The Safety and Efficacy of Aspiration Thrombectomy by Small Bore Aspiration Catheter for Medium Vessel Occlusion (MeVO)

Background/Objectives: Recent randomized controlled trials (RCTs) have not demonstrated the efficacy of me-chanical thrombectomy (MT) for medium vessel occlusion (MeVO), partly due to device selection bias. Notably, small-bore aspiration catheters were not evaluated. This study aimed to assess the safety and efficacy of the ADAPT (A Direct Aspiration First Pass Technique) approach using small-bore aspiration catheters as a first-line treatment for MeVO. Methods: We conducted a retrospective, single-center cohort study of patients who underwent MT for MeVO between March 2023 and April 2025. Patients were categorized based on the initial thrombectomy technique: ADAPT versus stent retriever (SR) or combined ap-proaches. The primary efficacy outcome was successful reperfusion, defined by the ex-panded Thrombolysis in Cerebral Infarction (eTICI) score. The primary safety outcome was the incidence of device-related adverse events. Results: A total of 54 consecutive MeVO cases were identified, comprising 9 cases treated with ADAPT (with small-bore aspiration catheters used in 89% of these) and 45 cases treated with stent retriever or combined techniques. Successful reperfusion (eTICI ≥2b50) was achieved in 100% of the ADAPT group and eTICI ≥2b67 in 77.8%. The ADAPT group showed a significantly higher rate of eTICI ≥2b50 (p < 0.05) and a lower incidence of device-related complications (odds ratio: 1.82 × 10⁻⁹; p = 0.029) compared to the SR/combined group. Conclusions: The ADAPT using small-bore aspiration catheters demonstrated high reperfusion success and a lower risk of device-related complications, suggesting it may serve as an effective first-line strategy for MeVO treatment.