Discussion
Whether patients returning after index PVI with new atypical AFL
represent an attractive target for redo ablation has not been the
subject of rigorous investigation. We sought to investigate the rates of
arrhythmia-free 1y survival in two cohorts of patients presenting with
recurrent arrhythmia following PVI: those with atypical AFL only, and
those with recurrent AF (with or without flutter). The main findings of
our study are: 1) Patients undergoing repeat ablation for atypical AFL
after index AF ablation have
enlarged LA and higher LAVi; 2)
Use of RF energy in the index AF
ablation is higher among patients developing recurrent atypical AFL; 3)
Isolated roof dependent AFL and peri-mitral AFL account for roughly 60%
for post-PVI flutters observed; 4) 1-year
arrhythmia free survival rate is
higher among patients undergoing repeat ablation for atypical AFL as
compared to recurrent AF.
We found that LA diameter and LA volume was significantly greater among
patients developing atypical AFL as compared to AF after the index
ablation. This finding is in line with previous studies which reported
that greater LA diameter(4) and
LAVi(5) independently predict de novo
atypical AFL, highlighting the role of intrinsic structural alteration
in mediating fixed reentry.
We also observed that the use of RF energy for index ablation was
significantly higher among the patients developing recurrent atypical
AFL as compared to recurrent AF. A number of previous studies have
reported the factors predictive of atypical AFL recurrence after AF
ablation(6-8), and few of the
studies(9,10)
evaluated the predictive value of energy source (RF vs. cryo) during AF
ablation. Julia et al (9); reported in
their study that RF AF ablation is associated with a higher incidence of
recurrent atypical AFL as compared to CB AF ablation. However, on
adjusted analysis to determine the predictors of atypical AFL, the
predictive value of RF ablation was attenuated. Although we did not have
further data related to index AF ablation to perform an adjusted
predictor analysis, our study with a large sample size is important in
suggesting that CB ablation of AF may be associated with a lower
incidence of atypical AFL recurrence as compared to RF ablation. Similar
to several other previously published
studies(6,11-13),
Our study suggests that roof dependent and perimitral atypical atrial
flutters are common in pre ablated patients. Our results derived from a
large sample size extend the support to the hypothesis that previous AF
ablation predisposes to the development of perimitral and roof dependent
flutter forms.
To the best of our knowledge, our study is the first with a relatively
large sample size to evaluate the prognostic significance of recurrent
atypical AFL after index AF ablation on the success of the repeat
ablation. Ammar et al (14), in their
small retrospective study, showed that recurrent atrial tachycardia
after PsAF ablation is associated with a better success rate of repeat
ablation procedure compared to recurrent persistent AF. In contrast, our
study included both types of AF patients at the time of index ablation
and comprised a greater proportion of PAF patients than PsAF patients.
Additionally, we also demonstrated that patients undergoing repeat
ablation for atypical AFL were older with dilated LA and higher LAVi
compared to those presenting with recurrent AF; these factors are
associated with poor ablation outcomes. Our results are interesting in
demonstrating that despite the association with factors predictive of
poor outcomes of the ablation procedure, patients undergoing repeat
ablation for atypical AFL have a better success rate as compared to
those for recurrent AF.
The findings of our study should be interpreted with attention to the
associated limitations, including: 1) Limitations inherent to a
single-center, retrospective, and observational study; 2) We did not
have detailed data related to index AF ablation for all patients,
precluding an adjusted analysis to determine predictive factors for
atypical AFL recurrence; 3) LA diameter and LA volume were not available
for all the included patients; 4) lack of continuous ECG monitoring
during follow-up might have contributed to an underestimation of
arrhythmia recurrence rate.
In conclusion, based on our experience, roof dependent, and perimitral
flutter are the common forms of atypical AFL after index AF ablation.
Patients developing atypical AFl after index AF ablation have dilated LA
and higher LAVi and arrhythmia free survival rate of first repeat
ablation is higher for patients presenting with recurrent atypical AFL
as compared to recurrent AF.