Atrial fibrillation in cardiac resynchronization recipients with and without prior arrhythmic history. How much of arrhythmia is too much?

Abstract

Background: The aim of the study was to assess long-term incidence of atrial fibrillation (AF) in cardiac resynchronization (CRT) recipients with and without prior arrhythmic history, factors predisposing to arrhythmia, as well as to evaluate the prognostic power of cumulative arrhythmia burden, duration of the longest episode and the number of episodes.

Methods: Device-collected data on AF episodes during 24 months in 96 participants of a randomized CRT-trial were analyzed (15% in NYHA class IV, sinus rhythm, median left ventricular ejection fraction 24% and QRS 169 ms). Blindly adjudicated major adverse car­diac events (MACE) and any-cause death were censoring variables.

Results: Two-year incidence of AF was 70%, including 66% of patients without previous AF history. No baseline characteristics distinguished those who developed new onset AF. Percent of time spent in AF, but not number of episodes predicted mortality (adjusted hazard ratio [HR] 1.05 ± 95% confidence interval CI 1.01–1.10) and MACE incidence (HR 1.03 ± 1.01–1.07; p = 0.03). Duration of the longest episode also predicted mortality (HR 1.06 ± 1.01–1.12; both p = 0.03). Prognostic impact of AF load was marked only in patients with slower ventricular response (< 98/min), but was independent from CHADS₂ scores, pacing burden, or prior atrioventricular nodal ablation.

Conclusions: Seven out of 10 CRT-patients had AF within 2 years, including two-thirds of subjects without arrhythmic history. No baseline features distinguished those who developed new onset AF. Arrhythmia burden and duration of the longest episode, but not number of episodes influenced outcomes in CRT-patients, irrespectively from pacing burden or prior atrioventricular node ablation.