title: Use of an intracardiac electrogram eliminates the need for a surface ECG during implantable cardioverter-defibrillator follow-up.
abstract: BACKGROUND
  A surface electrocardiogram (SECG) for pacing threshold measurements during routine implantable cardioverter-defibrillator (ICD) follow-up can be cumbersome. This study evaluated the use of an intrathoracic far-field electrogram (EGM) derived between the Can and superior vena cava (SVC) electrode -- the Leadless electrocardiogram (LLECG), in dual chamber ICDs in performing pacing threshold tests.
  
  
  METHODS
  The LLECG was evaluated prospectively during atrial and ventricular pacing threshold testing as a substudy of the Comparison of Empiric to Physician-Tailored Programming of Implantable Cardioverter-Defibrillators trial (EMPIRIC) in which dual chamber ICDs were implanted in 888 patients. Threshold tests were conducted at 1 volt by decrementing the pulse width. Follow-up at three months compared pacing thresholds measured using LLECG with those using Lead I of the surface ECG (SECG). The timesaving afforded by LLECG was assessed by a questionnaire.
  
  
  RESULTS
  The median threshold difference between LLECG and SECG measurements for both atrial (0.00 ms, P = 0.90) and ventricular (0.00 ms, P = 0.34) threshold tests were not significant. Ninety percent of atrial and ventricular threshold differences were bounded by +/- 0.10 ms and -0.10 to +0.04 ms, respectively. We found that 99% of atrial and ventricular thresholds tests at six and 12 months attempted using LLECG were successfully completed. The questionnaire indicated that 65% of healthcare professionals found LLECG to afford at least some timesaving during device follow-ups.
  
  
  CONCLUSIONS
  Routine follow-up can be performed reliably and expeditiously in dual chamber Medtronic (Minneapolis, MN, USA) ICDs using LLECG alone, resulting in overall timesaving.
authors: Wessex Cardiothoracic Centre, Southampton University Hospital Trusts, Southampton, UK.
authors: Kevin A
authors: KA
authors: Michael
authors: Brett J
authors: BJ
authors: Peterson
authors: Arthur M
authors: AM
authors: Yue
authors: Ryan D
authors: RD
authors: Wilson
authors: Li
authors: L
authors: Wang
authors: Kevin
authors: K
authors: Ousdigian
authors: Bruce
authors: B
authors: Wilkoff
authors: Laurence
authors: L
authors: Sterns
authors: John M
authors: JM
authors: Morgan
mesh_terms: D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000628:therapy*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies