Evaluation of the Achieve Mapping Catheter in Cryoablation for Atrial
Fibrillation: A Prospective Randomized Trial
Yi Gang,1 Hanney Gonna,1,2 Giulia Domenichini,1 Michael Sampson,1 Niloufar Aryan,1
Mark Norman,3,1 Elijah R. Behr,1 Zia Zuberi,4,1 Paramdeep Dhillon,5,1 Mark M. Gallagher1,5
Short Title: Achieve mapping catheter in cryoablation for AF
Institutions:
1) Cardiology Clinical Academic Group
St. George's University Hospitals NHS Foundation Trust
St. George's, University of London
2) National Heart & Lung Institute, Imperial College London, London, United Kingdom
3) Frimley Park Hospital, Frimley, United Kingdom
4) The Royal Surrey County Hospital, Guildford, United Kingdom
5) St Peter’s Hospital, Chertsey, United Kingdom
Correspondence:
Mark M. Gallagher
Department of Cardiology, St. George’s Hospital
Blackshaw Road, London, SW17 0QT, United Kingdom
Tel. +44 (0)208 725 5578
Fax. +44 (0)208 725 3328
[email protected]
Page 1 of 29
Abstract
Purpose To establish the role of Achieve mapping catheter in cryoablation for
paroxysmal atrial fibrillation (PAF) in a randomised trial.
Methods A total of 102 patients undergoing their first ablation for PAF were
randomized at 2:1 to an Achieve- or lasso-guided procedure. Study patients were
systematically followed up for 12 months with Holter monitoring. Primary study
endpoint was acute procedure success. Secondary endpoint was clinical outcomes
assessed by AF free at 6 and 12 months after the procedure.
Results Of 102 participants, 99% of acute procedure success was achieved.
Significantly shorter procedure duration with the Achieve- than with a lasso-guided
group (118±18 vs. 129±21 min, p<0.05) was observed as was the duration of
fluoroscopy (17±5 vs. 20±7 min, p<0.05) by subgroup analysis focused on procedures
performed by experienced operators. In the whole study patients, procedure and
fluoroscopic durations were similar in the Achieve- (n=68) and lasso-guided group
(n=34). Transient phrenic nerve weakening was equally prevalent with the Achieve and
lasso. No association was found between clinical outcomes and mapping catheter
used. Use of second generation cryoballoon (n=68) reduced procedure time
significantly compared to the first generation balloon (n=34); more patients were free
of AF in the former than the latter group during follow-up.
Conclusions Use of the Achieve mapping catheter can reduce procedure and
fluoroscopic durations compared with lasso catheters in cryoablation for PAF after
operators gained sufficient experience. The type of mapping catheter used does not
affect procedure efficiency and safety by models of cryoballoon.
Key Words: AF Ablation; Randomized Controlled Trial; Cryoballoon; Circular Mapping
Catheter; Cryoablation.
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1 Introduction
Pulmonary vein isolation (PVI) is the most important component of catheter ablation
for patients with paroxysmal atrial fibrillation (PAF), and constitutes a sufficient therapy
in the majority of cases.[1] PVI can be accomplished using a cryoballoon ablation
catheter more efficiently than by “point-by-point” ablation using radiofrequency energy.
[2;3]
The Achieve Mapping Catheter® (Medtronic) is an octapolar circular mapping
catheter that passes through the central lumen of the cryoballoon, permitting PV
electrogram recording during cryotherapy delivery,[4] even in the presence of
substantial structural abnormality.[5] Before the Achieve catheter became available,
PV electrograms were recorded using a traditional “lasso-style” multipolar circular
mapping catheter either by delivering it through the same trans septal sheath as the
cryoballoon before and after cryotherapy or by delivering it through a separate trans
septal puncture, in which case it can be used during cryotherapy in any vein other than
the one being cryoablated at that time.[6] The Achieve mapping catheter was designed
with the expectation of improved procedural efficacy and safety compared to the
conventional ‘lasso-style’ mapping catheter. Although a few early studies reported its
clinical value, randomised trials focusing on the Achieve mapping catheters in
cryoballoon ablation for AF are sparse.
The current study aimed to assess the efficacy, efficiency and safety of the Achieve
mapping catheter compared to the lasso-style circular mapping catheter in a
randomized study design in PVI procedure for patients with PAF. During enrolment for
this trial, the original Arctic Front (AFO) was superseded by the Arctic Front
Advance;[7-10] we managed this transition in a stratified manner to allow comparison
between the devices.
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2 Methods
2.1 Study population
We recruited patients with PAF[11] who underwent their first AF ablation into this
study at St. George’s Hospital (London, UK) between November 2011 and October
2013. PAF patients who were suffering from symptomatic PAF, refractory to medical
therapy and aged greater than 18 years old were eligible for recruitment. Patients who
had prior left atrial ablation or any contraindication to left atrial ablation were excluded.
Study patients underwent trans esophageal echocardiography within one-week before
the procedure; no other form of pre-procedure cardiac imaging was utilized.
Study participants were randomly assigned to 2 arms, cryoballoon ablation with
either the usage of an Achieve mapping catheter or a lasso-guided technique.
Treatment was randomized in a 2:1 (Achieve: lasso) manner by using a computergenerated randomization number. This unequal allocation was chosen because all of
the operators were experienced in the lasso-guided technique before the study began
but had little or no experience with the Achieve mapping catheter. We assigned more
cases to the Achieve-guided group so that significant experience in the Achieve-guided
technique could be accumulated by each operator, allowing us to perform subgroup
analysis to correct for this obvious confounding factor. The assignment was revealed
to the operator in the EP laboratory at the beginning of the procedure.
This study complies with the Declaration of Helsinki; the research protocol was
approved by the Research Ethical Committee of London, and all participants had given
written informed consent before the procedure.
2.2 Ablation procedure
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A standard PVI procedure was performed on all cases.[12] The investigators used
two or three points of venous access, one of which was used to place of a diagnostic
catheter in the coronary sinus. A single trans septal puncture was performed and a
venogram of each PV was obtained. The selection of cryoballoon size (23 vs. 28mm)
was based on PV size using venography. Before each delivery of cryotherapy, the
quality of occlusion was quantified (details in caption of Figure 1) by venography
(Figure 1), and by measuring the pressure recorded through the central lumen of the
balloon catheter. When necessary, a second balloon of different size may be used, but
this practice was discouraged throughout the study. General anesthesia was available
to patients who requested it.
In patients assigned to the lasso group, the PVs were mapped with a lasso circular
mapping catheter before and after cryotherapy, using a single trans septal puncture
and delivering the mapping catheter through the dedicated cryoballoon sheath
(FlexCath Steerable Sheath). If the Achieve was used, the PV electrograms were
monitored continuously during the cryoballoon freeze in each PV. The time-to-isolation
(TTI) was recorded whenever the effect of acute isolation was visible during
cryotherapy. TTI was defined from the onset of ablation to electrogram elimination or
dissociation of PV potentials and calculated using the clock time displayed on the Bard
system. After all PVs were treated, each PV was again mapped to confirm and record
the persistence of isolation that was achieved at 15 minutes post-ablation.
In all procedures, at least two cryoballoon ablation deliveries were applied to each
of the PV ostia. The delivery of cryotherapy could be aborted at the discretion of the
operator if either: 1) the PV was not isolated within 100 seconds; 2) if the temperature
failed to descend to -40C; or 3) any warning signs of phrenic nerve injury observed. All
satisfactory freezes lasted for 240-300 seconds. The standard freezing cycle duration
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of 300 seconds was applied in all cases using the AFO and the first 27 cases performed
using the AFA; thereafter, the freeze duration was reduced to 240 seconds in the AFA
group to avoid potential freezing complications after more information regarding the
AFA became available.
The AFA catheter became available during our study enrollment, we introduced it in a
stratified manner designed to avoid an order effect and compare it objectively to the
older model of cryoballoon with a balance between AFA and AFO in each of the
randomized assignment groups.
After all of the PVs were treated by this protocol, if necessary any remaining points
of electrical communication were ablated with a large curve Freezor Max ablation
catheter delivered via the existing trans septal puncture or a second trans septal
puncture at the discretion of the operator.
During cryotherapy of right side PVs, the diagnostic catheter was re-sited from the
coronary sinus to the superior vena cava for continuous pacing of the phrenic nerve
(PN). PN capture was constantly monitored by palpation of the thoracic cage at the
level of the xiphisternum. If weakening or loss of diaphragmatic movement in response
to the pacing stimuli was noted, the freezing delivery was immediately stopped, and
the balloon was quickly deflated by pressing the stop button on the Cryo Console twice.
The procedural endpoint was defined as persistent PVI, which was verified by
circular mapping catheter recordings at least 15 minutes after the last application of
cryotherapy to that vein. Data were collected throughout the study by a dedicated
researcher instructed by the operator during the procedure, and the data were
reviewed by the operator at the end of each case.
2.3 Procedural complications
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Complications were defined prospectively as unintended consequences of the
procedure that led to patient suffering or to prolongation of the patient’s hospital
admission. Major adverse events were defined as complications that constituted a
threat to life, involved blood loss requiring transfusion, prolonged the hospital
admission to more than one week or led to adverse symptoms or functional limitation
extending for longer than three months.
Any alteration of phrenic nerve function was recorded. Transient phrenic weakening
(tPNW) defined as weakening or loss of diaphragmatic response to PN during
cryotherapy with a full return to normal strength before the end of the procedure; tPNW
did not fulfill our prospective definition of a complication and was considered as a
warning sign of an averted events. Temporary phrenic nerve injury (tPNI) was defined
as a weakening of phrenic response to electrical stimulation that persisted beyond the
end of the procedure but was followed by a full return to normal function by the
following day; because this prompted a pre-discharge chest radiograph and therefore
delayed discharge by several hours, it was considered as a complication. Phrenic
nerve palsy (PNP) was diagnosed if there was a loss of phrenic response persisting to
the end the procedure with elevation of the hemidiaphragm chest radiography on the
following or subsequent days.
2.4 Study follow-up
All AF ablation patients were scheduled to be discharged from hospital the day after
the procedure. Every participant was interviewed at their bedside the morning after
ablation and a telephone interview was conducted at 2-months after the procedure by
a dedicated researcher. Further follow-ups were scheduled at 3-, 6-, and 12-months
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post ablation with attendance at an arrhythmia clinic, including a 48-hour Holter monitor
at each follow-up point.
AF recurrence was defined as any episode of AF/AT >30 seconds, either
symptomatic or asymptomatic, documented on a Holter ECG and/or 12-lead resting
ECG[13] or other long-term ECG recording devices [9] [14] during follow up. A 3-month
blanking period was applied to calculations of freedom from AF.[9]
2.5 Statistical analysis
Continuous variables are presented as mean ± SD, where appropriate. Categorical
variables are expressed as numbers and percentage of patients. Comparison of
numeric values of all measurements was performed using the Mann-Whitney U-test or
Student's 2-tail t test depending on the data distribution, and comparison of categorical
variables was tested by chi- square or Fisher exact test, as appropriate. All statistical
analyses were performed using the SPSS software (SPSS v20, IL, USA) or Microsoft
Excel (2010). A p value < 0.05 was considered statistically significant.
2.6 Power Calculations
A prospective power calculation was performed based on the standard deviation of
the procedure duration and fluoroscopy duration for 10 consecutive Arctic Front
procedures performed while the study was being designed. With a sample size of 102
and a 2:1 randomisation we calculated a 90% probability of being able to detect a 14
minute difference between the groups in the procedure duration at a 5% significance
level.
3 Results
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3.1 Patients
A total of 102 participants (age 62±12 years, range 22.6 – 83.2 years, 52 male) were
randomized and treated (Figure 2). Sixty-eight patients were randomized to the
Achieve- and 34 to the lasso- group. There was no significant difference in clinical
characteristic between the study groups (Table 1). Twenty patients in the Achieve
group and 9 in lasso group (29 vs. 26%, p=ns) underwent their ablation procedure
under general anesthesia. All study patients completed their 6-month follow up. Two
participants died of causes unrelated to ablation procedure or the arrhythmia before
12-month follow up. Another 2 participants withdrew/lost from the follow-up between 6
and 12 months post ablation.
3.2 Comparison of the mapping techniques
The mean procedure time, measured from skin puncture to the removal of the last
venous sheath, was similar in the Achieve and the lasso groups (126±20 vs. 129±21
min, p=ns). No significant difference was observed in the fluoroscopic time between
Achieve and lasso (21±13 vs. 20±7 min, p=ns) in the whole study population.
Because the study began soon after the introduction of the Achieve mapping
catheter, all the operators were were all inexperienced in its use at the start of the study
but were experienced in the use of the cryoballoon directed by lasso mapping and
guide wire delivery. We therefore reanalyzed the data excluding operators who were
still in the first 10 cases of their experience with the Achieve mapping catheter. In the
subgroup (n=51) who underwent an Achieve-guided procedure by an operator with an
experience record >10 cases, procedure time was significantly shorter with the
Achieve- than with a lasso-guided approach (118±18 vs. 129±21 min, p<0.05) as was
the duration of fluoroscopy (17±5 vs. 20±7 min, p<0.05; Figure 2).
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3.3 Procedural data
The procedure of PVI was completed by cryoballoon alone in 96 cases (94%).
Additional touch-up ablation to a PV using a Freezor Max catheter was required in 6
cases (6%). Ablation of the cavotricuspid isthmus was performed at the same
procedure in 22 cases for documented typical atrial flutter using the technique as we
have previously described,[15] and balanced across the mapping catheter groups. No
other arrhythmia substrate was ablated in any study patient.
A 28 mm cryoballoon was used in 75 cases (74%), and a 23 mm cryoballoon in 29
cases (28%). In two cases (2%) the operator had to change from a 23 to a 28mm
balloons or vice versa. AFO was used in 34 and AFA in 68 cases of the 102 procedures
with similar clinical characteristics in both groups (Table 1). The mean procedure time
with the AFA was significantly shorter than with the AFO. The AFA catheter reached
nadir temperature significantly faster than the AFO (p<0.05; Figure 3). The use of AFA
was similar in the Achieve and lasso groups (71% vs. 65%, p=ns).
3.4 Pulmonary vein isolation
A total of 413 PVs were treated in study patients, and 99% of identified PVs with PV
signals were successful isolated.
PV conduction was present at the end of the
procedure in only one vein each in two cases, both performed with the Achieve
mapping catheter and AFO. Acute PV isolation was achieved with cryoballoon alone
in 65 cases (96%) of Achieve and in 31 cases (91%) of Lasso group (p=ns).
In the Achieve group, the TTI was observed in 62% of identified PVs with a mean of
TTI of 47±38 seconds (range 2 – 215 seconds). A significantly shorter TTI was noted
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in patients treated with the AFA than with AFO (34.6±23.4 vs. 43.1±39.1 seconds,
p<0.01).
The degree of PV occlusion was shown to predict the response to therapy (Figure
1). The distinction between grade 4 and grade 5 was significant: therapies associated
with grade 5 occlusion gave significantly shorter time to isolation of the vein (40±27 vs.
53±39 seconds, p<0.05) and significantly colder nadir temperatures (-53.6±8.6 vs. 50.8±12.5°C, p<0.05) compared to those associated with a grade 4 occlusion. The PV
occlusion degree was similar in the Achieve and lasso groups. The pressure recorded
through the central lumen of the balloon catheter showed a trend toward higher values
with occlusions of greater quality but the pressure did not predict the TTI.
3.5 Procedure complications
Only one major complication occurred in this study. A patient undergoing lassoguided ablation with AFA under general anesthesia developed substantial bleeding
into the endotracheal tube during the first cryotherapy to the RSPV. After losing
approximately 500ml of blood in 1 minute, the bleeding stopped in response to
termination of the freeze with emergency deflation of the balloon, removal of the guide
wire from the PV and reversal of heparin. Emergency bronchoscopy showed no
ongoing bleeding, but there was evidence of recent bleeding through the right upper
lobe bronchus. The patient made an uncomplicated recovery and was discharged two
days later; he remained in sinus rhythm during follow-up.
There were three other complications in the entire study: two cases of femoral
haematoma or pseudoaneurysm requiring thrombin injection and one case of tPNI that
continued to the end of the procedure. This phrenic nerve injury was not evident on
chest radiography the following day and produced no symptom. The rate of
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complication was unrelated to assignment (Achieve vs. Lasso), to the model of
cryoballoon, or to the size of the balloon (Table 2). Two of the three complications
happened in cases when general anesthesia was used.
A weakening of diaphragmatic response to phrenic stimulation followed by a full
return of function before the end of the procedure was observed in 24 cases (23.5%).
The incidence of this threatened complication was not significantly associated with the
assignment to Achieve or lasso group, the size or model of cryoballoon used, or the
mode of anesthesia.
3.6 Clinical outcomes
Of 102 participants, 80 cases (78%) were free from AF at 6-month post ablation. At
12 months, 78 of 98 (79%) cases who had completed 12-month follow-ups remained
AF free with or without antiarrhythmic drugs. The clinical outcome was not associated
with the Achieve or lasso mapping catheter used but associated with the cryoballoon
model (87% vs. 62%, p=0.004, at 6 months; 88% vs. 61%, p=0.002, at 12 months for
AFA vs. AFO). No association was noted between clinical outcome and the cryoballoon
size, or the mode of anesthesia.
4 Discussion
Our study has shown a significant reduction in procedure time and fluoroscopy
duration with the Achieve mapping catheter, that happens after operators gained a
great deal of experience in its use; such advantage was not demonstrated when
operators were still in early stage of the learning curve. This study has confirmed the
findings from other reports that use of the second-generation cryoballoon significantly
shortens procedure time and is associated with better clinical outcomes.
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4.1 Procedure efficiency
The achieve catheter, which is deployed through the Arctic Front guide wire lumen,
could minimize the number of catheter exchanges and hence of shorten procedure
time. However, the expected efficiency gain was not demonstrated in this study while
it included the cases of Achieve-guided procedure performed by operators with limited
experience. Subgroup analysis eliminates the confounder and proves the advantage
of the novel catheter. Our findings are not fully consistent with that reported in early
studies,[4] however, operator information was not available in most previous nonrandomized studies on the Achieve.[9;10;16;17] People who practice in this area
would agree that operator dexterity is a significant confounding factor; it can affect
study findings. Our results demonstrate that there is a learning curve before an
operator reaches full efficiency with the Achieve catheter.
Our findings are consistent with those from other published studies [8-10] regarding
the AFA, which allows the freezing time to be reduced while attaining similar or better
rates of PVI. This improvement of efficiency attributes mainly to the features of the new
cryoballoon but not correlated with type of mapping catheter used.
4.2 Procedure safety
Achieve catheter allows the procedure to be performed using a single transseptal
puncture. One may expect a better safety record of procedures for this reason;
however, there are multiple factors which could affect overall rate of procedure
complications. This study confirms that cryoablation is a safe method of achieving PVI,
with a rate of serious complication of less than 1% in our series.
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Our results demonstrate that single transseptal puncture and single-balloon
strategy is almost always practical, efficient, and safe even without preselection for
anatomic suitability based on any pre-procedure imaging of PV for cryoballoon therapy.
In the Straube et al. study, CT/MRI were used to determine PV anatomy.[10] Straube
et al. used 23- plus 28 mm cryoballoon in 21% of the study patients.[10] Other
investigators reported using both balloons in as many as 47.7% of cases.[18] This
study has proven a single-balloon strategy is fiscally more achievable.
Other studies reported that AFA was associated to a greater incidence of PNP
when compared with AFO. This was not observed in our study regarding the
association between incident of PNP or tPNW and AFA. The use of Achieve did not
increase or decrease the advert events. Close monitoring was constantly applied
during ablating the right PVs and the freezing would be terminated if the temperature
dropped below -65 °C. Great incidence of PNP can be reduced with such strategy.
4.3 Procedure efficacy
The achieve catheter may provide real-time PV signals during PVI procedures using
an Arctic Front cryoballoon, allowing real-time verification of PVI during delivery of
cryotherapy. Potentially, real-time verification of PVI could guide cryotherapy and
improve procedure efficacy and efficiency by allowing the operator to titrate the dose
of cryotherapy according to effect. We did not use the data derived from the Achieve
in this way.
In previous research populations, the Achieve has registered electrograms of
sufficient quality to determine TTI in 31– 76%[4] [10] [19] [20] of PVs. Failure to register
clear electrograms during therapy may occur due to an absence of excitable tissue in
the vein wall or because the shape of the vein requires that the achieve catheter is
Page 14 of 29
placed in a distal position to attain sufficient stability to support the balloon. We have
tried to minimize this effect by using the larger balloon size in 75% of cases to place
the balloon and therefore the Achieve mapping catheter as proximally as possible in
the vein. When electrograms could not be observed during cryotherapy, the Achieve
mapping catheter can be used to determine the presence or absence of electrograms
in the proximal part of the vein or in the antrum of the vein before and after therapy in
the same way as a lasso-type catheter.
Chierchia et al. observed real-time PVI in 55% of cases, [4] Kuhne et al. reported
seeing real-time isolation in 50%.[19] Furnkranz et al.[20] found it in 49% of targeted
PVs using AFO and 76% using AFA. No such difference was observed in our study or
by Straube et al. (31% vs. 44%),[10] between AFO and AFA suggesting that the effect
described by Furnkanz et al. may represent an order effect with improvement in their
utilization of the Achieve mapping catheter as they gained experience with it.
The 2nd generation cryoballoon is designed to provide a more contiguous lesion by
delivering cryotherapy more uniformly with the expectation of improved procedural
efficacy and clinical outcome compared to the 1st generation cryoballoon. The
improved efficacy has been demonstrated by a number of clinical studies. [8;20]
Consistent with previous literature, our study shows a 99% of acute PVI and improved
clinical outcome. Again, this is not related to either Achieve or lasso catheter.
4.4 Study limitations
This study was conducted in a single center by operators already experienced in the
use of the Arctic Front and of lasso-style catheters but initially without experience in
the use of the Achieve mapping catheter. This lack of experience may have reduced
our ability to detect the advantages of the Achieve in whole study population. The
Page 15 of 29
introduction of the AFA during the recruitment complicated the data analysis and
interpretation.
The approach of comparing catheters in an open-label manner might raise a
potential bias if operators started with a preferred concept. In a study of methods as
dis-similar as the Achieve mapping catheter and the lasso, there was no alternative to
an open-label design. We have tried to minimize any effect of bias by using multiple
operators, most of whom had no conflict of interest and all of whom had an interest in
minimizing procedure duration for ethical and practical reasons.
We may have underestimated the potential benefits of the Achieve mapping
catheter because of the limited utilization of the information derived from it in the
current study. Our rigid protocol did not permit the operator to adjust the duration of
cryotherapy according to TTI. This limitation was inevitable because no information on
the correlation between TTI and long term outcome was available at the time the study
was designed. It remains to be determined whether the tailoring of therapy based on
TTI information from the Achieve mapping catheter can improve the efficacy and
efficiency of ablation procedures.
4.5 Study implications and future work
The findings of this randomized trial support that it is more efficient to use the
Achieve catheter in conjunction with the newer cryoballoon in PVI. This study indicates
operators have to pass a significant learning curve in performing the procedure before
benefiting from the device. There has no universal consensus on the optimal duration
of cryotherapy delivery; further investigation on how the visible TTI may guide the
therapy is warranted aiming to shorten the procedure time without compromising the
efficacy and clinical outcome. The grading system for pulmonary vein occlusion that
Page 16 of 29
we designed for this trial was potentially a predictor of TTI. It requires further verification
to determine its role in PVI.
5 Conclusion
Use of the Achieve mapping catheter can reduce procedure and fluoroscopic
durations compared to established catheters used for pulmonary vein mapping in
cryoballoon ablation for PAF, only after operators gained sufficient experience. The
type of circular mapping catheter used does not affect the procedure efficiency and
safety demonstrated by 2nd generation cryoballoon, which has improved overall
procedure efficiency of cryoballoon ablation in PAF without compromising safety
compared with the first generation cryoballoon.
Conflict of interest: the primary investigator (MMG) received research funding from the
Medtronic that provided salary for one of the researchers (YG).
Acknowledgment
This work was supported by an unrestricted educational grant from Medtronic AF
Solutions, Medtronic Limited. We wish to thank Gavin Wormull, Ralf Meyer and Hae
Lim of Medtronic AF Solutions for providing research funding and technical support.
We thank all Cardiac Physiologists in the EP lab and in the ECG department of St
George’s Hospital, as well as the nursing staff at the lab and James Hope wards, for
their constant support in this study.
Page 17 of 29
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fibrillation after cryoballoon ablation: insights from the multicenter Sustained
Treatment of Paroxysmal Atrial Fibrillation (STOP AF) Trial. Circ Arrhythm
Electrophysiol 7(1),69-75.
15. Dhillon PS, Domenichini G, Gonna H, Bastiaenen R, Norman M, Gallagher MM
(2014) Feasibility and efficacy of simultaneous pulmonary vein isolation and
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Table 1. Comparison of baseline characteristics.
All patients
Achieve
Lasso
AFA
AFO
(N=102)
(N=68)
(N=34)
(N=68)
(N=34)
Age (years)
62±12
63±12
59±12
60±13
64±11
Male (n, %)
52 (51%)
34 (50%)
18 (53%)
33 (49%)
19 (56%)
BMI (kg/m2)
28±6
28±6
29±7
28±6
29±6
LA dilation
21 (20%)
14 (21%)
7 (21%)
13 (19%)
8 (24%)
LV dysfunction
4 (4%)
4 (6%)
0
1 (1.5%)
3 (8.8%)
AF duration* (month)
46±42
47±39
43±49
44±40
48±47
AF = atrial fibrillation; AFA = Arctic Front Advance; BMI = body mass index; LA = left
atrium; LV = left ventricle; AFO = Arctic Front Original.
*AF duration is the interval from the first diagnosis of AF to the time of the ablation.
p=ns for all comparisons.
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Table 2. Comparison of outcome characteristics.
All patients
Achieve
Lasso
AFA
AFO
(N=102)
(N=68)
(N=34)
(N=68)
(N=34)
Procedure time (minutes)
128±27
127±28
129±27
122±25*
140±28
Ablation time (minutes)
71±22
73±23
67±19
67±18†
81.0±26
Fluoroscopic time (minutes)
21±12
21±13
20±7
20±12
22±10
General anesthesia (n, %)
28 (28%)
19 (28%)
9 (27%)
20 (30%)
8 (24%)
tPNW (n, %)
24 (24%)
19 (28%)
5 (15%)
14 (21%)
10 (29%)
Complication
4 (4%)
3 (4%)
1 (3%)
1 (2%)
3 (9%)
AF free at 6 months
80 (78%)
50 (73%)
30 (88%)
58
22 (65%)
(87%)‡
*p=0.002 compared to AFO; †p=0.001 compared to AFO; ‡ p=0.004 compared to AFO.
AF = atrial fibrillation; AFA = Arctic Front Advance; AFO = Arctic Front Original; tPNW
= temporary phrenic weakening.
Page 23 of 29
Fig. 1 Occlusion quality and results
The degree of occlusion of the pulmonary vein obtained for each cryothermal therapy
delivery was quantified on a scale of 1-5 using the following criteria:
Grade 5 occlusion described an appearance in which contrast injected through the
central lumen of the balloon catheter was seen to remain in the peripheral pulmonary
veins without accumulation close to the balloon.
Grade 4 occlusion was associated with a distribution of contrast density that was
homogeneous from the peripheral veins to the surface of the balloon, or was more
concentrated at the balloon than in the peripheral veins but showed no visible leakage
of contrast to the left atrium.
Grade 3 occlusion was used when there was a visible point or points of leakage of
contrast from vein to atrium, but the overall flow was so slow that the vein remained
densely opacified by contrast for >5s after injection; the contrast leak had a thread- or
hair-like appearance.
Grade 2 was used when a larger leak was larger but vein opacification still occurred.
Grade 1 was used when the leak was so severe that no opacification of the vein
occurred, just a stream of contrast from the injection point past the balloon to the atrium.
Fig. 2 Flow diagram of the study groups
This diagram shows the patient numbers in the randomized groups of the Achieve or
Lasso mapping catheter, in relation to the Arctic Front Advance or the Arctic Front
Original and the anesthesia mode.
Fig. 3 Comparison of equipment for procedure and fluoroscopy duration
Page 24 of 29
The graphs show procedure duration and fluoroscopic duration are significantly shorter
in the Achieve group by subgroup analysis; the differences are not shown in the whole
study population between mapping catheter groups but are found significant between
cryoballoon groups.
Fig. 4 Comparison of catheters for characteristics of cryotherapy
The balloon temperature reached -20, -30°C and nadir temperature significantly faster
in Arctic Front Advance than the Arctic Front Original (p=0.000, p=0.003, and p=0.001,
respectively). The nadir temperature reached was colder in the Arctic Front Advance
than in the Arctic Front group (Panel B). There were no significant differences between
the Achieve and Lasso groups in any of these characteristics (Panel A).
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Figure 1
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Figure 2
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Figure 3
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A
B
Advance
ArcticFr ont
Temperature (˚C)
Achieve
Lasso
Time (seconds)
Figure 4
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