Incidence of atrioventricular block and chronic atrial flutter/fibrillation after implantation of atrial pacemakers; follow-up of more than ten years.

The incidence of atrioventricular (AV) block and chronic atrial flutter/fibrillation was determined in 41 patients, mean age 62.2 years (22 to 88 years) who received atrial pacemakers before October 1980. The mean follow-up period was 12.3 years, range 11-14.4 years. Twenty-five patients suffered from bradycardia-tachycardia syndrome, 13 symptomatic bradycardia, and 3 bradycardia related ventricular tachycardia. At follow-up: 18 patients (44%) had permanent I-AV block; 11 patients had II-AV block, 9 patients (22%) transient Wenckebach block and 2 patients (5%) transient Mobitz block, all asymptomatic. The cumulative incidence of III-AV block was 1 (2.5%). Chronic atrial flutter/fibrillation occurred in 6 patients (15%), 5 were not pacemaker-dependent; 1 received a ventricular pacemaker. Seventeen patients died after a mean of 7 years (0.6-12.2 years). Cumulative survival rate of 58% for 14.4 years, did not differ from a matched cohort of the normal population. There were no pacemaker related deaths. We conclude that long-term atrial pacing was safe and effective. The incidence of III-AV block and chronic atrial flutter/fibrillation was low.