No effect of enoxaparin on outcome of aneurysmal subarachnoid hemorrhage: a randomized, double-blind, placebo-controlled clinical trial

Object. From the moment an intracranial aneurysm ruptures, cerebral blood flow is impaired, and this impairment mainly determines the outcome in patients who survive after the initial bleeding. The exact mechanism of impairment is unknown, but activation of coagulation and fibrinolysis correlate with clinical condition and outcome after aneurysmal subarachnoid hemorrhage (SAH). The purpose of this study was to determine whether enoxaparin, a low-molecular-weight heparin, which is a well-known anticoagulating agent, has any effect on the outcome of aneurysmal SAH postoperatively. Methods. In this randomized, double-blind, single-center clinical trial, 170 patients (85 per group) with aneurysmal SAH were randomly assigned to receive either enoxaparin (40 mg subcutaneously once daily) or a placebo, starting within 24 hours after occlusion of the aneurysm and continuing for 10 days. Analysis was done on an intention-to-treat basis. Outcome was assessed at 3 months on both the Glasgow Outcome and modified Rankin Scales. Patients were eligible for the study if surgery was performed within 48 hours post-SAH, and no intracerebral hemorrhage was larger than 20 mm in diameter on the first postoperative computerized tomography scan. At 3 months, there were no significant differences in outcome by treatment group. Of the 170 patients, 11 (6%) died, and only 95 (56%) had a good outcome. Principal causes of unfavorable outcome were poor initial condition, delayed cerebral ischemia, and surgical complications. There were four patients with additional intracranial bleeding in the group receiving enoxaparin. The bleeding was not necessarily associated with the treatment itself, nor did it require treatment, and there were no such patients in the placebo group. Conclusions. Enoxaparin seemed to have no effect on the outcome of aneurysmal SAH in patients who had already received routine nimodipine and who had received triple-H therapy when needed. Routine use of low-molecular-weight heparin should be avoided during the early postoperative period in patients with SAH, because this agent seems to increase intracranial bleeding complications slightly, with no beneficial effect on neurological outcome.