Risk factors for the rupture of anterior communicating artery aneurysms: Coexistence of fetal-type posterior cerebral artery and A1 segment hypoplasia/agenesis

To investigate the effect of the coexistence of fetal-type posterior communicating artery (fPCA) and anterior cerebral artery (ACA) A1 segment agenesis/hypoplasia on the rupture of an anterior communicating artery (AComA) aneurysm.A total of 216 patients consecutively presenting with AComA aneurysms between January 2014 and December 2021 on digital subtraction angiography were evaluated. Patients without three-dimensional rotational angiography images, those aged under 18 years, those with suspected mycotic aneurysms, and those with dissecting and giant aneurysms were excluded from the study. The aneurysms were divided into two groups as ruptured and non-ruptured. Hemodynamic filling patterns were classified into four different types.The study included 192 AComA aneurysms, 44.8% (n = 86) ruptured and 55.2% (n = 106) non-ruptured. According to hemodynamic filling patterns, in type 1, the frequency of non-ruptured aneurysms was statistically significantly higher than that of ruptured aneurysms (39.5% vs 18.9%; p = 0.001). In type 4, where fPCA and ACA A1 segment agenesis/hypoplasia coexists, the frequency of ruptured aneurysms was significantly higher than that of non-ruptured aneurysms (10.5% vs 22.7%; p = 0.026). The most common aneurysm size range was 4-7 mm (n = 85; 44.3%). There was no statistically significant difference in size between the ruptured and non-ruptured aneurysms (p = 0.627).According to the hemodynamic filling classification, we observed that the presence of type 4 filling pattern, i.e., the coexistence of ACA A1 segment agenesis/hypoplasia and fPCA, increased the risk of rupture in AComA aneurysms.