—It has been known for some time that digitalis, by blocking the AV node, can increase antegrade conduction over the accessory pathway and, in the process, increase the ventricular rate in atrial fibrillation and atrial flutter.1 More recently, studies show that lidocaine and verapamil therapy also can cause rapid ventricular rates along with ventricular fibrillation in cases of ventricular preexcitation with atrial fibrillation or atrial flutter.2In addition, recent studies show that reciprocating tachycardia can degenerate into atrial fibrillation and that, during conversion of reciprocating tachycardia to normal sinus rhythm by verapamil therapy, the sinus rhythm can be transiently preceded by atrial fibrillation.3I, therefore, agree with Dr Hasegawa that there should be careful examination and observation of patients with ventricular preexcitation who are receiving digitalis, lidocaine, and verapamil for the treatment of supraventricular tachyarrhythmias.
Richardson JM. Ventricular Preexcitation-Reply. Arch Intern Med. 1983;143(11):2218. doi:10.1001/archinte.1983.00350110209051