R-(–)-Flecainide is primarily used as an antiarrhythmic agent to treat and manage certain types of irregular heartbeats, specifically ventricular and supraventricular arrhythmias. It works by blocking sodium channels in the heart, which helps to stabilize the heart's electrical activity and restore a normal rhythm. This makes it particularly effective in conditions like atrial fibrillation, paroxysmal supraventricular tachycardia, and life-threatening ventricular arrhythmias. It is often prescribed when other treatments have not been effective, as it is a potent medication with a specific mechanism of action. Additionally, it is used in some cases to prevent recurrent episodes of arrhythmias, improving overall cardiac function and reducing the risk of complications. Careful monitoring is required during its use due to its potential to cause proarrhythmic effects in certain patients.