Abstract 13734: Human Atrial Fibrillation is Initiated by Repolarization Alternans and the Formation of a Predominant Spiral Wave
HYPOTHESIS: To determine whether triggers initiate human atrial fibrillation (AF) by causing beat-to-beat oscillations (alternans) of action potential duration (APD) leading to the formation of a spiral wave or focal source that drives the atrium into AF.
BACKGROUND: Recent studies have discovered that human atrial fibrillation may be initiated then maintained by localized spiral waves (rotors). Additionally, abnormalities in human atrial repolarization (action potential duration, APD alternans) have been identified as dynamic substrates for AF initiation.
METHODS: In 19 patients with AF (n=5 persistent; age 62+10; LA diameter 42+6 mm) at EP study, we recorded atrial activation via 64-electrode basket catheters in the right and left atrium during AF induction by pacing from cycle lengths (CL) accelerating from 600-500ms (100-120bpm). Monophasic action potentials were used to quantify APD alternans continuously during induction. We studied activation patterns preceding and at the precise point of AF initiation in relation to APD dynamics.
RESULTS: Slow rate pacing activated the atria uniformly (figure A, evenly spaced activation contours in left atrium). After rapid triggers, the onset of human AF was heralded by the formation of one predominant spiral wave in 16/19 patients, lying in the left (n=10, figure C) and right (n=6) atria. APD alternans arose and increased in magnitude in 16/19 patients prior to AF initiation, and in 13/16 patients in whom AF initiated by the formation of a spiral wave (p<0.05; figure B). In these cases, APD alternans had magnitude 25+26 ms at sites 20+9 mm from the spiral wave core.
CONCLUSIONS: Human atrial fibrillation initiates by the formation of a predominant spiral wave (rotor) in the context of marked repolarization dispersion from APD alternans. Future studies should examine whether interventions to attenuate atrial repolarization alternans may suppress the milieu for human AF initiation.
- © 2012 by American Heart Association, Inc.