title: Ventricular pacing site separation by cardiac computed tomography: validation for the prediction of clinical response to cardiac resynchronization therapy.
abstract: Cardiac Resynchronization Therapy (CRT) fails to provide benefit in up to one-third of patients. Maximizing the geographic separation of right and left ventricular pacing lead sites has been suggested as one way to improve response. Cardiac CT provides an opportunity to explore 3-dimensional inter-lead distance (ILD) measures for the prediction of CRT response. The objective of this study was to investigate associations between standardized measures of ILD by cardiac CT and echocardiographic response to CRT. Forty-two consecutive patients undergoing CRT had serial clinical and echocardiographic evaluations performed in addition to a post-procedural cardiac-gated CT with blinded measurement of direct and circumferential (via the myocardium) ILD measures. Clinical response to CRT, the primary clinical outcome, was defined as a ≥15% reduction in LVESV using echocardiography at 6-months. The mean age and ejection fraction was 63.6 ± 8.9 years and 25.2 ± 7.8%, respectively. The primary outcome occurred in 35 of 42 patients (83%). Both direct and circumferential CT-based ILD measures were associated with the primary outcome by univariate analysis. Receiver Operator Characteristic analysis identified Circumferential ILD to have the strongest predictive accuracy (AUC 0.78). Inter- and intra-observer reproducibility of CT-derived ILD measures was excellent. Circumferential ILD measures on cardiac CT are predictive of clinical response to CRT. Incorporation of these measures into the selection of optimal pacing targets, particularly from pre-procedural CT coronary vein imaging may be of therapeutic benefit and warrants further investigation.
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Modi
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.affiliation: Robarts Research Institute, University of Western Ontario, London, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Scholl
authors.affiliation: Robarts Research Institute, University of Western Ontario, London, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Stirrat
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Wong
authors.affiliation: Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, Calgary, AB, Canada.|Department of Diagnostic Imaging, University of Calgary, Calgary, AB, Canada.
authors.forename: Carmen
authors.initials: C
authors.lastname: Lydell
authors.affiliation: Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, Calgary, AB, Canada.|Department of Diagnostic Imaging, University of Calgary, Calgary, AB, Canada.
authors.forename: Vamshi
authors.initials: V
authors.lastname: Kotha
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Gula
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: Allan C
authors.initials: AC
authors.lastname: Skanes
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Leong-Sit
authors.affiliation: Division of Cardiology, Schulich School of Medicine & Dentistry, London, Canada.
authors.forename: David
authors.initials: D
authors.lastname: McCarty
authors.affiliation: Robarts Research Institute, University of Western Ontario, London, Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Drangova
authors.affiliation: Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute, Calgary, AB, Canada. jawhit@ucalgary.ca.|Department of Diagnostic Imaging, University of Calgary, Calgary, AB, Canada. jawhit@ucalgary.ca.
authors.forename: James A
authors.initials: JA
authors.lastname: White
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D058409:Cardiac Resynchronization Therapy Devices; D004452:Echocardiography; D004867:Equipment Design; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right
keywords: CRT response; Cardiac computed tomography; Cardiac failure; Cardiac resynchronization therapy (CRT); Inter-lead distance; Lead separation; Left ventricular lead