[Frequency of atrial pacing in patients with intermittent atrial fibrillation and 2nd or 3rd degree atrioventricular block. Thera DR Pacemaker Study Group]

Patients with 2nd or 3rd degree AV-block and paroxysmal atrial fibrillation could be suitable for VDDR pacemakers, if they are not or rarely paced in the atrium. We studied in 23 of these patients 1 month after DDDR pacemaker implantation, how often they were paced in the atrium with usual pacemaker programmings; patients with < 10% atrial pacing were compared with patients with > or = 10% atrial pacing. In case automatic mode switch was programmed, the number of mode switch episodes was assessed as a marker for the frequency of atrial tachyarrhythmias. Atrial pacing < 10% of the time occurred in seven, pacing from 10 to 19% in six, from 20 to 29% in two, and > or = 30% of the time in eight patients. Five of the seven patients with < 10% atrial pacing were paced in the DDD mode, but only four of 16 patients with > or = 10%. Usual clinical findings were unable to predict patients with rare atrial pacing. Patients with < 10% as well as with > or = 10% atrial pacing had < 10 mode switch episodes in 67% each.

During short-term follow-up after DDDR pacemaker implantation 30% of the patients with paroxysmal atrial fibrillation and second or third degree AV-block, with present usual pacemaker programmings, rarely had atrial pacing, that means < 10% of the time. These patients would be probably suitable for VDDR pacemakers. Rare atrial pacing had no influence on the occurrence of automatic mode switch episodes.