Abstract 2349: New Insights into the Mechanism of Chronic Atrial Fibrillation in Patients
Introduction: The mechanism(s) of chronic atrial fibrillation (AF) in humans is/are not well understood. We performed epicardial mapping of chronic AF in patients undergoing open heart surgery to test the hypothesis that chronic AF is due to 1or more drivers.
Methods: Seven patients with chronic AF (1 month to >15 years duration) were mapped for a duration of 1 to 5 minutes during AF. Atrial electrograms (AEGs) were simultaneously recorded from 404 –512 epicardial electrodes arranged in bipoles along with ECG lead II. 40 – 60 secs were analyzed per patient in multiple segments of 10 to 20 sec each. For all segments, both FFT and cycle length (CL) variability were analyzed for each site. Regular activity at each site was defined as the mean CL +/− 15 ms.
Sites with regular activity (CL’s range 165–215 ms) were found in 6 out of 7 patients;
Two or more sites with regular activity but with distinct CL’s existed simultaneously;
Each patient had 3– 4 dominant peak FFT frequencies;
Most of the sites of regularity were distributed in the left atrium and Bachmann’s bundle; only 20 % were found in the right atrial free wall;
Only 15% of the sites showed regularity that was present for the whole 60 secs analyzed; typically, regularity at one site would return later at the same CL after a period of irregularity;
Activation sequence maps sometimes suggested that sites with regular activity were replaced by regularity from the neighboring sites, albeit at different CLs.
In the patient with the longest standing AF, no areas of regularity were found.
Conclusion: Regarding the mechanism(s) of chronic AF in these patients,
sites of prolonged regularity, some lasting 60 seconds, is not consistent with a multiple reentrant wavelet mechanism;
the simultaneous presence of several sites with regular activation at different CLs, speaks against the single driver hypothesis;
multiple unstable drivers best explains the mechanism of chronic AF in all but one of these patients.