Does the current knowledge suggest a more aggressive approach?
As the ablative techniques and the technology in the field evolve, how
to perform isolation of LPW remains a very debatable, controversial
issue. Studies in which creation of linear lesions as to isolate LPW
have been employed, have produced different results (1,9). In this
respect, Tamborero et al reported that LPWI provided by linear lesions
does not improve the clinical outcome of circumferential PVI. They have
provided LPWI by performing a roof line and a floor line (two lines
connecting the contralateral PV encircling lesions). In addition, mitral
isthmus ablation was performed in all patients. In the study by Sayuri
et al, the same pattern of lesions has been proposed, but several issues
need to be addressed when linear lesions in the LA posterior wall are
taken in account. There is an inherent technical difficulty to provide a
successful electrical LPW isolation by a set of linear radiofrequency
lesions, due to the complex anatomical architecture of the atrial
musculature. Again, even if conduction block along the lines is achieved
during the procedure, one cannot rule out the occurrence of gaps over
time and, thus dormant conduction may take place during the follow-up.
In fact, in the study by Sayuri et al, reconnection of posterior wall is
reported in 65% of patients after the second procedure. Nearly 70% of
patients in the study by Tamborero et al had reconnection of the roof
line or recurrence of electrical activity within the LPW that led to AF
relapses. Therefore, it is conceivable that there are still doubts about
the durability of linear lesions in the LPW for the promotion of
“durable box lesion”. Needless to say that all these attempts of LPWI
without proven of effective isolation of the target structure make
difficult to properly assess the true impact of this ablative approach
on clinical outcome at follow-up. This does not mean that isolation of
LPW is not worth performing. Indeed, surgical isolation of the LPW has
been proved to be durable and effective in improving the freedom from
atrial arrhythmias in patients with any kind of clinical presentations
of AF (10). In this regards, the effectiveness of LPWI has been recently
highlighted by hybrid approach, in which surgeon and electrophysiologist
are side-by-side as to achieve the best clinical results in patients
with persistent AF (11). In particular, the hybrid Convergent procedure
as a minimally invasive closed-chest procedure performed on the beating
heart that combines epicardial RF ablation—focused on the LPW—
followed by complementary endocardial catheter ablation has been proved
to significantly reduce the AF burden and improve the clinical outcome
of patients with persistent and long-persistent AF. In detail, the
epicardial component seeks to debulk as much of the LPW as can be
accessed, principally limited by the oblique sinus. Posterior segments
of the PV ostia/antra may also be reached and ablated in most cases. The
endocardial component supplements the epicardial lesions around the
pericardial reflections and any incompletely ablated LPW areas and
addresses any remaining gaps between the PV and LPW lesion sets
(including anterior segments), ensuring PV electrical isolation. The
importance to deliver epicardial and endocardial lesions set is mainly
dictated to overcome the degree of disparity between the endocardium and
epicardium that can induce and sustain fibrillatory activity. Therefore,
the overlap between the epicardial and endocardial lesion sets is
preferred to avoid arrhythmogenic gaps and ensure transmurality. Single-
and multicenter studies have reported freedom from AF or any atrial
tachyarrhythmia to be 66%–95% at 1 year after the hybrid Convergent
procedure, with 52%–81% arrhythmia-free without antiarrhythmic drugs
(see 7 Malaki) A report of 81% of patients in SR after 4 years suggests
favorable durability but additional long-term data are necessary(see 23
Malaki). These results are especially encouraging since the procedure
has been frequently used in the most refractory patient populations.