title: Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study.
abstract: OBJECTIVE
  Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker.
  
  
  RESULTS
  Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms.
  
  
  CONCLUSIONS
  Early assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial.
  
  
  BACKGROUND
  ClinicalTrials.gov ID NCT02004873.
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université Bordeaux, IHU LIRYC, Bordeaux, France ritterph@free.fr.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ritter
authors.affiliation: Clinical Electrophysiology Department of Cardiology, Medical Centre, Hungarian Defence Forces, Budapest, Hungary.
authors.forename: Gabor Z
authors.initials: GZ
authors.lastname: Duray
authors.affiliation: Department of Cardiology, Linz General Hospital, Johannes Kepler University School of Medicine Linz, Linz, Austria.
authors.forename: Clemens
authors.initials: C
authors.lastname: Steinwender
authors.affiliation: Department of Cardiology, Kyorin University Hospital, Tokyo, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Soejima
authors.affiliation: Electrophysiology and Pacing Unit, National Heart Institute, Kuala Lumpur, Malaysia.
authors.forename: Razali
authors.initials: R
authors.lastname: Omar
authors.affiliation: Hospital Clínic, Universitat de Barcelona, Catalonia, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Mont
authors.affiliation: St Antonius Ziekenhuis, Nieuwegein, the Netherlands.
authors.forename: Lucas V A
authors.initials: LV
authors.lastname: Boersma
authors.affiliation: Academisch Medisch Centrum (AMC), Amsterdam, the Netherlands.
authors.forename: Reinoud E
authors.initials: RE
authors.lastname: Knops
authors.affiliation: New York University, New York, NY, USA.
authors.forename: Larry
authors.initials: L
authors.lastname: Chinitz
authors.affiliation: State Key Laboratory of Cardiovascular Disease Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Division of Electrophysiology, Department of Cardiology, CARE Hospitals and CARE Foundation, Hyderabad, India.
authors.forename: Calambur
authors.initials: C
authors.lastname: Narasimhan
authors.affiliation: The Ohio State University, Columbus, OH, USA.
authors.forename: John
authors.initials: J
authors.lastname: Hummel
authors.affiliation: Emory University Hospital, Atlanta, GA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Lloyd
authors.affiliation: Catharina Ziekenhuis, Eindhoven, the Netherlands.
authors.forename: Timothy Alexander
authors.initials: TA
authors.lastname: Simmers
authors.affiliation: University of Pittsburgh Medical Center UPMC Presbyterian, Pittsburgh, PA, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Voigt
authors.affiliation: Medtronic plc, Mounds View, MN, USA.
authors.forename: Verla
authors.initials: V
authors.lastname: Laager
authors.affiliation: Medtronic plc, Mounds View, MN, USA.
authors.forename: Kurt
authors.initials: K
authors.lastname: Stromberg
authors.affiliation: Medtronic plc, Mounds View, MN, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Bonner
authors.affiliation: Medtronic plc, Mounds View, MN, USA.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Sheldon
authors.affiliation: Cardiovascular Section, University of Oklahoma Health Sciences Center, OU Medical Center, Oklahoma City, OK, USA.
authors.forename: Dwight
authors.initials: D
authors.lastname: Reynolds
mesh_terms: D000368:Aged; D054537:Atrioventricular Block / Q000628:therapy*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008839:Microelectrodes; D061646:Operative Time; D010138:Pacemaker, Artificial; D061214:Patient Safety; D011446:Prospective Studies; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods; D012804:Sick Sinus Syndrome / Q000628:therapy*; D016896:Treatment Outcome
keywords: Leadless cardiac pacemaker; Miniaturization; Transcatheter pacing system