcome were highest if only one retrieval attempt was required (adjusted OR 4.91, 95%CI 2.55–9.44) and decreased considerably for the second (adjusted OR 2.37, 95%CI 1.19–4.72) and third attempts (adjusted OR 3.07, 95%CI 1.39–6.76).

Conclusion Successful reperfusion within the first three retrieval attempts is associated with improved clinical outcome compared to patients without reperfusion. We conclude that at least three retrieval attempts should be performed in EVT of posterior circulation strokes.

Disclosure of Interest Dr Thomall: personal fees from Acandis, grants and personal fees from Bayer, personal fees from Bristol Myers Squibb/Pfizer, Boehringer Ingelheim, Daiichi Sankyo, Portola, Stryker outside the submitted work. Dr Fiehler reports grants and personal fees from Acandis, Cerenovus, Medtronic, Microvention, personal fees from Penumbra, and from Phenox outside the submitted work; and CEO of Eppdata. Dr Maros reports grants from German Federal Ministry for Economic Affairs and Energy, Zentrales Innovationsprogramm Mittelstand (ZF 4514602TS8) outside the submitted work.