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. 2016 Sep 23;5(9):e003885.
doi: 10.1161/JAHA.116.003885.

Challenges and Outcomes of Posterior Wall Isolation for Ablation of Atrial Fibrillation

Prabhat Kumar  1 , Ayotunde M Bamimore  1 , Jennifer D Schwartz  1 , Eugene H Chung  1 , Anil K Gehi  1 , Andy C Kiser  2 , James P Hummel  1 , J Paul Mounsey  3
Affiliations

Challenges and Outcomes of Posterior Wall Isolation for Ablation of Atrial Fibrillation

Prabhat Kumar et al. J Am Heart Assoc. .

Abstract

Background: The left atrial posterior wall (PW) often contains sites required for maintenance of atrial fibrillation (AF). Electrical isolation of the PW is an important feature of all open surgeries for AF. This study assessed the ability of current ablation techniques to achieve PW isolation (PWI) and its effect on recurrent AF.

Methods and results: Fifty-seven consecutive patients with persistent or high-burden paroxysmal AF underwent catheter ablation, which was performed using an endocardial-only (30) or a hybrid endocardial-epicardial procedure (27). The catheter ablation lesion set included pulmonary vein antral isolation and a box lesion on the PW (roof and posterior lines). Success in creating the box lesion was assessed as electrical silence of the PW (voltage <0.1 mV) and exit block in the PW with electrical capture. Cox proportional hazards models were used for analysis of AF recurrence. PWI was achieved in 21 patients (36.8%), more often in patients undergoing hybrid ablation than endocardial ablation alone (51.9% versus 23.3%, P=0.05). Twelve patients underwent redo ablation. Five of 12 had a successful procedural PWI, but all had PW reconnection at the redo procedure. Over a median follow-up of 302 days, 56.1% of the patients were free of atrial arrhythmias. No parameter including procedural PWI was a statistically significant predictor of recurrent atrial arrhythmias.

Conclusions: PWI during catheter ablation for AF is difficult to achieve, especially with endocardial ablation alone. Procedural achievement of PWI in this group of patients was not associated with a reduction in recurrent atrial arrhythmias, but reconnection of the PW was common.

Keywords: atrial fibrillation; catheter ablation; hybrid ablation; posterior wall box; posterior wall isolation.

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Figures

Figure 1
Figure 1
A, Lesion sets to an isolated posterior wall, with a silent posterior wall on voltage mapping after completion of ablation. B, A patient unable to isolate the posterior wall despite lesion sets for posterior wall isolation, with electrical activity in areas of the posterior wall. Gray areas show bipolar peak‐to‐peak voltage during sinus rhythm <0.1 mV, and purple areas show bipolar voltage during sinus rhythm of >0.5 mV.
Figure 2
Figure 2
An example of entrance and exit block in the PW. A, An isolated PW potential (red arrow) evident during sinus rhythm. B, Capture of PW (green arrows) with pacing without capturing the rest of the atrium, proving exit block from the PW box. CS indicates coronary sinus; CS dist, bipole recording distal coronary sinus; CS prox, bipole recording proximal coronary sinus; PW, posterior wall; PW map, bipole recording potential inside the posterior wall box; PW pace, bipole used to pace from the posterior wall box. STIM, stimulation channel.
Figure 3
Figure 3
Kaplan–Meier curve showing freedom from atrial arrhythmias after index ablation procedure in patients with (green line) and without (red line) procedural isolation of the posterior wall (no statistically significant difference in survival free of atrial arrhythmia).
See this image and copyright information in PMC

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