title: Sensitivity and specificity of the subcutaneous implantable cardioverter defibrillator pre-implant screening tool.
abstract: BACKGROUND
  The sensitivity and specificity of the subcutaneous implantable cardioverter defibrillator (S-ICD) pre-implant screening tool required clinical evaluation.
  
  
  METHODS
  Bipolar vectors were derived from electrodes positioned at locations similar to those employed for S-ICD sensing and pre-implant screening electrodes, and recordings collected through 80-electrode PRIME®-ECGs, in six different postures, from 40 subjects (10 healthy controls, and 30 patients with complex congenital heart disease (CCHD); 10 with Tetralogy of Fallot (TOF), 10 with single ventricle physiology (SVP), and 10 with transposition of great arteries (TGA)). The resulting vectors were analysed using the S-ICD pre-implant screening tool (Boston Scientific) and processed through the sensing algorithm of S-ICD (Boston Scientific). The data were then evaluated using 2 × 2 contingency tables. Fisher exact and McNemar tests were used for a comparison of the different categories of CCHD, and p < 0.05 vs. controls considered to be statistically significant.
  
  
  RESULTS
  57% of patients were male, mean age of 36.3 years. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the S-ICD screening tool were 95%, 79%, 59% and 98%, respectively, for controls, and 84%, 79%, 76% and 86%, respectively, in patients with CCHD (p = 0.0001).
  
  
  CONCLUSIONS
  The S-ICD screening tool was comparatively more sensitive in normal controls but less specific in both CCHD patients and controls; a possible explanation for the reported high incidence of inappropriate S-ICD shocks. Thus, we propose a pre-implant screening device using the S-ICD sensing algorithm to minimise false exclusion and selection, and hence minimise potentially inappropriate shocks.
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospitals NHS Trust, United Kingdom; Faculty of Medicine University of Southampton, United Kingdom. Electronic address: mehmoodzeb@hotmail.com.
authors.forename: Mehmood
authors.initials: M
authors.lastname: Zeb
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospitals NHS Trust, United Kingdom; Faculty of Medicine University of Southampton, United Kingdom.
authors.forename: Nick
authors.initials: N
authors.lastname: Curzen
authors.affiliation: Boston Scientific, United Kingdom.
authors.forename: Venugopal
authors.initials: V
authors.lastname: Allavatam
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospitals NHS Trust, United Kingdom; Boston Scientific, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Wilson
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospitals NHS Trust, United Kingdom.
authors.forename: Arthur
authors.initials: A
authors.lastname: Yue
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospitals NHS Trust, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Roberts
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospitals NHS Trust, United Kingdom; Faculty of Medicine University of Southampton, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Morgan
mesh_terms: D000328:Adult; D000465:Algorithms; D018780:Body Surface Potential Mapping / Q000379:methods; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004554:Electric Countershock / Q000295:instrumentation / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006330:Heart Defects, Congenital / Q000145:classification / Q000150:complications*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D018579:Patient Selection; D011183:Postoperative Complications / Q000517:prevention & control*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D019919:Prosthesis Implantation / Q000009:adverse effects / Q000379:methods; D012680:Sensitivity and Specificity; D006113:United Kingdom
keywords: Congenital heart disease; Sensing algorithm; Subcutaneous implantable cardioverter; Sudden cardiac death