Drugs Used in Cardiac Arrhythmias

Cardiac arrhythmias range from the fast-beating tachyarrhythmias–which include atrial fibrillation, ventricular tachycardia, and fibrillation and the slow-beating bradyarrhythmias–which include sick sinus syndrome and heart blocks. Compounded with other co-existent cardiovascular risk factors, these arrhythmias can result in enhanced mortality rates—including sudden cardiac deaths. Aberrations in cardiac impulse formation or conduction can result in arrhythmias and the antiarrhythmic drugs exert their action by optimally tilting these imbalances. The chapter includes in-depth discussion on the various antiarrhythmic drugs—classified based on both the classical Singh-Vaughan Williams system (1970) and the modernized system of classification proposed by Lei et al. (Circulation 138:1879–96, 2018); the former includes four classes (Class 1, 2, 3, and 4) and the latter includes additional four classes (Class 0, 5, 6, and 7). The clinical application with the guiding principles for antiarrhythmic drug use is also elucidated.