Class IV antiarrhythmics

Class IV antiarrhythmics

Non-dihydropyridine calcium antagonists diltiazem and verapamil act as class IV antiarrhythmics. By inhibiting the Ca2+influx during the plateau phase, the intracellular Ca2+ concentration will drop. This results in a decreased excitability of the cell. Hence, the conduction through the AV node is delayed.

Other beneficial effects like negative inotropy and vasodilation are already described with the calcium antagonists. Verapamil and diltiazem are indicated in case of supraventricular tachycardia.


Mr. P (59) has had longstanding hypertension and recently developed CHF. He now returns with atrial fibrillation. How would you treat the patient?


Verapamil may cause which of the following adverse effects?


Which of the following antiarrhythmics may worsen angina symptoms by increasing myocardial oxygen requirements? 


Which of the following statements concerning use of calcium antagonists as antiarrhythmics is FALSE: 


Mr. P has supraventricular tachycardia in which he experiences episodes of syncope and chest pain, but he does not want to undergo ablation surgery. What is the best choice to treat his arrhythmia?