This randomized controlled trial (LOMAGHI Study) compared low-dose (4.5 g) versus high-dose (9 g) intravenous magnesium sulfate (MgSO₄) and placebo in 450 adults presenting to the emergency department with rapid atrial fibrillation (AF). All participants received standard AV nodal blockers. At 4 hours, therapeutic response was higher in the magnesium