title: Implantable CRT device diagnostics identify patients with increased risk for heart failure hospitalization.
abstract: OBJECTIVE
  To determine the association between device-determined diagnostic indices, including intrathoracic impedance, and heart failure (HF) hospitalization.
  
  
  METHODS
  Clinical and device diagnostic data of 558 HF patients indicated for CRT-D therapy (In Sync Sentry, Medtronic Inc.) were prospectively collected from 34 centers. Device-recorded intrathoracic impedance fluid index threshold crossing event (TCE), mean activity counts, tachyarrhythmia events, night heart rate (NHR) and heart rate variability (HRV) were compared within patients with vs. without documented HF hospitalization.
  
  
  RESULTS
  Mean follow-up was 326 +/- 216 days. Patients hospitalized for HF had significantly higher rates of TCE, a higher percentage of days with the thoracic impedance fluid index above the programmed threshold, a higher percentage of days with low activity, with low HRV or with high NHR. Multivariate analysis showed that TCE resulted in a 36% increased probability of HF hospitalization. Both TCE duration and patient activity were also significantly associated with hospitalization. Kaplan Meier analysis indicated that patients with more TCE events were significantly more likely to be hospitalized (log rank test, p = 0.005).
  
  
  CONCLUSIONS
  Decreased intrathoracic impedance, low patient activity and low HRV were all independently associated with increased risk for HF hospitalization in HF patients treated with resynchronization therapy. Device-derived diagnostic data may provide valuable and reliable indices for the prognostic stratification of HF patients.
authors.affiliation: Istituto Auxologico S. Luca, Milan, Italy. perego@auxologico.it
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Perego
authors.forename: Maurizio
authors.initials: M
authors.lastname: Landolina
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vergara
authors.forename: Maurizio
authors.initials: M
authors.lastname: Lunati
authors.forename: Gabriele
authors.initials: G
authors.lastname: Zanotto
authors.forename: Alessia
authors.initials: A
authors.lastname: Pappone
authors.forename: Gabriele
authors.initials: G
authors.lastname: Lonardi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Speca
authors.forename: Saverio
authors.initials: S
authors.lastname: Iacopino
authors.forename: Annamaria
authors.initials: A
authors.lastname: Varbaro
authors.forename: Shantanu
authors.initials: S
authors.lastname: Sarkar
authors.forename: Doug A
authors.initials: DA
authors.lastname: Hettrick
authors.forename: Alessandra
authors.initials: A
authors.lastname: Denaro
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002307:Cardiography, Impedance; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate / Q000502:physiology; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008297:Male; D016012:Poisson Distribution; D011446:Prospective Studies; D012306:Risk