Autonomic modulation of complex fractionated atrial electrograms in patients with paroxysmal atrial fibrillation

In patients with atrial fibrillation (AF), complex fractionated atrial electrograms (CFAE) have been shown to be located at the anatomic sites of ganglionated plexi (GP). This study aimed at investigating the contribution of parasympathetic activity to formation of CFAE.

Twelve patients (aged 55 ± 11 years, five females) with paroxysmal AF were studied. Following electroanatomical mapping of the left atrium, GP were identified by high frequency stimulation (HFS), 12-24 V in a conscious state, and assessment of CFAE during AF was performed with the use of dedicated software. Fractionated activity was measured at each GP site by interval confidence levels (ICL) and average complex interval (ACI), and was compared to measurements obtained 1 min after intravenous administration of 1 mg of atropine.

In total, 30 out of 48 GP could be identified by HFS. CFAE were detected at all sites where GP were found. ICL was significantly lower after atropine administration only at ARGP (5.4 ± 2.7 vs. 2.8 ± 2.1, p = 0.028), whereas no significant difference was detected pre- or post-atropine at any GP in ACI. Considering all fractionation values from the four GP, a statistically significant reduction of the ICL score was observed (4.6 ± 3.4 vs. 5.8 ± 2.9, p = 0.03) after atropine administration, whereas no significant differences were observed in the ACI score (144.5 ± 24.0 post-atropine vs. 146.7 ± 27.7 pre-atropine, p = 0.620). The average RR interval became significantly shorter post-atropine (575.8 ± 139.1 vs. 637.2 ± 158.7, p = 0.004).

Our data do not support the hypothesis that parasympathetic activity plays the dominant role in electrogram fractionation.