Posterior wall isolation does not improve outcomes in ablation for persistent AF
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In patients with persistent atrial fibrillation undergoing catheter ablation, adding posterior wall isolation to pulmonary vein isolation did not improve rates of AF recurrence compared with pulmonary vein isolation alone, data show.
“The posterior wall of the left atrium is embryologically related to the pulmonary veins and houses the septopulmonary bundle, which had been proposed to play a role in the maintenance of persistent AF. As such, posterior wall isolation (PWI) had evolved and become popularized, with nonrandomized studies showing promising results,” Peter M. Kistler, MBBS, PhD, head of clinical electrophysiology research at the Baker Heart and Diabetes Institute and head of electrophysiology at the Alfred Hospital in Melbourne, Australia, and colleagues wrote in JAMA. “However, successful PWI can be challenging, given epicardial connections and the close proximity of the esophagus with an attendant risk of inadvertent injury.”
To determine whether adding PWI to pulmonary vein isolation (PVI) could reduce AF recurrence in patients with persistent AF, Kistler and colleagues conducted the randomized CAPLA trial of 338 patients (median age, 66 years; 77% men).
One group “underwent wide antral pulmonary vein isolation followed by posterior wall isolation involving linear ablation at the roof and floor to achieve electrical isolation,” according to the study, whereas the other group underwent PVI alone.
No difference in outcomes
The primary endpoint of freedom from any documented atrial arrhythmia of 30 seconds or longer without antiarrhythmic medication at 12 months after a single procedure occurred in 52.4% of the PWI/PVI group and 53.6% of the PVI-alone group (between-group difference, –1.2 percentage points; HR = 0.99; 95% CI, 0.73-1.36; P = .98), according to the researchers.
There were also no differences between the groups at 12 months in freedom from atrial arrhythmia with or without antiarrhythmic medicine after multiple procedures (PWI/PVI, 58.2%; PVI alone, 60.1%; HR = 1.1; 95% CI, 0.79-1.55; P = .57), freedom from symptomatic atrial arrhythmia with or without antiarrhythmic medicine after multiple procedures (PWI/PVI, 68.2%; PVI alone, 72%; HR = 1.2; 95% CI, 0.8-1.78; P = .36) and AF burden (0% in both groups; P = .47).
Procedural times were longer in the PWI/PVI group (142 minutes vs. 121 minutes; P < .001), as were ablation times (34 minutes vs. 28 minutes; P < .001), according to the researchers.
There were six complications in the PWI/PVI group and four complications in the PVI-alone group, the researchers wrote.
“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,” Kistler and colleagues wrote.
Managing expectations
In a related editorial, Rod Passman, MD, MSCE, director of the Center for Arrhythmia Research, Jules J. Reingold Professor of Electrophysiology and professor of medicine (cardiology) and preventive medicine at Northwestern University Feinberg School of Medicine, agreed that the results were “disappointing” and wrote: “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.
“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 endpoints 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,” Passman wrote.
Reference:
Perspective
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Two key questions need to be considered. No. 1, was the technique optimal, and no. 2, was this lesion set deployed in a patient population that could stand to benefit from ablation beyond PVI only? In this study, PWI was performed by highly skilled operators using rigorous endpoint definitions. That being said, the complex anatomy of the posterior wall (including the septopulmonary bundle which can be "protected" from radiofrequency energy by interposed fat) can be difficult to durably isolate even in the best of hands. However, perhaps the key factor regarding why this important trial was "negative" was the patient population. While the patients in this study had persistent AF, a median AF burden of 0% in both arms suggests that the patients in this study had a relatively mild form of persistent AF. This study cannot exclude the possibility of PWI being beneficial in more advanced forms of persistent AF.
I do not think it is time to completely write off posterior wall isolation. It is very plausible that with pulsed field ablation we will be able to more effectively obtain transmural ablation of the posterior wall without compromising safety.
A key takeaway from this study was that PWI can be done safely. While this study suggests that PWI shouldn't be used in all patients with persistent AF, the safety data suggest that it can reasonably be considered in selected patients.
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