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A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Subcutaneous or Transvenous Defibrillator Therapy
Reinoud E Knops1, Louise R A Olde Nordkamp1, Peter-Paul H M Delnoy1
1From the Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, University of Amsterdam (R.E.K., L.R.A.O.N., L.V.A.B., T.F.B., A.-F.B.E.Q., L.S., W.S., A.W., K.C.W., J.R.G., K.M.K., M.C.B., J.G.P.T., A.A.M.W.), ERN GUARD-Heart (E.R.B., P.D.L., A.A.M.W.), and the Department of Cardiology, OLVG (J.S.S.G.J.), Amsterdam, the Department of Cardiology, Isala Heart Centre, Zwolle (P.-P.H.M.D.), the Department of Cardiology, St. Antonius Hospital, Nieuwegein (L.V.A.B.), the Department of Cardiology, Flevoziekenhuis, Almere (N.R.B.), the Department of Cardiology, Radboud University Medical Center, Nijmegen (M.A.B.), the Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht (K.V.), the Department of Cardiology, Amphia Hospital, Breda (M.A.), Werkgroep Cardiologische Centra Nederland, Utrecht (M.A.), and the Department of Electrophysiology, Catharina Hospital, Eindhoven (F.A.L.E.B.) - all in the Netherlands; the First Department of Medicine-Cardiology, University Medical Center Mannheim, and the German Center for Cardiovascular Research Partner Site Heidelberg-Mannheim, Mannheim (J.K.), Klinik für Innere Medizin III, Schwerpunkt Kardiologie und Angiologie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel (H.B.), the Department of Medicine I, Ludwig-Maximilians University Hospital, and the German Center for Cardiovascular Research, Munich Heart Alliance, Munich (S.K.), and the Department of Electrophysiology, Heart Center at University of Leipzig, Leipzig (S.R.) - all in Germany; the Division of Cardiology Section of Electrophysiology, Emory University, Atlanta (M.F.E.-C.); the Cardiology Clinical Academic Group, St. George's, University of London and St. George's University Hospitals NHS Foundation Trust London (E.R.B.), and Office of the Director of Clinical Electrophysiology Research and Lead for Inherited Arrhythmia Specialist Services, University College London and Barts Heart Centre (P.D.L.), London, the Oxford Biomedical Research Centre, Oxford University Hospitals NHS Trust, Oxford (T.R.B.), and Liverpool Heart and Chest Hospital, Liverpool (D.J.W.) - all in the United Kingdom; Valley Health System, Ridgewood, NJ (S.M.); the Department of Cardiology, Homolka Hospital, Prague, Czech Republic (P.N.); and CorVita Science Foundation, Chicago (M.C.B.).
Background:
The subcutaneous implantable cardioverter-defibrillator (ICD) was designed to avoid complications related to the transvenous ICD lead by using an entirely extrathoracic placement. Evidence comparing these systems has been based primarily on observational studies.
Methods:
We conducted a noninferiority trial in which patients with an indication for an ICD but no indication for pacing were assigned to receive a subcutaneous ICD or transvenous ICD. The primary end point was the composite of device-related complications and inappropriate shocks; the noninferiority margin for the upper boundary of the 95% confidence interval for the hazard ratio (subcutaneous ICD vs. transvenous ICD) was 1.45. A superiority analysis was prespecified if noninferiority was established. Secondary end points included death and appropriate shocks.
Results:
A total of 849 patients (426 in the subcutaneous ICD group and 423 in the transvenous ICD group) were included in the analyses. At a median follow-up of 49.1 months, a primary end-point event occurred in 68 patients in the subcutaneous ICD group and in 68 patients in the transvenous ICD group (48-month Kaplan-Meier estimated cumulative incidence, 15.1% and 15.7%, respectively; hazard ratio, 0.99; 95% confidence interval [CI], 0.71 to 1.39; P = 0.01 for noninferiority; P = 0.95 for superiority). Device-related complications occurred in 31 patients in the subcutaneous ICD group and in 44 in the transvenous ICD group (hazard ratio, 0.69; 95% CI, 0.44 to 1.09); inappropriate shocks occurred in 41 and 29 patients, respectively (hazard ratio, 1.43; 95% CI, 0.89 to 2.30). Death occurred in 83 patients in the subcutaneous ICD group and in 68 in the transvenous ICD group (hazard ratio, 1.23; 95% CI, 0.89 to 1.70); appropriate shocks occurred in 83 and 57 patients, respectively (hazard ratio, 1.52; 95% CI, 1.08 to 2.12).
Conclusions:
In patients with an indication for an ICD but no indication for pacing, the subcutaneous ICD was noninferior to the transvenous ICD with respect to device-related complications and inappropriate shocks. (Funded by Boston Scientific; PRAETORIAN ClinicalTrials.gov number, NCT01296022.).
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