title: Ventricular structure in ARVC: going beyond volumes as a measure of risk.
abstract: BACKGROUND
  Altered right ventricular structure is an important feature of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), but is challenging to quantify objectively. The aim of this study was to go beyond ventricular volumes and diameters and to explore if the shape of the right and left ventricles could be assessed and related to clinical measures. We used quantifiable computational methods to automatically identify and analyse malformations in ARVC patients from Cardiovascular Magnetic Resonance (CMR) images. Furthermore, we investigated how automatically extracted structural features were related to arrhythmic events.
  
  
  METHODS
  A retrospective cross-sectional feasibility study was performed on CMR short axis cine images of 27 ARVC patients and 21 ageing asymptomatic control subjects. All images were segmented at the end-diastolic (ED) and end-systolic (ES) phases of the cardiac cycle to create three-dimensional (3D) bi-ventricle shape models for each subject. The most common components to single- and bi-ventricular shape in the ARVC population were identified and compared to those obtained from the control group. The correlations were calculated between identified ARVC shapes and parameters from the 2010 Task Force Criteria, in addition to clinical outcomes such as ventricular arrhythmias.
  
  
  RESULTS
  Bi-ventricle shape for the ARVC population showed, as ordered by prevalence with the percent of total variance in the population explained by each shape: global dilation/shrinking of both ventricles (44 %), elongation/shortening at the right ventricle (RV) outflow tract (15 %), tilting at the septum (10 %), shortening/lengthening of both ventricles (7 %), and bulging/shortening at both the RV inflow and outflow (5 %). Bi-ventricle shapes were significantly correlated to several clinical diagnostic parameters and outcomes, including (but not limited to) correlations between global dilation and electrocardiography (ECG) major criteria (p = 0.002), and base-to-apex lengthening and history of arrhythmias (p = 0.003). Classification of ARVC vs. control using shape modes yielded high sensitivity (96 %) and moderate specificity (81 %).
  
  
  CONCLUSIONS
  We presented for the first time an automatic method for quantifying and analysing ventricular shapes in ARVC patients from CMR images. Specific ventricular shape features were highly correlated with diagnostic indices in ARVC patients and yielded high classification sensitivity. Ventricular shape analysis may be a novel approach to classify ARVC disease, and may be used in diagnosis and in risk stratification for ventricular arrhythmias.
authors.affiliation: Cardiac Modelling Department, Simula Research Laboratory, PO Box 134, Oslo, Norway. kristin@simula.no.|Center for Cardiological Innovation, Oslo, Norway. kristin@simula.no.
authors.forename: Kristin
authors.identifier: http://orcid.org/0000-0002-2469-7039
authors.initials: K
authors.lastname: McLeod
authors.affiliation: Cardiac Modelling Department, Simula Research Laboratory, PO Box 134, Oslo, Norway.|Center for Cardiological Innovation, Oslo, Norway.
authors.forename: Samuel
authors.initials: S
authors.lastname: Wall
authors.affiliation: Department of Cardiology and Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway.|University of Oslo, Oslo, Norway.|Center for Cardiological Innovation, Oslo, Norway.
authors.forename: Ida Skrinde
authors.initials: IS
authors.lastname: Leren
authors.affiliation: Department of Cardiology and Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway.|University of Oslo, Oslo, Norway.|Center for Cardiological Innovation, Oslo, Norway.
authors.forename: Jørg
authors.initials: J
authors.lastname: Saberniak
authors.affiliation: Department of Cardiology and Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway.|University of Oslo, Oslo, Norway.|Center for Cardiological Innovation, Oslo, Norway.
authors.forename: Kristina Hermann
authors.initials: KH
authors.lastname: Haugaa
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001331:Automation; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005240:Feasibility Studies; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D020257:Ventricular Remodeling; D055815:Young Adult
keywords: ARVC; CMR; Principal component analysis; Risk assessment; Shape modes