Atrial fibrillation burden, progression, and the risk of death: A case-crossover analysis in patients with cardiac implantable electronic devices

Aims Atrial fibrillation (AF) is associated with increased mortality, but the temporal relationship between AF burden (AFB) and death among patients with cardiac implanted electronic devices is unknown. We sought to characterize the timing and progression of AFB before death. Methods and results Using Merlin.net TM remote monitoring (RM) data, we analysed weekly AFB in patients age ≥55 years implanted with dual-chamber pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy devices whose death was verified in the Social Security Death Index and who had continuous RM from 1 year to 4 weeks preceding death. Atrial fibrillation burden was defined as amount of time per week atrial rate exceeded a set threshold of 180 b.p.m. Case-crossover analysis was used to compare the AFB at every week to 6 control weeks at the start of the year before death. There were 3131 patients meeting analysis criteria (age at death 76 ± 8 years, 70% men). Weekly increase in AFB >6 h was associated with increased odds of death, which was greatest at 4 weeks before death [odds ratio (OR) 2.30, 95% confidence interval (CI) 2.09-2.53; P < 0.001]. Atrial fibrillation progression week-to-week >24 h was associated with the greatest odds of death (OR 12.95, 95% 8.72-19.22; P < 0.001). A combination of AFB >6 h per week and activity <0.5 h per day was associated with an increased odds of death. Conclusion In this large patient cohort, AFB progression accelerated in the weeks leading to death. Continuous monitoring of AFB may help identify device patients who may be at risk for adverse outcomes, including death.