Europace (2008) 10, 1336–1339
doi:10.1093/europace/eun189
SHORT COMMUNICATION
Is atrial fibrillation with very short cycle length suitable
for ablation? A case report
Igor Diemberger1*, James McCready2, Laurence Nunn2, and Anthony W.C. Chow2*
1
Institute of Cardiology, University of Bologna, Azienda Ospedaliera S.Orsola-Malpighi, Bologna, Italy; and 2Department of
Cardiac Electrophysiology, The Heart Hospital, UCLH Foundation Trust, 16–18 Westmoreland Street, London W1G 8PH, UK
Received 5 May 2008; accepted after revision 25 June 2008; online publish-ahead-of-print 14 July 2008
KEYWORDS
Atrial fibrillation;
Ablation;
Mapping;
Remodelling;
Persistent
We present a case of a 36-year-old woman with highly symptomatic persistent atrial fibrillation (AF)
refractory to sotalol, flecainide, and external direct current (DC) cardioversion. The patient underwent
biatrial mapping and ablation procedure for AF. Both atria were characterized by refractory properties
which were much shorter than reported previously. Global fibrillatory activity was present with a
median cycle length of 120 ms (range: 62–143). Extensive map-guided ablation sets had to be delivered
to both left and right sides before effective DC cardioversion enabled sinus rhythm (SR) restoration. The
patient remained in SR at 9 months of follow-up.
Introduction
Most strategies currently used to ablate persistent atrial
fibrillation (AF) are aimed at eradicating discrete highfrequency regions of activity to increase atrial wavelength
and prevent AF. Specific patients may require different
extent of atrial ablation to achieve success.1 However,
there are no current reports of marked global changes in
atria refractoriness, leading to a widespread short cycle
length (CL) AF. We present the case of a young woman
with both atria globally fibrillating with very short CL. Strategies used to perform ablation are also presented.
Case report
A 36-year-old woman was referred for AF lasting 10 years,
despite previous treatment with sotalol and later flecainide
plus diltiazem. She presented hypertensive cardiomyopathy
and complained of exertional chest pain, although angiography excluded coronary artery disease. She also presented
sickle cell trait. She had undergone at least three previous
electrical direct current (DC) cardioversions for persistent
AF; the last one in 2003 which led to the maintenance of
sinus rhythm (SR) until 2006. In this occasion, although previously effective, electrical cardioversion (combined with
pre-treatment with flecainide plus diltiazem) failed to
* Corresponding authors. Tel: þ39 0516363498 (I.D.); þ44 2075738888;
fax: þ44 2075838847 (A.W.C.C.)
E-mail address: [email protected] (I.D.) or anthony.chow@
uclh.nhs.uk (A.W.C.C.)
restore SR. In view of her age, symptoms, and deterioration
of the LV function with AF, a decision was made to proceed
with AF ablation. After obtaining informed consent, an electrophysiological cardiac mapping study was performed.
Multipolar catheters were placed in the right atrium, Hisbundle, right ventricular apex, and coronary sinus (CS). A
4 mm irrigated tipped ablation catheter and a circumferential 20-pole mapping catheter were advanced into
the left atrium (LA) through trans-septal catheterization.
The three-dimensional LA geometry was reconstructed
using the Ensite NavX system (St Jude Medical, Endocardial
Solutions, St Paul, MN, USA). The average CL of the fibrillatory waves recorded at the pulmonary veins ostia and almost
the entire LA was unusually short (median 120 ms, range
62–143; Figures 1 and 2). As shown by the dominant frequency map (Figure 2), the majority of the LA had an activation frequency within 7 and 16 Hz. The strategy used for
radiofrequency (RF) ablation initially consisted of wide
area circumferential ablation and ostial isolation until all
pulmonary veins were electrically disconnected, followed
by a roof line and a line encircling the LA appendage,
which had particularly short AF CLs activation (Figure 1B).
The patient remained in AF despite initial regularization of
activation in the LA (Figure 3). The ablation was then
extended to the CS, until complex fractionate signals were
eradicated. However, further mapping of the right atrium
confirmed that most of the myocardium had very short CL
similar to the LA before the ablation (Figure 4). Accordingly,
the right atrium was then targeted for AF ablation, with
lesions delivered at the superior vena cava junction,
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2008.
For permissions please email: [email protected].
Case of persistent AF with short cycle length
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Figure 1 Intra-cardiac electrograms after trans-septal catheterization showing fibrillatory activity in the left upper pulmonary vein (A) and
in the left atrial appendage (B) before electrical disconnection. Measurement of 10 consecutive fibrillatory cycle is provided as a visual estimate of the average cycle length. Abl, ablation catheter; CS, coronary sinus; Opt, circumferential 20-pole mapping catheter.
Figure 2 Dominant frequency map of the left atrium before the radiofrequency ablation. The virtual geometry of the chamber is shown in
antero-posterior and postero-anterior projections. Note that almost all the surface presents a high-frequency activation according to the
scale reported on the left (median frequency was around 8.5 Hz, equivalent to 120 ms of cycle length). MV, mitral valve annulus.
isthmus, and lateral wall. Despite regularization and an
initial increase in the CL to 230 ms (without any noticeable
fluctuations in AF CL), restoration of SR was achievable
only through electrical DC cardioversion (200 J biphasic
single shock). The patient has been taken off all antiarrhythmic drugs and warfarin after 6 months from the ablation and is still maintaining SR at 9 months from the
procedure.
Discussion
Studies of human atrial electrophysiology suggest that normally atrial refractoriness is 180–250 ms, but can be
shorter in focal driver areas often associated with complex
fractionated electrograms.1 This case evidences advanced
atrial remodelling with profound global electrophysiological
changes in refractoriness, involving both atria to an extent
(almost global) that exceeds previously reported values
both in humans2 and in animal3 studies. It is now recognized
that persistent AF can progressively shorten atrial effective
refractory periods,1 but rarely below 180 ms. This is the first
report of AF intervals averaging 120 ms on both atria, with
areas presenting intervals that reach 50–60 ms. Such short
AF intervals pose further difficulties in forming global strategies for RF ablation in patients with persistent AF.
In these patients, the ablation procedure is a sequentialtailored approach focusing on different targets such as
complex fractionated atrial electrograms, areas of short
CL activity, and sites of dominant frequency.1 During ablation, AF CL usually prolongs until the atrium can no longer
sustain the fibrillatory process and AF terminates (converting directly to SR or to atrial tachycardia, which can then
1338
I. Diemberger et al.
Figure 3 Intra-cardiac electrograms after the isolation of all four pulmonary veins and ablation encircling left atrial appendage showing the
persistence of high-frequency potentials in the coronary sinus, despite regularization and prolongation in cycle length of electrical activity in
the left atrial appendage (A). The following mapping of the coronary sinus (B) with the ablation catheter evidenced the presence of rapid and
fractionate signals in this site. Measurement of 10 consecutive fibrillatory cycle is provided as a visual estimate of the average cycle length.
Abl, ablation catheter; CS, coronary sinus; Opt, circumferential 20-pole mapping catheter.
Figure 4 Intra-cardiac electrograms of the right atrium showing the presence of very short cycle length similar to the left atrium before the
ablation of both of the right atrium free wall (A) and in proximity to the superior vena cava vein (B). Measurement of 10 consecutive fibrillatory cycle is provided as a visual estimate of the average cycle length. Abl, ablation catheter; CS, coronary sinus; Opt, circumferential
20-pole mapping catheter.
be ablated). However, in this patient, despite achieving
a broad regularization of local activity after extensive ablation of selected areas, the global atrial activity appeared to
be almost unchanged. The persistence of AF with areas of
short CL activity after pulmonary vein isolation (Figure 3)
supports the concept that (at least in chronic AF), despite
their importance in AF triggering, their role of AF maintenance appears to be less definite. These results and our data
Case of persistent AF with short cycle length
highlight the extent of human substrate remodelling, which
occurs in chronic AF. This phenomenon can also explain the
absence of a left-to-right gradient in atrial frequency in
patients with AF lasting .1 month but present in patients
with paroxysmal AF.4
Additional factors affecting atrial refractoriness include
autonomic impairment, scars, and changes in the cellular
membrane function. Intriguingly, sickle cell trait is associated with a shift in the autonomic nervous system activity,5
which can explain some of the peculiarities of this case. Of
note, we required electrical cardioversion to restore SR,
despite the extensive ablation of the high-frequency nests
on both left and right sides. This appears to be in contrast
with previous findings by Nademanee,6 showing a high incidence of AF conversion during ablation. However, Oral
et al.7 provided different results while adopting a similar
approach to AF ablation (i.e. guided by complex atrial electrograms), and they also underlined the absence of a
relationship between acute AF termination (during ablation)
and long-term freedom from recurrent arrhythmia. A plausible explanation of our results can be that in such cases a
complete elimination of the substrate may be unattainable,
but the modification of arrhythmic triggers and probably of
the autonomic influences8 might had been enough to avoid
AF re-induction. This finding suggests that AF ablation can
still be effective to achieve SR in patients with persistent
patients, but may require extensive substrate modification.
Limitations of the study
We performed a electrophysiological study according to the
routine protocol adopted in our Institution for AF ablation:
this includes the use of bipolar recordings. To avoid the
possible bias of ‘double-counting’ atrial fibrillatory signals9,
we used only sharp discrete atrial electrograms with a
minimum sampling time of 10 s per site to confirm consistency
of the reported average AF CLs and of the dominant frequency
map. Despite the limited duration of the follow-up (9 months
1339
from the procedure and 3 months from anti-arrhythmic drugs
discontinuation), we think that the persistence of SR in this
particular case might have been unlikely without extensive
modification of arrhythmic triggers (and probably of autonomic influences).
Funding
J.M. has a research grant supported by St Jude Medical.
A.W.C.C. also holds a research grant from Boston Scientific.
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