title: Specific considerations with the automatic implantable atrial defibrillator.
abstract: BACKGROUND
  Internal atrial defibrillation has been evaluated as an alternative approach to the external technique for more than 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 (IAD).
  
  
  RESULTS
  For any new therapy, it is imperative to demonstrate safety, efficacy, tolerability with improvement in quality of life, and cost-effectiveness compared with therapeutic options already available. Maintenance of sinus rhythm or prolonged duration in arrhythmia-free intervals should be demonstrated clearly with an IAD. Initial clinical experience with the Metrix system indicates stable atrial defibrillation thresholds, appropriate R wave synchronization markers, no shock-induced ventricular proarrhythmia, and excellent detection of atrial fibrillation (AF) 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
  Preliminary experience with the Metrix system suggests that the IAD may offer a therapeutic alternative for a subgroup of patients with drug-refractory, symptomatic, long-lasting, and infrequent episodes of AF. 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 AF.
authors.affiliation: Department of Medicine-Cardiology, University of Bonn, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Jung
authors.forename: C
authors.initials: C
authors.lastname: Wolpert
authors.forename: B
authors.initials: B
authors.lastname: Esmailzadeh
authors.forename: S
authors.initials: S
authors.lastname: Spehl
authors.forename: S
authors.initials: S
authors.lastname: Herwig
authors.forename: B
authors.initials: B
authors.lastname: Schumacher
authors.forename: T
authors.initials: T
authors.lastname: Lewalter
authors.forename: H
authors.initials: H
authors.lastname: Omran
authors.forename: P G
authors.initials: PG
authors.lastname: Kirchhoff
authors.forename: B
authors.initials: B
authors.lastname: Lüderitz
mesh_terms: D000465:Algorithms; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D003362:Cost-Benefit Analysis; D017147:Defibrillators, Implantable / Q000009:adverse effects / Q000191:economics; D004554:Electric Countershock / Q000009:adverse effects / Q000191:economics; D004562:Electrocardiography / Q000706:statistics & numerical data; D006801:Humans; D011788:Quality of Life; D011859:Radiography