title: Clinical safety of the Iforia implantable cardioverter-defibrillator system in patients subjected to thoracic spine and cardiac 1.5-T magnetic resonance imaging scanning conditions.
abstract: BACKGROUND
  Implantable cardioverter-defibrillators (ICDs) are generally considered a contraindication to magnetic resonance imaging (MRI).
  
  
  OBJECTIVE
  The purpose of the ProMRI Phase C study, a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI Iforia ICD system during MRI.
  
  
  METHODS
  Patients were enrolled after ICD implantation, with either a dual-chamber DR-T or single-lead VR-T DX system. Study-defined, nondiagnostic cardiac or thoracic spine MRI was performed at least 1 week after enrollment. ICDs were placed into MRI mode with ventricular fibrillation (VF) detection/therapy programmed "off" before scan and restored to non-MRI mode after scan. Interrogation was performed before, immediately after, and 1 month post-MRI. The primary end-points were (1) ventricular pacing threshold increase >0.5 V from pre-MRI to 1 month post-MRI; (2) R-wave amplitude decrease >50% from pre-MRI to 1 month post-MRI or R-wave amplitude <5 mV at 1 month post-MRI; and (3) MRI and ICD system-related serious adverse device effects.
  
  
  RESULTS
  One hundred seventy patients were enrolled at 39 US centers. One hundred fifty-three patients underwent MRI (25.7% cardiac, 74.3% thoracic spine) and completed follow-up. Freedom from the primary end-points was met in all but 1 subject, in whom reduced R-wave amplitude was detected 1 month post-MRI. No serious adverse device effects occurred during the course of the study.
  
  
  CONCLUSIONS
  These results demonstrate the clinical safety and efficacy of the ProMRI ICD system in patients subjected to thoracic spine and cardiac MRI imaging in 1.5-T scanners.
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama. Electronic address: kawad@uabmc.edu.
authors.forename: Khaled
authors.initials: K
authors.lastname: Awad
authors.affiliation: Chesapeake Regional Medical Center, Chesapeake, Virginia.
authors.forename: John
authors.initials: J
authors.lastname: Griffin
authors.affiliation: University of Michigan, Ann Arbor, Michigan.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Crawford
authors.affiliation: Cardiology Center of Amarillo, Amarillo, Texas.
authors.forename: S
authors.initials: S
authors.lastname: Lane Cox
authors.affiliation: Montefiore Medical Center, Bronx, New York.
authors.forename: Kevin
authors.initials: K
authors.lastname: Ferrick
authors.affiliation: University of Iowa Hospitals and Clinics, Cardiology, Iowa City, Iowa.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mazur
authors.affiliation: St. Mary Medical Center, Langhorne, Pennsylvania.
authors.forename: Rafael E
authors.initials: RE
authors.lastname: Pena
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Lloyd
authors.affiliation: Biotronik, Inc, Lake Oswego, Oregon.
authors.forename: Justin
authors.initials: J
authors.lastname: Michalski
authors.affiliation: Biotronik, Inc, Lake Oswego, Oregon.
authors.forename: Whitney
authors.initials: W
authors.lastname: Johnson
authors.affiliation: Louisiana Heart Rhythm Specialists and Lafayette General Medical Center, Lafayette, Louisiana.
authors.forename: William M
authors.initials: WM
authors.lastname: Bailey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000075202:Contraindications; D017147:Defibrillators, Implantable; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D013122:Spinal Diseases / Q000150:complications / Q000175:diagnosis*; D013904:Thoracic Vertebrae / Q000473:pathology*; D014693:Ventricular Fibrillation / Q000150:complications / Q000628:therapy*; D055815:Young Adult
keywords: Clinical trial; Iforia; Implantable cardioverter-defibrillator; Magnetic resonance imaging; Safety; Tachycardia