Abstract TMP100: The Effect Of Prehospital Treatment With Magnesium On Symptomatic Hemorrhagic Transformation In Cerebral Ischemia

Introduction: Symptomatic hemorrhagic transformation (sHT) is a known complication of acute ischemic stroke and is associated with worse outcomes. Previously, low serum magnesium levels have been associated with higher rates of sHT. This study evaluated the effect of prehospital treatment with intravenous magnesium on rates of sHT. Methods: Subjects were participating in the NIH Field Administration of Stroke Therapy Magnesium (FAST-MAG) clinical trial. A total of 20 grams of magnesium or matching placebo was administered via 4 gram bolus in the field followed by 16 gram infusion over 24 hours. All subjects with cerebral ischemia were evaluated for the presence of symptomatic hemorrhagic transformation defined as an increase in NIHSS >=4 points in the setting of imaging showing new hemorrhage within the ischemia territory. Results: A total of 1245 cases of cerebral ischemia were evaluated by paramedics on average 40 (SD 85) minutes and treated with magnesium or placebo on average 63 (SD 85) minutes after last known well time. Study population was age 71 (SD 18), 45% female, 78% white, 14% black, 8% Asian, 20% Hispanic ethnicity, 36% were treated with intravenous TPA, 78% hypertensive and 23% diabetic. Median NIHSS at ED arrival was 7 [IQR2-15]. There were 187 cases of clinical deterioration of which 43 were due to hemorrhagic transformation (3.4%). Rates of sHT were not statistically different in those who received magnesium vs. placebo (17/632 [2.7%] vs 26/613 [4.2%], p=0.134). Although HT was more common in TPA cases (6% vs 2%, p<0.001), magnesium had no effect on sHT in this subgroup 5.3% vs 7.3%, p-0.399 Conclusions: Hyper-acute high-dose intravenous magnesium did not lead to a significant decrease in rates of sHT following acute ischemic stroke. It is possible that a subgroup with low baseline magnesium levels could have benefited.