Abstract 19408: Noninvasive Electrocardiographic Imaging Demonstrates Early Structural and Functional Changes Associated with Paroxysmal Atrial Fibrillation in Humans
BACKGROUND: Atrial fibrillation (AF) causes and perpetuates with a remodeling process that involves both functional (ion channel, connexin) and structural (fibrosis) changes to atrial tissue. Presently, there is no noninvasive method to study this process in humans. Noninvasive electrocardiographic imaging (ECGI) could provide insight into remodeling processes associated with early AF.
METHODS: Noninvasive ECGI was performed during sinus rhythm on 20 patients with a history of paroxysmal AF undergoing pulmonary vein isolation procedure after antiarrhythmic drug washout period. Eight patients with no history of AF and normal ventricular function were used for controls. For functional analysis, total atrial conduction time (TACT) and left atrial conduction time (LACT) were measured. For structural analysis, left atrial posterior wall (LAPW) voltage was measured. To account for patient-specific torso variability, this value was indexed to the maximal left atrial appendage voltage (indexed LAPW).
RESULTS: Compared to controls, patients with AF had longer TACT (100 vs. 79 ms control, p<0.005) and longer LACT (55 vs. 39 ms control, p = 0.034, top left figure). There were no differences in raw LAPW voltage (0.40 vs. 0.47 mV control, p = 0.53), but significant differences existed after adjusting for patient-specific torso variability (0.36 vs. 0.64 mV control, p < 0.020, top right figure). These differences were strongly associated with duration of PAF diagnosis. Subtle functional differences were observed early in AF, while significant functional and structural changes were seen with AF diagnosis of longer duration (5+ years, see bottom figure).
CONCLUSIONS: Very early in human AF, functional effects of ion channel and connexin remodeling are evident with delayed global and regional electrical activation. With longer AF, more pronounced delay and measurable decrease in electrogram voltage are likely a combined effect of ion channel adaptation and early fibrosis.
- © 2012 by American Heart Association, Inc.