Background: Current guidelines suggest the use of atrial synchronous mode (VDD) pacemakers in patients with atrioventricular (AV) block and normal sinus node function. However VDD mode is being used much less than expected. The objectives of our study were to evaluate the efficacy of VDD pacing in long-term follow-up and to find risk factors for VDD loss. Methods: We retrospectively evaluated all patients with VDD pacemakers who were implanted in our center between 1995 and 2007. Results: During the study period, 123 consecutive patients with AV block (51% men, age 62 ± 17.8 years) received a VDD pacemaker. Mean follow up duration was 4.5 ± 3.2 years. At the last follow up visit, 21 patients (21.6%) lost their original VDD mode and were programmed to ventricular-basedpacing (VVIR) (undersensing,11; chronic AF,7; SND,3). In 28 patients, VDD mode was restored or maintained by increasing atrial sensitivity. No episodes of atrial oversensingwere observed. In multivariate analysis history of paroxysmal AF (p = 0.007, odds ratio 36.6, 95% confidence interval 2.7-493.7) and p wave lower than 1 mv during the follow up (p = 0.021, odds ratio 7, 95% confidence interval 1.3-36.7), were found risk factors to VDD loss. Conclusions: VDD pacing has good long-term performance. Absence of paroxysmal AF history predicts maintenance of VDD pacing mode. Taking into account that no atrial oversensing was observed, our recommendation is to increase atrial sensitivity when P wave amplitude declines to less than 1 mv.
IntroductionHigh degree atrioventricular (AV) block represents approximately half of permanent pacing indications. Hemodynamic advantages, reduction in the development of atrial fibrillation, and better quality of life are gained by a mode of pacing which preserves AV synchrony compared with ventricular demand pacing.1 -4 Advantages of single lead atrial synchronous mode (VDD) over regular DDD pacing are: it is a less complex implant procedure, and has lower implantation and follow-up costs.5,6 VDD pacing utilizing a single-pass lead with far-field atrial sensing bipoles is a potentially simpler approach to provide the physiological benefits of AV synchronous pacing with a single-lead system. Despite this, VDD pacing is utilized in only 1% to 11%, 1% to 16%, and 2% to 20% of patients receiving pacemakers in America, Asia, and Europe, respectively. 7 This may be related to concern regarding stability of atrial sensing or development of sinus node disease. Most of the previous studies evaluated VDD pacing during a relatively short follow-up. 8 -12 Although some risk factors for losing VDD mode pacing such as old age, low P value, high right-atrial dimension, and atrial dipole placement in low atria were found, 13,14 criteria to optimize atrial sensitivity and VDD pacing have not been completely defined. The aim of our study was to evaluate the efficacy and stability of VDD