Single lead atrial vs. dual chamber pacing in sick sinus syndrome: extended register-based follow-up in the DANPACE trial.

Aims: The DANPACE trial randomized patients with sick sinus syndrome (SSS) to single lead atrial (AAIR) or dual chamber (DDDR) pacemaker (PM). After 5 years follow-up, no difference in overall survival, stroke or heart failure (HF) was observed, whereas risk of atrial fibrillation (AF) and PM reoperation were increased in the AAIR group. The present study aimed to investigate very long term risk of death, AF hospitalization, stroke, HF and rate of change in pacing mode using national register-based data.

Methods and results: The study population consisted of all 1384 patients included at Danish PM centres in the DANPACE trial randomized to AAIR (n = 696) or DDDR (n = 688). Long-term follow-up data was obtained from Danish national registers. Analysis was intention-to-treat. results: During mean follow-up of 8.9 years, 413 patients (59.3%) died in the AAIR-group compared to 367 (53.3%) in the DDDR-group (adjusted hazard ratio 1.03; 95% confidence interval 0.90-1.19; P = 0.65). We observed no difference in risk of AF hospitalization, stroke or HF. During extended follow-up, annual rate of pacing mode change to DDDR in the AAIR group was 4.5%, and higher than the 2.3% observed during trial conduct.

Conclusion: This register-based long-term follow-up study indicates that there is no difference in mortality among patients with SSS randomized to AAIR or DDDR pacing, even with very long follow-up. Nor is there any difference in risk of AF hospitalization, stroke or HF. The higher rate of pacing mode-change to DDDR in the AAIR group suggests a different management of patients with an AAIR PM after the DANPACE trial.