Stereotactic radiosurgery for brain arteriovenous malformations as expected curative treatment: outcomes of patients included in the prospective registry of a pragmatic trial.

Abstract

TOBAS (Trial Of Brain Arteriovenous malformations Study) is a pragmatic study comprising two randomized trials and prospective registries of patients with brain arteriovenous malformations (AVMs). We report the results of the stereotactic radiosurgery (SRS) registry. TOBAS uses an algorithm integrating clinical judgment and randomization. When SRS was selected as the preferred curative modality and randomized allocation of SRS vs. observation was judged unreasonable, patients were included in the SRS registry (with/without pre-SRS embolization). The primary outcome was mRS>2 at last follow-up. Secondary outcomes included serious adverse events (SAEs), AVM rupture, radiation-induced changes, and MR-angiographic results at 3 years. Analyses were intent-to-treat. From June 2014 to May 2021, 1010 patients were recruited; 105(10.4%) were offered participation in the SRS registry. After exclusions, 94 patients were analyzed; most had ruptured (n=64/94(68%)), small AVMs (0-3 cm) (84(89%)), within eloquent brain (57(61%)). Pre-SRS embolization was performed in 19(20%); four were cured and 3 had endovascular complications, leaving 87/94 (93%) patients who received SRS. The median SRS dose was 22 Gy(IQR 20-24). During a mean follow-up of 51 months, the primary outcome (mRS>2) occurred in 7/94(7%;95% CI:4%-15%), with SAEs in 16/94(17%; 95% CI:11%-26%), including AVM rupture in 5/94(5%;95% CI:2%-12%), and symptomatic radiation-induced changes in 6/87(7%;95% CI:3%-14%). Three-year imaging follow-up, available in 79/94 (84%) confirmed AVM occlusion in 51/79(65%;95% CI:54%-74%) or 54%(95% CI:44%-64%) of all patients. In this prospective registry, radiosurgery with or without embolization was relatively safe, but of moderate efficacy, with 3-year AVM occlusion in 54%-65% patients.