Long-term follow-up of DDD and VDD pacing: a prospective non-randomized single-centre comparison of patients with symptomatic atrioventricular block.

Aims: This prospective non-randomized single-centre registry compared clinical outcome, pacing parameters, and long-term survival in patients receiving VDD or DDD pacemaker (PMs) for symptomatic atrioventricular (AV) block.

Methods And Results: Single-lead VDD (n= 166) and DDD (n= 254) PMs were implanted in 420 successive patients with isolated AV block between January 2001 and December 2009. At the end of the follow-up period [median 25 (1-141) months], there was no difference in the incidence of atrial fibrillation [11.2% in the VDD group; 11.4% in the DDD group (P= 0.95)], myocardial infarction [31.1% in the VDD group; 25.2% in the DDD group (P= 0.20)], or dilated cardiomyopathy [9.9% in the VDD group; 8.9% in the DDD group (P= 0.74)]. At last follow-up, 65.9% of the VDD PMs and 89.3% of the DDD PMs were still programmed in their original mode with good atrial sensing. Due to permanent atrial fibrillation, 7.9% patients out of the VDD group had been switched to VVIR mode and 8.7% patients out of the DDD group to VVIR or DDIR mode. The P-wave amplitude was poor (sensed P-wave <0.5 mV) in 19.1% of the VDD PM and 1.6% of the DDD PM (P< 0.001) and 7.1% of the VDD patients and 0.4% of the DDD patients had been switched to VVIR pacing mode due to P-wave undersensing and AV dissociation (P= 0.003). Symptomatic atrial undersensing requiring upgrading was similar in both groups. The overall survival, adjusted for age, was not significantly different in the VDD and the DDD group (log rank: 0.26). Moreover, Cox survival analysis excluded the pacing mode as a significant predictor of mortality [hazard ratio (HR) = 0.79, confidence interval (CI) (0.46-1.35), P= 0.39].

Conclusion: Comparing VDD and DDD pacing, a significantly larger number of VDD-paced patients developed poor atrial signal detection without clinical impact. However, atrial under sensing did not influence the incidence of atrial fibrillation, myocardial infarction, dilated cardiomyopathy, or mortality.