Significance of supraventricular arrhythmias induced by electrophysiologic studies.

The clinical history and the findings on Holter monitoring of 767 patients (without evidence of ventricular pre-excitation on the ECG) were compared with the results of electrophysiological studies to assess the significance of supraventricular arrhythmias induced by intracardiac study. The studies were undertaken to determine the cause of syncope, conduction disturbances or tachycardia. In 570 patients (group 1) supraventricular arrhythmias were not induced. On Holter monitoring, 36 (6%) had evidence of supraventricular tachycardias, including atrial flutter, atrial fibrillation and paroxysmal junctional tachycardia. In 86 patients (group 2) one atrial extrastimulus induced a paroxysmal junctional tachycardia; 79 (82%) of these patients had had spontaneous supraventricular tachycardia (SVT). In 111 patients (group 3) another type of SVT was induced: The movement of the catheter induced atrial flutter or fibrillation in nine patients, eight (89%) of whom had spontaneous SVT. Atrial pacing at a rate less than 200 bpm induced atrial flutter or fibrillation in 14 patients of whom nine (64%) had SVT. Ventricular pacing induced SVT in 15 patients, of whom 14 (64%) had SVT. An atrial extrastimulus during sinus rhythm induced atrial echoes in 62 patients, 47 (76%) of whom had SVT. The atrial extrastimulus during sinus rhythm induced atrial tachycardia in 11 patients, nine (82%) of whom had SVT.