Long-term reliability of AAI mode pacing in patients with sinus node dysfunction and low Wenckebach block rate

To compare the risk of atrioventricular (AV) conduction disturbance between patients with sinus node dysfunction on AAI pacing who had a low or high Wenckebach block rate (WBR).

Patients with sinus node dysfunction and normal AV conduction those underwent an electrophysiological study were studied. The patients were classified into two groups: Group L was with the patients with a WBR of 100 to 129 per minute and Group H was with the patients with a WBR > or = 130 per minute. All patients followed up every 3-6 months after an AAI pacemaker implantation. A total of 102 patients, including 35 Group L and 67 Group H, were followed for 90 +/- 44 months. Six patients died from non-cardiac cause and five patients required a new atrial lead implantation due to lead failure during follow-up. Symptomatic bradycardia requiring a new ventricular lead implantation developed in four patients (annual incidence 0.5%). In Group L, two patients developed AV block (annual incidence 0.7%). In Group H, two patients developed bradycardic atrial fibrillation (annual incidence 0.4%). Kaplan-Meier analysis revealed no significant difference between the two groups (P = 0.2983).

These results suggest that a long-term risk of developing AV conduction disturbance is low even in patients with a WBR of 100 to 129 per minute.