AV block and changes in pacing mode during long-term follow-up of 399 consecutive patients with sick sinus syndrome treated with an AAI/AAIR pacemaker

This retrospective study included a large cohort of consecutive patients pr imarily implanted at Skejby University Hospital with an AAI/AAIR pacemaker because of sick sin us syndrome (SSS) from July 1981 to July 1999. The prim ary aim of the study was to analyze the risk of developing AV block during long-term follow-up. A secondary aim was to study the incidence and reasons for changes in pacing mode caused by other than AV block. A total of 399 p atients (231 women, mean age 71 +/- 13.5 years) were identified. Mean follo w-up was 4.6 +/- 3.4 years and occurred at death, reoperation with mode cha nge, pacemaker explant, or end of study. During follow-up, 44 patients had a ventricular lead implanted with a mean delay of 2.8 +/- 3.1. years (range 1 day-10.4 years) after the primary implantation. A total of 30 patients r eceived a ventricular lead because of AV block or AF with bradycardia (annu al incidence 1.7%). Another 14 patients received a ventricular lead without having documented A V block or AF with pauses (annual incidence 0.8%), The present observational study documents that in patients with SSS treated wi th AAI/AAIR pacing, AV block requiring implantation of a ventricular lead o ccurs at a rate of 1.7% per year. It is considered that AAI/AAIR pacing is safe and reliable as treatment for patients with SSS and normal AV conducti on.