title: Safety, efficacy, and performance of new discrimination algorithms to reduce inappropriate and unnecessary shocks: the PainFree SST clinical study design.
abstract: BACKGROUND
  Implantable cardioverter defibrillator (ICD) shock therapy improves survival of patients at risk for sudden cardiac death. The high sensitivity of ICDs to detect tachycardia events is accompanied by reduced specificity resulting in inappropriate and unnecessary shocks. Up to 30% of ICD patients may experience inappropriate shocks, which are most commonly caused by lead noise, oversensing of T-waves, and supraventricular tachycardias. The new Protecta ICD and cardiac resynchronization therapy devices have been designed to minimize inappropriate and unnecessary shocks through novel SmartShock(TM) technology algorithms targeting these causes.
  
  
  METHODS
  The PainFree SST study is a prospective, multicentre clinical trial, which will be conducted in two consecutive phases. Phase I will assess safety and any delay that may arise in ventricular fibrillation (VF) arrhythmia detection time using new algorithms. Phase II will evaluate reduction of inappropriate and unnecessary shocks at 1 year of follow-up. Additional objectives will include Quality of Life, healthcare utilization, safety of extending the ventricular tachyarrhythmia/VF interval detection duration (18 out of 24 vs. 30 out of 40 intervals), and reasons for inappropriate shock. Up to 2000 subjects in 150 centres worldwide will be enrolled with a follow-up of at least 1 year. Subjects enrolled in Phase I will continue in Phase II of the study and data from all enrolled subjects will contribute to the analysis of Phase II objectives.
  
  
  CONCLUSIONS
  Inappropriate and unnecessary shock delivery remains a significant clinical issue for patients receiving device therapies, which has considerable consequences for patients and the healthcare system. The PainFree SST study will investigate the ability of new algorithms to reduce inappropriate shocks. Results from this study are expected in mid-2013.
authors.affiliation: Division of Cardiology, Fondazione Cardiocentro Ticino, Via Tesserete 48, CH-6900 Lugano, Switzerland. angelo.auricchio@cardiocentro.org
authors.forename: Angelo
authors.initials: A
authors.lastname: Auricchio
authors.forename: Albert
authors.initials: A
authors.lastname: Meijer
authors.forename: Takashi
authors.initials: T
authors.lastname: Kurita
authors.forename: Edward
authors.initials: E
authors.lastname: Schloss
authors.forename: Karin
authors.initials: K
authors.lastname: Brinkman
authors.forename: Marieke
authors.initials: M
authors.lastname: Claessens-van Ooijen
authors.forename: Laurence
authors.initials: L
authors.lastname: Sterns
mesh_terms: D000465:Algorithms; D058409:Cardiac Resynchronization Therapy Devices / Q000009:adverse effects*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004869:Equipment Safety; D006801:Humans; D007391:International Cooperation; D011446:Prospective Studies; D012107:Research Design; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000628:therapy*