The purpose of this study is to determine the efficacy of Magnesium sulphate for the rate and rhythm control of the new onset (within 48 hours) atrial fibrillation in the hemodynamically unstable patients, admitted in the medical intensive care unit patients.

Atrial fibrillation is one of the most common arrhythmia, reported in the hemodynamically unstable patients in the intensive care unit. Loss of atrial contraction and the sequential atrioventricular contraction decrease the overall cardiac output which results in severe inadequate tissue perfusion. Medications aim for rate and rhythm control are recommended to treat new onset atrial fibrillation. These drugs (verapamil, diltiazem, amiodarone and beta blockers) may further compromise the patients' cardiac output by its' negative inotropic effect.

Magnesium sulphate with the cell membrane threshold potential stabilizing effect has been reported as an effective drug for rate and rhythm control for post-operative atrial fibrillation and the atrial fibrillation presented in the hospital emergency unit. However, there was inadequate data about the efficacy of Magnesium sulphate for treatment of new onset atrial fibrillation in the hemodynamically unstable patients admitted in the medical intensive care unit.

Inclusion Criteria:

• Admitted in medical intensive care unit
• Age 18 years or more
• New onset atrial fibrillation (within 48 hours), persist for at least 1 hour, ventricular rate 120 beats per min or more without evidence of volume depletion (CVP 8 mmHg or more or receive volume resuscitation about 20-30 ml/kg), oxygen saturation not less than 90%, serum Potassium level between 3.0-5.0 mEq/l, serum Calcium level between 8.0-11.0 mg/dl

Exclusion Criteria:

• Chronic atrial fibrillation
• Severe valvular heart disease including severe mitral regurgitation, mitral stenosis, aortic regurgitation, aortic stenosis, tricuspid regurgitation, tricuspid stenosis, pulmonic regurgitation or pulmonic stenosis
• Indicated for electrical cardioversion
• Severe hypomagnesemia (serum Magnesium < 1.2 mg/dl)
• Severe hypermagnesemia (serum Magnesium > 5.0 mg/dl)
• Renal insufficiency with creatinine > 3.0 mg/dl without renal replacement therapy