Several studies have shown that unnecessary right ventricular pacing (Vp) has detrimental effects. The ANSWER study evaluated whether minimization of Vp improves clinical outcome compared to standard DDD pacing in patients (pts) referred for dual chamber pacemaker implantation.

ANSWER is a randomized, long term follow-up, multicenter, international trial comparing SafeR, a mode designed to minimize Vp by promoting intrinsic conduction, to standard DDD (AV delay left to physician’s discretion). Pts enrolled suffered from sinus node disease (SND), intermittent AV block (AVB) or allegedly permanent AVB. All pts were programmed in SafeR at implant. 1 month after implant, pts were randomized 1:1 to either SafeR or DDD. All adverse events were blindly adjudicated by a Clinical

Event Committee. Secondary endpoints, presented here, included a composite of cardiac deaths and HF hospitalizations and cardiovascular (CV) hospitalizations, at 3 years. Treatment groups were compared based on an intention-totreat principle.

650 pts were enrolled in 43 centers in 7 countries (72.4±11.2 years, 55.2% males, 52.0% SND, 41.8% intermittent AVB and 6.2% permanent AVB) and implanted with a dual chamber pacemaker. 632 pts were randomized (314 in SafeR and 318 in DDD). Median%Vp was 11.5% in SafeR vs. 93.6% in DDD (p<0.001). The time to cardiac death or first HF hospitalization (figure) and the time to first hospitalization for CV event were both significantly increased in SafeR vs. DDD group (p=0.018 and p=0.050, respectively). The duration of hospitalization due to CV reason was significantly decreased in SafeR vs. DDD (1.55±5.4 vs. 3.05±11.6 days, p=0.037).

As compared to DDD, the SafeR pacing mode significantly increased the time to cardiac death or first HF hospitalization, the time to first CV hospitalization and significantly reduced the duration of hospitalizations for any CV reason.