Abstract 15769: Association of Rate-dependent Conduction Block of Coronary Sinus - Left Atrial Connections With Atrial Fibrillation/Flutter Initiation at EP Study
Introduction: Although clinically recognized, variations in distal coronary sinus musculature and left atrial myocardium (CS-LA) connections have not been systematically evaluated.
Hypothesis: We sought to test the hypotheses that a) CS-LA connections vary in location and susceptibility to rate dependent conduction block, and b) are associated with atrial arrhythmia induction.
Methods: The study cohort included 21 consecutive patients (age 64±10.64 years, 71.4% male, 23.8% persistent) with AF who underwent CS-LA mapping prior to AF ablation. Pacing and recording were performed using decapolar, quadripolar, and duodecapolar catheters in the CS, high right atrium (HRA), and left atrium (LA), respectively (Figure). Trains of 10 pacing stimuli were performed from each of the following sites: CS proximal, CS distal, LA septum, lateral LA, and HRA, at the following cycle lengths (CL): 1000, 500, 400, 300, and 250ms while recording from the other catheters.
Results: With the CS 9-10 bipole just inside the CS ostium, CS-LA connections were observed in 36.8% at CS 9-10, 8.8% at CS 7-8, 12.3% at CS 5-6, 7.0% at CS 3-4, and 35.1% at CS 1-2. Eleven patients (52%) had AF/Flutter induced during the pacing protocol. Rate-dependent conduction block of a CS-LA connection at CL ≥250 ms was present in 91% of those with versus none of those without AF/flutter induction (P<0.001), and occurred at pacing CL of 1000 ms in 0%, 500 ms in 7.1%, 400 ms in 14.2%, 300 ms in 35.7%, and 250 ms in 42.9%.
Conclusions: Rate-dependent CS-LA conduction block is associated with AF/Flutter induction in patients with drug refractory AF undergoing ablation. The presence of dual muscular CS-LA connections, coupled with uni-directional block in one connection, may serve as a substrate for single or multiple reentry beats and arrhythmia induction.
Author Disclosures: D. Huang: None. J.E. Marine: None. J. Li: None. T. Zghaib: None. E.G. Ipek: None. M. Balouch: None. H. Ashikaga: None. R.D. Berger: None. S. Sinha: None. D.D. Spragg: None. H. Calkins: None. S. Nazarian: None.
- © 2016 by American Heart Association, Inc.