Abstract DP281: Conscious Sedation Versus General Anesthesia for Onyx Middle Meningeal Artery Embolization in Subacute/Chronic Subdural Hematoma: safety and disposition in EMBOLISE

Background: General anesthesia (GA) is commonly used for middle meningeal artery (MMA) embolization, yet conscious sedation (CS) may enable broader access and outpatient pathways. We evaluated safety, procedural metrics, and disposition by anesthesia type in EMBOLISE. Methods: Post-hoc analysis of EMBOLISE subjects undergoing Surgery + Onyx MMA embolization for subacute/chronic subdural hematoma. Subjects were grouped by CS (N=41) vs GA (N=155). Outcomes included CEC-adjudicated serious adverse events (SAEs), stroke, serious ICH, mortality (30/90 days and study exit), retreatment ≤90 days, discharge disposition, hospital length of stay (LOS), and procedural metrics. Group comparisons used Fisher’s exact test and unpaired t-tests. Results: Baseline characteristics were similar, except a higher rate of bilateral SDH per core lab in CS (41.5% vs 23.9%, p=0.031). Embolization success was 100% in both groups; mean Onyx volume and procedure/fluoroscopy times were similar (Onyx 0.78±0.57 vs 0.87±0.68 mL, p=0.43; procedure 59.0±25.4 vs 65.2±32.1 min, p=0.25; fluoro 30.2±11.8 vs 27.9±14.0 min, p=0.32). Safety was comparable: CEC SAE through 30 days 14.6% vs 18.1% (p=0.82); through exit 29.3% vs 35.5% (p=0.58). Serious ICH at 30 days was 0% vs 4.5% (p=0.35); stroke through exit 2.4% vs 1.9% (p=1.00). All-cause mortality was similar at 30 days (4.9% vs 2.6%, p=0.61), 90 days (7.3% vs 4.5%, p=0.44), and exit (9.8% vs 6.5%, p=0.50). Retreatment ≤90 days: 2.4% vs 4.5% (p=1.00). Discharge home was numerically higher with CS (70.7% vs 62.6%, p=0.37); mean LOS was similar (6.85±5.08 vs 7.66±6.41 days, p=0.46). Conclusions: In EMBOLISE, CS provided comparable safety to GA for Onyx MMA embolization despite more bilateral SDH in the CS group, with similar LOS and a trend toward higher discharge home. These data support CS as a safe alternative to GA and motivate prospective evaluation of CS-based outpatient/ambulatory pathways.