Ablation strategy for ATP-induced AF
According to the current expert consensus statement on catheter and
surgical AF ablation, if a reproducible initiation of AF from non-PV
foci after PV isolation, focal ablation at the site of origin should be
considered.14 However, localization and elimination of
non-PV AF triggers can be challenging because of the transient nature of
non-PV triggers and diverse locations to perform focal ablation.
Zhang et al. reported the foci triggering AF could not be localized
because of the transient effect of ATP in 10 out of 39
patients.9 Kuroi et al. reported the patients with
atrial AF foci had worse clinical outcomes than patients with SVC
foci.10
Thus, these previous studies imply the difficulty of identifying the
precise foci from the initial beat using the current mapping techniques.
Some of these unidentified or residual foci might be associated with GP.
In our study patients, we could eliminate non-PV foci by the GP-based
approach without performing detailed activation mapping. In this
context, targeting the GP site, not the presumably earliest site, might
be a useful alternative ablation strategy in patients with ATP-induced
AF.
However, we should recognize the high specificity but low sensitivity of
the vagal response to HFS.
Calò et al. demonstrated the efficacy of GP ablation in RA in patients
with vagal paroxysmal AF. Thirty-four patients were randomly assigned
for a selective ablation at sites with positive HFS response or an
extensive approach at anatomic sites of GP. They concluded that the
anatomical ablation of RA GPs is effective in about 70% of
patients.15 They did not perform PV and SVC isolation
in both groups, whereas we employed the GP-based approach after PV/Box
and SVC isolation. These lesion sets should affect some parts of the
posterior and superior RA GP. Therefore extensive anatomic ablation of
posterior and superior RA GP might not be necessary for our patients.
Recently, cardioneuroablation targeting the fractionated atrial
potentials during sinus rhythm, called AF-Nest, has been applied to
vagal AF.16, 17 Pachon et al. demonstrated a mean of
33.6±13 AF-Nest ablation completely abolished the vagal response induced
by pulsed electric field delivered from the internal jugular
vein.17
If our approach did not suppress the ATP-induced AF, we should consider
performing these extensive ablation techniques. These extensive or
anatomical ablations have potential risks of complications such as
inappropriate sinus tachycardia and risks of recurrence as atrial
tachycardia caused by formation of an arrhythmogenic substrate or
critical channels among the cloud-like lesions.
Nevertheless, prospective randomized controlled study is warranted to
determine the optimal ablation strategy for ATP-induced AF after PV/Box
and SVC isolation.