Atrial pacing in the management of sick sinus syndrome: long-term observation for conduction disturbances and supraventricular tachyarrhythmias.

Atrial pacing (AAI) in sick sinus syndrome (SSS) has been questioned because of the risk of distal conduction disturbances (DCD) and atrial tachyarrhythmias. The authors studied the incidence of clinically relevant DCD and arrhythmias in 52 SSS patients with AAI. The observation time was 25-67 (mean 48) months. Invasive electrophysiologic investigation was performed preoperatively in 29 cases and preoperative atrial pacing to Wenckebach block or to 150 ppm in 23. The preoperative investigation showed prolonged HV-time in three cases and Wenckebach block at 110 ppm in one case, while six patients had LAH-block, five RBB-block and two first degree AV-block. No further DCD developed in any of these patients. Second-degree type I AV-block developed in two patients after 2 and 19 months, respectively. One had been treated with digitalis and verapamil and was asymptomatic. The other patient, who had a low ventricular rate, experienced near-syncope. These two blocks could not be predicted from the preoperative and peroperative investigations. In five patients (10%) permanent atrial fibrillation developed during the follow-up period. The incidence of concomitant supraventricular tachyarrhythmias in the patients with the bradycardia-tachycardia syndrome appeared to be unaffected by the pacemaker treatment.