The predictive value of cerebral blood flow perfusion for cSAH following flow-restricting head and neck artery angioplasty.

OBJECTIVE: The pathogenesis of convexal subarachnoid haemorrhage (cSAH) remains unclear. Investigating the role of cerebral blood flow (CBF) perfusion in cSAH holds clinical value. METHODS: We retrospectively reviewed the clinical, laboratory, and preoperative computed tomography perfusion (CTP) or arterial spin labelling data of patients who underwent angioplasty for flow-restricting head and neck artery lesions at four centres (2021–2024). A standardised protocol was used for multi-slice region of interest analysis in watershed regions to calculate the affected/unaffected perfusion ratio. Firth’s penalised-likelihood regression identified independent cSAH risk factors, and model utility was assessed by decision curve analysis. RESULTS: Postoperative cSAH occurred in 41 of 3967 patients (1.0%). Analysis of 111 patients (21 with cSAH, 90 without intracranial haemorrhage [ICH]) revealed that the cSAH group had significantly higher preoperative watershed relative CBF (rCBF) in global anterior, posterior, and overall regions (all P < 0.05). Multivariable analysis identified preoperative watershed rCBF ≥ 1.1 (odds ratio [OR] 9.20, 95% confidence interval [CI] 2.58–40.23; P < 0.001) and prolonged prothrombin time (PT) (OR 3.21, 95% CI 1.69–7.44; P < 0.001) as independent risk factors. Higher mean platelet volume (MPV) was protective (OR 0.47, 95% CI 0.20–0.99; P = 0.046). The prediction model (corrected area under the curve 0.882) provided net clinical benefit. cSAH did not affect 90-day outcomes (P = 0.198). CONCLUSION: Following flow-restricting angioplasty, the cSAH rate was approximately 1%. Preoperative watershed hyperperfusion was a key predictor. Prolonged PT increased cSAH risk, whereas elevated MPV was protective. With appropriate management, cSAH may not worsen prognosis.