Charge-density mapping to evaluate non-pulmonary vein substrate in patients with paroxysmal atrial fibrillation: the ACUPRED study
Authors: Pannone L , Mojica J , Della Rocca D G , Vergara P , Sorgente A , Overeinder I , Bala G , Almorad A , Stroker E , Sieira J , La Meir M , Brugada P , Chierchia G B , Sarkozy A , De Asmundis C 
Published: May 2024

Abstract

Background/introduction
Pulmonary veins (PV) electrical isolation (PVI) is the main ablation strategy for the treatment of paroxysmal atrial fibrillation (AF), since the description of PV triggers. However, non-PV substrate and triggers in AF are not a negligible clinical issue. Indeed, in up to 22% of patients with AF recurrence after PVI, all PV are found isolated. Non-PV triggers can be demonstrated in up to 10-15% of non-selected patients at first AF ablation and non-PV substrate has been related to functional slow conduction and fibrosis also in paroxysmal AF.

Purpose
The aim of this study is to evaluate non-PV substrate (slow conduction) and triggers with charge-density (CD) mapping in patients with paroxysmal AF.

Methods
All patients, were prospectively enrolled in 2023. Inclusion criteria for the study were: 1) paroxysmal AF patients undergoing PVI procedure with a single-shot device and 2) CD mapping pre- and post- PVI. CD mapping was performed during CS proximal pacing at cycle length (CL) 600 ms and CS proximal pacing at CL 300 ms, pre- and post- PVI. Conduction velocity (CV) magnitude (in cm/s) and vector (direction and sense) were calculated offline for each CD map for all anatomical vertices. Reduction map was defined as the map of CV magnitude difference between CL 600 ms and CL 300 ms, Figure 1. Refraction map was defined as the map of CV direction difference between CL 600 ms and CL 300 ms, Figure 1. Non-PV substrate was defined at pre-PVI maps as: 1) slow conduction (&lt;30 cm/s) at CL 600 ms or CL 300 ms, or 2) difference in CV magnitude (&gt;25 cm/s) at reduction map, a marker of functional slow conduction (induced by fast pacing), or 3) difference in CV direction more than 90° between two neighboring vertices at refraction map, a marker of anisotropy, Figure 1. Non-PV triggers were defined as non-PV premature atrial contractions &gt;10/min or inducing AF.

Results
A total of 43 patients (60.6 ± 11.2 years, 74.4% males) with paroxysmal AF undergoing first procedure PVI were analyzed. Non-PV substrate was found in 13 patients (30.2%). Non-PV triggers were found in 3 patients (6.9%), including one patient on the posterior wall near right PV antra and two patients on the posterior wall near the left PV antra. At a mean follow-up of 5.6 months, a total of 5 patients (11.6%) experienced a recurrence. Patients experiencing a recurrence had more frequently non-PV substrate (80.0% vs 23.7%, p=0.024) and lower CV magnitude at CL 600 ms pre-PVI (72.3 cm/s vs 83.1 cm/s, p=0.04). At survival analysis for 34 patients (79.1%) out of the 2 months blanking period, patients with non-PV substrate had lower freedom from AF recurrence (56% vs 90%, p=0.0028), Figure 2.

Conclusion
In patients with paroxysmal AF undergoing index PVI, non-PV substrate or triggers can be found in up to 37.1% of cases. Non-PV substrate is associated with worse arrhythmic prognosis.Figure 1Figure 2