Linear ablation for AF
Multiple previous studies have reported that linear ablation for PsAF is
associated with favorable medium term outcomes, with success rates of
69-88% at 1-1.5 year after CA.6,18,19 Gaita et al.
reported that PVI plus linear ablation is superior to PVI alone in
maintaining SR during a maximum follow-up period of 3
years.20 while the superiority of linear ablation have
not been consistently demonstrated compared with PVI
alone.9,10,21 The concept of linear ablation was
derived from the evidence of high success rate of the surgical MAZE
procedure.22 Roof and MI lines have a potential
benefit for alteration of AF wavelet propagation and elimination of
spectral components by complete bidirectional block of linear lesions.
In addition, these linear lesions lead to reduction of excitable LA
myocardial mass, the attenuation of vagal
innervation23 and elimination of non-PV foci,
especially relating to the ligament of Marshall.24,25Although the endpoint of linear ablation is clear, establishing linear
block, especially during MI line ablation, maybe challenging. Incomplete
linear ablation has been associated with the occurrence of
macro-reentrant AT,26,27 and AF
recurrences.28,29 In the present study, although acute
success rates of linear ablation were relatively high (94% in roof
line, 81% in MI line), roof and MI lines were reconnected in 38% and
54% of patients at re-do procedures. Nevertheless, the incidence of
linear gap-related AT was observed in only 13%, which was statistically
similar with EGM-guided ablation group. These results may suggest that
complete linear block is important for the modification of AF substrate,
rather than for avoiding occurrence of macro-reentrant AT. It was
possible to create durable linear lesions by using steerable sheaths in
our study compared with other previous studies, which may have led to a
better clinical outcomes.