title: Right ventricular stimulation threshold at ICD implant predicts device therapy in primary prevention patients with ischaemic heart disease.
abstract: OBJECTIVE
  Myocardial excitability is known (amongst other reasons) to be related to the degree of ischaemia, contractile dysfunction and heart failure. It was hypothesized that the right ventricular (RV) stimulation threshold has prognostic value with respect to the occurrence of ventricular arrhythmias (VAs) and patient survival in recipients of an implantable cardioverter defibrillator (ICD).
  
  
  RESULTS
  Ischaemic heart disease patients receiving an ICD at Leiden University Medical Center as primary prevention for sudden cardiac death were included in this study. Right ventricular thresholds were determined at ICD implant. Data were collected on VAs triggering ICD therapy and on all-cause mortality. A total of 689 consecutive patients were included (87% male, age 63 ± 11 years, left ventricular ejection fraction (LVEF) 29 ± 11%) and followed for a median of 28 months. Post-implant RV-threshold was 0.7 ± 0.5 volt (V) at 0.5 ms pulse duration. Best dichotomous separation was reached at a cut-off of 1 V. During follow-up, 167 (24%) patients received appropriate ICD therapy, 88 (13%) had appropriate shocks and 134 (19%) died. Cumulative appropriate shock incidence for patients with RV threshold ≥ 1 V (n = 166) was 16% at 1 year, 24% at 3 years and 34% at 5 years compared with 4, 11 and 17% for patients with an RV-threshold < 1 V (n = 523). Adjusted hazard ratio of RV threshold ≥ 1 V was 2.0 (95% CI: 1.4-2.9) for appropriate therapy, 3.3 (95% CI: 2.0-5.4) for appropriate shocks and 1.6 (95% CI: 1.1-2.5) for mortality.
  
  
  CONCLUSIONS
  The RV stimulation threshold at ICD implant has a strong independent prognostic value for the occurrence of VAs triggering appropriate ICD therapy, appropriate shocks and mortality.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
authors.forename: Jael Z
authors.initials: JZ
authors.lastname: Atary
authors.forename: C Jan Willem
authors.initials: CJ
authors.lastname: Borleffs
authors.forename: Johanna G
authors.initials: JG
authors.lastname: van der Bom
authors.forename: Serge A I P
authors.initials: SA
authors.lastname: Trines
authors.forename: Marianne
authors.initials: M
authors.lastname: Bootsma
authors.forename: Katja
authors.initials: K
authors.lastname: Zeppenfeld
authors.forename: Lieselot
authors.initials: L
authors.lastname: van Erven
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
mesh_terms: D000368:Aged; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D011322:Primary Prevention; D011379:Prognosis; D011446:Prospective Studies; D013318:Stroke Volume / Q000502:physiology; D017180:Tachycardia, Ventricular / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D014693:Ventricular Fibrillation / Q000401:mortality / Q000503:physiopathology / Q000628:therapy