A 55-year-old male exhibits a repolarizing arrhythmia of varying amplitude. Which medication may have caused this?

The correct choice is sotalol, as it is a medication known to cause a variety of repolarization abnormalities on the electrocardiogram (ECG), particularly T-wave changes and potential polymorphic ventricular tachycardia. Sotalol is a class III antiarrhythmic drug that significantly prolongs the QT interval, which can lead to torsades de pointes, a form of polymorphic ventricular tachycardia characterized by varying amplitudes in the QRS complexes.

This association with repolarization abnormalities is specific to sotalol because it directly affects cardiac repolarization through its action on potassium channels, prolonging the action potential duration and refractoriness. The varying amplitudes observed in the arrhythmia are consistent with this medication's known side effects.

The other medications listed have different mechanisms and are less likely to cause similar repolarization issues. Propranolol, for instance, is a non-selective beta-blocker primarily used for arrhythmias associated with sympathetic stimulation and does not prolong the QT interval significantly. Lidocaine, an antiarrhythmic agent used mainly for ventricular arrhythmias, works by blocking sodium channels, which influences depolarization rather than repolarization. Diltia