Standalone Middle Meningeal Artery Embolization Versus Conservative Management for Nontraumatic Subdural Hematoma

BACKGROUND: Recent randomized control trials have demonstrated the efficacy and safety of middle meningeal artery embolization (MMAE) as an adjunct to conventional management for patients with nonacute subdural hematoma (SDH); however, a large majority of trial participants received surgical evacuation as part of the standard of care. Thus, the efficacy and safety of standalone MMAE compared with conservative management (CM) for patients with nonsurgical SDH are unclear. METHODS: This was a retrospective cohort study of the 2019 to 2021 Nationwide Readmissions Database in the United States. Patients with nonsurgical nontraumatic SDH were identified, and MMAE patients were matched with similar CM patients using propensity scores calculated from demographics, comorbidities, and initial hospitalization outcomes. Patients were followed up to 300 days. The primary end point was composite surgical rescue or death, and secondary end points included surgical rescue and all-cause mortality by 180 days. RESULTS: A total of 24 465 patients with nonsurgical nontraumatic SDH were identified; 2228 (9.1%) underwent MMAE. After propensity score matching, 6675 patients remained in the CM group and 2217 in the MMAE group. At 180 days, MMAE patients had a significantly lower risk of surgery or death compared with CM (8.2% versus 10.9%; relative risk, 0.75 [95% CI, 0.59–0.96]; P =0.022) and lower risk of death (1.1% versus 3.0%; relative risk, 0.38 [95% CI, 0.17–0.86]; P =0.020). Rates of surgical rescue among MMAE and CM patients at 180 days were similar (7.1% versus 8.4%; relative risk, 0.85 [95% CI, 0.63–1.14]; P =0.27). Time-to-event analyses for the entire 300-day study follow-up period confirmed that while MMAE was associated with a lower cumulative risk of all-cause mortality (hazard ratio, 0.55 [95% CI, 0.35–0.87]; P =0.010), it was not associated with a different risk of surgical rescue (hazard ratio, 1.00 [95% CI, 0.76–1.31]; P =1.00). CONCLUSIONS: Standalone MMAE may be beneficial for patients with nonsurgical nontraumatic SDH by reducing the long-term risk of all-cause mortality.