Epicardial stimulation accelerated the development of sustained atrial fibrillation compared to endocardial pacing (70% vs 14% at 3 weeks).
Does epicardial instrumentation and pacing accelerate the development of atrial fibrillation in a sheep model compared to endocardial pacing?
In a sheep model of atrial fibrillation, epicardial stimulation rather than epicardial instrumentation alone accelerates the development of sustained AF, highlighting the impact of experimental setup on arrhythmia inducibility.
Absolute Event Rate: 70% vs 14%
INTRODUCTION: Atrial electrical remodeling, shortening of the atrial effective refractory period (AERP) underlying atrial fibrillation (AF) has been described in different animal models. However, there remains some controversy regarding the time course of this electrical remodeling and the need for secondary factors in the development of AF. We investigated the effect of instrumentation on the inducibility of AF. We hypothesized that epicardial instrumentation could be a confounding factor that accelerates the development of AF. METHODS AND RESULTS: Thirty sheep were rapidly atrially paced at 600 beats/min for 15 weeks: 15 were endocardially instrumented and paced (endo), and 15 were both endocardially and epicardially instrumented. Six of these animals were endocardially paced (sham) and 9 were epicardially paced (epi). The underlying rhythm was determined at regular intervals, and electrophysiologic study was performed. AF developed significantly faster in the epi group. After 3 weeks of pacing, the cumulative incidence of sustained AF (>1 hour) already was 70% in this group versus only 14% and 20% in the endo and sham groups, respectively. After 15 weeks of pacing, this difference was no longer evident. Baseline AERP and minimal AERP, reached before the development of AF, were not significantly different in the three groups. Epicardial instrumentation (epi and sham) increased baseline left and right atrial pressures, but only epicardial stimulation (epi) led to early development of AF. CONCLUSION: In this sheep model of AF, the experimental setup is a major determinant of the inducibility of AF. Not epicardial instrumentation per se but epicardial stimulation accelerated the development of AF. Different animal models
Willems et al. (Tue,) conducted a other in Atrial fibrillation (n=30). Epicardial stimulation vs. Endocardial pacing (endo) and sham was evaluated on Cumulative incidence of sustained atrial fibrillation (>1 hour) after 3 weeks of pacing. Epicardial stimulation accelerated the development of sustained atrial fibrillation compared to endocardial pacing (70% vs 14% at 3 weeks).