Neurological outcomes after out-of-hospital cardiac arrest due to aneurysmal subarachnoid hemorrhage: a multicenter cohort study

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) due to aneurysmal subarachnoid hemorrhage (aSAH) is rare but associated with extremely poor prognosis. Data on neurological outcomes and prognostic factors are limited. METHODS: We conducted a retrospective multicenter cohort study across 12 French neuro-ICUs including all adult patients admitted alive after OHCA-aSAH between 2014 and 2024. Demographics, cardiac arrest characteristics, aSAH severity, ICU management, and 6-month neurological outcomes (modified Rankin Scale, mRS) were collected. Firth penalized logistic regression was applied to explore predictors of favorable outcome. RESULTS: Among 15,907 SAH admissions, 164 patients had OHCA-aSAH. Median age was 54 [43-62] years; 47.5% were male. Only 8 patients (4.9%) achieved favorable outcome (mRS ≤ 3) while 156 (95.1%) had poor outcome (mRS ≥ 4), including 154 deaths (mRS 6). Low-flow duration tended to be shorter, epinephrine use lower, and pupillary abnormalities less frequent among survivors, although no independent statistical association could be confirmed. All patients receiving pre-hospital antiplatelet or anticoagulant therapy (n = 14, 8.7%) had poor outcome. External ventricular drainage, ICP monitoring, and endovascular aneurysm treatment were more frequent, and ICU and hospital length of stay were longer, in survivors. One hundred and eight patients (65.8%) progressed to brain death within 1 [1-2] day. Penalized regression did not identify independent predictors of good outcome, though pupillary abnormalities and epinephrine use were associated with progression toward brain death. CONCLUSIONS: OHCA-aSAH carries a dismal prognosis, with < 5% achieving favorable neurological recovery. Selected patients may benefit from aggressive neurocritical care, and the high rate of brain death emphasizes the importance of organ donation pathways.