LOCAL CONDUCTION DELAY SITES IN THE LEFT ATRIA IN PATIENTS WITH PERSISTENT ATRIAL FIBRILLATION: PRELIMINARY RESULTS

Aim: To explore conduction abnormalities in the left atrium (LA) under programmed pacing in patients with atrial fi brillation (AF) and to investigate the relationship between the conduction delay sites and the localization of fi brosis area and electrical rotors.
Materials and methods: Activation and voltage mapping was performed in 10 patients (5 females, age 56,6±9,0 y.o) with paroxysmal (n=2) and persistent (n=8) AF before pulmonary vein isolation procedure using CARTO 3 System (Biosense Webster, Inc, USA) (n=9) and Rhythmia HDx System (Boston Scientifi c, Inc, USA) (n=1). In those patients who had AF rhythm (n=9), sinus rhythm was recovered by electrical cardioversion in 15 minutes before the catheter procedure. Cardiac mapping was conducted under programmed pacing (5 basic stimulus with 600 ms coupling interval and the 6th stimulus with 320 ms coupling interval) from the coronary sinus. Before the procedure some patients with AF rhythm (n=5) underwent non-invasive cardiac mapping (Amycard 01 C System, Amycard, LLC, Russia). AF was induced during programmed pacing in one patient; in the remaining 9 patients, the mapping procedure was completed. Slow conduction sites were detected in the LA in all patients with persistent AF while no one patient with paroxysmal AF have signifi cant conduction delay.
The slow conduction sites were found in the posterior region (n=2), in the posterior-superior region and in the roof (n=2), in the anterior-medial region (n=2) and in the posterior-lateral region (n=1) of the LA. Their diameter was 8.6±0.6 mm under the basic and 9.7±0.6 under the short coupling interval. Conduction delay was 46 ± 4 ms under the basic and 54±5 ms under the short coupling interval. Low voltage zones (magnitude < 0.5 mV) were detected in 3 patients with persistent AF. Only in one case the low voltage zone coincided with the conduction delay site. Electrical rotors were detected in all 5 examined patients. Localization of the stable rotors did not well match with the slow conduction sites.
Conclusions: The study confi rmed the presence of local conduction delay sites in patients with persistent AF. The conduction abnormalities can play a signifi cant role in genesis of AF. 

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