title: Prolonged Electromechanical Interval Unmasks Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy in the Subclinical Stage.
abstract: BACKGROUND
  Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is characterized by high incidence of ventricular arrhythmias. Overt ARVD/C is preceded by a subclinical stage with lack of detectable ECG and structural abnormalities. Activation delay is present before structural abnormalities and is a hallmark of arrhythmogenesis. Deformation imaging may unmask activation delay in the subclinical stage.
  
  
  METHODS
  Three groups were compared: (1) mutation-positive definite ARVD/C-patients fulfilling 2010 Task Force criteria (TFC) (n = 44); (2) asymptomatic mutation carriers not fulfilling TFC and without history of ventricular arrhythmias (n = 31); and (3) controls (n = 30). All underwent ECG and echocardiographic deformation imaging. As a surrogate for local activation delay the electromechanical interval (EMI) was measured, defined as time between onset-QRS and onset of shortening. Arrhythmic outcome (PVC-count, VT) of asymptomatic mutation carriers was correlated with EMI and ECG TFC.
  
  
  RESULTS
  In definite ARVD/C-patients, EMI was prolonged in all lateral RV segments. In asymptomatic mutation carriers, prolonged EMI was detected in the subtricuspid area in 14/31. Terminal activation duration ≥55 milliseconds (definition: supporting information) was the only ECG abnormality in this group (8/31). After a mean follow-up of 4.2 ± 3.1 years 10/31 asymptomatic mutation carriers experienced arrhythmic outcome. Prolonged subtricuspid EMI was the only parameter significantly associated with arrhythmogenesis during follow-up.
  
  
  CONCLUSIONS
  In ARVD/C-patients, EMI prolongation was present throughout the RV. In asymptomatic mutation carriers, prolonged EMI in the subtricuspid area is often detected without any additional abnormalities. These preliminary results indicate that prolonged EMI is a new parameter unmasking activation delay in the subclinical stage and may contribute to risk stratification.
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Mast
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Arco J
authors.initials: AJ
authors.lastname: Teske
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.|Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Anneline Sjm
authors.initials: AS
authors.lastname: Te Riele
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Groeneweg
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jeroen F
authors.initials: JF
authors.lastname: Van Der Heijden
authors.affiliation: Department of Radiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Loh
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Pieter A
authors.initials: PA
authors.lastname: Doevendans
authors.affiliation: Department of Medical Physiology and Cardiology, University Medical Center Utrecht, The Netherlands.
authors.forename: Toon A
authors.initials: TA
authors.lastname: Van Veen
authors.affiliation: Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Dennis
authors.initials: D
authors.lastname: Dooijes
authors.affiliation: Department of Medical Physiology and Cardiology, University Medical Center Utrecht, The Netherlands.|Department of Experimental Cardiology, Heart Center, Academic Medical Center, Amsterdam, The Netherlands.|ICIN-Netherlands Heart Institute, Utrecht, The Netherlands.
authors.forename: Jacques M
authors.initials: JM
authors.lastname: De Bakker
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.|ICIN-Netherlands Heart Institute, Utrecht, The Netherlands.
authors.forename: Richard N
authors.initials: RN
authors.lastname: Hauer
authors.affiliation: Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Cramer
mesh_terms: D000328:Adult; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D055815:Young Adult
keywords: activation delay; arrhythmogenic right ventricular dysplasia/cardiomyopathy; deformation imaging; diagnosis; echocardiography; risk stratification; ventricular arrhythmias