Background Successful stroke treatment with mechanical thrombectomy (MT) involves appropriate patient selection and rapid re-canalisation. Queen Elizabeth Hospital Birmingham provides MT to patients presenting to our own Emergency Department (group A) or transferred from other regional hospitals (group B).

Aims To assess timelines in MT delivery and patient selection factors which may affect outcomes.

Methods Data from all stroke patients receiving MT in 2015–2018 were collected retrospectively. Change in NIHSS score (at presentation and at 24 hours) and procedure success (TICI score 2b or 3) were recorded.

Results 102 patients underwent MT (group A=43, group B=59).Mild initial deficit (NIHSS <6) and any pre-existing disability (Modified Rankin >0) were associated with worsening NIHSS scores (+2 and +13.5 respectively). >80% of these patients were in group A, indicating a tendency to select local patients with radiological evidence of proximal MCA thrombus or with dysphasia but mild NIHSS, whereas NIHSS-based patient selection was more strictly applied for group B. We found no differences in outcome dependent on delivery of MT inside/outside the 6-hour window.

Conclusions In the absence of clinical trial evidence for MT in patients with low NIHSS, caution in selecting these patients for MT is advised.