Elevated Blood Pressure and Culprit Aneurysm Rebleeding During the Unsecured Period of Aneurysmal Subarachnoid Hemorrhage: A Systematic Review.

In aneurysmal subarachnoid hemorrhage, rebleeding prior to securing the culprit aneurysm leads to significant morbidity and mortality. Elevated blood pressure has been identified as a possible risk factor. In this systematic review, we evaluated the association between elevated blood pressure and aneurysm rebleeding during the unsecured period. We searched MEDLINE, Embase + Embase Classic, and CENTRAL, from inception to March 8th, 2024. We included studies of adults with aneurysmal subarachnoid hemorrhage reporting at least one blood pressure measurement during the unsecured period and a measure of association with rebleeding. Results were stratified by blood pressure thresholds, effect measure, and adjustment for confounding. Separate meta-analyses were performed for each of these groups. Our search identified 5,209 citations. After screening, 15 studies were included in our review. All studies were observational in design and at moderate or high risk of bias. Meta-analysis of the unadjusted results produced mixed findings across the systolic blood pressure (SBP) thresholds: SBP > 140 mm Hg, unadjusted odds ratio (uOR) 1.03 (95% confidence interval [CI] 0.55-1.93; I² = 66%); SBP > 160 mm Hg, uOR 3.35 (95% CI 1.44-7.81; I² = 83%); SBP > 180 mm Hg, uOR 1.52 (95% CI 0.40-5.81; I² = 89%); and SBP > 200 mm Hg, uOR 7.99 (95% CI 3.60-17.72; I² = 0%). Meta-analysis of adjusted results was only possible at an SBP > 160 mm Hg; adjusted hazard ratio 1.13 (95% CI 0.98-1.31; I² = 0%). The overall quality of evidence as assessed by the Grading of Recommendations, Assessment, Development, and Evaluations tool was rated as very low. Based on very low quality evidence, our systematic review failed to determine whether there is an association between elevated blood pressure during the unsecured period and increased risk of culprit aneurysm rebleeding.