An empirical posterior box isolation (POBI) was not found to improve the rhythm outcome of catheter ablation or have an effect on the type of recurrent atrial arrhythmia in patients with atrial fibrillation (AF), according to a study published in the Journal of the American College of Cardiology: Clinical Electrophysiology.

Using an open-label, prospective, multicenter, randomized protocol, researchers examined whether complete electrical isolation of the posterior wall of the left atrium led to improvements in the rhythm outcome following catheter ablation for persistent AF. They evaluated 207 patients with persistent AF who underwent radiofrequency catheter ablation (RFCA) for symptomatic and drug-refractory non-valvular AF and were randomly assigned to receive circumferential pulmonary vein isolation (CPVI) alone (n=105) or in combination with a complete POBI (n=102).

Study participants were given a transthoracic echocardiography before undergoing RFCA, and received CPVI and cavotricuspid isthmus ablation. A voltage map-guided point ablation for any remnant atrial potentials on the posterior wall of the left atrium was conducted to achieve complete POBI. Patients were followed-up at 1, 3, 6, and 12 months and every 6 months thereafter, or whenever symptoms occurred after the RFCA. AF recurrence was defined as any episode of AF or atrial tachycardia with a duration ≥30 seconds.

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Patients who had received CPVI alone or in combination with POBI had comparable rates of early recurrence (ie, within 3 months of RFCA; 40.0% vs 45.1%, respectively; P =.548) and of clinical recurrence (23.8% vs 26.5%, respectively; P =.779) during the follow-up (mean, 16.2±8.8 months).

Of the 52 patients who had clinical recurrence, 45 had AF, and 7 had atrial tachycardia.  The percentages of patients with atrial tachycardia who received CPVI alone vs in combination with POBI were comparable for atrial tachycardia (16.0% vs 11.1%, respectively; P =.913) and for the need for cardioversion (6.7% vs 13.7%, respectively; P =.093). Total ablation time was longer in patients receiving CPVI plus POBI compared with CPVI alone (5365±2358 seconds vs 4289±1837 seconds; P <.001).

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Study limitations include a small cohort, the lack of a strategy that included complex fractionated atrial electrogram ablation, and the lack of testing for pulmonary vein isolation (eg, with adenosine provocation).

“Addition of posterior wall ablation achieving no remnant electrical potential on posterior wall by point-by-point ablation was technically feasible. However, routine addition of posterior wall ablation did not improve the rhythm outcome. More sophisticated technique such as a tailored ablation strategy by individual electrical characteristics of substrate and more effective ablation methods are needed,” noted the study authors.


Lee JM, Shim J, Park J, et al. The electrical isolation of the left atrial posterior wall in catheter ablation of persistent atrial fibrillation [published online October 30, 2019]. JACC Clin Electrophysiol. doi: 10.1016/j.jacep.2019.08.021