Background: Increased blood pressure (BP) variability has been associated with worse outcomes in acute stroke. Magnesium has been shown to have both vasoactive and cardio-active properties that could potentially attenuate blood pressure variability emergently.
Objective: To investigate whether intravenous magnesium sulfate can minimize blood pressure variability in hyperacute stroke.
Methods: All patients with a diagnosis of stroke (cerebral ischemia, intracerebral hemorrhage) enrolled in the NIH Field Administration of Stroke Therapy-Magnesium (FAST-MAG) phase 3 trial were included. FAST-MAG was a multicenter, randomized, double-blind, placebo-controlled study looking at whether initiation of magnesium sulfate (20 grams/24 hours) in the prehospital setting of acute stroke would reduce disability. Study agent was initiated prior to hospital arrival < 2 hours from symptom onset. Blood pressure variability was defined as the standard deviation (SD) of systolic blood pressure of all readings obtained by 4 hours after initiation of study agent. BP variability was compared using t-test of the bootstrapped SD between groups.
Results: In total, 1,700 patients were included in the study with a median of 6 (IQR 5-6) BP readings, of which 1,245 had cerebral ischemia (CI), 387 had intracerebral hemorrhage (ICH), and 68 had stroke mimics. Of those with CI, 632 received magnesium and 613 placebo; the standard deviation of systolic blood pressure was not significantly different between those who received magnesium and those who did not (14.9mmHg vs. 15.3mmHg, p=0.315). In the ICH population (195 magnesium, 192 placebo), magnesium treatment also did not affect BP variability (22.5mmHg vs. 21.1mmHg, p=0.197). For the overall study group, hyperacute magnesium treatment had no effect on blood pressure variability (16.7mmHg vs. 16.6mmHg, p=.907).
Conclusion: Treatment with magnesium did not reduce BP variability in hyperacute stroke.