class IV drugs in atrial fibrillation

Last reviewed 05/2021

Drugs such as verapamil and diltiazem increase the refractory period of the atrioventricular node and so control the ventricular response to atrial fibrillation.

Disadvantages of verapamil include:

• a lower rate of conversion to sinus rhythm than with class IV or class I drugs
• a danger of malignant ventricular arrhythmias if there is underlying Wolff-Parkinson-White syndrome
• a lack of efficacy in paroxysmal atrial fibrillation