When does rebleeding occur in subarachnoid hemorrhage? Revisiting rebleeding cases with a focus on blood pressure.

BACKGROUND: Initial and recurrent bleeding are the leading causes of unfavorable outcomes following subarachnoid hemorrhage (SAH). We aimed to investigate rebleeding immediately after SAH ictus, focusing on its timing and systolic blood pressure (SBP). METHODS: Consecutive patients with spontaneous SAH treated from January 1999 to June 2022 were reviewed. Rebleeding was defined as a sudden deterioration into a coma, sudden pupillary dilation with a spike in SBP, or increased SAH/extravasation of contrast medium on imaging studies. Clinical data were examined for associations with rebleeding and outcomes. RESULTS: Among 940 patients (64% women, mean age 64 ± 13, 73% poor-grades), 273 episodes of rebleeding occurred in 221 patients (23.5%); 139 in 129 patients (13.7%) before and 134 in 112 patients (11.9%) after hospitalization, and 19 patients (2.0%) in both. Rebleeding peaked immediately after ictus and decreased exponentially, associated with higher initial-measured SBP, and worse neurological and computed tomography grade. SBP on arrival was higher in patients with rebleeding (178 mmHg, IQR 140-204 mmHg) than in those without (148 mmHg, IQR 100-180 mmHg) (P <0.001). Higher SBP was associated with increased rebleeding (OR = 9.843; P <0.0001), lower mortality (OR = 0.0281; P = 0.0084), but not with favorable outcomes (OR = 1.686; P = 0.22). When comparing subgroups in 20 mmHg increments, rebleeding, unfavorable outcomes, and mortality increased in the subgroups with SBP ≥181 mmHg, ≤100 and >160 mmHg, and ≤100 mmHg, respectively. CONCLUSIONS: Higher SBP on arrival was associated with rebleeding, and SBP 101-160 mmHg exhibited favorable outcomes.