title: Analysis of different device-based intrathoracic impedance vectors for detection of heart failure events (from the Detect Fluid Early from Intrathoracic Impedance Monitoring study).
abstract: Detect Fluid Early from Intrathoracic Impedance Monitoring (DEFEAT-PE) is a prospective, multicenter study of multiple intrathoracic impedance vectors to detect pulmonary congestion (PC) events. Changes in intrathoracic impedance between the right ventricular (RV) coil and device can (RVcoil→Can) of implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy ICDs (CRT-Ds) are used clinically for the detection of PC events, but other impedance vectors and algorithms have not been studied prospectively. An initial 75-patient study was used to derive optimal impedance vectors to detect PC events, with 2 vector combinations selected for prospective analysis in DEFEAT-PE (ICD vectors: RVring→Can + RVcoil→Can, detection threshold 13 days; CRT-D vectors: left ventricular ring→Can + RVcoil→Can, detection threshold 14 days). Impedance changes were considered true positive if detected <30 days before an adjudicated PC event. One hundred sixty-two patients were enrolled (80 with ICDs and 82 with CRT-Ds), all with ≥1 previous PC event. One hundred forty-four patients provided study data, with 214 patient-years of follow-up and 139 PC events. Sensitivity for PC events of the prespecified algorithms was as follows: ICD: sensitivity 32.3%, false-positive rate 1.28 per patient-year; CRT-D: sensitivity 32.4%, false-positive rate 1.66 per patient-year. An alternative algorithm, ultimately approved by the US Food and Drug Administration (RVring→Can + RVcoil→Can, detection threshold 14 days), resulted in (for all patients) sensitivity of 21.6% and a false-positive rate of 0.9 per patient-year. The CRT-D thoracic impedance vector algorithm selected in the derivation study was not superior to the ICD algorithm RVring→Can + RVcoil→Can when studied prospectively. In conclusion, to achieve an acceptably low false-positive rate, the intrathoracic impedance algorithms studied in DEFEAT-PE resulted in low sensitivity for the prediction of heart failure events.
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts. Electronic address: kheist@partners.org.
authors.forename: E Kevin
authors.initials: EK
authors.lastname: Heist
authors.affiliation: Eastern Virginia Medical and Sentara Norfolk General Hospital, Norfolk, Virginia.
authors.forename: John M
authors.initials: JM
authors.lastname: Herre
authors.affiliation: Division of Cardiovascular Medicine and Davis Heart and Lung Institute, The Ohio State University, Columbus, Ohio.
authors.forename: Philip F
authors.initials: PF
authors.lastname: Binkley
authors.affiliation: Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Adrian B
authors.initials: AB
authors.lastname: Van Bakel
authors.affiliation: Methodist University Hospital, Memphis, Tennessee.
authors.forename: James G
authors.initials: JG
authors.lastname: Porterfield
authors.affiliation: Methodist University Hospital, Memphis, Tennessee.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Porterfield
authors.affiliation: St. Jude Medical, Sylmar, California.
authors.forename: Fujian
authors.initials: F
authors.lastname: Qu
authors.affiliation: St. Jude Medical, Sylmar, California.
authors.forename: Melanie
authors.initials: M
authors.lastname: Turkel
authors.affiliation: Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania.
authors.forename: Behzad B
authors.initials: BB
authors.lastname: Pavri
mesh_terms: D000368:Aged; D000465:Algorithms; D058406:Cardiac Resynchronization Therapy; D002307:Cardiography, Impedance / Q000295:instrumentation*; D017097:Electric Impedance; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011654:Pulmonary Edema / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D015203:Reproducibility of Results; D014481:United States / Q000453:epidemiology