Intracranial Arterial Calcification and Its Impact on Subsequent Ischemic Cerebral Events: A Retrospective Cohort Study.

Background: Intracranial arterial calcification (IAC), commonly detected on CT/CTA during ischemic stroke work-up, may reflect atherosclerotic burden relevant to recurrence. We evaluated whether CTA-detected IAC was associated with subsequent ischemic cerebral events. Methods: This retrospective single-center cohort included patients with ischemic stroke or transient ischemic attack admitted to a tertiary stroke unit between 2010 and 2023. IAC was assessed on index-event CTA using volumetric quantification and the Babiarz score. Time to first recurrent ischemic cerebrovascular event was analyzed using multivariable Cox regression. Robustness was evaluated through adjustment for stroke etiology and CTA acquisition parameters, penalized regression, bootstrap internal validation, and competing-risk analysis accounting for death. Results: Among 556 patients (median age, 71.5 years [IQR, 62.3-78.6]; 354 male), 60 (10.8%) experienced recurrence during a median follow-up of 3.5 years (IQR, 1.8-7.5). Median IAC volume was higher in patients with recurrence than in those without recurrence (45.0 mm3 [IQR, 14.1-143.2] vs. 18.3 mm3 [IQR, 0-105.6]; p = 0.01). A one-unit increase in log10(IAC + 1), corresponding to a tenfold increase in IAC + 1, was associated with a higher recurrence hazard (HR, 1.63; 95% CI, 1.18-2.24; p = 0.003). The model had a C-index of 0.727, and the association remained consistent across sensitivity analyses. Babiarz scores correlated strongly with volumetric IAC measurements in the intracranial carotid and vertebral arteries (ρ ≥ 0.93; p < 0.01). Conclusions: Greater CTA-derived IAC burden was associated with a higher hazard of recurrent ischemic cerebrovascular events. Quantitative IAC assessment warrants further investigation as a potential imaging marker of recurrence risk, although external validation is required before clinical implementation.