1. health and fitness
2. therapy

Europace (2008) 10, 528–535
doi:10.1093/europace/eun072
Dual-chamber defibrillators reduce clinically significant
adverse events compared with single-chamber devices:
results from the DATAS (Dual chamber and Atrial
Tachyarrhythmias Adverse events Study) trial
Jesus Almendral1*, Fernando Arribas2, Christian Wolpert3, Renato Ricci4, Pedro Adragao5,
Erik Cobo6, Xavier Navarro7, and Aurelio Quesada8, the DATAS Steering Committee and Writing
Committee on behalf of the DATAS Investigators
1
Received 8 December 2007; accepted after revision 22 February 2008; online publish-ahead-of-print 7 April 2008
KEYWORDS
Defibrillation;
Tachyarrhythmias;
Pacing
Aims This randomized trial evaluated clinically significant adverse events (CSAEs), in patients implanted
with dual-chamber (DC) vs. single-chamber (SC) implantable cardioverter defibrillator (ICD). DC-ICD had
atrial tachyarrhythmia (AT) therapy capabilities. Strict programming recommendations were reinforced.
Methods and results Patients with conventional SC-ICD indication were randomized to DC-ICD, SC-ICD, or
a DC-ICD programmed as an SC-ICD (SC-simulated) and followed for 16 months. Patients in the DC and SCsimulated groups crossed over after 8 months. The primary endpoint was a composite of CSAE: all-cause
mortality; invasive intervention; hospitalization (.24 h) for cardiovascular causes; inappropriate shocks
(two or more episodes); and sustained symptomatic AT lasting .48 h. The outcome variable was a prespecified score that corrected for clinical severity and follow-up duration. Three hundred and thirtyfour patients were analysed (DC-ICD, n ¼ 112; SC-ICD, n ¼ 111; SC-simulated, n ¼ 111). The mean left
ventricular ejection fraction was 0.36 + 0.13, 69% were in functional class II. CSAE occurred in 65
DC-ICD, 82 SC-ICD, and 84 SC-simulated patients. The outcome variable was 33% lower in the DC-ICD
group (OR 0.31; 95% CI 0.14–0.67; P ¼ 0.0028). Mortality was 4% in DC, 9% in SC, and 10% in SC-simulated.
Conclusion In patients with a standard SC-ICD indication, DC-ICD was associated with less CSAE when compared with SC-ICD.
Introduction
The therapeutic benefits of implantable cardioverter defibrillators (ICDs) have been primarily studied in patients
* Corresponding author: Servicio de Cardiologia (Planta 5), Hospital
Gregorio Maran
˜on, Doctor Esquerdo, 46, 28007 Madrid, Spain. Tel: þ34
915868281; fax: þ34 915868018.
E-mail address: almendral@secardiologia.es
implanted with single-chamber (SC) devices. However, dualchamber (DC)-ICDs provide atrial pacing, atrioventricular
(AV) synchrony, information about the atrial rhythm during
tachycardia, and (some DC-ICD) electrical therapy for
atrial tachyarrhythmias (ATs). On the other hand, DC-ICDs
involve a more complex implant procedure and some of
these features could even be harmful.
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2008.
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Cardiology Department, Hospital General Universitario Gregorio Maranon, Madrid, Spain; 2Cardiology Department, Hospital
Universitario 12 de Octubre, Madrid, Spain; 3Cardiology Department, University Hospital of Mannheim, Mannheim, Germany;
4
Heart Diseases Department, Hospital San Filippo Neri, Roma, Italy; 5Cardiology Department, Hospital Santa Cruz,
Carnaxide, Portugal; 6Estadistica e Investigacion Operativa, Universitat Politecnica de Catalunya, Barcelona, Spain;
7
Scientific and Clinical Department, Medtronic Iberica, Barcelona, Spain; 8Cardiology Department, Hospital General
Universitario de Valencia, Valencia, Spain
Dual- vs. single-chamber ICD: the DATAS trial
When the DATAS Trial started its inclusion phase, in year
2000,1 the information regarding DC-ICD was emerging.2
Two additional concerns were: (a) some laboratory findings,
available at that time, suggested negative effects of right
ventricular (RV) pacing;3 (b) clinical studies had suggested
that the ICD electrode could itself be proarrhythmic, at
least transiently after implantation,4 raising the concern
for some proarrhythmic effect of the atrial electrode.
The DATAS Trial was designed to compare DC-ICD (capable
of electrical therapies for AT) and SC-ICD, the outcome
being clinically significant adverse events (CSAEs).
We hypothesized that both the potential for device-related
complications and the potential to reduce or increase spontaneous deleterious effects of the primary disease process
would translate into relatively simple and clinically measurable consequences, i.e. CSAE. In order to reduce the potentially negative effects of RV pacing and homogenize the
population, strict programming recommendations were
made to reduce RV pacing, with the tools available in the
ICD at that time. Finally, in order to assess the potential
for proarrhythmia (and for a better look at AT in SC
devices), a ‘third arm’ of patients with a DC hardware but
a SC programming was added to the usual parallel design.
The main outcome of the trial is presented here.
Study design, randomization, and data collection
The design of the trial has been published.1 Briefly, DATAS was a
prospective, multicentre, randomized study, with three arms:
SC-ICD, DC-ICD, and a DC-ICD system but programmed as SC-ICD
(‘SC-simulated arm’) (Figure 1). The DC-ICD and SC-simulated
arms crossed over after 8 months (‘programmed crossover’). All
other crossovers were considered ‘premature crossovers’ and had
to be authorized by an independent Adverse Events Advisory Committee (AEAC). In addition, the AEAC analysed all events (masked
as to the patient’s group assignments), classified all adverse
events, and validated primary endpoints. The study complies with
the Declaration of Helsinki. The study protocol was approved by
the IRB at each centre, and informed consent of the subjects was
obtained. The randomization procedure was centralized through a
specifically designed web site. DATAS investigators are listed in
the Appendix.
Follow-up started immediately after randomization. A 1-month
wash out period was implemented after programmed crossover.
Primary endpoint and main outcome
The primary endpoint was a composite of five pre-determined CSAE:
(i) all-cause mortality, (ii) invasive intervention due to cardiovascular cause, (iii) hospitalization (longer than 24 h) or prolongation of
hospitalization due to cardiovascular cause, (iv) inappropriate
shocks: two or more episodes with inappropriate shocks, and (v)
sustained symptomatic ATs that (a) require urgent termination or
(b) lasted more than 48 h leading to therapeutic intervention.
Since this composite endpoint was specifically designed to assess
the global impact of clinically relevant events, a CSAE-score was
created in order to rank clinical severity. Death was obviously the
worst outcome; we assigned a high score to a premature crossover
because it represented a basic failure of the assigned therapy.
Point assignment was as follows: each CSAE: 1 point; death:
maximum number of CSAE points in any individual patient in the
entire study plus one; premature crossover: maximum number of
CSAE points in any individual patient in that study period. Main
outcome was defined as the CSAE-score over length of follow-up,
i.e. CSAE-score rate.
Patient eligibility criteria
Patients were eligible for the study if they met a standard Class I
indication for an SC-ICD according to the 1998 ACC/AHA guidelines
for implantation of cardiac pacemakers and antiarrhythmia
devices. After November 2001, patients as those enrolled in the
MUSTT study5 were also accepted for inclusion. Every patient
eligible for ICD therapy was screened at each centre.
Exclusion criteria were the following: (i) permanent AT;
(ii) absence of structural heart disease; (iii) implantation criteria
for DC pacing: symptomatic sinus node disease, second degree AV
block (except asymptomatic Mobitz I), and complete AV block;
(iv) a previously implanted pacemaker or ICD; (v) mechanical right
heart valve; (vi) any medical condition that would preclude the
testing required by the protocol; (vii) any medical condition that
would limit study participation; (viii) the patient is unwilling or
unable to cooperate or give written informed consent; (ix) legal
guardians (of a minor) refuse to give informed consent; (x) inaccessibility for follow-up at the study centre; (xi) indication for
cardiac resynchronization therapy; (xii) enrolment or planning to
be enrolled in another clinical trial.
Implantable cardioverter defibrillator devices and
programming
All devices were commercially available from Medtronic Inc.
(Minneapolis, MN, USA). The DC devices had automatic atrial
tiered antitachycardia therapies.
There were strong programming recommendations as previously
reported1 and summarized as follows: (i) for all devices, a zone
with antitachycardia pacing for cycle length ,360 ms; (ii) for SC
(or SC-simulated) devices: (a) stability criteria of 50 ms for arrhythmia discrimination; (b) lower pacing rate of 50 bpm or less; (iii) for
DC devices: (a) arrhythmia discrimination via the ‘PR logic’ function; (b) lower pacing rate of 70 bpm, in the DDD mode; (c) paced
AV of 230 ms, sensed AV of 200 ms, or even longer values to
reduce RV pacing; (d) atrial tachycardia detection zone: atrial
cycle length 320 ms; (e) atrial fibrillation detection: atrial cycle
length ,150 ms; (f) tiered therapies for AT (antitachycardia
pacing, 50 Hz, cardioversion).
Statistical analysis
Figure 1 Study design. Flow chart of the three arms of the study.
It should be noted that: (a) the DC group included twice the number
of patients since it pooled together patients from the two crossover
arms (first period of DC/SC-simulated group and second period of
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Methods
529
530
SC-simulated/DC true group) and (b) every patient in the SC group
would be followed for a longer period of time (17 months) than
patients in DC (8 month); (c) in order to make groups as comparable
as possible, a 1-month ‘window’ (absence of adverse events counting) was opened at the 9th month in the SC arm. We accounted for
this disparity in follow-up duration by calculating a CSAE-score rate;
defined as the CSAE-score value divided by months of follow-up. The
intention-to-treat principle was used.
Two statistical analyses were pre-planned before and during the
inclusion phase in the absence of any information about allocated
group. The protocol, as well as the sample size calculation, was
based on the distribution free Mann–Whitney–Wilcoxon statistic.
In order to obtain a more standard effect size measure, an
additional primary analysis was changed to the odds ratio (OR) of
CSAE-score between DC and SC obtained from SAS GENMOD procedure with the length of follow-up as an ‘offset’ variable and
making the assumption of a negative binomial distribution in order
to allow the over-dispersion introduced by the highest values
imputed to deaths. Both statistics would be able to observe a combination of effects both in the reduction of the proportion of
patients with tendency to develop a CSAE, as well as in the mean
of CSAE over all patients.
J. Almendral et al.
Primary endpoint
The absolute number of CSAEs was 65 in the DC group when
compared with 82 in the SC and 84 in the SC-simulated
groups (Figure 3A). The correspondent CSAE-score is
depicted in Figure 3B. The rate of CSAE-score (Figure 3C)
was 33% lower in the DC group, a difference that was statistically significant (P ¼ 0.0028; OR 0.31; 95% CI 0.14–
0.67). The proportion of patients performing better with
DC was also statistically significant (P ¼ 0.030; OR 0.56;
95% CI 0.51–0.62). A secondary sensitivity analysis was performed, including also the 20 patients randomized but not
included in the analysis, showing similar results.
Although the study was not powered to make statistical
comparisons for each of the components of the primary endpoint, these are shown in Table 4 and Figure 4. Of note, total
mortality was similar in SC (9%) and SC-simulated (10%)
groups, but tended to be lower in the DC group (4%).
Discussion
Main findings
Sample size and power for the main analysis
Results
Study population
Patients were enrolled between November 2000 and
December 2003. Figure 2 depicts a flow diagram of patients
entering the trial with a final number of 334 patients for
analysis. Their relevant clinical data are provided in Table 1.
Device implantation and follow-up
Lead- and procedure-related complications are depicted in
Table 2. There were no statistically significant differences
among groups, with a non-significant trend towards a
higher procedure-related complication rate in DC-ICD,
even if considering DC and SC-simulated (identical hardware, see fourth column in Table 2) as a single group [14/
223 (6.3%) vs. 3/111 (2.7%), P ¼ NS].
Of the 334 patients, 12 (3.6%) were lost to follow-up
(Figure 2). The mean follow-up duration was 16 months in
DC, 15.6 in SC, and 15.5 in SC-simulated.
There were no significant differences among groups in the
percentage of patients on each cardioactive medication at
hospital discharge, and at 8- or 17-month follow-up,
except for digoxin at the 8-month follow-up (12% in DC, 3%
in SC-simulated, P ¼ 0.03).
There were 20 premature crossovers during follow-up with
only one of those being in the SC-ICD arm (Table 3, Figure 2).
The percentage of ventricular pacing, obtained from
the device counters at each follow-up visit, is shown in
Table 3.
Primary outcome
Since efficacy for termination of ventricular tachyarrhythmias is expected to be identical in SC and DC devices, but
common sense suggests that DC-ICD may have more complications but also some advantages and risks, we addressed
the question of whether adverse events differ in these two
types of ICD. Some DC-ICDs are also able to sense and
treat AT,6,7 with the ability to potentially improve the
clinical status of patients by reducing AT burden, an
additional element of the study. Not all adverse events
have the same clinical implications, and what finally
matters is the likelihood of those that (whether produced
or reduced by ICD) are clinically relevant, i.e. resulting in
death, an invasive intervention, hospitalization, undesired
shocks, or prolonged ATs (what we have considered as
CSAE). For these reasons, our study focused on CSAE and a
score was developed for further ‘tuning’ by assigning a
‘weight’ to each CSAE.
Several studies have now been published comparing DC
and SC-ICD,8–14 but to the best of our knowledge, this is
the first study with a pooled CSAE as the primary endpoint.
The results of the primary outcome of the DATAS study are,
in this sense, unique, as they show that this outcome variable is better with a DC-ICD than with an SC-ICD device.
Procedure/lead-related complications
The overall incidence of lead- and device-related complications of 9% compares favourably with that of most
recent ICD trials of SC- and DC-ICD that provided a detailed
report of complications.8,10 Most of the complications
resulted in a CSAE, indicating that the parameters selected
for our composite CSAE were sensitive enough to pick up
procedure- and lead-related complications.
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The assumed effect of the DC treatment was a reduction from 30 to
15% in the proportion of patients who develop a CSAE, as well as a
15% reduction in the mean of CSAE (from 6 to 5.1). The estimated
sample size1 was 200 (DC true) vs. 100 (SC true) patients followed
for 8 months, with a two-sided a ¼ 0.05 and a power of 88.8%.
The sample size was set up to 360 patients (120 patients per
arm), considering loses in follow-up.
The main finding of this study is that in a setting where the
excess hardware-related complications of DC devices are
limited and the RV pacing effects are reduced by strict programming, the impact of CSAEs was lower in patients with a
DC-ICD than in patients with an SC-ICD device.
Dual- vs. single-chamber ICD: the DATAS trial
531
Table 1 Patient baseline characteristics
Characteristic
DCa (n ¼ 112)
SC (n ¼ 111)
SC-simulateda (n ¼ 111)
Age in years, mean + SD
Male, n (%)
NYHA functional class 2, N/total (%)
Clinical History, n (%)
Hypertension, n/total (%)
Diabetes, n (%)
Coronary artery disease, n (%)
Cardiomyopathy, n/total (%)
Valvular heart disease, n/total (%)
Indications for ICD therapy, n (%)
VF or cardiac arrest
Sustained VT
Syncopal VT/syncope with inducible VT/VF
Primary prevention
Laboratory findings
LVEF
Bundle branch block, n (%)
66 + 9
92 (82)
77/110 (70)
(n ¼ 112)
54 (48)
20 (18)
98 (87)
46 (41)
11 (10)
63 + 10
100 (90)
77/108 (71)
(n ¼ 111)
55/109 (50)
32 (29)
99 (90)
56/110 (51)
11/110 (10)
62 + 11
90 (81)
70/109 (64)
(n ¼ 110)
64 (58)
28 (25)
88 (80)
51 (46)
19 (17)
31 (28)
46 (41)
19 (17)
16 (14)
41 (37)
42 (38)
16 (14)
12 (11)
47 (42)
37 (33)
16 (14)
11 (10)
34 + 12
24 (21)
35 + 13
26 (23)
39 + 14
33 (30)
DC, dual chamber; ICD, implantable cardioverter defibrillator; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association; SC, single
chamber; VF, ventricular fibrillation; VT, ventricular tachycardia.
a
Refers to original randomization assignment arm to which these patients belonged during the first 8-month follow-up study period.
Ventricular pacing
The issue of the negative effects of RV pacing on ventricular
function facilitating heart failure has been of increasing
interest,15 and this deleterious effect shown to be clinically
relevant in DAVID.9 More recently, subanalyses from randomized clinical trials (RCTs) have described the effect of the
proportion of paced beats on clinical outcome.16–18 In our
study, this effect was not so obvious. The number of heart
failure-related hospitalizations was higher in DAVID than in
DATAS (13.3 and 22.6% in SC and DC, respectively, at 1
year in DAVID, 5 and 8% at 8 months in DATAS). DAVID
selected patients with lower left ventricular ejection fraction (LVEF) (mean LVEF 27% in DAVID and 36% in DATAS) and
had more ventricular pacing (60% in DAVID and 40% in
DATAS).
The recent INTRINSIC RV trial showed if ventricular pacing
is minimized with an algorithm, DC-ICD is not inferior to
SC-ICD.13 Our results, with an intermediate decrease in
%RV pacing producing less deleterious effects, could be
consistent with these findings.
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Figure 2 Summary of patient recruitment and follow-up.
532
J. Almendral et al.
Table 2 Lead- and procedure-related complications
Variable
Lead-related complications
Atrial lead dislodgement (%)
Atrial lead reposition (%)
Ventricular lead dislodgement and reposition (%)
Total (%)
Procedure-related complications
Venous access problem (%)
Pocket infections (%)
Pocket haematoma (%)
Pneumotorax (%)
RV perforation (%)
Total (%)
DC (n ¼ 112)
SC (n ¼ 111)
SC-simulated (n ¼ 111)
1 (0.9)
0
1 (0.9)
2 (1.8)
0
0
4 (3.6)
4 (3.6)
3
1
3
7
(2.7)
(0.9)
(2.7)
(6.3)
4 (1.8)
1 (0.4)
4 (1.8)
9 (4.0)
1
1
2
2
0
6
0
1
1
0
1
3
2
2
1
2
1
8
(1.8)
(1.8)
(0.9)
(1.8)
(0.9)
(7.2)
3 (1.3)
3 (1.3)
3 (1.3)
4 (1.8)
1 (0.4)
14 (6.3)
(0.9)
(0.9)
(1.8)
(1.8)
(5.4)
(0.9)
(0.9)
(0.9)
(2.7)
DC þ SC-simulated (n ¼ 223)
DC, dual chamber; SC, single chamber; RV, right ventricular.
Atrial tachyarrhythmias
Table 3 Follow-up: premature crossover, proportion of
ventricular pacing
DC
(n ¼ 112)
SC
(n ¼ 111)
SC-simulated
(n ¼ 111)
Premature
crossover
Due to
symptoms
Due to venous
access
Due to atrial
lead problems
Unclear reason
Total
Ventricular pacing
Mean % of
paced beats
Median no. of %
paced beats
P with .40%
paced beats (%)
DC!SCsim
SC!DC
SCsim!DC
1
1
9
3
0
0
4
0
0
1
9
0
1
2
11
40 + 35
3+9
6 + 13
30
0
1
42 (43)
2 (2)
1 (1)
Total mortality
DC, dual chamber; SC, single chamber; RV, right ventricular; P,
patients.
Inappropriate shocks
The extent to which DC-ICD devices decrease inappropriate
therapies has been controversial. Some studies found no
benefit of DC devices.8,14 More recently, both in a population with slow VT10 and in a more general population,11
a modest reduction was found. Since frequent ICD shocks
are detrimental for patient’s well-being, in our clinically
focused approach, it was considered that two or more
inappropriate shocks (first inappropriate shock could just
mean a need for reprogramming, then preventing further
inappropriate shocks) represented a significant problem.
Our results point in a similar direction as these recent
studies: it is infrequent to have two or more inappropriate
shocks, but seems to be even more so in patients with
DC-ICD.
Two RCTs reported a non-significant trend towards a higher
mortality in DC-ICD.9,12 A recent RCT,13 including only
patients in whom a DC algorithm minimized ventricular
pacing to ,20%, reported non-inferiority of DC-ICD with a
favourable mortality trend. In DATAS, with a strict but relatively simple programming and no patient exclusion as to the
amount of ventricular pacing, mortality trended similarly.
Moreover, the mortality of the SC-simulated group (10%)
was similar to that of the SC group, showing inherent consistency of our findings. It can be argued that the short
follow-up in DATAS (before crossover) minimizes the deleterious effects of RV pacing. However, an increase in mortality
was an early effect in DAVID.9
In contrast to the other reported RCT, our study included
electrical therapy for AT. ATs in patients with decreased LVEF
are associated with an increase in total mortality, and the
composite of death or hospitalization.20 AT left untreated
could promote ventricular tachyarrhythmias.21 Inappropriate recognition and therapy of AT could even lead to a
vicious life-threatening cycle.22
Limitations
The follow-up might have been too short to reveal differences in heart failure-related hospitalizations and related
mortality, since by the crossover design of DATAS, each DC
patient was not followed for .8 months. However, hospitalizations in the second 8-month period tended to decrease in
all arms.
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Variable
Several reports have substantiated the efficacy of some
DC-ICD to detect and terminate AT.6,7 However, since most
of these ATs lasted only minutes to hours19 and the symptomatic status was largely ignored (device retrieved arrhythmias), their clinical significance is unclear. In contrast, our
study considered AT as part of the primary endpoint only if
the episodes were symptomatic and/or long-lasting requiring therapeutic intervention, thus with undisputable clinical
significance. As such, they were observed in a minority of
patients, but mostly in patients with SC devices.
Dual- vs. single-chamber ICD: the DATAS trial
533
Figure 3 Number, score, and rate of score of clinically significant adverse events. CSAE, clinically significant adverse effects. See text for
details.
Table 4 Clinically significant adverse effects: death, invasive
interventions, hospitalizations, inappropriate shocks,
long-duration AT, each further divided into first and second
follow-up periods, and into individual components
DC
(n ¼ 112)
SC
(n ¼ 111)
SC-simulated
(n ¼ 111)
Death (%)
1st period/2nd
period
Arrhythmic
Heart failure
Other
Invasive
interventions (%)
1st period/2nd
period
Hospitalizations (%)
1st period/2nd
period
Arrhythmia
related (%)
1st period/2nd
period
CHF related (%)
1st period/2nd
period
Device/procedure
related (%)
Other (%)
Inappropriate shocks
(%)
1st period/2nd
period
Long-duration AT (%)
1st period/2nd
period
4 (4)
3/1
10 (9)
7/3
11 (10)
8/3
0
2
2
10 (9)
3
5
2
11 (10)
1
4
6
12 (11)
9/1
6/5
9/3
47 (42)
31/16
42 (38)
31/11
51 (46)
42/9
18 (16)
18 (16)
17 (15)
13/5
16/2
12/5
14 (13)
8/6
6 (5)
5/1
19 (16)
16/3
4 (4)
3 (3)
5 (5)
11 (10)
3 (3)
15 (14)
13 (12)
10 (9)
7 (6)
3/0
13/0
7/0
1 (1)
1/0
6 (5)
4/2
3 (3)
3/0
AT, atrial tachyarrhythmias; CHF, congestive heart failure; DC, dual
chamber; P, patients; SC, single chamber.
It is possible that recently introduced sophisticated algorithms designed to minimize RV pacing could have further
decreased RV pacing.13,23 However, they were introduced
after the enrolment of patients in DATAS.
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Variable
Figure 4 Odds ratio for each individual clinically significant
adverse effect.
Premature crossovers are a limitation of RCT. Despite the
need for AEAC authorization, 10% of the patients
implanted with a DC-ICD hardware crossed over as opposed
to 1% in the SC-ICD. This was likely to have reflected the
ease for ‘software crossover’ once the DC hardware is in
place (in the DC and SC-simulated arms) when compared
with a ‘hardware upgrade’ (in the SC-ICD arm). However,
our scoring system severely penalized the premature crossover, thus correcting for this difference.
Clinical implications
The characteristics of our patient population seem to be
similar to those of other recently published ICD series in
which patients were not selected based on LV function10–12
534
and thus represents an unselected ICD population, with
mean LVEF over 0.30. To this extent, DATAS can be considered representative of the daily clinical ICD practice in
typical European countries.
In this context, the DATAS study demonstrates a reduction
in pooled CSAE with the use of DC-ICD. The study’s conclusions could lead to the development of trials to explore
if CSAE can be reduced even further with algorithms
intended to minimize RV pacing.
Funding
This study was funded in full by Medtronic.
Acknowledgements
This study would not have been possible without Mercedes Ortiz,
from Hospital Gregorio Maran
˜on (Madrid, Spain), our study data
coordinator.
Author contributions: original idea and launching of the study:
Aurelio Quesada. Members of the Steering Committee: Aurelio
Quesada, Jesus Almendral, Fernando Arribas, Christian Wolpert,
Renato Ricci, Pedro Adragao, Xavier Navarro. Statistical design
and analysis: Erik Cobo. Funding to pay the Open Access publication
charges for this article was provided by Medtronic.
www.clinicaltrials.gov Identifier: NCT00157820.
Appendix
DATAS Investigators and study centres:
B. Lu
¨deritz, J. Schwab, T. Lewalter, R. Schimpf, University Hospital, Bonn, Germany; M. Santini, R. Ricci, C. Pignalberi, M. Russo, San
Filippo Neri, Rome, Italy; P. Hanrath, Ch. Stellbrink, K. Mischke,
R. Koos, University Hospital RWTH, Aachen, Germany; J. Brugada,
L. Mont, M. Matas, H. Clinic i Provincial, Barcelona, Spain; J. Gill,
R. Simon, A. Rinaldi, N. Gall, St Thomas’ Hospital, London, UK;
M. Glikson, Sheba Medical Center, Tel-Hashomer, Israel; J. Roda,
S. Villalba, V. Palanca, J. Belchi, H. General Universitario, Valencia,
Spain; C. Muto, M. Canciello, G. Carreras, B. Tuccillo, Loreto Mare
Hospital, Naples, Italy; A. Arenal, E. Gonzalez-Torrecillas,
F. Atienza, H. Gregorio Maran
˜on, Madrid, Spain; M. Borggrefe,
S. Spehl, 1st Department of Medicine Cardiology, University Hospital
Mannheim, Mannheim, Germany; J.L. Merino, R. Peinado, H. La Paz,
Madrid, Spain; J.C. Rodriguez, O. Medina, J. Garcı´a, H. Insular de
Gran Canaria, Las Palmas, Spain; F. Morgado, Santa Cruz, Lisbon,
Portugal; I. Lozano, J. Toquero, R. Arroyo, H. Puerta de Hierro,
Madrid, Spain; J.M. Ormaetxe, M. Arkotxa, H. de Basurto, Bilbao,
Spain; G. Steinbeck, E. Hoffman, S. Janko, U. Dorwarth,
Ludwig-Maximilian-University Hospital, Mu
¨nchen, Germany;
M. Geist, V. Turkisher, Wolfson Medical Center, Holon, Israel;
P. Della Bella, G. Fassini, C. Carbucicchio, F. Giraldi, Centro Cardiologico Monzino, Milano, Italy; P. Golino, M. Viscusi, F. Mascia, Hospedale Civile, Caserta, Italy; L. Tercedor, M. Alvarez, H. Virgen de las
Nieves, Granada, Spain; J.G. Martinez, A. Iban
˜ez, H. General Universitario, Alicante, Spain; A. Moya, E. Rodriguez, C. Alonso,
H. Valle Hebron, Barcelona, Spain; M. Lopez Gil, J. Sanz, H. 12
Octubre, Madrid, Spain; R. Garcia-Civera, R.Ruiz, S. Morell,
R. SanJuan, H. Clinico Universitario, Valencia, Spain;
A. Garcı´a-Alberola, J. Martinez, J.J. Sanchez, H. Virgen de la
Arrixaca, Murcia, Spain; M. Manz, D.Burkhardt, A. Markewitz,
Krankenhaus Marienhof, Koblenz, Germany; E. Castellanos,
L. Rodriguez-Padial, H. Virgen de la Salud, Toledo, Spain;
M. Sassara, A. Achilli, E. Scabbia, Civile Hospital, Viterbo, Italy;
J. Olagu
¨e, J.E. Pareja, M.J. Sancho-Tello, H. La Fe, Valencia,
Spain; S. Hohnloser, G. Gro
¨nefeld, Johann Wolfgang Goethe University, Frankfurt, Germany; T Fuchs, Assaf Harofe Medical Center,
Tzerifin, Israel; W. Jung, N. Schwick, B. Roggenbuck-Schwilk, Klinikum Villingen-Schwenningen, Villingen, Germany; B. Lemke,
T. Lawo, T. Deneke, S. Holt, BG Kliniken Bergmannsheil, Bochum,
Germany; G.Baumann, H. Bondke, M. Claus, Campus Charite
Mitte, Berlin, Germany; A. Maresta, S. Silvani, D. Cornacchia,
E. Tampieri, Civile Hospital, Ravenna, Italy; J.J. Manzano,
A. Medina, E. Caballero, F. Wangu
¨emert, H. General Dr Negrı´n,
Las Palmas, Spain.
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Conflict of interest: J.A. has received honoraria from Medtronic,
Guidant (now Boston Scientific), Johnson & Johnson and St Jude
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Johnson. C.W. has received honoraria from Medtronic and St Jude
Medical for lectures. E.C. is a consultant for Ferrer International
and Medtronic, and receives teaching grants from Instituto de Formacio
´n Novartis. X.N. is an employee of Medtronic. A.Q. is currently
conducting research sponsored by Medtronic and has served as a
paid consultant for Medtronic and Boston Scientific.
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