ANTIARRHYTHMIC AGENTS:

Antiarrhythmic agents are medication used to control abnormal heartbeats and abnormal cardiac rhythms. There are a multitude of agents, all with specific effects and side effects. Here is a generalization of the effects of each class on the ECG. Specific agents should be looked up elsewhere.

CLASS 1a:

Wide QRS; prolonged QTc interval; flattening or inversion of the T waves; U waves

CLASS 1b:

Shortening of QTc interval; Shortening of PR interval

CLASS 1c:

Wide QRS; prolonged QTc interval; prolonged PR interval

CLASS III:

Wide QRS; prolonged QTc interval; prolonged PR interval

CLASS II:

Little effect on the ECG; can cause bradycardia or atrioventricular (AV) blocks

CLASS IV:

Little effect on the ECG; can cause bradycardia or atrioventricular (AV) blocks

Class 1a, 1c, and III agents are pro-arrhythmic.