P1020Persistent AF patients with limited areas of low voltage have a similar benefit from pulmonary vein isolation as compared to paroxysmal AF patients: insight from the SMOP study
Authors: Frigerio L , Sanzo A , Cornara S , Chieffo E , La Greca C , Sirico G , Scopinaro A , Solimene F , Fedele L , Augello G , Marrazzo N , Turreni F , Tritto M , Rordorf R 
Published: June 2020

Abstract

Background
Pulmonary vein isolation (PVI) performed with radio-frequency catheter ablation (CA) is an effective therapy for atrial fibrillation (AF). However previous data have suggested that PVI is less effective in persistent (PER) vs. paroxysmal (PAR) AF. Atrial fibrosis and scar, indeed, are an important substrate involved in persistent AF, and some author correlate them to an increased rate of recurrences after CA. For this reason several adjunctive ablation strategies have been suggested for invasive treatment in PER AF pts. However, there is a lack of evidence on their effectivness in current literature.

Objective
the aim of our study was to assess the rate of AF recurrences in PAR and PER AF patients after a first pulmonary vein isolation (IVP) procedure, and their relationship with low voltage areas of the left atrium assessed by means of high density mapping performed before CA.

Methods
we analyzed 214 patients of the SMOP-AF study (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric registry enrolling patients with both PAR and PER AF undergoing a first radio-frequency CA procedure aimed to obtain permanent PVI . High-density mapping was performed in sinus rhythm using the CARTO system before PVI. Areas with less than 0,5 mV on mapping were defined as low voltage zone (LVZ); LVZ was indexed on the atrial area. Comparisons were made by cross-tables and Chi-square test or Student T test.

Results
Patients with PER AF (n = 44, 21%) were older (63 ± 9 vs 58 ± 10 yrs, p = 0.01), but notably with no difference in LVEF and atrial dimensions as compared to pts with PAR AF. In addition no statistical difference was observed in procedural variables, except for a greater LVZ area on atrial mapping (8 ± 18 % vs. 5 ± 15 %, p = 0.04) and a longer p wave duration (115 ± 21 msec vs. 103 ± 18 msec, p = 0.01) in pts with PER AF. The incidence of recurrence in the overall population was 15.3% at 3 months and 13.7% from 3 to 12 months: there was no statistical difference in success-rate between PER and PAR pts (respectively 79,5% vs 86% p value = 0.315 in blanking period and 85,3% vs 86,5% p value = 0.8 at 3-12 months follow-up). No statistical difference was observed for ablation variables (number of lesion, contact force, force time integral) in pts with vs. without recurrences.

Conclusion
Our study showed that pulmonary vein isolation alone seems to be as effective in paroxismal and persistent AF patients with low degree of left atrial fibrosis. Our data call into question the idea that PVI alone is not effective in PER AF. High density mapping of the LA could help to identify a subset of PER AF patients with a limited extension of low voltage areas (i.e around 10% of the overall LA surface) that could benefit from PVI without adjunctive ablation strategies. Our data needs to be confirmed in a longer follow-up.