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Background A1 hypoplasia is associated with anterior communicating artery (AcomA) aneurysms, but optimal imaging follow-up timing remains unclear. This study aimed to investigate whether concomitant A1 hypoplasia influences the post-treatment outcomes of AcomA aneurysms.Methods This retrospective cohort study (2013–24) included patients treated endovascularly for AcomA aneurysms, grouped by the presence or absence of A1 hypoplasia. Outcome measures included complete occlusion and good clinical outcomes at short term and long term follow-up, aneurysm recurrence, retreatment rates, and procedure related complications. Subgroup analysis compared treatment modalities within the A1 hypoplasia group.Results 298 AcomA aneurysms were included (median age 58 years, 63% women), with 205 in the symmetric group and 93 in the A1 hypoplasia group. Anterior dome projection was more common with A1 hypoplasia (61% vs 46%; P=0.01), as were recurrence rates (31% vs 15%; P=0.005). A1 hypoplasia correlated with reduced long term complete occlusion rates (OR 0.32, P=0.01). In A1 hypoplasia patients, coiling/balloon assisted coiling showed lower long term occlusion rates (P=0.008), higher recurrence (P=0.049), and a trend toward increased retreatment (P=0.07). Stent assisted coiling was linked with higher long term occlusion rates (P=0.009) and a trend toward reduced retreatment (P=0.07). Flow diverter treatment showed no significant effect.Conclusion In this study, A1 hypoplasia affected long term outcomes of endovascular treatment for AcomA aneurysms, leading to lower occlusion and higher recurrence rates. Closer long term monitoring is needed in these patients.