Abstract 13586: Analysis of a Different Device-Based Intrathoracic Impedance Vector for Detection of Heart Failure Events: Results of the DEFEAT-PE Study
Background: Detection of changes in intrathoracic impedance measured between the right ventricular (RV) coil and the device can (RVcoil→Can) of implantable cardioverter defibrillators (ICDs) is approved for clinical use in detection of pulmonary congestion (PC) events. However, an RVring→Can vector has not been evaluated for this purpose.
Objective: The DEFEAT-PE study is a prospective study that evaluated the performance of an RVring→Can vector to detect changes in intrathoracic impedance vectors associated with CHF events.
Methods: An initial derivation set of 75 patients was used to analyze optimal impedance vectors for detection of PC events, and a vector of RVring-Can was selected for prospective analysis. 162 patients were then enrolled in DEFEAT-PE (81 with ICDs and 81 with cardiac resynchronization therapy ICDs, 64+13 yrs, 72% male, EF 25+10%, 54% ischemic, all with at least 1 prior PC event). PC events during the study were adjudicated by a blinded clinical events committee. Device-detected impedance changes were considered true positive if associated within 30 days prior to a PC event, and false positive if otherwise.
Results: There were 98 patient years of follow up and 79 PC events. The sensitivity for prediction of PC events was not significantly different when comparing RVring→Can (sensitivity=36.1%, 95% CI=29.0-43.3%) vs. RVcoil→Can (sensitivity=37.4%, CI=28.6-46.1%, p=0.56) at a FPR of ≤ 1.5/year. Curves comparing sensitivity vs. FPR for both vectors at various impedance threshold cutoffs for detection of PC events are shown (figure).
Conclusions: The RVring→Can vector analyzed in DEFEAT-PE provides similar prediction of PC events when compared to the RVcoil→Can vector. This vector could be used in ICDs, and potentially in other cardiac implantable electrical devices. However, based on overall performance, transthoracic impedance appears to have limitations in the early detection of acute heart failure events.
- © 2011 by American Heart Association, Inc.