Adding posterior-wall ablation to pulsed-field therapy missed its mark in persistent AF

Ablation for atrial fibrillation works by electrically isolating the pulmonary veins, the usual source of the errant signals. In persistent AF — the kind that does not stop on its own — pulmonary vein isolation (PVI) alone is less effective, and electrophysiologists have long suspected the back wall of the left atrium is part of the problem [s1]. The obvious move is to isolate that posterior wall too. A new randomised trial using the newest ablation energy tested exactly that, and the headline result is a cautionary one [s1].

What the trial did

PIFPAF-PFA was an investigator-initiated, multicentre, randomised superiority trial run at 6 centres in Switzerland, with blinded end-point adjudication [s1]. Patients with symptomatic, persistent AF were enrolled from November 2023 to February 2025, and one-year follow-up was completed in February 2026 [s1]. All 206 randomised patients — mean age 65.8 years (SD 9.2), and 165 (80.1%) men — were treated with pulsed field ablation (PFA), a non-thermal energy that destroys heart tissue with electrical pulses rather than heat or cold [s1]. They were assigned 1:1 to PFA-based PVI with posterior-wall isolation (102 patients) or PFA-based PVI alone (104 patients), and every patient received an implantable cardiac monitor afterwards so that recurrences could be caught continuously rather than at clinic visits [s1].

The primary end point was the first recurrence of atrial tachyarrhythmia between days 91 and 365 after ablation, adjudicated by an independent committee blinded to which procedure each patient had received [s1].

The result

Recurrence occurred in 51 of 102 patients (50.6%) in the posterior-wall group and in 63 of 104 patients (60.6%) in the PVI-alone group — a rate ratio of 0.75 (95% CI, 0.51–1.09; P = .13) [s1]. That confidence interval crosses 1.0, so on its primary end point the trial did not demonstrate that adding posterior-wall isolation helps. Of 29 prespecified secondary outcomes, 22 were not significantly different [s1].

A few secondary signals did point the extra ablation's way. Mean atrial arrhythmia burden — the share of monitored time spent in arrhythmia — was 6.9% with posterior-wall isolation versus 11.0% without (a difference of −4.1 percentage points; 95% CI, −8.0 to −0.2; P = .04) [s1]. And when recurrence was redefined to count only longer episodes, the rate ratios moved further in favour of the extra lesion set: 0.64 (95% CI, 0.41–0.99) for episodes of at least one hour, 0.37 (95% CI, 0.18–0.78) for episodes of at least one day, 0.40 (95% CI, 0.18–0.88) for episodes of at least two days, and 0.51 (95% CI, 0.22–1.23) for episodes of at least seven days [s1]. The safety composite — a bundle that counted tamponade needing drainage, lasting phrenic-nerve palsy, serious vascular injury, stroke and death up to day 90 — occurred in just 2 patients in the posterior-wall group [s1].

Why this echoes an earlier trial

The result is not a surprise so much as a confirmation. In 2023, the CAPLA trial asked the same question using the older thermal ablation and reached a flatly null answer: among 338 patients, 89 (52.4%) who had posterior-wall isolation added were free from recurrent arrhythmia at 12 months versus 90 (53.6%) who had PVI alone — a difference of −1.2% (hazard ratio, 0.99; 95% CI, 0.73–1.36; P = .98) [s2]. PIFPAF-PFA brought the newer energy source to the same question and, on the end point that was prespecified to settle it, landed in the same place [s1][s2].

The gap between the null primary result and the favourable burden and long-episode findings is the interesting part. It suggests posterior-wall isolation may be shifting the character of recurrence — fewer long runs, less total time in arrhythmia — without changing whether a patient has any recurrence at all. For a symptom-driven condition, less time in AF is not nothing. But a secondary end point that was significant while the primary was not is a hypothesis for the next trial, not a basis for changing practice.

What to watch

Whether a larger trial powered on arrhythmia burden, rather than on any-recurrence, is run — because that is where the signal here lives. The two trials together make a reasonable case that adding posterior-wall isolation does not reliably keep more patients arrhythmia-free, whichever energy is used [s1][s2]. Pulsed field ablation makes the extra lesions faster and, in this trial, safely [s1]; the open question is no longer whether it can be done but whether the modest burden reduction it buys is worth the additional procedure time. For now, the primary end point is the one that counts, and it did not clear the bar.

This article is informational and is not medical advice.

Sources

• [s1] Roten L, Maurhofer J, Krisai P, et al. "Pulmonary Vein Isolation Using Pulsed Field Ablation With vs Without Posterior Wall Isolation in Patients With Symptomatic Persistent Atrial Fibrillation: The PIFPAF-PFA Randomized Clinical Trial." JAMA, published online 29 August 2026. https://doi.org/10.1001/jama.2026.17598
• [s2] Kistler PM, Chieng D, Sugumar H, et al. "Effect of Catheter Ablation Using Pulmonary Vein Isolation With vs Without Posterior Left Atrial Wall Isolation on Atrial Arrhythmia Recurrence in Patients With Persistent Atrial Fibrillation: The CAPLA Randomized Clinical Trial." JAMA, 329(2):127–135, published online 10 January 2023. https://doi.org/10.1001/jama.2022.23722