Comparison of Antero-Lateral Versus Antero-Posterior ElectrodePosition for Biphasic External Cardioversion of Atrial Flutter
F. Sc, Achertz,
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miThducautreatment for atrial flutter is the restoration of sinus rhythm,which can be achieved by the administration of antiarrhyth-mi 9tratieelethadetigthepro(Auseatrgreatris
This was a prospective, randomized, single-center trial to
000doic drugs, overdrive stimulation, catheter ablation, andnsthoracic electrical cardioversion.10 For a defined pa-nt population (e.g., acute symptomatic patients), externalctrical cardioversion is a substantial first-line treatmentt is commonly available. Cardioversion techniques and
vices for different rhythm disorders are clinically inves-ated.1113 Among these, the allocation of the electrodes isfocus of interest. Different electrode positions have beenposed; the anterior-posterior (A-P) and anterior-lateral
-L) electrode positions are the most recommended andd variants.1316 Trials of the electrical cardioversion of
ial fibrillation have shown that the A-P position hasater efficacy than the A-L position.15,16 For commonial flutter, the optimal position for placing the electrodesyet unknown. This prospective trial was designed to
compare the efficacy of the A-P electrode position to that ofthe A-L electrode position in the electrical cardioversion ofcommon atrial flutter. We screened 130 patients in ouroutpatient clinic, emergency room, intensive care unit, orwards. Patients were eligible for the study if, according tocurrent guidelines, the electrical cardioversion of atrial flut-ter was indicated by, for example, imminent cardiac decom-pensation, hypotension, or angina pectoris. Patients wereineligible for this trial if they aged 18 years, pregnant, orplanned for cardioversion of arrhythmias other than com-mon atrial flutter. All patients underwent diagnostic proce-dures and eventual treatment for the prevention of embolicstroke and systemic embolism according to actual guide-lines14 for the management of patients with atrial fibrillationor flutter. After cardioversion, all patients were required tobe anticoagulated for 4 weeks.14 The local ethics com-mittee approved the study, and the study was in compliancewith the Declaration of Helsinki. All patients gave writteninformed consent. The study was registered at ClinicalTrials.gov (protocol record UKE-2383). The hypothesis was that 1of 2 (A-L vs A-P) electrode positions would have greaterefficacy than the other for the cardioversion of atrial flutter.The efficacy of the 2 different electrode positions was theprimary end point. As secondary end points, we defined the
University Hospital Hamburg-Eppendorf, Heart Center, Department ofdiology, Hamburg, Germany. Manuscript received March 23, 2009;ised manuscript received and accepted July 2, 2009.*Corresponding author: Tel: 49-40-74105-4120; fax: 49-40-74105-2967.E-mail address: firstname.lastname@example.org (T. Risius). This study was presented in part at the 28th Annual Scientific Sessionhe Heart Rhythm Society, Denver, Colorado, May 9 to 12, 2007.
2-9149/09/$ see front matter 2009 Elsevier Inc. All rights reserved. www.AJConline.org:10.1016/j.amjcard.2009.07.027Tim Risius, MD*, Kai Mortensen, MD, TjarkHanno U. Klemm, MD, Rodolfo Ventura, MD
Thomas Rostock, MD, Thomas Mein
External cardioversion is an established andatrial flutter. The superiority of the biphasicflutter, but whether electrode position affecttion is not known. The aim of this trial wacompared with anterior-posterior (A-P) electOf 130 screened patients, 96 (72 men, mean agassigned to a cardioversion protocol with egroup, 48 patients received sequential biphasconsisting of 50, 75, 100, 150, or 200 J. The mfor A-P, p 0.001) and mean number of shocp 0.001) required for successful cardioversThe efficacy of the first shock with 50 J in[73%]) was also highly significantly greaterelectrode position (18 of 48 patients [36%])position increases efficacy and requires fewcardioversion of common atrial flutter. Therecommended for the external cardioversionInc. All rights reserved. (Am J Cardiol 2009
Common atrial flutter is a highly prevalent atrial arrhyth-a1,2 caused by trapped excitation in the right atrium.3,4romboembolic stroke57 and uncontrolled ventricular ratee to loss of atrial function are common complications andse morbidity and mortality in affected patients.1,8 Thehwemer, MD, Muhammet A. Aydin, MD,im Barmeyer, MD, Boris Hoffmann, MD,MD, and Stephan Willems, MD
portant tool to terminate symptomaticeform has been demonstrated for atrialfficacy of cardioversion in this popula-evaluate whether anterior-lateral (A-L)position improves cardioversion results.12 years) were included and randomly
A-L or A-P electrode position. In eachveform shocks using a step-up protocolenergy (65 13 J for A-L vs 77 13 J8 1.01 for A-L vs 1.96 1.00 for A-P,ere significantly lower in the A-L group.-L electrode position (35 of 48 patientsthe first shock with 50 J in the A-P
0.001). In conclusion, the A-L electrodeergy and shocks in external electricale, A-L electrode positioning should bemmon atrial flutter. 2009 Elsevier5471550)
termine the efficacy of the different electrode positions ingroup of patients with symptomatic atrial flutter withications for acute electrical cardioversion.
1548 The American Journal of Cardiology (www.AJConline.org)an energy requirement, the mean number of cardiover-n shocks, and cumulative cardioversion efficacy. Directlyfore cardioversion, patients were randomized in a 1:1io to undergo cardioversion in either the A-P or A-Lctrode position by computer-generated randomization.r all cardioversion procedures, a Zoll M-Series deviced Zoll MFE self-adhesive pads (Zoll Medical, Chelms-d, Massachusetts) were used. Patients were sedated withpofol and/or midazolam at the physicians discretion.rdioversion was done under general anesthesia in thestabsorptive state. Successful cardioversion was definedconversion from atrial flutter to sinus rhythm for 30onds.The shock protocol and starting energies were based onfindings of Kerber et al16 and Kerber.17 Patients receiveduential shocks of increasing energy of 50, 75, 100, 150,200 J as necessary for successful cardioversion. A cross-er between electrode positions was planned in case of a
le 1ient characteristics
iable All A-P A-L pValue(n 96) (n 48) (n 48)
e (years) 62 12 62 12 62 13 0.14n 72 (75%) 37 (77%) 35 (73%) 0.63vious cardioversions 15 (16%) 7 (14%) 8 (17%) 0.21ration of atrial flutter
(hours)48 48 (50%) 24 (50%) 24 (50%) 1.0048 48 (50%) 24 (50%) 24 (50%) 1.00
dy mass index (kg/m2) 25 4.7 26 5.0 24 4.3 0.38y surface area (m2) 2 0.2 2 0.2 1.9 0.2 0.38
16 (17%) 8 (17%) 8 (17%) 1.0034 (35%) 17 (35%) 17 (35%) 1.00
I 36 (38%) 19 (40%) 17 (35%) 0.8310 (10%) 4 (8%) 6 (12%) 0.73
edian II II IIpertension 41 (39%) 21 (44%) 20 (42%) 0.83onary artery disease 30 (31%) 11 (23%) 19 (39%) 0.08vular disease 16 (17%) 5 (10%) 11 (23%) 0.17ial septal defect 10 (10%) 3 (6%) 7 (14%) 0.31diomyopathy (dilatative,
ischemic, etc.)5 (5%) 1 (2%) 4 (8%) 0.35
t ventricular functionormal 68 (70%) 36 (75%) 32 (67%) 0.50ild dysfunction 7 (7%) 3 (6%) 4 (8%) 0.69oderate dysfunction 17 (18%) 8 (17%) 9 (19%) 0.78
evere dysfunction 4 (4%) 1 (2%) 3 (6%) 0.29edian Normal Normal Normal
tiarrhythmic drugs atcardioversion
miodarone 12 (12%) 5 (10%) 7 (15%) 0.75lecainide 10 (10%) 5 (10%) 5 (10%) 1.00blockers 23 (24%) 12 (25%) 11 (23%) 0.80
otalol 6 (6%) 1 (2%) 5 (10%) 0.20ata are expressed as mean SEM or as number (percentage). Theree no significant differences in the clinical characteristics between theups.ile shock of 200 J for a final second shock of 200 J withalternative electrode position.
negroAll continuous variables are expressed as mean SD.e primary end point was the efficacy of the differentctrode positions. Differences were compared using Stu-nts t test, the Mann-Whitney U test, and the chi-squaret. Multivariate regression analysis was performed tontify predictors of the need for high energy for successfuldioversion. Statistical significance was accepted at p0.05.SS version 13.0 (SPSS, Inc., Chicago, Illinois) was used
analysis. The sample size was calculated using theample Students t test ( 0.05, 2 sided; 0.2 for
% statistical power) as 90 patients/group. An interim anal-s was planned after the inclusion of 45 patients/group%); statistical significance was accepted at p 0.05.ring interim analysis, 96 patients had already been in-ded in the study. After interim analysis, the study wasmaturely terminated.
One hundred thirty patients were screened for possiblerticipation in this study. Ninety-six patients (72 men,an age 62 12 years) were eligible and gave writtenormed consent for participation in the study. Clinicalaracteristics are listed in Table 1. The 2 groups showed nonificant differences in anthropometric data and underly-cardiac disease (e.g., hypertension or the use of medi-
ions). Table 2 lists the reasons for exclusion from thedy. All 96 patients could be successfully cardioverted tous rhythm. In both the A-P and A-L groups, 2 patients
96 Patientswith common-type Atrial Flutter included
48 Patientscardioverted with
A-P electrode position
48 Patientscardioverted with
A-L electrode position
Success at:50 Joule: 1875 Joule: 19100 Joule: 8150 Joule: 1200 Joule: 2
Success at:50 Joule: 3575 Joule: 9100 Joule: -150 Joule: 2200 Joule: 2
mean energy:77 13 Joule
mean energy:65 13 Joule
Cross-Over:A-P A-L: 1A-L A-P: 1
Figure 1. Course of trial.
le 2sons of exclusion from trial
tory of atrial fibrillation 7emaker or implantable cardioverter-defibrillator 4used consent 10common atrial flutter 7tory of heart surgery 2bility to follow step-up protocol 4al 34eded the maximum energy of 200 J. One patient in eachup needed a crossover to the alternative electrode posi-
1549Arrhythmias and Conduction Disturbances/Electrode Position for Atrial Flutter Cardioversionn. The 2 patients were then successfully cardioverted bys second final shock of 200 J (Figure 1). Cardioversion
ure 2. Cumulative cardioversion efficacy of biphasic shocks showingp) mean energy and (middle) mean number of shocks, as well asttom) number of successfully treated patients with first shock.
ure 3. Efficacy of cumulative cardioversion (CV) in the A-L and A-Pups.s counted as successful for the group to which thetient was switched. No major complications, adverse naents, or major skin irritations were reported in the A-PA-L group.The efficacy of the first shock with 50 J (Figure 2) in theL group (35 of 48 patients [73%]) was highly signifi-tly (p 0.001) greater than in the A-P group (18 of 48%]), with no significant difference (p 0.84) in trans-racic impedance (77 17 for A-L vs 76 15 forP) between groups. The cumulative cardioversion effi-y for the shocks of 50, 75, 100, 150, and 200 J (73%,
%, 92%, 96%, and 100% for A-L; 38%, 77%, 94%, 96%,d 100% for A-P) showed a significant difference only for
2 lowest shock strengths (p 0.001 for 50 J and p 4 for 75 J; Figure 3). There was no significant differenceween groups for the higher shock strengths (p 0.62 for0 J, p 0.81 for 150 J, and p 0.77 for 200 J). Multivariateistic regression showed 3 independent variables predictingcessful cardioversion with high energy levels: body massex 25 kg/m2 (p 0.003), coronary artery disease (p 49), and valvular disease (p 0.004).
scussionIn our study, the A-L electrode position was superior toA-P electrode position. Multiple previous studies havend an advantage of the A-P electrode position11,15,16,18,19the electrical cardioversion of atrial fibrillation. These
dies examined electrode position solely for atrial fibril-ion and lacked a defined step-up protocol. The currentidelines for the treatment of patients with atrial flutter areluded in the guidelines for atrial fibrillation. Atrial fibril-ion requires large amounts of myocardial tissue as astrate, whereas atrial flutter requires only critical aspects
the right atrial isthmus to perpetuate, which may accountthe different successful electrode positions.
The superiority of A-L electrodes might be explained byctroanatomic properties of the human thorax. Modernaging technologies have demonstrated that different elec-de positions alter the spatial distribution of peak currentlivery to myocardial tissue.20 For the A-L electrode po-ion, it was shown that this electrode placement leads to adiac current flow entering at the frontal right atrial wall
d leaving via the inferior vena cava.21 A-L electrodesght produce the peak cardiac current flow into the reentrycuit of typical atrial flutter in the right atrium. In 1981,thout knowing exactly the pathologic mechanism of typ-l atrial flutter,4,5,22 Kerber et al16 found the A-L electrodesition preferable to the A-P position for cardioversion ofial flutter. Earlier studies found increasing success ratesth increasing shock strengths.11,15,16,23,24 High shockengths might have a high rate of complications anduld be avoided.25 Cumulative efficacy at low shock
engths in our study was greater with the A-L electrodesition (Figure 3).No differences were shown for high shock strengths100 J). This might be due to sufficiently high shock fielddients in the anterior portion of the thorax, as described by
rchhof et al.15 Four patients needed high shock strengths of00 J despite using the A-L electrode position and biphasicveform.
26,27From previous studies, high body mass index, coro-ry artery disease,28 and valvular disease29 are known to
1550 The American Journal of Cardiology (www.AJConline.org)uence the success of cardioversion at high energy levels.ltivariate logistic regression of our data found a bodyss index 25 kg/m2, coronary artery disease, and valvu-disease to be independent predictors of the need for high
ergy for successful cardioversion in our study. All 4tients who were successfully cardioverted with high
ck strengths presented with 2 of these predictors. It isportant to note that all patients could successfully bedioverted to sinus rhythm, in contrast to previous studiesth atrial flutter15,16,30,31 or atrial fibrillation,11,15,16,24,30,31hough this might not be generalized to younger patients,the study population had a mean age of 62 years.The physicians and patients could not be blinded to thectrode positions, because only 2 electrodes could beplied per patient at a time for technical reasons. For safetysons, we decided to use self-adhesive patches. Duringr trial, another study11 showed advantages for handheldddles over self-adhesive patches. Using handheld paddlesy have led to even less mean applied energy in the A-L
d A-P electrode positions.
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Comparison of Antero-Lateral Versus Antero-Posterior Electrode Position for Biphasic External Cardioversion of Atrial FlutterMethodsResultsDiscussionReferences