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Efficacy of a Dual Chamber Defibrillator

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  • Efficacy of a Dual Chamber Defibrillator

    [Efficacy of a Dual Chamber Defibrillator]

    Author: Erica (---.atlnga1.dsl-verizon.net)

    Date: 10-30-02 19:53

    European Heart Journal

    September 2002 (Volume 23, Number 18)

    Efficacy of a Dual Chamber Defibrillator With Atrial Antitachycardia Functions in Treating Spontaneous Atrial Tachyarrhythmias in Patients With Life-Threatening Ventricular Tachyarrhythmias

    Ricci R, Pignalberi C, Disertori M, et al.

    European Heart Journal. 2002;23(18):1471

    Atrial tachycardias, including atrial fibrillation (AF), are common in patients suffering from ventricular arrhythmias. AF has been associated with problems in such patients: It can lead to inappropriate ventricular shocks in patients treated with an implantable cardioverter defibrillator (ICD), and it has been clearly identified as an indicator of poor prognosis, placing patients at risk for thromboembolic events and other complications. As a result, interest has been raised in the possibility of using dual-chamber implantable defibrillators to treat patients with ventricular arrhythmias and AF.

    The authors of this study examined data from 112 patients (88 male) implanted with a new dual-chamber defibrillator with atrial antitachycardia functions (Medtronic model 7250). This device incorporates a dual chamber detection algorithm to discriminate between atrial and ventricular tachyarrhythmias. Atrial therapies include high frequency burst, ramp pacing (50Hz), and atrial cardioversion.

    Of these patients, 76 had ischemic heart disease, and the mean ejection fraction was 40%. AF was documented prior to implantation in 55% of cases. Patients were followed at 1 month and every 3 months thereafter. Stored electrograms and event markers from the device were used to assess therapy appropriateness and efficacy. Patients were followed for a mean of 11 months.

    Results

    Two patients required explantation: one for system infection and the other for cardiac transplantation. There were 933 ventricular tachyarrhythmia episodes, and cardioversion was successful in all of the ventricular fibrillation and 92% of the ventricular tachycardia episodes. There were 414 episodes of sustained atrial tachyarrhythmias detected with a positive predictive value of 93.5%, a specificity of 91.2%, and a sensitivity of 100%. Inappropriate detection was due to far-field R wave oversensing.

    Antitachy pacing for atrial tachycardia was 71.3% effective, 50 Hertz pacing for AF was 36.2% effective, and atrial cardioversion was 62.5% effective (crude estimates). Patients tolerated shock better when they received a single effective cardioverting shock than when they received multiple ineffective shocks. There was no circadian variation in the episodes of atrial tachyarrhythmias.

    Editor's Comments

    Prior studies have shown that approximately 25% of patients who need an ICD for ventricular arrhythmias have documented atrial arrhythmias prior to implantation, and this study confirmed their relatively common occurrence.

    In a finding also reported by others, inappropriate detection was found to be due to far-field R wave oversensing. Careful selection of atrial lead site during implantation and individual programming of the atrial sensitivity of the device are required to reduce or prevent this problem. It was interesting to note the partial success of 50 Hz pacing for AF. It is possible that at the beginning of many episodes, the AF may be partially organized and susceptible to pacing. In a randomized crossover trial, Friedman[1] showed an 87% reduction in AF burden using a dual-chamber ICD.

    Overall, the results suggest that the electrophysiologist should consider implanting a dual-chamber ICD in patients who have or are likely to develop atrial arrhythmias.

    Reference

    Friedman PA, Dijkman B, Warman EN, et al. Atrial therapies reduce atrial arrhythmia burden in defibrillator patients. Circulation. 2001;104:1023-1028. Abstract.

    Abstract

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    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Heather I (65.247.157.---)

    Date: 10-31-02 10:18

    Thanks for posting this article Erica. I have copied it and am going to take it to my upcoming appt. at the Mayo.

    Heather

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Lisa Salberg (208.47.172.---)

    Date: 10-31-02 13:32

    HOLD on here guys.. THIS IS NOT AN HCM study in fact these patients are likley to have DCM and it is only for those with AF on top of that.

    DO not run to the doc asking for these devices based on this study... WHile it may have application for those with HCM at some point... that is not the intention of this paper.

    Lisa

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Erica (---.biz.dsl.gtei.net)

    Date: 10-31-02 13:41

    Oh ... what is DCM?

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Lisa Salberg (208.47.172.---)

    Date: 10-31-02 14:06

    Dilated cardiomyopathy - or other forms of heart failure this is where you would see a loss of ejection fraction '...Of these patients, 76 had ischemic heart disease, and the mean ejection fraction was 40%...'

    Those with HCM tend to have normal or high EF's.

    Atrial Defib's hold promise for the future but many many questions need to be answered first.

    Lisa

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Erica (---.biz.dsl.gtei.net)

    Date: 10-31-02 14:10

    Thanks for the heads up and informative reply! It's almost the weekend once again!

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Board Moderator (Sarah Beckley (---.client.attbi.com)

    Date: 11-01-02 13:38

    FYI: a few facts ---atrial fib occurs in approximately 20% of HCM patients. Pacing for HCMers with afib is usually contraindicated. Afib can be caused by many other things and DCM is unrelated to HCM.

    So whenever you see a new "cure" or "fix" for atrial fibrillation, it usually means for everyone but US!

    Sarah

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Janis (---.proxy.aol.com)

    Date: 11-03-02 15:17

    Erica,

    Please give me your e-mail address. I would like to talk with you about your father.Thanks. Janis Grant

    Threegrands @ aol.com

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    [Re: Efficacy of a Dual Chamber Defibrillator]

    Author: Erica (---.atlnga1.dsl-verizon.net)

    Date: 11-03-02 21:47

    Hi Janis! My mother's name is the same as yours ... but she spells is Janice!

    I look forward to hearing from you soon!

    Best regards,

    Erica Stolzenberg

    [email protected]
    NOTE: This is a post from the previous forum message board.
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