A 70-year-old woman with heart failure on furosemide and chronic sotalol therapy presents with syncope. Serum potassium is 2.8 mEq/L. Cardiac monitoring reveals a polymorphic ventricular tachycardia at 240 bpm with characteristic twisting of QRS complexes around the baseline. QTc is 540 ms. What is the most appropriate immediate pharmacotherapy?

• A Intravenous amiodarone
• B Intravenous procainamide
• C Intravenous verapamil
• D Intravenous magnesium sulfate ✓

Explanation

Torsades de Pointes is a polymorphic ventricular tachycardia occurring in the setting of QT prolongation. Intravenous magnesium sulfate is the first-line treatment regardless of serum magnesium levels. Sotalol, a class III antiarrhythmic, likely caused acquired long QT here. Class IA and III agents like procainamide and amiodarone further prolong QT and are contraindicated. Verapamil is ineffective for ventricular arrhythmias.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.