RT-191
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Initial experience with the
implantable atrial defibrillator
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Werner Jung, Christian Wolpert,
Susanne Herwig, Susanne Spehl, Bahman Esmailzadeh*, Christian Schneider*, Heyder Omran,
Paul G. Kirchhoff*, Berndt Lüderitz.
Departments of Medicine-Cardiology and *Cardiovascular Surgery, University of
Bonn, Bonn, Germany
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Abstract
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The frequency of atrial fibrillation and its economic
impact on the health care system ensure that atrial fibrillation will be a focus for
future research. Internal atrial defibrillation has been evaluated as an alternative
approach to the external technique for over two decades. Previous studies in animals and
humans have shown that internal atrial defibrillation is feasible with relatively low
energies. The promising results achieved with internal atrial defibrillation have
facilitated the development of an implantable atrial defibrillator. For any new therapy,
it is imperative to demonstrate safety, efficacy, tolerability with improvement in quality
of life, and cost-effectiveness compared to already available therapeutic options. Most
importantly, the efficacy and safety rates with a new therapy should be better or at least
as good than those observed with previously available means. Maintenance of sinus rhythm
or prolonged duration in arrhythmia free intervals should be clearly demonstrated with an
implantable atrial defibrillator. Initial clinical experience with the MetrixTM
system indicates stable atrial defibrillation thresholds, appropriate R wave
synchronization markers, no shock induced ventricular proarrhythmia, and excellent
detection of atrial fibrillation with a specificity of 100%. Ventricular proarrhythmia has
not been reported for correctly R-wave synchronized low energy shocks when closely coupled
to RR intervals and long-short cycles are avoided.
Conclusions. The preliminary experience with the MetrixTM system
suggests that the implantable atrial defibrillator may offer a therapeutic alternative for
a subgroup of patients with drug refractory, symptomatic, long lasting, and infrequent
episodes of atrial fibrillation. Further efforts must be undertaken to reduce the patient
discomfort associated with internal atrial defibrillation in an attempt to make this new
therapy acceptable to a larger patient population with atrial fibrillation. Finally,
cost-effectiveness and quality of life analyses comparing an implantable atrial
defibrillator with alternative therapeutic approaches will be needed.
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Key Words
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Atrial fibrillation
refractory AF, chronic AF, implantable atrial defibrillator, discomfort, safety, efficacy,
tolerability, proarrhythmia, Metrix multicenter clinical trial, Framingham study, OA
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