Association of embolization with long-term outcomes in brain arteriovenous malformations: a propensity score-matched analysis using nationwide multicenter prospective registry data

Background: Brain arteriovenous malformations (AVMs) account for 25% of hemorrhagic strokes in young adults. Although embolization has been widely performed as a stand-alone procedure to cure brain AVM, it is undermined whether patients benefit from this treatment. This study aimed to compare the long-term outcome of hemorrhagic stroke or death in patients with either conservative management or stand-alone embolization for AVM. Methods: The study population was derived from a nationwide multicenter prospective collaboration registry (the *BLINDED* registry) between 2011.08 and 2021.08. The propensity score-matched survival analysis was performed in the overall and stratified AVM cases (unruptured and ruptured) respectively, to compare the long-term outcome of hemorrhagic stroke or death, and neurological status. The efficacy of distinct embolization strategies was also evaluated. Hazard ratios (HRs) with 95% confidence intervals were calculated using Fine-Gray competing risk models. Results: Of the 3,682 consecutive AVMs, 906 underwent either conservative management or embolization as the stand-alone management strategy. After propensity score matching, a total of 622 (311 pairs) patients constituted an overall cohort. The unruptured and ruptured subgroups were composed of 288 cases (144 pairs) and 252 cases (126 pairs), respectively. In the overall cohort, embolization did not prevent long-term hemorrhagic stroke or death compared with conservative management (2.07 vs. 1.57 per 100 patient-years; HR, 1.28 [95%CI, 0.81-2.04]). Similar results maintained in both unruptured AVMs (1.97 vs. 0.93 per 100 patient-years; HR, 2.09 [95%CI, 0.99-4.41]) and ruptured AVMs (2.36 vs. 2.57 per 100 patient-years; HR, 0.76 [95%CI, 0.39-1.48]). Stratified analysis showed that the target embolization might be beneficial for unruptured AVMs (HR, 0.42 [95%CI, 0.08-2.29]), while the curative embolization improved the outcome of ruptured AVMs (HR, 0.29 [95%CI, 0.10-0.87]). The long-term neurological status was similar between these two strategies. Conclusions: This prospective cohort study did not support a substantial superiority of embolization over conservative management for AVMs in preventing long-term hemorrhagic stroke or death.