Hypomagnesemia is most associated with which heart rhythm disturbance?

• A. Atrial fibrillation
• B. Torsades de Pointes
• C. Sinus tachycardia
• D. Ventricular fibrillation

Answer: (B)

Hypomagnesemia disrupts the heart’s electrical stability by altering ion channels involved in repolarization, which prolongs the QT interval. This prolongation raises the risk of early afterdepolarizations that can trigger a polymorphic ventricular tachycardia known as torsades de pointes. Torsades has a characteristic twisting of the QRS complexes around the baseline and can progress to more dangerous rhythms if not addressed. The other rhythms listed are not as specifically linked to low magnesium: atrial fibrillation and sinus tachycardia are common in many situations and aren’t classic direct consequences of hypomagnesemia, while ventricular fibrillation is a chaotic rhythm that can arise from various causes but is not the hallmark association with magnesium deficiency.