Thrombectomy for medium-sized cerebral vessel occlusion: Size does matter.

Introduction: Randomised controlled trials comparing endovascular thrombectomy (EVT) to medical treatment in patients with medium vessel occlusion (MeVO) suggested neutrality or futility of EVT. We studied whether the size difference between thrombectomy device and the occluded vessel influenced MeVO outcomes.

Patients and methods: This was a retrospective single-centre observational study comprising EVT-treated patients with occlusion of the M2 branch of the middle cerebral artery on digital subtraction angiography. The diameter of the occluded M2 was measured and compared to the manufacturer's recommendation for the minimal vessel size. Based on this device-to-vessel size ratio, we divided the patients into three groups: A) ratio ⩽1.0 (device smaller or equals the vessel size), B) 1.0 < ratio ⩽ 1.2 (device larger, difference ⩽20%), and C) ratio >1.2 (device larger, significant difference >20%). The primary outcomes were futility (3-month modified Rankin scale 5 or 6) and symptomatic intracranial haemorrhage (sICH).

Results: In the cohort of 146 patients (median age 73; 47.3% women), 58.9% were in group A, 13.7% in group B and 27.4% in group C. Patients in group C had more frequently sICH (20.0%) compared to group A (7.0%) and group B (5.0%), and the highest futility rate (34.2% vs 17.3% vs 25.0%, respectively). In the adjusted analyses, belonging to the group C was associated with sICH (OR 3.32 [1.04-10.64]) and mRS 5-6 (OR 2.84 [1.09-7.37]).

Discussion and conclusions: The size of the thrombectomy device relative to the size of the occluded vessel is associated with haemorrhagic complications and futile outcomes.