AAIsafeR limits ventricular pacing in unselected patients.

INTRODUCTION: Dedicated pacing modes, such as AAIsafeR, prevent ventricular (V) pacing in selected patients. We report our experience in consecutive unselected patients. METHODS: All data collected in recipients of Symphony DR 2550 pacemakers (ELA Medical, Montrouge, France) were retrospectively analyzed. At each visit, the percentage of V and atrial (A) pacing and the number of endless-loop tachycardia (ELT) episodes detected by the device were retrieved. Data were pooled according to pacing mode and compared with non-paired Student's t-test. Between April 2004 and July 2005, our center recruited 147 patients (mean age = 80 +/- 9 years, 54% men) treated for AV block (n = 58), sinus node dysfunction (n = 48) or other indications (n = 41). Mean age at implant was 80 +/- 9 years, and 54% were men. AAIsafeR(R) was programmed in 96 patients, DDD(R) in 43, DDI in 7, and DDD/AMC in 1 patient. In DDD mode, the mean resting AV delay was set at 150 +/- 17 ms. Patients were seen 1 month after implantation of the pacing system to verify its proper function, and every 6 months thereafter. At each follow-up, the percentage of ventricular and atrial pacing, and the number of ELT detected by the device, were recorded. RESULTS: The mean follow-up was 7 +/- 6 months (range 1-21). No device was reprogrammed from AAIsafeR(R) to DDDI(R) because of permanent AF. Only 6 devices (6.25%) were automatically reprogrammed from AAIsafeR(R) to DDD(R) during follow-up due to permanent AV block. An empirical choice of AAIsafeR pacing mode at the time of implantation was effective in 94% of patients, allowing a significant decrease in the percentage of V pacing. AAIsafeR versions 1 or 2 significantly decreased the percentage of V pacing (9 +/- 21%) compared with DDD (95 +/- 14%), DDD/AMC (31 +/- 34%), and DDI (87 +/- 20%) pacing (P < 0.00001). The mean percentage of V pacing was 12 +/- 24% (median 0%, range 0-94) in AAIsafeR1 versus 4 +/- 12% (median 0%, range 0-52) in AAIsafeR2 (P = .055). In 16 devices upgraded from AAIsafeR version 1 to version 2, with follow-up analyzable in both modes, the mean percentage of V pacing decreased from 6.4 +/- 15.1% to 2.6 +/- 9.7% (ns). No adverse effect related to the AAIsafeR modes was observed. No patient reported palpitation, dyspnea, or lightheadedness attributable to overdrive pacing by the AF prevention algorithms, and there was no rehospitalization, need for cardioversion, device-related complication, or death. CONCLUSIONS: In unselected pacemaker recipients, AAIsafeR reliably prevented V pacing compared with other pacing modes. No adverse effects were reported by any patient. Furthermore, maintaining spontaneous AV conduction protected the patients against ELT episodes.

Incidence and predictive factors of atrial fibrillation in paced patients.

We have designed a prospective observational study to analyze the incidence and predictive factors of atrial fibrillation (AF) during a long follow-up, in a large population. Atrial fibrillation episodes were documented by the fallback mode switch (FMS) provided by implanted pacemakers. We have included 377 patients (61% men). The pacing indications were atrioventricular (AV) block (49%), sinus node disease (SND, 16%), bradycardia-tachycardia syndrome (BTS, 5%), AV block + SND (19%), AV block + BTS (6%), and BTS + SND (5%). The mean age at implant was 75 +/- 12 (range 28-95). Atrial fibrillation before inclusion was documented in 10% of patients. Drug therapy at first follow-up included beta-adrenergic blockers (17% of the patients), amiodarone (13%), and others (16%). The mean follow-up was 30 +/- 24 weeks. At least one AF episode was stored during follow-up in the memory of 169 pacemakers (45%). Among patients without history of AF at implant, 46% had documented FMS during follow-up. Patients with AF received more antiplatelet medications than patients without AF (P = 0.03). In patients with AF, New York Heart Association functional class was slightly higher, amiodarone and sotalol were more often prescribed, and the proportion of hypertension was higher than in patients without AF. However, these trends were not statistically significant. A significant higher incidence of premature atrial beats was observed in patients with AF than patients without AF (P < 0.0002). Patients with AF had a lower atrial percentage of paced events (55%) than patients without AF (63%, P < 0.02). These preliminary results confirm the high incidence of AF in paced patients and suggest a preventive effect of atrial pacing. The effects of other clinical variables may be confirmed with a longer follow-up in a larger population.