Pulmonary vein isolation (PVI) remains the cornerstone of all catheter-based treatment
strategies in atrial fibrillation (AF). Currently, PVI is recommended (class IA indication)
after one failed or intolerant class I or III antiarrhythmic drug (AAD) to improve symptoms,
either in paroxysmal (PaAF) or persistent AF (PeAF). However, PVI can be also considered as
first-line treatment to achieve rhythm control, particularly in cases when
tachycardia-induced cardiomyopathy is suspected, a circumstance likely more related to a
higher AF burden or PeAF.
PVI has been proven to be effective in treating PeAF, although long-term ablation outcomes
have been significantly less satisfactory than in PaAF. In a recent metaanalysis, PVI in PeAF
achieved an arrhythmia-free survival at 12 months of 66.7%, with > 80% of the patients off
AAD. Other ablation strategies combining PVI plus additional substrate ablation (linear
ablation and/or complex fractionated atrial electrogram ablation) have been unable to
demonstrate better outcomes than PVI-alone.
On the other hand, recent advances both in technology and ablation protocols have resulted in
greatly improved outcomes after PVI. The introduction of contact force-sensing catheters,
novel estimates of lesion size [ablation index (AI) or lesion size index, and the fact of
ensuring lesion contiguity (≤ 6 mm inter-lesion distance) have markedly improved
arrhythmia-free survival after PVI, particularly in PaAF.
The CLOSE clinical study analyzed the utility of ablation index (AI), a novel formula
developed to assess real-time effect of RF delivery and improve the rates of PVI, with 91.3%
of the patients free from AF/AT/atrial flutter (AFL) at 12 months follow-up. The CLOSE
protocol targeted an interlesion distance (ILD) of 6 mm and AI ≥ 400 at the posterior wall
and ≥550 at the anterior wall. Recently, Hussein et al. demonstrated that the use of
AI-guided PVI alone performed with radiofrequency energy in a point-by-point wide area
circumferential ablation (WACA) pattern according to CLOSE protocol achieves good clinical
outcomes in persistent AF patients at 12 months follow-up. Finally, a more recent,
personalized PVI strategy, aiming for contiguous lesions with AI titration according to the
local left atrial wall thickness (LAWT) as per multidetector cardiac tomography (MDCT), has
demonstrated to achieve an arrhythmia-free survival > 95% at 12 months in PaAF.
Up to date, there are no randomized studies for persistent AF ablation comparing the outcomes
of PVI-alone procedures performed with a personalized ablation protocol that uses the
information of left atrial wall thickness (LAWT), compared with the CLOSE protocol.
The investigators hypothesized that PeAF-by-LAWT, a personalized protocol that uses a
contact-force catheter, a multichannel radiofrequency (RF) generator, and integrated LAWT
information to adapt the ablation index (AI) target to the subjacent LAWT, is safe, while
showing at least the same efficacy and better efficiency than the CLOSE protocol for
persistent AF ablation.
This is a two-arm, single-blind, single-center, randomized controlled trial. The study will
be conducted in a tertiary hospital with an electrophysiology team of qualified investigators
with proven experience in performing atrial fibrillation ablation.