title: Intraoperative Defibrillation Testing of Subcutaneous Implantable Cardioverter-Defibrillator Systems-A Simple Issue?
abstract: BACKGROUND
  The results of the recently published randomized SIMPLE trial question the role of routine intraoperative defibrillation testing. However, testing is still recommended during implantation of the entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) system. To address the question of whether defibrillation testing in S-ICD systems is still necessary, we analyzed the data of a large, standard-of-care prospective single-center S-ICD registry.
  
  
  RESULTS
  In the present study, 102 consecutive patients received an S-ICD for primary (n=50) or secondary prevention (n=52). Defibrillation testing was performed in all except 4 patients. In 74 (75%; 95% CI 0.66-0.83) of 98 patients, ventricular fibrillation was effectively terminated by the first programmed internal shock. In 24 (25%; 95% CI 0.22-0.44) of 98 patients, the first internal shock was ineffective and further internal or external shock deliveries were required. In these patients, programming to reversed shock polarity (n=14) or repositioning of the sensing lead (n=1) or the pulse generator (n=5) led to successful defibrillation. In 4 patients, a safety margin of <10 J was not attained. Nevertheless, in these 4 patients, ventricular arrhythmias were effectively terminated with an internal 80-J shock.
  
  
  CONCLUSIONS
  Although it has been shown that defibrillation testing is not necessary in transvenous ICD systems, it seems particular important for S-ICD systems, because in nearly 25% of the cases the primary intraoperative test was not successful. In most cases, a successful defibrillation could be achieved by changing shock polarity or by optimizing the shock vector caused by the pulse generator or lead repositioning.
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany gerrit.frommeyer@ukmuenster.de.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Frommeyer
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Zumhagen
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Dirk G
authors.initials: DG
authors.lastname: Dechering
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Larbig
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Bettin
authors.affiliation: Division of Cardiac Surgery, Department of Cardiothoracic Surgery, University of Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Löher
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Köbe
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Reinke
authors.affiliation: Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Eckardt
mesh_terms: D000328:Adult; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000295:instrumentation*; D004562:Electrocardiography; D005260:Female; D005858:Germany; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D011322:Primary Prevention / Q000295:instrumentation* / Q000379:methods; D011474:Prosthesis Design; D011475:Prosthesis Failure; D019919:Prosthesis Implantation / Q000295:instrumentation* / Q000379:methods; D012042:Registries; D012189:Retrospective Studies; D055502:Secondary Prevention / Q000295:instrumentation* / Q000379:methods; D014693:Ventricular Fibrillation / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*
keywords: defibrillator testing; device complications; implantable cardioverter‐defibrillator, subcutaneous; sudden cardiac death