Right Atrial Complexity Evolves With Stepwise Left-Sided Persistent Atrial Fibrillation Substrate Ablation and Predicts Outcomes.

Abstract

This study sought to study the relation between outcomes of modified stepwise atrial fibrillation (AF) substrate ablation and dynamic electrogram characteristics in the coronary sinus (CS) and right atrium (RA). Identifying patients with persistent AF who will benefit from limited lesion sets versus those requiring extensive substrate modification is challenging. We studied 70 patients undergoing persistent AF ablation, 43 with acute success (successful ablation [sABL], AF termination, or noninducibility) and 27 with failure (failed ablation [fABL], no termination, or induced AF of >5minutes). Dominant frequency (DF) and sample entropy (SampEn, increasing with signal complexity) were measured on 30-second recordings of wide-coverage simultaneous RA and CS electrograms during baseline AF and induced AF post-pulmonary vein isolation and after left-sided electrogram-guided ablation steps (on the CS with or without the left atrium [LA]). At baseline AF, patients with sABL exhibited lower RA SampEn (p=0.023) and lower CS DF (p=0.030) compared to fABL. A positive RA-to-CS SampEn gradient predicted ablation failure (48% vs. 19% for patients in fABL vs. sABL; p=0.015). A positive RA-to-CS DF gradient developed in patients with fABL after extra-pulmonary vein substrate modification, unlike patients with sABL (p=0.0008). At 24months, 76% of patients were AF free, and 68% were arrhythmia free. sABL was associated with fewer AF recurrences (hazard ratio: 0.31; 95% confidence interval: 0.12-0.84; p=0.021). A negative RA-to-CS SampEn gradient at baseline was associated with freedom from AF (-0.14 ± 0.19 vs. 0.04 ± 0.18; p=0.002). RA greater than CS electrogram complexity gradients at baseline or developing during ablation are associated with unfavorable acute and long-term outcomes of persistent AF ablation. These parameters allow monitoring of the effects of left-sided substrate ablation and, therefore, a rational choice of additional RA substrate modification.