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

Abstract

BackgroundThe 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 ResultsFifty‐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.

A mesh‐type flexible tip catheter vs a contact force catheter for catheter ablation of atrial fibrillation: A prospective nonrandomized 1:1 matched study

“…We estimated the sample size based on pilot data from the participating institution and previous reports 18,19 . To calculate a proper sample size, we used R software version 3.5.2 (R Foundation for Statistical Computing, Vienna, Austria) with the “pwr” package (parameters: p1 = 0.38, p2 = 0.20, power = 80%, α = .05).…”

Posterior Wall Isolation in Atrial Fibrillation Ablation

“…Kumar et al were able to demonstrate posterior wall isolation in roughly half of patients with combined epicardial-endocardial ablation. 24 However, in five patients in whom posterior wall isolation was achieved at the index procedure who returned for subsequent repeat ablations, all had recurrence of conduction to the posterior wall.…”

“…Kumar et al noted that, when these criteria were rigidly applied, that, although it was possible to achieve electrical silence of the posterior wall (< 0.1 mV) with the inability to capture the heart with pacing from within the LA box in essentially all cases, in a significant proportion of patients, LA posterior wall dissociation could not be achieved, and it was not always possible to demonstrate local LA capture with pacing from within the box (ie, evidence of LA posterior wall block was frequently uncertain-see also the following). 24 The alternative technique for LA posterior wall isolation-the obliteration of LA posterior wall potentials with multiple ablation lesions 30,31 -results in electrical silence of the LA posterior wall in all cases. The outcome can only be defined by voltage mapping because there should be no electrically viable myocardium in the ablated segments to allow for reliable pace capture.…”

“…Kumar et al report their results in 57 patients with significant structural heart disease, failed previous endocardial ablation, or longstanding persistent AF, of whom 30 underwent endocardial ablation and 27 underwent hybrid endocardial and epicardial ablation, respectively. 24 Their endpoint, entrance and exit block with the ability to dissociate the posterior wall from the remaining atria, was difficult to achieve, with successful isolation of the posterior wall in only 23% of endocardial-only ablations and in 52% of hybrid ablations. Over a median follow-up of 10 months, recurrent arrhythmias occurred in 25 patients (44%) (specifically, atrial tachycardia in seven and AF in 18).…”

Left atrial posterior wall isolation affects complex fractionated atrial electrograms in persistent atrial fibrillation

“…9,10 Left atrial posterior wall isolation (LAPWI) has been part of the surgical Maze procedure and has yielded good results as an open surgical procedure. 11 Although LAPWI is challenging to achieve with the use of endocardial catheter ablation, 12,13 some previous studies have reported the effectiveness of LAPWI to suppress AF recurrence after catheter ablation. [14][15][16][17] However, the mechanisms of the AF-suppressing effects of LAPWI are still unclear.…”