The magnitude of blood pressure control to reduce the risk of rebleeding has not been established, but a decrease in systolic blood pressure to <160 mm Hg is reasonable (Class IIa; Level of Evidence C). (New recommendation) 3. For patients with an unavoidable delay in oblitera- tion of aneurysm, a significant risk of rebleeding, and no compelling medical contraindications, short- term (<72 hours) therapy with tranexamic acid or aminocaproic acid is reasonable to reduce the risk of early aneurysm rebleeding (Class IIa; Level of Evi- dence B). (Revised recommendation from previous guidelines) Surgical and Endovascular Methods for Treatment of Ruptured Cerebral Aneurysms Microsurgical clip obliteration of intracranial aneurysms was the primary modality of treatment before 1991, when Gug- lielmi first described occlusion of an aneurysm by an endo- vascular approach with electrolytically detachable coils.139 With advancements in both microsurgical and endovascular approaches, algorithms to determine the proper patient pop- ulation and aneurysmal characteristics for each treatment are continually undergoing refinement. The only multicenter randomized trial comparing microsurgical and endovascular repair, ISAT, randomized 2143 of 9559 screened patients with aSAH across 42 neurosurgical centers.140 For a patient to be considered eligible for the trial, neurosurgeons and inter- ventionalists had to agree that the aneurysm was comparably suitable for treatment with either modality. Primary outcomes included death or dependent living, and secondary outcomes included risk of seizures and risk of rebleeding. 