IA antiarrhythmic drugs are mainly sodium channel blockers, which resist arrhythmias by inhibiting conduction velocity in atrial, ventricular and Purkinje fiber fast response tissues. The commonly used IA antiarrhythmic drugs mainly include quinidine and procainamide. Quinidine has a direct effect on the cell membrane, mainly inhibiting the transmembrane potential of sodium ions and affecting the zero term of action potential, and is suitable for maintenance treatment of atrial fibrillation or atrial flutter after electrical diversion, but it is less used nowadays due to its more adverse effects. Procainamide is a membrane stabilizer and is only used intravenously for short-term control of severe, symptomatic arrhythmias. Antiarrhythmic drugs have an arrhythmia-causing effect in addition to an arrhythmia-resistance effect. Therefore, the application of antiarrhythmic drugs should be properly used under the guidance of a physician to exert their positive therapeutic effects and to avoid toxic side effects to the greatest extent possible.