Long-Term Clinical Effects of Ventricular Pacing Reduction With a Changeover Mode to Minimize Ventricular Pacing in a General Pacemaker Population

Study Questions:

Does AAI-DDD changeover mode to minimize right ventricular pacing (VP) improve outcome compared with DDD in a general dual-chamber pacemaker population?


ANSWER was a randomized, controlled, multicenter trial assessing proprietary algorithm to reduce VP (SafeR, Sorin, France) versus standard DDD programming in sinus node disease (SND) or atrioventricular block (AVB) patients. Patients were followed for 3 years. Prespecified coprimary endpoints were VP and the composite of hospitalization for heart failure (HF), atrial fibrillation (AF), or cardioversion. Prespecified secondary endpoints were cardiac death or HF hospitalizations and cardiovascular hospitalizations.


A total of 650 patients were enrolled (52.0% SND, 48% AVB) at 43 European centers and randomized in SafeR (n = 314) or DDD (n = 318). The SafeR mode showed a significant decrease in VP compared with DDD (11.5 vs. 93.6%, p < 0.0001 at 3 years). All-cause deaths and syncope did not differ between randomization arms. No significant difference between groups (hazard ratio [HR], 0.78; p = 0.30) was found for the coprimary composite of hospitalization for HF, AF, or cardioversion. SafeR showed a 51% risk reduction in experiencing cardiac death or HF hospitalization (HR, 0.49; p = 0.02) and 30% in experiencing cardiovascular hospitalizations (HR, 0.70; p = 0.05).


SafeR safely and significantly reduced VP in a general pacemaker population though had no effect on hospitalization for HF, AF, or cardioversion, when compared with DDD.


Prior studies have shown that modes reducing ventricular pacing can reduce the risk of developing AF in patients with SND. In patients with intermittent AVB and in those with significantly prolonged PR interval, it has been uncertain whether VP reduction algorithms are helpful. This study adds to the contradictory results of prior studies and suggests that the risk of hospitalization for HF or AF is not significantly reduced by the VP reduction algorithm. If is important to note, however, that neither this nor prior studies were designed to assess the burden of fused or pseudofused pacing, which may well affect the relevant clinical outcomes.

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