Electrogram dispersion mapping for repeat ablation in patients with persistent atrial fibrillation

Abstract Background/Introduction While pulmonary vein isolation (PVI) is a key guideline endpoint for atrial fibrillation (AF) ablation, strategies for repeat ablation are debated, particularly when PVs are isolated. Electrogram dispersion mapping identifies dynamic substrates using existing catheters, remote from the PVs and may confer benefit to additional ablation. Purpose To describe the outcome of repeat ablation using electrogram mapping to identify areas of mechanistic significance in persistent AF patients. Methods Patients undergoing repeat ablation for persistent AF were recruited from two international centers. A five spline catheter was used to mark areas of electrogram dispersion before any ablation using previously described criteria. After confirming PVI, or re-isolation of PVs if necessary, ablation of all dispersion areas was performed. If termination to atrial tachycardia (AT) occurred, this was mapped using conventional methods. Patients who terminated to sinus underwent reinduction pacing protocols to map any further AT or AF inducible. Patients were followed up at 12 months with continuous event monitors, and beyond 12 months based on local guidelines. Results In total, 167 AF patients were enrolled: age 66 ± 8 yrs; 32% female; mean LA diameter 4.8 cm. PVI was present in 108 (64%) of patients. All patients underwent LA mapping, and 75 (45%) underwent right atrial (RA) mapping. Patients had an average of 3.2 LA and 1.4 RA ablation sites. The total number of dispersion sites in patients was similar in patients with and without PVI, (4.1 ± 2 and 3.6 ± 1 respectively). AF terminated in 144 patients (86%), with an overall conversion to sinus rhythm obtained by ablation in 42% of the patients. Patients were followed for an average of 2.92 ± 0.9 years. At 12 months, 159 (95%) patients were AF free, and 124 (74%) remained free of atrial arrhythmia. Of those patients, only 8 (5%) had AF, with 35 (21%) recurring with AT or atrial flutter (AFL). Of the 70 patients who terminated to sinus with repeat ablation, only 2 (2.9%) recurred with AF and 26 (37.1%) had recurrence of atrial arrhythmia (AF/AT/AFL) as a whole throughout the entire follow-up period (P0.05). Patients with and without PVI at redo procedure did not have a statistically significant difference in recurrence of AF (Figure 1, P = 0.80) nor recurrence of atrial arrhythmia (Figure 2, P = 0.63) during total follow up time by log rank test. Conclusions In a difficult to treat population of persistent AF patients requiring a repeat ablation procedure, electrogram mapping led to rates of freedom from AF at 12 months similar to first time ablation series. Additionally, those with PVI present at time of procedure had similar benefit from this approach compared to those with reconnected veins. This is the largest demonstration of a technique that confers benefit in a PVI isolated subgroup of purely redo ablations for persistent AF.Figure 1:Percent AF FreeFigure 2:Percent AF/AT/AFL Free