Abstract 9323: Localized Reentrant Activation in the Left Atrium During Human Atrial Fibrillation: Relationship to Complex Fractionated Atrial Electrograms and Low Voltage Zones

Abstract

Introduction: In humans, the existence of reentrant sources maintaining AF and the underlying electroanatomic substrate has not been well defined. Our objective was to determine the prevalence of localized reentrant activation in the left atrium (LA) during human AF and whether complex fractionated atrial electrograms (CFAEs) or low voltage areas co-localize with these sites. Methods: We prospectively studied 32 patients (57±8yrs, 88% persistent AF) undergoing AF catheter ablation. Bipolar EGMs were recorded for 2.5sec during AF using a roving 20-pole circular catheter in the LA. Reentrant activation was defined as sequential temporal activation of bipoles around the circular catheter. Bipolar EGM fractionation index (FI) and bipolar voltage were used to define CFAEs (FI>7) and low voltage areas (<0.1 mV), respectively. Results: In 21 (66%) patients, 47 reentrant sites were identified. Few (9%) lasted 2.5sec (CL 183±6ms) (Figure, panel A and C), while the majority (91%) were nonsustained (duration 610±288ms, CL 149±11ms) (Figure, panel B and D). Reentrant sites were most common in the PV antrum (71%) and posterior LA (25%). CFAEs were recorded from 18±12% of LA area and most (92±7%) were not associated with reentrant sites. However, 85% of reentrant sites contained CFAEs (Figure, Panel B and D). Very low voltage (<0.1mV) areas comprised 12±10% of LA area and were present in 23% of reentrant sites. Conclusions: In patients with predominantly persistent AF, localized reentrant activation is commonly present, but tends to be transient (<1 second). Although most CFAEs do not co-localize with reentrant sites, the high prevalence of CFAEs and very low voltages within the circuit may indicate slow conduction in diseased myocardium that is necessary for sustaining reentry.