Abstract 18756: Focal Impulse and Rotor Mapping (FIRM): Analysis of Basket Electrode-endocardial Proximity
Introduction/Hypothesis: Reports of outcomes of atrial fibrillation (AF) ablation guided by FIRM have thus far been promising. FIRM maps are derived from atrial electrograms acquired using a 64 electrode “basket” catheter. There are significant discrepancies between atrial endocardial and basket geometries, and we sought to analyze individual basket electrode-endocardial proximities.
Methods: In 13 patients with persistent AF undergoing FIRM-guided ablation, extensive fast anatomical mapping of right (RA, N=10) and/or left (LA, N=9) atria using the CARTO™ system (Biosense) yielded comprehensive, high quality endocardial geometries. Basket location projected within these geometries permitted assessment of endocardial proximity of each basket electrode. Proximity was defined as “near” (within 5 mm of nearest endocardial surface), “distant” (5-10 mm), and “very distant” (>10 mm). In analyzing proximity status of groups of electrodes which comprised observed rotors, “uniform near” was defined as all electrodes within 5 mm of endocardium, “mixed” was defined as some electrodes within 5 mm and others beyond 5 mm, and “uniform far” as all electrodes beyond 5 mm.
Results: Right atrium: Among 10 patients, 54% of electrodes were near, 22% of electrodes were distant, and 24% of electrodes were very distant. Among 15 discrete rotors observed in 7 patients, 6 (40%) were uniform near, 8 (53%) were mixed, and 1 (7%) was uniform far.
Left Atrium: Among 9 patients, 53% of electrodes were near, 24% of electrodes were distant, and 23% of electrodes were very distant. Among 17 discrete rotors observed in 9 patients, 8 (47%) were uniform near, 9 (53%) were mixed, and none were uniform far.
Conclusions: Electrodes used to construct FIRM maps are commonly distant from the endocardial surface. Contact heterogeneity is common among groups of electrodes comprising rotors. The implications of these observations for use and utility of the basket-derived FIRM technique are unclear.
Author Disclosures: S.R. Soma: None. D.R. Siddoway: None. R. Bazaz: None. A. Voigt: None. S. Jain: Research Grant; Modest; Medtronic. S. Saba: Research Grant; Modest; Medtronic , St Jude. Research Grant; Significant; Boston Scientific. D. Schwartzman: Research Grant; Modest; Biosense, Medtronic, Boston Scientific. Consultant/Advisory Board; Modest; Biosense, Avery Dennison, QuantMD, Epicardial Frontiers.
- © 2015 by American Heart Association, Inc.