Po-01-199 ablation parameters as predictors of atrial arrhythmia recurrence after pulmonary vein isolation alone in persistent af: a decaaf ii substudy

Impedance drop is a known predictor of good lesion formation after pulmonary vein isolation (PVI). We sought to assess the role of impedance drop (ID), and the ratio of ID over ablation index (ID/AI) in predicting Atrial Arrhythmia (AA) recurrence in pts with persistent atrial fibrillation (PrAF) undergoing PVI alone as the initial procedure. The DECAAF II Trial was a prospective randomized controlled trial of pts with PrAF undergoing first time ablation. Baseline demographics and risk factors were collected for all pts. All of the 843 pts in the study were considered for the analysis. Out of the 843 pts, 538 had ID data and 166 pts had ID/AI ratio data. Pts were instructed to provide single-lead home ECG strips once daily and during symptoms. The primary endpoint was single-procedure success, defined as freedom from recurrent AA following a 90-day blanking period through 365 days post-procedure. Means of ID and ID/AI were calculated for the whole population. To assess for the effect of ID on AA recurrence, pts were divided into 2 groups: pts with ID≥mean and pts with ID7.76 (52 vs 39%, p=0.02). This was consistent in the PVI only (54 vs 41%, p=0.02) and the PVI+fibrosis group (49 vs 36%, p=0.02). Pts with an ID/AI ratio<0.021 had significantly more AA recurrence compared to pts with ID/AI ratio≥0.021 (55 vs 35%, p=0.007). This finding was significant in the PVI only group (56% vs 33%, p=0.035) but not in the PVI+fibrosis groups (55 vs 38%, p=0.11). Moreover, the ratio of ID/AI showed better performance (AUC=0.6) than ID alone (AUC= 0.56) when predicting AA recurrence. Impedance drop, and the ratio of ID/AI both were significant predictors of AA recurrence in pts with PrAF undergoing PVI alone as the first ablation procedure. The ratio of ID/AI might be a better clinical tool in identifying patients at increased risk of AA recurrence.