Current ablation practices in patients with durably isolated
PVs
The fact that a large portion of patients with recurrent AF have durably
isolated PVs indicates that the source of AF must partially be located
outside the PVs. The mechanisms of AF in this specific subset of
patients are unknown. Although, ablation strategies targeting
extra-pulmonary AF foci/triggers have been effective in certain
sub-groups of patients, current evidence does not indicate that any
individual strategy is more effective than PVI, whether used alone or in
combination. This uncertainty explains the lack of consensus on the best
ablation strategy for treating these patients, suggesting that an
individualized approach may be necessary.
In the recent retrospective PARTY-PVI study, Benali et al. compared
outcomes of various ablation strategies during repeat ablation for AF in
367 patients with durably isolated PVs from 39 centers.(10) The majority
of patients were male (67%) with persistent AF as dominant recurrence
type (56.4%). Most patients received only one ablation strategy
(54.5%), followed by two or three (37.1% and 6.5%). Similar to our
study, they observed no significant difference in AF-free survival
across strategies, with LA size being the only independent predictor of
recurrence. In their analyses Benali et al. clustered similar strategies
to increase statistical power and therefore did not investigate the
individual effect of ablation strategies. Additionally, they did not
report data on the incidence of durably isolated PVs relative to all
patients undergoing repeat ablation, nor did they specify how many
patients received no additional ablation.
Recently, preliminary findings from the ASTRO-AF study were
presented.(13) This multicenter, prospective, randomized study compared
substrate modification and left atrial appendage isolation in 161
patients with durably isolated PVs.(13) They found no statistically
significant difference in AF/AT recurrence at one year between the two
ablation strategies. Of note, more than half of the patients had
undergone more than one prior ablation procedure. Due to futility, the
study was prematurely terminated after randomizing 63% of the planned
patient population.
In our study, posterior wall isolation was the predominant strategy
(58.4%) employed in patients with durably isolated PVs. The posterior
wall is widely accepted as a major extra-PV harbor for AF triggers and
drivers, partly attributed to the shared embryological development with
the PVs.(22,23) However, conclusive evidence regarding its efficacy
beyond PVI alone remains inconsistent and inconclusive, with currently
available data showing contrasting results.(24,25)
To date, few studies have reported on the outcomes of repeat ablation in
patients with durably isolated PVs. We observed a high rate of atrial
arrhythmia recurrence after ablation in these patients (52.8%). In the
PARTY-PVI study, Benali et al. observed a recurrence rate of 43.3% at 2
years after repeat ablation, which did not differ significantly between
different types of ablations or combinations of them.(10) In the
ASTRO-AF study, the recurrence rates of atrial arrhythmias at 1 year
were 48.3% for low-voltage area ablation and 44.5% for empirical left
atrial appendage isolation, showing no significant difference between
the two approaches.(13) De Pooter et al. observed a 39% recurrence rate
at 1 year after repeat ablation in patients with durably isolated
PVs.(11) During repeat ablation they performed either empirical trigger
ablation, which involved isolating the superior vena cava and/or
antralization of the PVI lesions, or substrate ablation, which included
creating linear lesions at the roof, mitral isthmus, and/or anterior
wall. Small single-center series showed similar recurrence rates, with
patients undergoing diverse strategies, including extra-pulmonary
trigger ablation, CFAE ablation, and linear ablation.(26,27) In contrast
to our study, none of the afore-mentioned investigations included a
control group of patients who did not undergo additional re-ablation.
The lack of evidence so far supporting a particular ablation strategy
highlights the importance of including such a control group in future
research.