Introduction A significant proportion of acute ischemic stroke (AIS) patients do suffer from a medium vessel occlusion (MeVO). Despite the lack of clearly established safety and efficacy through randomized trials, an increasing number of physicians are treating MeVO by performing mechanical thrombectomy.

Aim of Study Assess the efficacy of 3mm and 4mm Solitaire stentretrievers (Medtronic) in patients with AIS and a primary MeVO.

Methods A retrospective review of the MAD MT Consortium, which synthesizes prospectively maintained databases from 37 academic institutions across North America, Asia and Europe. We analyzed consecutive AIS patients who underwent mechanical thrombectomy with the Solitaire stentretriever for primary MeVO.

Demographic characteristics, MT complications, angiographic and clinical outcomes were evaluated separately for ’proximal’ and ’distal’ medium vessels occlusions (DMVO).

Results Between September 2017 and July 2021, 664 patients with a single MeVO were included. The Solitaire stentretriever was deployed in 86% ‘proximal’ and in 14% ‘distal’ medium vessels occlusions.

Overall (and for the DMVO), the successful reperfusion rate (mTICI 2b, 2c, 3) was 87% (94%). The first-pass effect was of 28% (44%). Control imaging at day one revealed symptomatic intracranial hemorrhage (≥4 deterioration in NIHSS) in 9% (4%). At 3 months, the rate of favorable outcomes (mRS 0-2) was 56% (59%).

Conclusion Thrombectomy using the 3mm or 4mm Solitaire stentretrievers appears to be effective in primary MeVO across various centers and among different physicians with an acceptable safety profile, although the results of the various randomized studies currently under way are needed to assess its safety.