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Electrophysiologists hoping to improve upon ablation therapy for persistent atrial fibrillation (Afib, AF) found no success going the extra mile to isolate the patient's left atrial posterior wall, according to a randomized trial.

People undergoing their first-time catheter ablation for Afib ended up with similar odds of a good outcome at 12 months -- freedom from any documented atrial arrhythmia of more than 30 seconds without antiarrhythmic medication -- whether standard pulmonary vein isolation (PVI) had been accompanied by posterior wall isolation (PWI) or not (52.4% vs 53.6%; HR 0.99, 95% CI 0.73-1.36).

PWI also made no difference in patients' need for repeat ablation within 12 months (9.4% vs 9.5%), reported Peter Kistler, MBBS, PhD, of the Heart Centre at the Alfred Hospital in Melbourne, Australia, and CAPLA trial colleagues, in .

"In the search for adjunctive strategies to improve ablation outcomes in patients with persistent AF beyond those achieved with PVI alone, the results of this study represent a further disappointment," they wrote.

Catheter ablation with PVI has been shown to be more effective for paroxysmal Afib than persistent Afib. Poor results for the latter prompted the pursuit of adjunctive strategies. One such strategy is PWI, which targets the left atrial posterior wall thought to be a source of Afib triggers in some people.

The good news in CAPLA was the 0% median Afib burden at 12 months, supporting catheter ablation as a rhythm control strategy that can improve quality of life, Kistler and colleagues said.

"From a patient perspective, a large reduction in AF burden may be more important than time to recurrence. So, while there may never be a complete cure for persistent AF, current and future treatments aimed at reducing AF burden below a threshold at which important clinical end points and quality of life will be favorably affected should be the true goal of treatment. In short, managing expectations will continue to be as important as managing this disorder," according to Rod Passman, MD, MSCE, of Northwestern University in Chicago.

Advancements in ablation technology are also a source of hope that the field can overcome technical challenges that result in many patients having electrical reconnections in areas that had been ablated.

"Whether new energy sources such as pulsed-field ablation or ultra-low temperature cryotherapy will provide durable transmural lesions that translate to better outcomes for this population remains to be seen, but their favorable risk profiles have provided needed optimism," Passman wrote in an .

Conducted in three countries, CAPLA investigators recruited symptomatic patients with persistent Afib refractory to at least one antiarrhythmic medication who were candidates for first-time catheter ablation using contemporary radiofrequency technology.

The study cohort was enrolled from July 2018 and March 2021 and consisted of 338 patients (median age, 65.6; 76.9% men) randomized to PVI alone or with PWI.

PWI added significantly more time to ablation procedures.

There was zero procedural mortality associated with PVI with or without PWI, and complications did not include cerebrovascular events or esophageal fistula.

Oral anticoagulation was mandated for a minimum of 3 months after ablation. Antiarrhythmic medication use was allowed during these 3 months. Those needing it beyond 3 months were allowed repeat ablation procedures; patients in the PVI-alone group were permitted to cross over and undergo PWI only in the presence of enduring PVI, otherwise they got a pulmonary vein re-isolation.

After 12 months, 97.6% of patients completed the study.

Kistler and colleagues acknowledged that they relied on a heterogenous approach to rhythm monitoring after ablation, as it was not financially feasible for the study to monitor all patients with implantable devices.

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