title: Reappraisal of cardiac magnetic resonance imaging in idiopathic outflow tract arrhythmias.
abstract: BACKGROUND
  Because of prognostic and therapeutic implications, the distinction between idiopathic right ventricular (RV) outflow tract (iRVOT) and arrhythmogenic RV cardiomyopathy (ARVC) is clinically important. Over the last 2 decades multiple reports have identified RV abnormalities using CMR in patients with idiopathic VT, suggesting a link between these arrhythmias and ARVC. The purpose of this study was to assess for structural abnormalities in patients with iRVOT tachycardia using contemporary cardiac magnetic resonance (CMR) imaging.
  
  
  RESULTS
  CMR was performed in 46 patients with iRVOT tachycardia and 16 normal controls, with quantitative evaluation of RV and left ventricular volumes and function, as well as assessment of myocardial fat and scar. iRVOT patients were similar to controls with respect to RV end-diastolic volumes (81 ± 19 mL/m(2) vs. 79 ± 18 mL/m(2) , P = 0.77) and RV ejection fraction (57 ± 8% vs. 59 ± 7%, P = 0.31). The prevalence of RV chamber dilation, defined using ARVC major task force criteria, was uncommon among iRVOT patients (9%) and controls (7%; P = 1.0). Regional RV wall motion abnormalities were present in 2 iRVOT patients who had concomitant RV dilation or dysfunction. CMR tissue characterization demonstrated absence of both myocardial scar and fat infiltration in all patients and controls.
  
  
  CONCLUSIONS
  In patients with the clinical diagnosis of iRVOT tachycardia, CMR reveals RV structure, function, and myocardial tissue characteristics similar to normal controls. These findings suggest that the vast majority of patients with RVOT arrhythmias have a primary electrical disorder that is not a forme-fruste of ARVC.
authors.affiliation: Division of Cardiology, Department of Medicine, Cornell University Medical Center, New York, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Markowitz
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Weinsaft
authors.forename: Louis
authors.initials: L
authors.lastname: Waldman
authors.forename: Maya
authors.initials: M
authors.lastname: Petashnick
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Liu
authors.forename: Jim W
authors.initials: JW
authors.lastname: Cheung
authors.forename: George
authors.initials: G
authors.lastname: Thomas
authors.forename: James E
authors.initials: JE
authors.lastname: Ip
authors.forename: Bruce B
authors.initials: BB
authors.lastname: Lerman
mesh_terms: D005260:Female; D006329:Heart Conduction System / Q000473:pathology*; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011664:Pulmonary Valve / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000473:pathology*
keywords: cardiac magnetic resonance; idiopathic ventricular tachycardia; right ventricular outflow tract; ventricular premature beats
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