EFFECT OF MAGNESIUM-SULFATE ON VENTRICULAR RATE CONTROL IN ATRIAL-FIBRILLATION

Study objectives: The objectives of this study were to assess the effi cacy of parenteral magnesium sulfate (MgSO4), digoxin, and combined Mg SO4-digoxin therapies in acutely lowering ventricular rates in patient s with newly recognized atrial fibrillation. Design: A randomized, dou ble-blinded, placebo-controlled clinical study. Setting: US Army terti ary care facility. Participants: Fifteen adults (mean age, 62 +/- 19 y ears) presenting with newly recognized atrial fibrillation and rapid v entricular rate (more than 99). Interventions: Patients were given an initial parenteral MgSO4 bolus with continuous infusion or placebo. Af ter 30 minutes, all patients were given 0.5 mg IV digoxin and followed for 3.5 hours. Measurements and main results: Ventricular rates were obtained at baseline, every 5 minutes for the first 30 minutes, and th en every 30 minutes for 3.5 hours. At 5 minutes, ventricular rates dec reased 16 +/- 7% (P<.02) with MgSO4; this was comparable with rate con trol with digoxin (18 +/- 9%) at 4 hours. Rate control tended (26 +/- 7%) to improve with combined therapy. Conclusion: Parenteral MgSO4 may be useful in the acute management of rapid ventricular rates in patie nts with atrial fibrillation.