Abstract 462: Secondary Analysis of Patients with M1 MCA Occlusions in the SUMMIT MAX Randomized Trial

Background The SUMMIT MAX trial compared the super‐bore (0.088”) HiPoint Reperfusion System (Route 92 Medical) to the Vecta 74/71 Aspiration System (Stryker), demonstrating reperfusion non‐inferiority and superiority of the HiPoint system, with higher first pass effect (FPE). We report a secondary analysis of patients with M1 middle cerebral artery occlusions treated in the SUMMIT MAX trial. Methods SUMMIT MAX was a prospective randomized controlled trial of patients with internal carotid artery or M1 middle cerebral artery occlusion treated within 8 hours. Patients were randomized 1:1 to the super bore HiPoint 88 or large bore Vecta 74 as the first‐line device. The primary efficacy endpoint was a final mTICI ≥ 2b using only the study device, with any use of adjunctive device adjudicated as failure; the primary safety endpoint was symptomatic intracranial hemorrhage (sICH) at 24 hours. Secondary analyses included first pass effect (FPE), successful delivery, and adjunctive device use. This secondary analysis evaluated the results of patients with M1 occlusions. Results The per protocol population of M1 occlusions in SUMMIT MAX consisted of 136 patients: 71 in the HiPoint arm and 65 in the Vecta arm. The primary efficacy endpoint in the M1 subset was achieved in 83.1% of HiPoint cases vs 52.3% of Vecta cases ( p =0.0002), with no significant difference noted in sICH (2.9% vs 3.1%). In the HiPoint arm, FPE 2C‐3 was significantly higher (52.1% vs 31.7%, p=0.023), while adjunctive device use was significantly lower (14.1% vs 47.7%, p<0.0001). Successful delivery of the HiPoint 88 to M1 occlusions was significantly higher than Vecta 74 (90.9% vs 71.9%, p=0.0064). After successful delivery of either the HiPoint 88 or Vecta 74 to an M1 occlusion, the FPE mTICI > 2C was numerically higher in patients treated with HiPoint 88 (55% vs 43.5%, p=0.33). Conclusions In this secondary analysis of SUMMIT MAX patients with M1 occlusions, treatment with the HiPoint 88 system was associated with significantly better delivery rates, FPE 2C‐3 and lower adjunctive device use. When evaluating all successful deliveries of either the HiPoint 88 or Vecta 74 to an M1 occlusion, there was a trend towards higher FPE 2C‐3 with super bore catheters.