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Characteristics of Ectopic Triggers Associated With Paroxysmal and Persistent Atrial Fibrillation: Evidence for a Changing Role
Study Questions:
Is persistent atrial fibrillation (PersAF) less dependent than paroxysmal atrial fibrillation (PAF) on short-coupled premature atrial complexes (PACs)?
Methods:
Holter monitoring was performed for 1-7 days in 49 patients with PAF (mean age 61 years), 24 patients with PersAF (mean age 57 years), and 24 controls, with no history of AF (mean age 60 years). Patients with PersAF who had AF throughout the monitoring period were excluded. The characteristics of atrial ectopy were analyzed. The reduction in PAC coupling interval relative to the prior normal R-R interval was defined as the coupling interval index (C-Index).
Results:
The median number of PACs/hour did not differ significantly between the patients with PAF (2.0) and PersAF (2.9). Both were significantly higher than in the controls (0.8 PACs/hour). The highest hourly counts of PACs occurred between 7 PM and 6 AM in patients with PAF and between 6 AM and 7 PM in patients with PersAF. The mean C-Index was significantly higher in patients with PAF (0.37) than in controls (0.33), but not significantly different from the patients with PersAF (0.34).
Conclusions:
PACs are more frequent in patients with AF than in controls. Hourly trends in PACs suggest that autonomic modulation of triggers is a larger factor in PAF than in PersAF.
Perspective:
It is well known that the efficacy of pulmonary vein isolation for preventing AF is much higher in patients with PAF than in patients with PersAF. This is because the pulmonary vein muscle sleeves commonly are the site of origin of the ectopy that triggers PAF, but typically do not play a major role in triggering or sustaining PersAF.
Keywords: Pulmonary Veins, Radiology Information Systems, Atrial Fibrillation, Electrocardiography, Heart Rate, Catheter Ablation, Atrial Premature Complexes, Autonomic Nervous System
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