title: Diaphragmatic myopotential oversensing in pacemaker-dependent patients with CRT-D devices.
abstract: OBJECTIVE
  To evaluate the incidence and clinical significance of diaphragmatic myopotential (dMP) oversensing in pacemaker (PM)-dependent patients with CRT-Ds.
  
  
  RESULTS
  We retrospectively evaluated patients with CRT-Ds implanted at our institution between January 2000 and August 2006. PM-dependent patients were identified, and the incidence of inappropriate detections due to dMP oversensing and their possible clinical implications (inappropriate therapies, syncope, and death of any cause) were evaluated. CRT-Ds were implanted in 122 patients, 37 were or became PM dependent. During a mean follow-up of 22 +/- 17 months, 7(18.9%) PM-dependent patients revealed inappropriate detections due to dMP oversensing. All oversensing episodes occurred in CRT-Ds with automatic gain control (AGC) sensing and integrated bipolar (IBP) leads in the RV apex. These detections led to inappropriate shocks in 2(5.4%) patients and syncope in 1(2.7%). Five (13.5%) patients died.
  
  
  CONCLUSIONS
  dMP oversensing in PM-dependent patients with CRT-Ds is an important problem, particularly in CRT-Ds with AGC sensing and IBP leads, with over 20% of patients with these devices revealing inappropriate detections. The clinical impact of dMP oversensing is less marked but relevant, with both inappropriate therapies and syncope occurring in this small group of 37 patients and the possibility of related deaths.
authors.affiliation: Hospital Santa Cruz, Centro Hospitalar de Lisboa Ocidental, EPE, Avenida Professor Reinaldo dos Santos, Carnaxide, Portugal.
authors.forename: Katya Reis
authors.initials: KR
authors.lastname: Santos
authors.forename: Pedro
authors.initials: P
authors.lastname: Adragão
authors.forename: Diogo
authors.initials: D
authors.lastname: Cavaco
authors.forename: Francisco Bello
authors.initials: FB
authors.lastname: Morgado
authors.forename: Rui
authors.initials: R
authors.lastname: Candeias
authors.forename: Sónia
authors.initials: S
authors.lastname: Lima
authors.forename: José Aniceto
authors.initials: JA
authors.lastname: Silva