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

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. 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 (1141) 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) (0.461.35), P 0.39]. 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.