Disparate evolution of right and left atrial rate during ablation of long-lasting persistent atrial fibrillation

Abstract

Objectives: The purpose of this study was to assess whether additional ablation in the right atrium (RA) improves termination rate in long-lasting persistent atrial fibrillation (PsAF).

Background: Prolongation of atrial fibrillation (AF) cycle length (CL) measured from the left atrial appendage predicts favorable outcome during catheter ablation of PsAF. However, in some patients, despite prolongation of AF CL in the left atrium (LA) with ablation, AF persists. We hypothesized that this persistence is due to RA drivers, and that these patients may benefit from RA ablation.

Methods: In all, 148 consecutive patients undergoing catheter ablation of PsAF (duration 25 +/- 32 months) were studied. AF CL was monitored in both atria during stepwise ablation commencing in the LA. Ablation was performed in the RA when all LA sources in AF had been ablated and an RA-LA gradient existed. The procedural end point was AF termination.

Results: Two distinct patterns of AF CL change emerged during LA ablation. In 104 patients (70%), there was parallel increase of AF CL in LA and RA culminating in AF termination (baseline: LA 153 ms [range 140 to 170 ms], RA 155 ms [range 143 to 171 ms]; after ablation: LA 181 ms [range 170 to 200 ms], RA 186 ms [range 175 to 202 ms]). In 24 patients (19%), RA AF CL did not prolong, creating a right-to-left frequency gradient (baseline: LA 142 ms [range 143 to 153 ms], RA 145 ms [range 139 to 162 ms]; after ablation: LA 177 ms [range 165 to 185 ms], RA 152 ms [range 147 to 175 ms]). These patients had a longer AF history (23 months vs. 12 months, p = 0.001), and larger RA diameter (42 mm vs. 39 mm, p = 0.005), and RA ablation terminated AF in 55%. In the remaining 20 patients, biatrial ablation failed to terminate AF.

Conclusions: A divergent pattern of AF CL prolongation after LA ablation resulted in a right-to-left gradient, demonstrating that the right atrium is driving AF in approximately 20% of PsAF.

Figure 1

Measurement of Atrial Fibrillation Cycle Length. A circular mapping catheter and the ablation catheter are placed in the right and left atrial appendages respectively. Using automated software with manual correction where necessary the AFCL is measured synchronosly using unambiguous recordings. The mean AFCL is determined from 30 seconds of continuous recording and in this example the cycle length of the right atrium is 151ms and in the left is 161ms.

Figure 2

Patient Flow Chart

Figure 3

Evolution of Atrial Fibrillation Cycle Length During Ablation. In group 1, AFCL measured from both the right and left atrial appendage prolongs in parallel, with termination of AF occuring in the left atrium. In Group 2a, where termination occurs during the right atrial ablation, the AFCL prolongs in the left atrium but not in the right atrium, with left atrial ablation. In Group 2b, the AFCL measured in the right atrium fails to prolong following PV isolation. Data compared using ANOVA on ranks to compare AFCL at baseline and after each step of the ablation inside each atrium, the p value representing the difference in AFCL occurring during ablation inside each atrium.

Figure 4

Sites of AF Termination Within The Right Atrium. Ant: Anterior Right Atrium, RAA: Right atrial appendage, SVC, Superior Vena Cava, Sept: Right Atrial Septum, Lat, Lateral Right Atrium, TC, Terminal Crest, Post: Posterior Right Atrium, CTI: Cavotricuspid Isthmus, IVC: Inferior Vena Cava.

Figure 5

Arrhythmia Free Survival By Site of Arrhythmia Termination. Kaplen Meier analysis of the recurrence of any atrial arrhythmia (Atrial fibrillation or Atrial Tachycardia). Group 1 Left atrial termination, Group 2a Right Atrial Termination, Group 2b Non-termination.