Background: Recent experimental evidence indicates that endogenous mechanisms against cerebral vasospasm can be induced via preconditioning (PC).
Objective: To determine whether these vascular protective mechanisms are also present in vivo in humans with aneurysmal subarachnoid hemorrhage (aSAH)
Methods: A multicenter retrospective cohort of aSAH patients was examined for ischemic PC stimulus: pre-existing steno-occlusive cerebrovascular disease and/or previous cerebral infarct (CVD). Generalized estimating equation models were performed to determine the effect of the PC stimulus on the primary endpoints: radiographic vasospasm, symptomatic vasospasm, and vasospasm-related delayed cerebral infarction, and the secondary endpoint: discharge modified Rankin Scale.
Results: Of 1043 patients, 321 (31%) had pre-existing CVD and 437 patients (42%) had radiographic vasospasm. Patients with pre-existing CVD were less likely to develop radiographic vasospasm (OR=0.67, 95% CI=[.489, .930], P=.016), but had no differences in other endpoints. In terms of secondary endpoint, patients with pre-existing CVD did not significantly differ from patients without pre-existing CVD in mortality or unfavorable outcome in multivariate analyses, although patients with pre-existing CVD were marginally more likely to die (P=.061).
Conclusion: This retrospective case-controlled study suggests that endogenous protective mechanisms against cerebral vasospasm - a pre-conditioning effect - may exist in humans, though these results could be the effect of atherosclerosis or some combination of PC and atherosclerosis. Additional studies investigating the potential of PC in aSAH are warranted.
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