ACA-A1 segment development affects basal ganglia infarct severity and thrombectomy safety in MCA occlusion.

INTRODUCTION

The lenticulostriate arteries (LSAs) demonstrate developmental variability that is linked to the A1 segment of the anterior cerebral artery (ACA) anatomy. In acute ischaemic stroke (AIS) with MCA occlusion, basal ganglia (BG) infarction extent and haemorrhagic transformation (HT) correlate with LSA involvement. This study aimed to assess whether ipsilateral A1-ACA variations influence BG infarction severity and thrombectomy outcomes.

PATIENTS AND

METHODS

A control cohort (n = 300) undergoing catheter angiography from September 2023 to November 2024 was used to define anatomical relationships between the A1-ACA and the medial LSA (mLSA). A thrombectomy cohort (n = 236; MCA occlusion) from January 2019 to November 2024 was stratified by A1-ACA status (normal vs hypoplastic/absent) on pre-intervention CTA. Final basal ganglia infarct volume (FIVBG) was quantified on 72-h post-procedure MRI/NCCT. Associations between A1-ACA status, FIVBG, HT and outcomes were analysed via multivariable regression. Mediation analysis evaluated FIVBG's role in A1-ACA anatomy and HT relationships.

RESULTS

Hypoplastic/absent A1 segments occurred in 16.3% (49/300) of controls, who had a reduced mLSA presence (6.1% vs 20.7%, P = .016) and increased predominant lateral LSAs (71.4% vs 50.6%, P = .007) compared to those with a normal A1. Among thrombectomy patients, hypoplastic/absent A1 (15.3%, 36/236) predicted larger FIVBG (median: 29.01 cm3 [24.4-37.8] vs median: 25.80 cm3 [21.5-32.5], P = .004) and higher HT rates (66.67% vs 34%, P < .01). Multivariable analyses confirmed A1 hypoplasia/absence was independently associated with FIVBG (β = 5.714; 95% CI, 2.860-8.569; P < .01) and HT (aOR = 3.059; 95% CI, 1.284-7.288; P = .012). Furthermore, FIVBG mediated 44% of the indirect effect of A1 development on HT post-EVT.

CONCLUSIONS

Hypoplastic/absent A1 segments correlate with impaired mLSA development, thereby exacerbating BG infarction and HT risk post-thrombectomy. As one of several predictors, A1 segment morphology on preprocedural CTA may help stratify patients at risk for larger BG infarcts and haemorrhagic complications.