Sotalol is proarrhythmic in the setting of left ventricular hypertrophy (wall thickness > 1.4 cm) and left ventricular systolic dysfunction and thus is contraindicated in these settings.

Sotalol can prolong the QT interval. It is recommended that sotalol be initiated in the inpatient setting in a  majority of cases in order to monitor the QT interval after each dose to prevent polymorphic ventricular tachycardia (Torsades de Pointes) from occurring which can be fatal.

Sotalol can cause severe bradycardia necessitating drug discontinuation.

Sotalol is a class III antiarrhythmic drug and acts by blocking cardiac potassium channels. Sotalol also has non-selective beta-blocker properties. Sotalol exhibits “reverse use-dependence” meaning at faster heart rates (when potassium channels are being used more), the antiarrhythmic effect is less.