Predictors of atrial fibrillation in patients with dual-chamber pacemakers: insights from the Canadian study on spontaneous atrioventricular conduction preservation (CAN-SAVER)

Abstract

Controversies still exist whether algorithms aiming at minimizing unnecessary ventricular pacing help prevent the development of atrial fibrillation in dual-chamber pacemaker recipients. Methods: The CAN-SAVE R study is a Canadian multi-centre randomized study that compared the efficacy the SafeR™ mode with DDD pacing with a long AV delay in a large population of pts not presenting with permanent high degree AV Block (AVB) or permanent atrial fibrillation (AF). The primary objective was to compare % of VP and the impact on AF. Results: 373 patients from10 centres were included: 63% males, mean age= 71±10 years, LVEF= 50±5%, LAVol= 24±3mL. Pacing indications were Sinus Node dysfunction (SND) (47%), AV block (24%), SND + AV block (14%) and other (mainly syncope: 15%). After 3 years, 353 pts (95%) completed their follow-up. Overall, median %VP was 9.5% in the DDD group vs. 0.0% in the SafeR group. This difference in %VP did not affect AF burden (median 0.01% vs. 0.00% respectively). However, patients with previous history of AF, mitral valve disease, dilated left atrium and programmed to DDD mode (vs. SAFE-R™) were more likely to be in persistent AF at the end of 3-year follow-up (table). View this table: Predictors for being in permanent AF after 3 years of follow-up (odds ratio and 95% confidence intervals) Conclusions: CAN-SAVER failed to show benefits in terms of AF burden with a diminution of %VP from 9.5% (DDD with long AV delay) to 0.0% (SafeR™ mode). However, when evaluated in terms of risk to develop permanent AF, SafeR™ mode appears to provide some protection compared to DDD pacing with long AV delays.