Improved Algorithm to Detect Fluid Accumulation via Intrathoracic Impedance Monitoring in Heart Failure Patients With Implantable Devices

Intrathoracic impedance fluid monitoring has been shown to predict worsening congestive heart failure (CHF) in patients with implantable devices. We developed and externally validated a modified algorithm to identify worsening heart failure (HF) by using intrathoracic impedance. The modified algorit...

Full description

Saved in:
Bibliographic Details
Published in:Journal of cardiac failure Vol. 17; no. 7; pp. 569 - 576
Main Authors: Sarkar, Shantanu, Hettrick, Douglas A., Koehler, Jodi, Rogers, Tyson, Grinberg, Yanina, Yu, Cheuk-Man, Abraham, William T., Small, Roy, Tang, W.H.Wilson
Format: Journal Article
Language:English
Published: United States Elsevier Inc 01.07.2011
Subjects:
Aged
Aged, 80 and over
Algorithms
Body Fluids - physiology
cardiac resynchronization therapy
Cardiography, Impedance - standards
Cardiography, Impedance - trends
Cardiovascular
Cohort Studies
Defibrillators, Implantable - standards
Defibrillators, Implantable - trends
Double-Blind Method
Electric Impedance
Female
Follow-Up Studies
Heart Failure - diagnosis
Heart Failure - physiopathology
Heart failure monitoring
Humans
implantable cardiac defibrillator
intrathoracic impedance
Male
Middle Aged
Reproducibility of Results
Retrospective Studies
implantable cardiac defibrillator
intrathoracic impedance
cardiac resynchronization therapy
Heart failure monitoring
ISSN:1071-9164, 1532-8414, 1532-8414
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Intrathoracic impedance fluid monitoring has been shown to predict worsening congestive heart failure (CHF) in patients with implantable devices. We developed and externally validated a modified algorithm to identify worsening heart failure (HF) by using intrathoracic impedance. The modified algorithm was developed by using published data from 81 CHF subjects averaging 259 days of follow-up. Device-measured daily impedance was input to both the existing and the modified intrathoracic impedance fluid monitoring algorithms to determine a reference impedance and a fluid index (FI). Separate validation sets included 326 cardiac resynchronization therapy device (CRT-D) patients with an average 333 days of follow-up (group 1) and 104 CRT-D/implantable cardioverter/defibrillator (ICD) patients followed for an average of 520 days (group 2). Clinicians and patients in group 2 were blinded to impedance and FI data. HF events included adjudicated HF hospitalizations or emergency room visits. Sensitivity was defined as the percentage of HF events preceded by FI exceeding the predefined threshold (60 Ω-d) within the last 2 weeks. Unexplained detections were FI threshold crossing events not followed by a HF event within 2 weeks. The modified algorithm significantly decreased unexplained detections by 30% ( P = .01; GEE) in the development set, 30% ( P < .001) in the group 1 validation set, and 43% ( P < .001) in group 2. Sensitivity did not change significantly in any group. Simulated monthly review of FI threshold crossings identified subjects at significantly greater risk of worsening HF within the next 30 days. A modified intrathoracic impedance based fluid detection algorithm lowered the number of unexplained FI threshold crossings and identified patients at significantly increased immediate risk of worsening HF.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:1071-9164
1532-8414
1532-8414
DOI:10.1016/j.cardfail.2011.03.002