Influence of minimized atrial pacing on risk of ventricular arrhythmias in patients with pacemakers due to sinus node dysfunction

The recent DANPACE II trial showed that minimized atrial pacing did not reduce the incidence of atrial fibrillation in patients with sinus node dysfunction (1). Bradyarrhythmia due to minimized atrial pacing could predispose patients to ventricular tachycardia (VT) or ventricular fibrillation (VF), but the relationship between pacing mode and risk of VT/VF has not been fully clarified.

To investigate the influence of minimized atrial pacing on the risk of VT/VF episodes in the DANPACE II trial.

The DANPACE II trial included patients with sinus node dysfunction undergoing a first-time pacemaker implantation between May 2014 and June 2021. Patients were randomly assigned to rate-adaptive atrioventricular synchronous pacing with a lower rate of 60 beats per minute (DDDR-60) or atrioventricular synchronous pacing with a lower rate of 40 beats per minute (DDD-40) and followed for two years via remote monitoring. The primary outcome of this secondary analysis was sustained or non-sustained VF or VT defined as ≥3 beats at ≥100 beats per minute. All electrogram-documented tachyarrhythmia episodes were individually adjudicated by cardiac electrophysiologists. We used the Cox proportional hazards model to evaluate the relationship between pacing mode and time to VT/VF. The association between VT/VF and risk of death was evaluated for exploratory purposes.

We included 463 of 539 patients enrolled in the DANPACE II trial. A total of 76 patients were excluded from these analyses because remote monitoring data was not available. The baseline characteristics of patients included were well balanced between the two treatment groups. The primary outcome of VT/VF occurred in 47 out of 239 (20%) patients in the DDDR-60 group and 46 of 224 (21%) patients in the DDD-40 group (hazard ratio [HR] 1.05, 95% confidence interval [CI] 0.70–1.57, P=0.83) (Figure 1). All except one event comprised short-lasting episodes of non-sustained VT. In the multivariable analysis, a history of atrial fibrillation was independently associated with a lower risk of VT (HR 0.54, 95% CI 0.33-0.89, P=0.02) (Table 1). Furthermore, the exploratory analyses suggested that incident VT was associated with a higher age- and sex-adjusted mortality (odds ratio 2.47, 95% CI 1.17-5.21, P=0.02).

In the DANPACE II trial population, episodes of non-sustained VT were detected in 20% of patients over a two-year observation period. We observed no difference in VT risk between treatment groups. A history of atrial fibrillation was associated with a lower risk of VT, and our study further indicated an association between non-sustained VT and increased mortality in this population.