System upgrade and its complications in patients with a single lead atrial pacemaker: data from the DANPACE trial.

AIMS: To investigate the indications for system upgrade with single lead atrial pacing (AAIR), complications associated with these re-interventions, and possible predictors for system upgrade among patients included in the Danish Multicenter Randomized Trial on AAIR vs. dual-chamber pacing (DDDR) in sick sinus syndrome (DANPACE). METHODS AND RESULTS: A total of 707 of 1415 patients were randomized to AAIR pacing. Mean follow-up was 5.5 ± 2.6 years. Information on indications for system upgrade and complications were collected by reviewing patient charts. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals (CI) for the association between predictors and system upgrade. Sixty-six patients (9.3%) in the AAIR group underwent system upgrade. Fifty-nine of these patients (89.3%) had a documented class I indication for system upgrade. Age (aOR 0.98 for each 1-year increase in age; 95% CI 0.6-1.0), and left atrial enlargement (aOR 1.9; 95% CI 1.0-3.8) were predictors for system upgrade. No single clinically applicable predictor for upgrade was identified. A total of 11 patients (16.7%) experienced at least one major complication after system upgrade. CONCLUSION: The majority of patients with AAIR pacing who underwent system upgrade had a class I indication. The incidence of major complications after system upgrade was high. The present data support the use of DDDR pacing rather than AAIR pacing in sick sinus syndrome.