Near Elimination of Ventricular Pacing in SafeR Mode Compared to DDD Modes: A Randomized Study of 422 Patients

Aims: SafeR performance versus DDD/automatic mode conversion (DDD/AMC) and DDD with a 250-ms atrioventricular (AV) delay (DDD/LD) modes was assessed toward ventricular pacing (Vp) reduction. Methods: After a 1-month run-in phase, recipients of dual-chamber pacemakers without persistent AV block and persistent atrial fibrillation (AF) were randomly assigned to SafeR, DDD/AMC, or DDD/LD in a 1: 1: 1 design. The main endpoint was the percentage of Vp (% Vp) at 2 months and 1 year after randomization, ascertained from device memories. Secondary endpoints include % Vp at 1 year according to pacing indication and 1-year AF incidence based on automatic mode switch device stored episodes. Results: Among 422 randomized patients (73.2 +/- 10.6 years, 50% men, sinus node dysfunction 47.4%, paroxysmal AV block 30.3%, bradycardia-tachycardia syndrome 21.8%), 141 were assigned to SafeR versus 146 to DDD/AMC and 135 to DDD/LD modes. Mean % Vp at 2 months was 3.4 +/- 12.6% in SafeR versus 33.6 +/- 34.7% and 14.0 +/- 26.0% in DDD/AMC and DDD/LD modes, respectively (P < 0.0001 for both). At 1 year, mean % Vp in SafeR was 4.5 +/- 15.3% versus 37.9 +/- 34.4% and 16.7 +/- 28.0% in DDD/AMC and DDD/LD modes, respectively (P < 0.0001 for both). The proportion of patients in whom Vp was completely eliminated was significantly higher in SafeR (69%) versus DDD/AMC (15%) and DDD/LD (45%) modes (P < 0.0001 for both), regardless of pacing indication. The absolute risk of developing permanent AF or of remaining in AF for > 30% of the time was 5.4% lower in SafeR than in the DDD pacing group (ns). Conclusions: In this selected patient population, SafeR markedly suppressed unnecessary Vp compared with DDD modes. (PACE 2012; 35: 392-402)