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ANSWER: Clinical benefit of the safer mode in a mixed dual chamber population: results from the answer study

ESC Congress 2014 - Hot Line report




By Martin Stockburger, FESC (Nauen, Germany)
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List of Authors
Stockburger M 1, Moreno J 2, Boveda S 3, Stancak B 4, Villacastin JP 5, Lazarus A 6, Sipoetz J 7, Garcia-Seara J 8, Rolando M 9, Defaye P 10
1 Charité University Hospital, Experimental and Clinical Research Center (ECRC), Berlin, Germany,
2 Arrhythmia Unit, Cardiology Department, Hospital Ramon y Cajal, Spain,
3 Arrhythmia Unit, Pasteur Private Hospital, Toulouse, France,
4 Hospital VUSCH, East slovakian Institute for Cardiac and Vascular Diseases, Kosice, Slovakia,
5 San Carlos Hospital, Madrid, Spain,
6 InParys, Ambroise Paré Private Hospital, Neuilly sur Seine, France,
7 Hanusch Krankenhaus, Vienna, Austria,
8 Hospital Clínico Universitario, 15706 Santiago de Compostela, Spain,
9 Sorin CRM SAS, Saluggia, Italy,
10 Albert Michallon University Hospital, Grenoble, France,


Several studies have shown that unnecessary right ventricular pacing (VP) may promote heart failure (HF) and atirial fibrillation (AF). The ANSWER study evaluated whether minimization of VP improves clinical outcome compared to standard DDD pacing in patients 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). Patients with sinus node disease (SND), intermittent AV block (AVB) or allegedly permanent AVB were enrolled. All pts were programmed in SafeR at implant. 1 month after implant, they were randomized 1:1 to SafeR or DDD. All adverse events were blindly adjudicated by a Clinical Event Committee. Reduction of VP and a composite of hospitalization for HF, AF, or cardioversion were co-primary endpoints. Secondary endpoints, presented here, included a composite of cardiac deaths and HF hospitalizations and cardiovascular hospitalizations, at 3 years. Intention-to-treat analyses were performed.
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 co-primary clinical composite endpoint did not significantly differ with SafeR vs. DDD (previously presented: HR=0.78; 95% CI: 0.48–1.25; p=0.30). The HF component of this endpoint tended to favour SafeR (HR=0.58; 95% CI: 0.31-1.09; p=0.09) whereas the AF component was neutral (HR=1.09; 95% CI: 0.56-2.09; p=0.80). The time to cardiac death or first HF hospitalization (figure, HR=0.49; 95%: CI 0.27–0.90; p=0.02) and the time to first cardiovascular hospitalization (HR=0.70; 95% CI: 0.49–1.00; p=0.05) were significantly prolonged in the SafeR vs. DDD group. The duration of hospitalization due to cardiovascular reason was significantly decreased in the SafeR vs. the DDD group (p=0.037, table).
The SafeR pacemaker mode significantly reduced VP compared to DDD in a broad population clinically indicated to dual chamber pacemaker due to sinus node disease or AV block. The risk in experiencing hospitalization for HF or AF or cardioversion was not significantly reduced by SafeR versus DDD. SafeR significantly increased the time to cardiac death or a first HF hospitalization, the time to first cardiovascular hospitalization and reduced the duration of cardiovascular hospitalizations.


By Michael Glikson, FESC (Ramat Gan, Israel)
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The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.