Stéphane Cade, Shahine Sedighian,
Agustin Bortone, Richard Gervasoni, Jean Christophe Macia, Florence
Leclercq, Robert Grolleau and Jean Luc Pasquié
Hôpital Arnaud de Villeneuve, Centre Hospitalier Universitaire,
Montpellier, France
Address for
correspondence: Jean Luc Pasquié, Hopital Arnaud de Villeneuve,
Centre Hospitalier Universitaire, 34295 Montpellier Cedex 5
France. E-mail: jl-pasquie@chu-montpellier.fr
Abstract
Aim. Atrial fibrillation (AFib) is a major clinical issue
and its occurrence is the main problem after catheter ablation of
atrial flutter. The long-term occurrence of AFib after common atrial
flutter ablation is still matter of debate as it may influence the
therapeutic approach. So, the aim of our study was to analyze the
determinants and the time course of AFib after radiofrequency catheter
ablation of chronic common atrial flutter.
Methods and Results. 89 consecutive patients (67.5 ± 12.0
yrs) underwent RF ablation of chronic common atrial flutter. 38.2 % had
previous history of paroxysmal AFib. 51% had no underlying structural
heart disease. Over a mean follow-up of 38 ± 13 months, the
occurrence rate of AFib progressively increased up to 32.9% at
the end of follow-up. The median occurrence time for AFib was 8 months.
AFib occurrence was significantly associated with previous AFib history
(P=0.01) but not with the presence of underlying heart disease
(P=n.s.). Of particular interest, in our study, AFib never occurred in
patients without previous AFib history. Palpitations after chronic
common atrial flutter ablation was mostly related to AFib.
Conclusion. In conclusion, after chronic common atrial flutter
ablation, AFib incidence progressively increased over the follow-up in
all patients. Patients with prior AFib history appeared to be a very
high risk group. In these patients, closer monitoring is mandatory and
the persistent risk of AFib recurrences may justify prolonged
anticoagulation policy.
Key words: atrial fibrillation; atrial flutter; follow-up;
radiofrequency catheter ablation
Introduction
As
recently demonstrated by Natale et al catheter ablation has become
first-line therapy for common atrial flutter (AFL) in patients without
structural heart disease and without left atrium enlargement
1. In a recent study by Anselme et al
2, one third of the patients still
complained with palpitations after AFL ablation despite a significant
improvement in quality of life and these symptoms were mostly related
to atrial fibrillation (AFib). AFib is a major cause of morbidity and
mortality, increasing risk for death congestive heart failure and stroke
3. Thus, identifying patients with
high risk of AFib occurrence after AFL ablation is of particularly high
importance as it may influence the therapeutic approach. After AFL
ablation, the long-term incidence of AFib is a major concern. However,
despite numerous studies on catheter ablation of atrial flutter data
are still discordant. In some studies, the risk of AFib after AFL
ablation appeared to be decreased in patients with previous history of
AFib
4-6
though it was not in other studies on large populations
7-9. Moreover, some
authors suggest from experimental studies an increased risk of AFib in
patients with chronic atrial flutter due to more severe atrial
remodeling compared to paroxysmal AFL
10.
Thus, the aim
of the present study was to determine the long-term incidence of atrial
fibrillation after chronic common atrial flutter ablation in a large
population and to analyse its determinants.
Methods
Study patients
and Ablation procedure
We considered
89 consecutive patients referred to our institution for chronic common
AFL ablation. All patients were in chronic common AFL at the time of
ablation procedure. Patients were studied in the postabsorptive state
under light sedation and after all antiarrhythmic drugs except
amiodarone had been stopped for > 5 half-lives. Based on the
initially described technique
11,
an electrophysiologically and anatomically guided ablation was
performed in the IVC-TA isthmus. The aim of the ablation was
termination of AFL with restoration of sinus rhythm associated to
bidirectional block in the cavo-tricuspid isthmus as commonly described
12.
Long-term
follow-up
Patients were
discharged the day after the procedure. Patients with previous AFib
history were discharged with antiarrhythmic (AA) therapy (amiodarone
200 mg/d or flecainide 200 mg/d). All patients had oral anticoagulants
for at least 6 months after the procedure. Later follow-up visits were
performed by the referring cardiologist. The referring cardiologists
were contacted by telephone and asked about the “arrhythmic” status of
the patients. All patients were contacted by telephone to confirm their
clinical status. Holter ECG recordings were systematically performed at
1 month, 3 months, 6 months and every 6 months thereafter. When a
patient complained with palpitations, Holter ECG recordings were
repeated until precise diagnosis was made.
Statistical
analysis
Continuous
variables were expressed as mean +/- SD. When pertinent, we calculated
the median value as well as the 25th-75th percentile for each value to
describe its distribution in the population. We defined as “Median
Occurrence Time 50” the median time of AFib occurrence for 50 % of the
population. The relationship between qualitative variables were
assessed by Chi square-test or Fischer Exact test depending on the size
of the population. Actuarial freedom from occurrence was determined
using the method of Kaplan and Meier. The comparison of actuarial
freedoms depending on the presence or not of one considered factor
(prior history of AFib; LVEF < 50%; Chronic obstructive lung
disease; AFib inducibility) was assessed using Log Rank test and
Wilcoxon test. A value of P < 0.05 was considered significant.
Results
Study
population
We studied 89
patients (79 men/ 10 women; mean age: 67.5 ± 12.0 yrs.) with
chronic common isthmus-dependent AFL (
Table
1). All of the patients were in chronic atrial flutter at the
time of the ablation procedure. Some of them had at least 1 previous
episode of atrial fibrillation before atrial flutter occurrence and
were considered as pts with previous AFib. None of them had AFL induced
by Ic antiarrhythmic treatment. The median duration of chronic
AFL before ablation procedure was 12 months (25th -75th percentile:
3-60 months). 38 % had previous paroxysmal AFib (median: 48 months;
25th-75th percentile : 8-72 months) but AFL always remained the major
symptomatic arrhythmia. All had failed several AA drugs and 92.1 % had
ongoing AA treatment including amiodarone in 71 patients. 49 % had LVEF
< 50 %. 12 % had previous CABG. Chronic obstructive lung
disease was observed in 20 % of the patients.
Initial
results and Follow-up
The mean
follow-up duration was 38 ± 13 months. Eight patients died
during follow-up (1 cerebrovascular disease, 4 coronary artery disease,
1 heart failure, 1 lung cancer, 1 acute respiratory failure in a pt
with severe pulmonary disease). Two patients had dual-chamber pacemaker
for sinus dysfunction and symptomatic second degree AV block 18 and 21
months respectively after ablation procedure. Thirty-four patients
remained under AA therapy after the ablation procedure.
At the end of
the 3-year follow-up, 32.9 % of the patients experienced AFib (
Table 2). The AFib “Median
Occurrence Time 50” was 8 months (25th-75th percentile: 2-24 months,
Table 2). During follow-up, 9
patients with LVEF < 50% developed chronic AFib. The actuarial
freedom from AFib is represented on
Fig
1. The actuarial freedom from AFib was significantly decreased
when previous AFib history was present (P = 0.001;
Fig 1). No significant difference in
the actuarial freedom from AFib was found considering LVEF (
Fig 1) and presence of chronic
obstructive lung disease.
Figure 1 : Top : Actuarial freedom from atrial
fibrillation episodes after ablation of chronic common atrial flutter; (Middle) : Actuarial freedom from
atrial fibrillation episodes after ablation of chronic common atrial
flutter considering the presence of previous history of atrial
fibrillation. AFib + indicates previous history of AFib; AFib –
indicates no previous history of AFib; (Bottom)
: Actuarial freedom from atrial fibrillation episodes after ablation of
chronic common atrial flutter considering the LVEF < 50%.
Among the
study population, 53 out of 89 patients visited their referring
cardiologist for various symptoms. Twenty-seven patients complained
with palpitations; only 4 of these patients were free of any
arrhythmia. On the contrary, 5 patients had asymptomatic AFib diagnosed
by Holter ECG recordings. However, palpitations were significantly
associated to AFib episodes (P = 0.01).
Discussion
In our study,
after chronic common AFL ablation we observed a progressive increase in
AFib incidence up to 32.9 % at 3 years. Prior AFib history was the only
determinant of AFib incidence. Moreover, palpitations after AFL
ablation were most of the time symptomatic of AFib episodes.
The
relationships between AFL and AFib are complex. In all of the previous
studies about AFL ablation
13-20
a previous AFib history was present in 20 to 55 % of the population.
However, the AFib occurrence rate after AFL ablation varies widely in
previously reported series. This rate was as high as 43 % as reported
by Philippon et al
17, 37.5
% in the study of Saoudi et al
18
or 31 % for Hsieh et al
9. In
our study, 38.2 % of patients had previous AFib history. After AFL
ablation, we had a progressive increase in AFib occurrence reaching a
32.9 %-occurrence rate by 36 months. Some authors more recently
concluded that AFL ablation could reduce the incidence of AFib from 55
% to 33 % on a mean follow-up of 496 ± 335 days
6. From our results, it appeared that the
main element was time i.e. the duration of follow-up as we had a
progressive increase in AFib occurrence rate. As a matter of fact,
Gilligan et al
8 showed a 59
%-cumulative occurrence rate of AFib and atypical flutter at 2 years
with only 27 % of patients remaining still free of atrial arrhythmias
at 5 years. This may also explain a lower AFib occurrence rate of 28 %
after ablation compared to a 53 %-AFib ocurrence rate before ablation
found by O’Callaghan et al
16;
the 28 %-AFib occurrence rate is the
12 month-value after AFL ablation that is even higher than in our study
after 1-year follow-up. Moreover, some authors found an increased
incidence of early AFib after AFL ablation
20,21. These early
episodes might be transient and self-limited
19
or associated with
mitral regurgitation
20. In
our study, AFib occurrence appeared
progressive. These discrepancies between studies may be due to
differences in the mean age of the population and more advanced heart
disease. This second point might explain also the fact that patients
with flutter only have a very low risk of fibrillation in our
follow-up, contrary to patients with previous AFib history. Some
authors have discussed a putative arrhythmogenic effect of ablation
lesion
4 or would have
expected an increased risk for AFib through
more severe atrial remodelling during chronic AFL
10, or may be
through larger anatomic conduction pathways in the chronic form
22;
in our study including only patients with chronic common flutter such
an arrhythmogenic effect was not detected.
However, our
study confirmed the clinical benefit of AFL ablation
described by O’Callaghan et al
16
or Anselme et al
2. Most of
the
patients remained asymptomatic without any AA treatment for patients
without prior AFib history. Moreover, in agreement with Anselme et al
2, patients presenting with palpitations
were mainly suffering from
AFib. Among the possible determinants of AFib occurrence after AFL
ablation , prior AFib history appeared to be a major factor. In a study
by Philippon et al
17, four
factors were found to predict an
increased risk for developing AFib after AFL ablation: structural heart
disease, previous history of AFib, high rate pacing-induced AFib and a
greater number of failed AA treatments in univariate analysis. In
multivariate analysis, only AFib inducibility was independently
associated to late occurrence of AFib
19.
In the same manner, Da
Costa et al
20 identified
independent predictors of early AFib after
AFL ablation: left ventricular ejection fraction and pre-ablation
history of atrial fibrillation. On a longer follow-up, Hsieh et al
showed that prior history of AFib and inducible AFib were independent
predictors of early occurrence of AFib and that prior history of AFib
was the only independent predictor of late occurrence of AFib
9. In
our study, the only factor associated to AFib occurrence was previous
AFib history. As reported by Sparks et al
10,
chronic atrial flutter
is associated to increased early AFib inducibility but it is not
demonstrated that it is associated to AFib occurrence in the long term.
As opposed to previous studies
17,20,21, the presence of
structural
heart disease (EF<50%) was not associatedwith increased AFib
occurrence in our study. These differences may be related to different
stages of the arrhythmic atrial disease or of the definition and
severeity of structural heart disease as suggested by Da Costa et al
20 and Philippon et al
17. Thus, the major determinant of AFib
after AFL ablation appeared to be prior AFib history. So, in patients
undergoing AFL ablation, patients without prior AFib have a low risk of
arrhythmia recurrence after the procedure without any AA treatment and
patients with prior AFib have a high risk of arrhythmia recurrence. In
these patients, AFL ablation will not relieve totally the symptoms and
may necessitate complementary treatment: appropriate anticoagulation,
continuation of suppressive antiarrhythmic therapy or additional AFib
ablation procedure.
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