title: Long-Term Stability and Clinical Utility of Amplified Atrial Electrograms in a Single-Lead ICD System with Floating Atrial Electrodes.
abstract: BACKGROUND
  Available atrial electrograms in implantable cardioverter defibrillators (ICDs) improve arrhythmia diagnosis, allow monitoring for atrial fibrillation, and may reduce the risk of inappropriate therapies. A recently introduced ICD system using a single-lead with floating atrial electrodes provides diagnostic capability of a dual-chamber system without placing an additional lead. Data on long-term clinical performance of this system are limited.
  
  
  METHODS
  We retrospectively analyzed data from 35 consecutive patients implanted with Biotronik VR-T DX devices and LinoxSmartDX leads. (Biotronik, SE & Co., Berlin, Germany) RESULTS: Of 35 patients (77% male, age 52 ± 11.28 years), 32 were followed for a mean of 432 ± 197 days (range 56-765). During implantation, average preamplified and amplified sinus P-wave amplitudes were 2.61 ± 1.39 mV (range 0.9-6.8 mV) and 8.7 ± 4.51 mV (range 1.4-18 mV), respectively. Despite statistically significant variations, the amplified P-wave amplitude measurements (calculated mean values over 3 months) remained within a clinically acceptable range during follow-up (5.4-8.7 mV). R-wave amplitude and ventricular pacing threshold measurements were stable over time. A total of 13 stored arrhythmia events (three ventricular tachycardia, eight supraventricular tachycardia, two atrial fibrillation) were reviewed. All of them showed readily interpretable atrial electrograms. Eight out of 10 (80%) supraventricular events were correctly classified by the device. Three patients received inappropriate ICD therapies.
  
  
  CONCLUSIONS
  The single-lead ICD system using a floating atrial dipole provides reliable recording of atrial signals during sinus rhythm and arrhythmias. Our data suggest that the system may offer diagnostic advantages of a dual-chamber device without potential risks of an additional atrial lead.
authors: Division of Cardiovascular Medicine, University of Iowa Hospitals and Clinics, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors: Nicole E
authors: NE
authors: Worden
authors: Division of Cardiovascular Medicine, University of Iowa Hospitals and Clinics, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors: Musab
authors: M
authors: Alqasrawi
authors: Division of Cardiovascular Medicine, University of Iowa Hospitals and Clinics, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors: Alexander
authors: A
authors: Mazur
mesh_terms: D000669:Amplifiers, Electronic; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000517:prevention & control*; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004567:Electrodes, Implanted; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
keywords: Biotronik; DX ICD system; atrial sensing; floating atrial electrodes; implantable cardioverter defibrillator