Decrement Evoked Potential (DEEP) Mapping of the Atria: Unmasking Atrial Fibrillation Substrate

Background Atrial myopathy may underlie the progression of atrial fibrillation (AF) from a treatable disease to an irreversible condition with poor ablation outcomes. Electrophysiological methods to unmask areas prone to re-entry initiation could be key to defining latent atrial myopathy.Methods Consecutive patients referred for AF ablation were prospectively included at four institutions. Decrement evoked potential mapping (DEEP) was performed in eight left atrial sites and five right atrial sites, from two different pacing locations (endocardially from the left atrial appendage, epicardially from the proximal coronary sinus). The electrograms (EGMs) during S1 600 ms drive and after an extra stimulus (S2 at 130 ms above atrial refractoriness) were studied at each location and assessed for decremental properties. Follow-up was 12 months.Results Seventyfour patients were included and 85% had persistent AF. A total of 17,614 EGMs were individually analysed and measured. Nine percent of the EGMs showed DEEP properties (local delay of .10 ms after S2) with a mean decrement of 33626 ms. DEEPs were more frequent in the left atrium than the right atrium (9.4% vs 8.0%; p,0.001) and more prevalent in persistent AF patients than paroxysmal AF patients (9.8% vs 4.6% p=0.001). Atrial DEEPs were more frequently unmasked in normal bipolar voltage areas and by epicardial pacing than endocardial pacing (9.6% vs 8.4%, respectively; p=0.004). Within the left atrium, the roof had the highest prevalence of DEEP EGMs.Conclusions DEEP mapping of both atria is useful for highlighting areas with a tendency for unidirectional block and reentry initiation. Those areas are more easily unmasked by epicardial pacing from the coronary sinus and more prevalent in persistent AF patients than in paroxysmal AF patients.

Automated summary

Atrial myopathy may contribute to the progression of atrial fibrillation and affect the success of ablation. DEEP mapping can identify areas prone to re-entry initiation and is more common in persistent AF patients compared to paroxysmal AF patients.