Used to treat various types of irregular heart rhythms, particularly ventricular arrhythmias such as premature ventricular contractions and ventricular tachycardia. It helps restore normal heart rhythm and maintain a regular heartbeat by slowing the electrical conduction in the heart. Often prescribed for patients with documented life-threatening arrhythmias due to its potential side effects. Also used in managing supraventricular tachyarrhythmias, including atrial fibrillation, especially in patients without structural heart disease. Its sodium channel blocking activity contributes to its antiarrhythmic effects.