Electrogram coupling as a measure of local conduction during atrial fibrillation

Epicardial wavefront conduction patterns during atrial fibrillation (AF) can be recorded using high-density contact mapping. Quantification of electrogram morphology similarity at adjacent recording sites during AF may characterize substrate complexity without the need for electrogram annotation. Electrogram coupling was quantified as the decay in reconstruction quality of a central electrogram by its neighbors at increasing distance. Coupling was computed in patients in paroxysmal AF (PAF, n=12) and persistent AF (persAF, n=9) with a 16 ×16 grid of electrodes (1.5mm electrode distance) with nonnegative least squares using only complete, symmetric topologies. Half-decay distance c0.5 was compared to conventional conduction-related contact mapping parameters. Electrogram coupling was weaker in persAF than in PAF (c0.5 (median±MAD): 2.4±0.5mm vs. 3.2±1.2mm, p<;0.02). High correlation was found between mean c0.5 and CV (ρ=0.80, p<;0.001). Other parameters showed only moderate or no correlation. Differences in AF conduction velocity between patients can be accurately described using a surrogate parameter based on the degree of electrogram coupling. This technique can for instance be applied to high-density contact recordings to quickly assess the Class I effect of antiarrhythmic drugs, both in atrial and ventricular recordings.