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

The pathogenesis of convexal subarachnoid haemorrhage (cSAH) remains unclear. Investigating the role of cerebral blood flow (CBF) perfusion in cSAH holds clinical value. 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. 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). 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.