title: Magnetic resonance imaging abnormalities in right ventricular outflow tract tachycardia and the prediction of radiofrequency ablation outcome.
abstract: BACKGROUND
  Recent reports have shown abnormalities on cardiac magnetic resonance imaging (MRI) in patients with right ventricular outflow tract (RVOT) tachycardia.
  
  
  OBJECTIVE
  OBJECTIVES of this study were to demonstrate abnormalities on MRI and signal-averaged ECG (SAECG) in patients with RVOT tachycardia and their correlation with the outcome of radiofrequency (RF) ablation.
  
  
  METHODS
  We studied 41 patients with symptomatic RVOT tachycardia and 15 controls. SAECG and cardiac MRI were performed on every subject. An evaluation of structural abnormality, chamber size, function, and wall motion abnormality of the left and right ventricle was performed by MRI. Focal wall thinning was evaluated by the black blood technique and fatty infiltration was evaluated by the T1 image with and without fat suppression.
  
  
  RESULTS
  MRI abnormalities were demonstrated in 24 (58.5%) patients with RVOT tachycardia. The abnormalities included localized wall bulging in 22 (53.7%), focal wall thinning in 10 (24.4%), and fatty replacement in 9 (22%) patients. MRI abnormality was found in only one patient in the control group (P < 0.001). Late potentials from SAECG were demonstrated in six (10.7%) patients but none in the controls (P = 0.117). Among 29 patients who underwent RF ablation, 3 patients had a failed procedure and 3 having arrhythmia recurrence needed repeated ablation. MRI abnormalities and late potentials were associated with an unfavorable outcome of RF ablation.
  
  
  CONCLUSIONS
  MRI abnormalities were frequently found in patients with RVOT tachycardia. MRI abnormalities and late potentials can predict outcomes of RF ablation.
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Bangkok, Thailand.
authors.forename: Rungroj
authors.initials: R
authors.lastname: Krittayaphong
authors.forename: Pairash
authors.initials: P
authors.lastname: Saiviroonporn
authors.forename: Thananya
authors.initials: T
authors.lastname: Boonyasirinant
authors.forename: Supaporn
authors.initials: S
authors.lastname: Nakyen
authors.forename: Prajak
authors.initials: P
authors.lastname: Thanapiboonpol
authors.forename: Wipawin
authors.initials: W
authors.lastname: Watanaprakarnchai
authors.forename: Krongkarn
authors.initials: K
authors.lastname: Ruksakul
authors.forename: Charuwan
authors.initials: C
authors.lastname: Kangkagate
mesh_terms: D017115:Catheter Ablation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery*; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*