Contact aspiration versus stent retriever thrombectomy for acute basilar artery occlusion (ANGEL-COAST): rationale and design of a multicentre, prospective, randomised, open-label, blinded-endpoint trial

BACKGROUND: Contact aspiration (CA) and stent retriever (SR) thrombectomy are two equally recommended first-line endovascular techniques for treating acute ischaemic stroke due to large vessel occlusion. Whether CA is more effective in achieving complete reperfusion compared with SR in patients with acute basilar artery occlusion (ABAO) remains unclear. AIM: This study aims to compare the efficacy and safety of CA versus SR as the first-line strategy during endovascular treatment in improving the rates of first-pass effect (FPE) for patients with ABAO. METHODS AND DESIGN: The ANGEL-COAST study is a prospective, multicentre, randomised controlled, open-label, blinded-endpoint (PROBE) clinical trial. Patients with acute ischaemic stroke due to ABAO within 24 hours from symptom onset will be recruited. Participants will be randomly assigned in a 1:1 ratio to either the CA or SR group. If the assigned treatment fails after three attempts, investigators may opt for alternative treatment strategies based on their clinical judgement. STUDY OUTCOMES: The primary endpoint is the FPE rate, defined as eTICI (Extended Thrombolysis in Cerebral Infarction) 2C/3 recanalisation after the first thrombectomy attempt without any rescue strategy. Key secondary endpoints include rates of modified FPE (eTICI ≥2b50), successful recanalisation (eTICI ≥2b50, eTICI ≥2b67, eTICI3) within ≤3 passes with the assigned device on conclusion of the procedure, procedural duration, use of rescue techniques and functional outcomes at 90 days, including modified Rankin Scale (mRS) 0-2 and mRS ordinal shift analysis. Safety outcomes include the rates of symptomatic intracerebral haemorrhage (sICH) at 36±12 hours, all-cause 90-day mortality and procedure-related serious adverse events. DISCUSSION: This is a head-to-head randomised trial to directly compare CA and SR in ABAO. The findings will help establish the optimal first-line endovascular treatment strategy for ABAO, potentially improving clinical outcomes in this high-risk group. TRIAL REGISTRATION NUMBER: https://www. CLINICALTRIALS: gov; Unique identifier: NCT05615038.