Hybrid ablation for atrial fibrillation: a systematic review
J Interv Card Electrophysiol
Hybrid ablation for atrial fibrillation: a systematic review
Mindy Vroomen 0 1
Laurent Pison 0 1
0 Cardiovascular Research Institute Maastricht , Maastricht , The Netherlands
1 Department of Cardiology, Maastricht University Medical Center , PO Box 5800, Maastricht , The Netherlands
Purpose Hybrid ablation for AF is performed in a growing number of centers. Due to absence of guidelines, operative approaches and perioperative care differ per center. In this review, an overview of findings from published studies on hybrid ablations is given, and related topics are discussed (e.g., one- and two-stage approaches, lesion sets, and patient management). Methods A systematic literature search was performed in the PubMed and Embase databases. All identified articles were screened and checked for eligibility by the two authors. Results Twelve studies describing a total of 563 patients were selected. Due to substantial differences in approaches (onestage, two-stage, sequential), surgical techniques (bilateral or monolateral thoracoscopy, subxiphoideal, transabdominal), energy sources (unipolar, bipolar), lesion sets (applying left or right atrial lesions), periprocedural care and endpoints (monitoring, definition of recurrence), and success rates (sinus rhythm after a mean of 26 months) are difficult to compare and varied from 27 % (without antiarrhythmic drugs, AADs) to 94 % (with AADs). For studies using bipolar devices, success rates with the use of antiarrhythmic drugs were at least 71 %. Major complications such as bleeding, sternotomy, and death occurred in 7 % of the total population (of which ten complications, 16 %, occurred in the concomitant cardiac surgery hybrid group).
Atrial fibrillation; Hybrid ablation; Endocardial-epicardial ablation; Review
Atrial fibrillation (AF) is the most common cardiac arrhythmia
with a lifetime risk of 25 % for people aged above 40 years.
Due to an aging population, the incidence is increasing even
further . Secondary to negative hemodynamic effects, AF
carries significant morbidity and mortality; stroke is the most
feared complication with a fivefold increased risk .
Therefore, treatment of AF is crucial and worthwhile.
Initially, rhythm control treatment of AF was limited to a
direct current shock or taking quinidine, and digitalis was
recommended for rate control [3, 4]. In 1982, the first catheter
ablation (CA) aimed at achieving rate control by ablation of
the atrioventricular junction [5, 6]. The first successful cut and
sew surgical treatment (cut and sew Maze procedure) was
performed in 1987 by Dr. Cox . As a result of increased
knowledge on AF, these procedures have changed extensively
over the years. Haissaguerre et al. recognized pulmonary vein
(PV) foci as initiators of AF, which currently forms the
cornerstone of most interventional treatments for AF .
According to current guidelines, pharmacological
treatment is still considered as the first step in the approach of
AF treatment. However, invasive strategies are gaining more
attention. In selected cases, CA , or even surgical ablation
[10, 11], could be considered as first-line therapy. Although
pulmonary vein isolation (PVI) is the cornerstone of AF
treatment, no uniform invasive treatment concept in the setting of
the nonparoxysmal AF forms exists. Due to suboptimal results
of both CA  and minimal invasive surgical strategies in
this difficult to treat group , surgeons and
electrophysiologists have combined strengths in the form of a hybrid AF
ablation (combination of endocardial catheter and surgical
epicardial ablation) to maximize success rates and minimize
procedural morbidities. Some ablation lesions associated with
the Cox-Maze, for example, cannot be performed minimally
invasive, though can be easily performed endocardially. This
hybrid approach, first described by Pak et al.  in 2007, has
already proved to be safe and effective and showed good
results in patients suffering from all types of AF .
Available data however is still scarce.
Hybrid ablation has now been carried out since a few years
and is applied more and more across the world. Absence of
guidelines on this procedure leads to the use of different
approaches and different insights with respect to patient
management. This review aims to provide an overview of findings
from published studies on hybrid ablation and discusses
related topics (e.g., one- and two-stage approaches, lesion sets, and
The authors have ascribed to the PRISMA standards for
systematic reviews . A systematic literature search was conducted in
the PubMed and Embase databases. Both structured MeSH
terms and free terms were used in the PubMed search. In the
Embase search, keywords and free terms were used. The terms
are used in such a way that any description that could resemble or
relate to hybrid ablation would be covered by the search. Table 1
Table 1 Literature search
MeSH terms and Free terms
(BAtrial fibrillation^[MeSH] OR BAtrial
fibrillation^[All Fields]) AND
((Bhybrid ablation^[All Fields]) OR
(Bhybrid procedure^[All Fields])
OR (Bhybrid approach^[All Fields])
OR (Bhybrid^[All Fields]) OR
[All Fields]) OR
[All Fields]) OR
(Bthoracoscopictranscatheter approach^[All Fields]))
(Atrial fibrillation) AND (hybrid ablation OR
hybrid procedure OR hybrid approach
OR endocardial-epicardial ablation OR
OR thoracoscopic-transcatheter approach)
provides an overview of the search terms. The search was
supplemented by manually searching reference lists of selected
Article inclusion resulted from a three-phase process that
consisted of the initial literature search, screening of the
literature resulting from the search, and evaluation of eligibility of
the articles provided by the screening. Only English literature
was included. No publication date or publication status
restrictions were imposed.
All articles reporting on hybrid ablation (i.e., more than
only a short description of what a hybrid ablation is) were
found eligible. First, titles and abstracts were screened. In case
of uncertainty, full-text reports were read to assess eligibility.
Reference lists of the selected articles were also checked based
on the aforementioned criteria. The two authors individually
conducted the article search, screening, and selection. In case
of disagreement regarding inclusion or exclusion, a paper was
discussed to establish consensus.
3.1 Search results
Following the literature search, 35 papers were included for
this review, including 10 review articles [17–26]. No
additional papers could be found in the Embase database. In Fig. 1, a
flow diagram of the article selection is depicted.
Only 16 of the 35 selected articles describe nonoverlapping
original research. The studies of Bulava et al.  and Kurfirst
et al.  are considered overlapping; of these two, Bulava
et al. comprises the most recent study and encloses the biggest
population. The same accounts for two articles written by La
Meir et al. [29, 30], one by Kumar et al. , and one by Pison
et al. , compared to a larger study by Pison et al. . Two
a Last search conducted on January 7, 2016
Fig. 1 Flowchart of systematic literature search in PubMed and study selection
articles published by Muneretto et al. [33, 34] are also
considered to report on the same patient population. Of these 16
articles, four more are excluded for the main table of this
review (Table 2). The article of Kumar et al.  was excluded
because it consists of only seven patients of which a part of the
PVs are treated just epicardial and a part just endocardial with
cryoenergy. In the study by R. Lee et al. , the
electrophysiology (EP) procedure was only performed after the surgical
ablation in case of a recurrence (n = 7, 29 %), which actually is
not a hybrid ablation according to the definition in the
guidelines . H.M. Lee et al.  operated eight patients and
describes a maximum follow-up period of only 6 months,
and Velagic et al.  mainly concentrates on the redo
procedures after a hybrid ablation.
Following this final selection, the main characteristics of
the 12 remaining studies are presented in Table 2. The studies
have all been published between 2011 and January 2016. The
mean age of the patients over all studies is 60 years (ranging
from 53 to 63), and 71 % is male (n = 405). Some articles
reported follow-up at different moments in the same study;
in Table 2, the follow-up moment with the largest patient
population is mentioned or, when the difference in population
AF duration (years) LAD (mm) (ls)pAF (%) FU (months) FU reached (%) Monitoring
SR (%) +/− AAD
List of studies on hybrid AF ablation
AF atrial fibrillation, LAD left atrial diameter, (ls)pAF long-standing persistent AF, FU follow-up, SR +/- AAD sinus rhythm with/without antiarrhythmic
drugs, ILR implantable loop recorder, 7-day 7-day holter monitoring, 24-h 24-h holter monitoring, holter not stated which is used
a Open concomitant hybrid surgery
b Including five patients with only epicardial ablation (not separated in baseline table in article)
was only little, the moment with the longest follow-up is
taken. In case of use of different monitoring types, the one with
the longest recording time is mentioned.
3.2 Patient selection
One of the most important issues in hybrid ablation is
patient selection. According to the guidelines, a minimally
invasive surgical ablation or a hybrid ablation can be
performed (as stand-alone procedures) in patients with
symptomatic AF after failure of CA, or in patients who prefer a
surgical/hybrid approach . In 2012, a European survey
showed that failure of CA was the most important
indication for performing a stand-alone invasive procedure .
However, looking at the publications on hybrid ablation,
this procedure mostly is not only applied in cases of failed
CA. In the study of Gehi et al. , only 36 out of 101
patients underwent a previous CA, Zembala et al. 
reported 8 out of 27 patients with previous CA, Krul
et al.  14 out of 31, La Meir et al.  9 out of 19,
and Pison et al.  39 out of 78. Only Mahapatra et al.
 performed hybrid ablation solely in patients with a
previous CA. Pison et al.  referred patients for a
hybrid procedure in cases of paroxysmal, persistent, or
longstanding persistent AF (PAF, pAF, lspAF) with a left atrial
(LA) volume index ≥29 mL/m2, after one or more failed
CA or based on patient preference. Gehi et al. 
considered a hybrid procedure if the patients were
expected to have a less efficient outcome of a standard CA,
which included patients after failed CA with concomitant
antiarrhythmic drugs (AADs), patients with pAF with
large LA size (not stated what is considered large) or
structural heart disease, and lspAF patients. Another
indication for a hybrid ablation, which is not mentioned in the
selected articles, could have been a thrombo-embolic
advantage with left atrial appendage (LAA) exclusion. The
indications for a stand-alone hybrid procedure are thus
expanding and are expected to increase in the future.
Besides having clearly outlined indications, it is also
important to be able to predict outcome. P-wave duration has
shown to be a marker of success of AF ablation procedures
and could be of help in the selection. Kumar et al.  found
that the P-wave duration immediately and significantly
shortened after a hybrid procedure, in both PAF and pAF patients.
Pre-procedural duration was found to be longer in pAF and
lspAF, than PAF patients; post-procedural, no difference
existed. The pre- versus post-procedural P-wave duration
was significant for patients without recurrence. This suggests
that patient selection based on type of AF may be possible
before the procedure, which enables individualization of
therapy. Besides P-wave duration, clearly type and duration of AF,
and LA diameter are predictors for the outcome, as well as the
presence of multiple risk factors like diabetes mellitus and
hypertension [19, 50].
3.3 One- or two-stage approach
The different options to perform a hybrid procedure are a
onestage approach (surgery and EP during the same procedure), a
sequential approach (EP later but during the same hospital
admission), and a staged approach (EP in a second hospital
admission, maximum 6 months after surgery). Muneretto et al.
 and Bisleri et al.  performed the EP 30–45 days after
the surgical ablation, Bulava et al.  6 to 8 weeks later, and
Gaita et al.  after the blanking period of 3 months. In two
studies [40, 46], a sequential approach was performed,
meaning EP circa 4 days after the surgical ablation (3 % of the
patients). Zembala et al.  first performed one-stage
procedures but changed (due to reimbursement issues) to a
twostage approach with a second admission 15–20 days after
the surgical ablation. Richardson et al.  and Gersak et al.
 performed both, in which the approach depended on
operator preferences in the first study. The staged approach was
used in 41 % of the patients (n = 232). Almost all patients with
a staged approach underwent the planned second step (97 %).
Of 195 patients was reported whether additional endocardial
ablation was necessary, this was the case in 56 % (n = 110).
All other studies [15, 36, 38, 39] described a one-stage
procedure (n = 321, 56 %).
3.4 Surgical approach
Fundamentally all hybrid procedures are minimally invasive;
however, the surgical approach itself can vary considerably.
Five groups used a bilateral thoracic approach [27, 38, 40, 41,
46], three groups used a right thoracic monolateral approach
[34, 35, 39], one used a subxiphoideal approach , and two
others used a transabdominal transdiaphragmatic approach
[36, 37]. The group of Pison et al. [15, 23, 32] used bilateral,
left and right monolateral thoracoscopic approaches. Gaita
et al.  was the only group to perform open hybrid surgery,
combined with valve or coronary surgery.
3.5 Ablation techniques
Surgical epicardial ablation can be performed with
cryoenergy, unipolar or bipolar radiofrequency energy (RF),
endocardial ablation with microwave energy, cryoenergy, and
unipolar RF. Bipolar RF was used epicardially in six series
[15, 27, 38, 40, 41, 46], which equals the reported use of
unipolar RF [34–37, 39, 42]. Gaita et al.  used cryoenergy
in their open hybrid procedure, but Kumar et al.  also used
cryoenergy in rare cases thoracoscopically. In the latter, in a
cohort of seven patients with Gold Class IV chronic
obstructive pulmonary disease (COPD), the right PVs were isolated
using epicardial bipolar RF (Atricure) and the left PVs were
isolated using an endocardial 28-mm cryoballoon.
3.6 Lesion sets
As expected, with the PVs being well-known foci for
developing AF, PVI was performed epicardially in all patients in all
studies. Additionally, performing an epicardial roof
(connecting line between the superior PVs) and inferior line
(connecting line between the inferior PVs), i.e., a box lesion,
is the most performed lesion set [15, 27, 34–36, 39, 41, 42].
Three papers only mention performing a roof line but not an
inferior line [37, 40, 43]. Krul et al. [38, 51] created roof lines
in case of pAF and lspAF, and only in selected cases also an
additional inferior line.
Besides PV with roof and inferior lines, some alternative
epicardial linear lesions can be created. These comprise a line
from the roof line to the left trigone, a line from the superior
PV to the LAA, a line from the RIPV to the coronary sinus
(CS), a superior vena cava (SVC) and inferior vena cava
(IVC) circumferential lesion, and an intercaval line (line
between SVC and IVC). The right atrial lesions are less
frequently used than the left atrial lesions. Whether or not these lesions
were made, differed per patient. The intercaval line is only
reported by Pison et al.  and Richardson et al. , which
in case of Pison et al. was only added to the treatment in case
of pAF or lspAF in combination with a dilated right atrium
(>58 mL). Lee et al.  also performed ablation of
ganglionated plexi and the ligament of Marshall. The latter was also
performed by Richardson et al. 
The endocardial lines are less described than the
epicardial lines. Reported lines are left mitral isthmus (MI)
line (from the inferior margin of the LIPV ostium to the
mitral annulus), cavotricuspid isthmus (CTI) lines
(between the IVC and the tricuspid annulus), and CS line
(distal CS to the os). In the published studies, performing
these endocardial lines strongly depended on the
presence of arrhythmias like atrial flutters, and on the
preference of the cardiologist. Also, complex fractionated
atrial electrograms (CFAE) ablation are described. The
MI and CTI lines are most performed [15, 27, 35, 36,
3.7 Left atrial appendage
The LAA is deemed to be the origin for more than 90 % of
emboli in nonvalvular AF . Despite its proven efficacy,
oral anticoagulation (OAC) therapy can lead to bleedings and
may be difficult to control in many patients. Therefore
nonpharmacological treatment strategies to reduce the risk of
stroke in AF patients have been developed, including LAA
occlusion or removal during rhythm surgery. Bisleri et al. 
and Gaita et al.  do not describe LAA therapy. Three
studies did not perform a thoracoscopic ablation, leading to
impossibility to address the LAA and necessity for OAC after
the ablation [36, 37, 42]. In cases of resternotomy in these
studies, the LAA was removed but no motivation for removal
was reported. Muneretto et al.  Bavoided LAA treatment^
(cited), since at that time, no safe and validated techniques for
exclusion of the LAA via a right thoracic approach existed. In
three studies [38, 40, 41, 46], the LAA was removed (using a
stapler or clip) in every patient but they did not substantiate the
reasoning. Bulava et al.  excluded the LAA whenever
deemed safe and feasible by the surgeon, which was the case
in 84 % of the patients.
The only groups giving clear argumentation for LAA
treatment were Pison et al. and La Meir et al. : Bin patients with
a CHA2DS2-VASC ≥1, or in the presence of a rapid firing
coming from the LAA, and when the procedure was deemed
safe, LAA ex clusion/closur e was performed under
transoesophageal echocardiographic (TEE) guidance
employing a stapler or a clip.^ They excluded/closed the
LAA in 35 patients, which is 44.9 %.
In none of the articles is spoken about TEE performed in
the follow-up to check LAA closure, so in this population, no
data is available on long-term occlusion and thromboembolic
processes in the LAA. Neither is information available on
what influence LAA exclusion/closure has on AF recurrence.
It could, however, be that LAA exclusion/closure positively
influences the results [53, 54].
3.8 Periprocedural care
The main topics discussed in the literature on periprocedural
care are use of AADs and regulation of OAC. Mahapatra et al.
 maintained the patients on warfarin for at least 1 month
prior to the hybrid procedure and stopped 5 days before.
Except for amiodarone, AADs were stopped for five
halflives. Krul et al.  discontinued OAC 3 to 4 days prior to
the procedure, and AADs were continued during admission.
Bulava et al.  stopped OAC 7 days before the hybrid
procedure, after which a low-molecular-weight heparin
(LWMH) was started until the evening before the procedure.
Other articles not clearly describe preoperative management.
After the procedure, Krul et al.  transferred the patients
to the ward, where coumarin derivates were restarted before
removal of the chest drains the day after the procedure.
Unfractionated heparin was started as soon as bleeding risk
allowed this and was continued until an INR of 2.0 was
reached. OAC was discontinued after 6 months. Muneretto
et al.  and Bisleri et al.  neither transported patients
to the intensive care unit (ICU), where in three other studies
[27, 42, 46], all patients were transported to the ICU. The latter
administered LMWH 6 h after surgery and restarted warfarin
after removal of thoracic drains. Five authors [15, 34, 37, 39,
40] gave AADs postoperatively to all patients and
recommended discontinuation after 3 months if the patient was free
of AF. They started warfarin on the second postoperative day
(target INR of 2.5) and stopped after 3 months if the patient
was in SR or had a CHA2DS2VASc score of <2. Bulava et al.
 did not prescribe any AAD at time of discharge. Gehi
et al.  prescribed OAC and an AAD for at least 6 weeks,
Lee et al.  for 6 months. Zembala et al.  administrated
intravenous amiodaron and heparin 1 h after the surgery for
48 h. On day 2, warfarin was started. In case of a staged
approach, patients were discharged on LMWH and after EP
warfarin was started which was replaced by aspirin after
6 months in case of SR. AADs were continued for 3 months.
3.9 Rhythm monitoring and endpoints
All studies used a long-term monitoring method, either 24-h
holter monitoring , 7-day holter monitoring [15, 27, 39,
42], or an implantable loop recorder [34, 35, 37, 41, 42]. Two
studies did not specify the duration of the holter [43, 46].
Mahapatra et al.  used a 7-day continuous autotriggered
monitor (CAT) and a 24-h holter. Patients with an implantable
loop recorder were instructed to return monthly to have their
monitors downloaded and interrogated. Further
electrocardiogram visits where performed in all studies, but time spans
differed, and patients were instructed to return in case of
Success was defined as the absence of AF and/or any other
supraventricular arrhythmia lasting more than 30 s on a 7-day
holter monitor during the entire follow-up after the blanking
period [27, 41, 42], which corresponds with the guidelines .
Three other studies included freedom of AADs in the
definition of success [15, 39, 40]. In two articles, a 24-h holter was
used to confirm freedom of AF [36, 38]. Some considered
stable SR as the absence of AF episodes lasting more than
5 min and an overall burden of 0.5 % of time spent in AF
on a monthly basis [34, 35]. Gaita et al.  considered
success if the patient maintained stable SR or suffered from only
brief episodes of paroxysmal tachyarrhythmia’s with
spontaneous restoration, but also patients requiring cardioversion
were considered successful if SR maintained after the
cardioversion. Gersak et al.  did not describe clear endpoints.
3.10 Procedural results and complications
Success rates (sinus rhythm after a mean of 26 months)
without the use of AADs from the studies presented in
Table 2 ranged from 27 %  to 87 % . Success
rates with the use of AADs ranged from 33 %  to
94 % . Concerning the studies which included a limit
of 30 s in their definition of recurrence, success rates
were 61 % , 74 % , 80 % , 84 % , and
87 % . In the study of Zembala et al. , nobody in
SR used AADs anymore. According to the difference
between unipolar and bipolar conducted ablations, the
mean of the success rates is in favor of the bipolar
devices (82.7 vs. 46.9 %). In seven of the articles [15, 27,
36–38, 42, 43], a total of 27 redo procedures are
reported. No information is given on findings during these
procedures. Velagic et al.  does describe findings of
redo procedures after hybrid ablation: in 36 % of the 14
patients recovered conduction was found, but only 9 %
of the PVs were reconnected and 7 % of the box lesions.
Only three papers report success rates by type of AF. Krul
et al.  reported, without use of AADs, 91.7 % for PAF
(n = 12), 77.8 % for pAF (n = 9), and 100 % for lspAF (n = 1).
Pison et al.  reported, without AADs, 76 % for PAF (n =
22), 62 % for pAF (n = 28), and 100 % for lspAF 100 % (n =
15), and with AADs 97 % for PAF (n = 28) and 85 % for pAF
(n = 29). La Meir et al.  reported 60 % for PAF (n = 3),
50 % in pAF (n = 2), and 20 % in lspAF (n = 2).
Bulava et al.  elaborated in their article EP
findings in relation to patients in SR and patients in a
tachyarrhythmia at the time of EP. Of the patients in
SR, 74.4 % of all PVs were isolated (n = 29/39). Of
the patients with a tachyarrhythmia, this was 72.2 %
(n = 8/11). In 30 % of all patients (n = 15), the box
lesion was found to be complete, with no difference in
patients in SR versus patients with an arrhythmia. At
the end of the EP, 100 % of the lesions were
completed. In 42 % of the patients in the study by Gaita et al.
, the lesion set was found to be incomplete: in 3
patients, the PVs were not completely isolated, in 3
patients the roof line, and in 11 patients the MI line.
At the time of EP, 15 of the 33 patients were in SR.
After EP, 79 % of the lesions could be completed. Of
the ten patients who never had recurrences, nine had a
complete lesion set after EP. In the patients where no
complete scheme could be achieved, 43 % were in SR,
all on AADs, and 57 % in permanent AF. Bisleri et al.
 found, during EP, in 91.1 % of the patients a
complete box lesion and reached 100 % after EP, for
Mahapatra et al. , this was 83.3 % and also
100 % at the end of the EP. In two articles only is
mentioned what is reached at the end of the EP (PVI),
97 %  and 100 % . Pison et al. reported a
complete box lesion at the time of EP in 64 % of the
patients and, after endocardial touch-up, at the end of
the EP in 100 %. La Meir et al.  found that during
EP, none of the patients with a complete box, and 17
out of 19 patients had at least one PV not isolated for
which endocardial touch-up was performed.
The periprocedural complications are listed in
Table 3. In total, 63 complications occurred (including
23 minor complications, e.g., pneumonia), which
concurs with 11 % of the patients. A major complication
occurred in 7 % of the patients (of which 16 % in the
concomitant cardiac surgery hybrid group) and death in
1.6 %. Three of the deaths occurred in the concomitant
group, excluding these gives a mortality rate of 1.1 %.
The main purpose of this review was to provide an overview
of findings and experiences from published studies on hybrid
ablations and to discuss related topics. The approaches,
techniques, lesion sets, periprocedural care, and endpoints
substantially differ per center, which makes it difficult to compare
results. Success rates (after a mean follow-up of 26 months)
without the use of AADs ranged from 27 to 87 %. The very
low success rate of Gaita et al.  most probably relates to
the fact that the population concerns patients with concomitant
surgery. La Meir et al.  and Gehi et al.  also report low
success rates; they both used unipolar devices which,
compared to bipolar devices, less reliably produce permanent
transmural lesions and are less effective in restoration of SR
[30, 55]. The failure of these two studies might thus relate to
the use of ineffective ablation techniques, though also when
using bipolar devices, linear lesions are not always completely
transmural and need touch-up during the endocardial part of
the hybrid ablation , and other articles in which unipolar
devices are used showed better results. These however
concern a lower number of patients with pAF and lspAF, and
lower existence of comorbidities.
The results of the hybrid approach have been compared
(nonrandomized) to standard minimally invasive surgical
approaches, showing better 1-year results in the hybrid group
. In another trial comparing CA to surgical ablation,
surgical ablation was found to be superior to CA, although the
procedural adverse events were significantly higher for
surgical ablation . However, due to some study limitations,
success and complication rates might be overestimated.
Another topic to highlight is the surgical approach. The
monolateral approach, compared to the bilateral approach,
reduces risk of complications as bleeding, pneumothorax,
and lung hernia [57, 58] and is supposed to be less painful,
improving the patient’s recovery. It is preferred in patients
with COPD. Since the heart is enlarged to the left of midline,
a right thoracic approach provides additional working space
compared to a left-sided approach. However, with a
rightsided approach it is more difficult to occlude or exclude the
LAA. In case of a left-sided approach, it is possible to isolate
the right PVs using the standard bipolar devices, which would
not be possible the other way around . To reach the left
PVs using a right thoracoscopy, an ablation probe delivering
continuous lesions encircling the origin of all PVs and the
posterior aspect of the LA all together, creating a box lesion,
is needed [34, 35, 39]. It is however doubtful if this probe can
create sufficient transmural lesions.
Probably the most discussed issue is whether the hybrid
ablation procedure should be performed in one stage,
sequential, or in two stages. Each approach has its opportunities but
also challenges. It seems that the main concern with a one-step
approach is that it is time-consuming for both the surgeon and
the electrophysiologist, and therefore, it even has been called a
Blogistical nightmare.^ Furthermore, the procedural
environment has to be optimized for both operators. Another
described disadvantage is the formation of edema of the
myocytes due to damage as result of the ablation, with
difficulty to test and reablate the same area with CA. Managing the
periprocedural anticoagulation (especially heparinisation after
transseptal puncture in combination with operation wounds)
can be challenging. CA in a second admission theoretically
could enable identification of areas of early reconnection.
Further, it allows gaps to develop and to be detectable, since
small gaps could have been missed at an initial procedure.
Richardson et al.  showed that a staged approach
increased the likelihood of discovering incomplete lesions;
however, this did not improve the time to recurrence. The
inconvenience for the patient is significantly lower in a
onestage approach compared to a sequential and two-stage
approach with a second hospital admission and a second time
anesthesia. Next, complications could be minimized in a
onestep approach: there is less risk of phrenic nerve damage or
esophageal injury since the surgeon can protect these
structures, and with an opened pericardium, the risk of tamponade
during transseptal puncture is lowered. A one-stage approach
allows for immediate electroanatomic mapping with
endocardial confirmation of isolation or incomplete isolation with the
possibility to add touch-up lesions endocardially, and it also
allows for guiding epicardial ablation, including identifying
substrates which may be more effectively targeted
epicardially. An argument to choose for a sequential, instead
of a two-stage, approach could be abating the risk that patients
in SR after the first procedure will not come back for a second
procedure, and the inconvenience for the patient will be lower
when only admitted once to the hospital. A head to head study
comparing the different approaches should be performed to
support the discussion on this topic.
The final but perhaps most important question to answer is,
why hybrid? And which patients should be advised to undergo
a hybrid ablation? There are several advantages of a hybrid
ablation. First, it is important to confirm conduction block of
the ablation lines, since incomplete lines makes the patient
susceptible for developing atrial flutters . Due to
immediate mapping, it is also possible to tailor the epicardial lesion
set. Next, some lines cannot be accomplished epicardially,
however easily endocardially, and it is easier to perform some
of the endocardial lesions epicardially (for example, ligament
of Marshall). Disadvantages are the prolonged procedure
time, heparinization after the surgical procedure and it
(possibly unnecessarily) exposes the patients to the risks of both CA
and thoracoscopy. The little available research shows that
mainly lspAF patients will have advantage of the hybrid
procedure compared to the surgical procedure , and that
patients with previous failed CA have advantage of a hybrid
procedure compared to a redo CA procedure .
Obviously, more research is needed to be able to answer these
questions well-founded and to compare the results of the
different ablation strategies. At the moment, some trials are
performed and answers are expected in the next years from
a m o n g o t h e r s t h e D E E P - A F ( N C T 0 1 2 4 6 4 6 6 ) ,
C O N V E R G E - A F ( N C T 0 1 9 8 4 3 4 6 ) , H A RT C A P - A F
(NCT02441738), and EHAFAR (registry) studies.
The field of AF ablation has dramatically changed over the
past years, with the most recent development a close
collaboration between an electrophysiologist and a cardiac surgeon in
the form of a hybrid AF ablation. Absence of guidelines on
this procedure leaded to various strategies for performing the
ablation, making it difficult to report results. Insufficient data
are available comparing hybrid ablation to surgical or catheter
ablation. This hinders drawing well-founded conclusions
about the procedure. Considering the available data, the
AAD-free success rates are satisfactory and hybrid ablation
is a promising procedure, but more (multicenter, randomized)
data are necessary to confirm the early results and give hybrid
ablation a definitive position in the guidelines for AF therapy.
Compliance with ethical standards
Laurent Pison is a consultant to Atricure.
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