Antiarrhythmic refers to a class of medications used to suppress or prevent cardiac arrhythmias (irregular heartbeats). These drugs work by altering the electrical activity of the heart, affecting ion channels (e.g., sodium, potassium, calcium) or adrenergic receptors to restore normal sinus rhythm, control ventricular rate, or prevent life-threatening tachyarrhythmias. Classification systems, such as the Vaughan Williams classification, categorize these agents based on their primary electrophysiological effects.