title: Inappropriate subcutaneous implantable cardioverter-defibrillator shocks due to T-wave oversensing can be prevented: implications for management.
abstract: BACKGROUND
  Inappropriate shocks (IASs) complicate implantable cardioverter-defibrillator (ICD) therapy. The management of IASs in patients with a subcutaneous ICD (S-ICD) differs from that in patients with a conventional ICD because of different sensing algorithms and programming options.
  
  
  OBJECTIVE
  To describe the management of IASs in patients with an S-ICD.
  
  
  METHODS
  Patients were implanted with an S-ICD between February 2009 and July 2012. The prevalence data and clinical determinants of IASs were prospectively collected. In the case of T-wave oversensing (TWOS), an exercise test was performed, and all possible sensing vectors were screened for TWOS. The absence of TWOS defined a suitable vector.
  
  
  RESULTS
  Eleven of 69 patients (54% men; mean age 39 ± 14 years; 73% primary prevention) received IASs after 8.9 ± 10 months of implantation (10.8% annual incidence rate). In 8 cases, TWOS caused IASs. Seven of these IASs occurred during exercise and 1 during atrial fibrillation with a high ventricular rate. To manage TWOS, in 7 of 8 patients the sensing vector was changed and in 5 of 8 patients the (un)conditional zone was changed. Hereafter, IASs recurred in 3 of 8 patients, in 2 because of programming errors. Hence, after reprogramming, we observed no IASs in 87.5% of the patients with TWOS during a follow-up of 14.1 ± 13 months.
  
  
  CONCLUSIONS
  IASs due to TWOS in the S-ICD can be managed by reprogramming the sensing vector and/or the therapy zones of the device using a template acquired during exercise. Exercise-optimized programming can reduce future IASs, and standard exercise testing shortly after the implantation of an S-ICD may be considered in patients at an increased risk for TWOS.
authors: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors: Kirsten M
authors: KM
authors: Kooiman
authors: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors: Reinoud E
authors: RE
authors: Knops
authors: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors: Louise
authors: L
authors: Olde Nordkamp
authors: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
authors: Arthur A M
authors: AA
authors: Wilde
authors: Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands. Electronic address: j.r.degroot@amc.uva.nl.
authors: Joris R
authors: JR
authors: de Groot
mesh_terms: D000328:Adult; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000628:therapy*; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects* / Q000295:instrumentation*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012307:Risk Factors
keywords: ICD programming; ICD sensing; Implantable cardioverter-defibrillator; Inappropriate shocks; Subcutaneous ICD; T-wave oversensing