Distal anterior cerebral artery aneurysms treated with flow diversion: experience of a large-volume center and systematic review of the literature

Background Evidence about the safety and the efficacy of flow diversion for distal anterior cerebral artery (DACA) aneurysms is scant. To provide further insight into flow diversion for aneurysms located at, or distal to, the A2 segment. Methods Consecutive patients receiving flow diversion for DACA aneurysms were retrieved from our prospective database (2014–2020). A PRISMA guidelines-based systematic review of the literature was performed. Aneurysm occlusion (O’Kelly–Marotta=OKM) and clinical outcomes were evaluated. Results Twenty-three patients and 25 unruptured saccular DACA aneurysms treated with flow diversion were included. Aneurysm size ranged from 2 mm to 9 mm (mean size 4.5 mm, SD ±1.6). Mean parent artery diameter was 1.8 mm (range, 1.2–3 mm, SD ±0.39). Successful stent deployment was achieved in all cases. Angiographic adequate occlusion (OKM C–D) at follow-up (14 months) was 79% (19/24 available aneurysms). No cases of aneurysm rupture or retreatment were reported. Univariate analysis showed a significant difference in diameter among aneurysms with adequate (4 mm) vs incomplete occlusion (7 mm) (P=0.006). There was one transient perioperative in-stent thrombosis, and three major events causing neurological morbidity: two stent thromboses (one attributable to the non-adherence of the patient to the antiplatelet therapy); and one acute occlusion of a covered calloso-marginal artery. Results from systematic review (12 studies and 107 A2–A3 aneurysms) showed 78.6% (95% CI=70–86) adequate occlusion, 7.5% (95% CI=3.6–14) complications, and 2.8%, (3/107, 95% CI=0.6–8.2) morbidity. Conclusions Flow diversion among DACA aneurysms is effective, especially among small lesions. However, potential morbidity related to in-stent thrombosis and covered side branches should be considered when planning this strategy.