title: Development of a magnetocardiography-based algorithm for discrimination between ventricular arrhythmias originating from the right ventricular outflow tract and those originating from the aortic sinus cusp: a pilot study.
abstract: BACKGROUND
  Although several reports address characteristic 12-lead electrocardiographic findings of outflow tract ventricular arrhythmias (OT-VAs), the accuracy of electrocardiogram-based algorithms to predict the OT-VA origin is sometimes limited.
  
  
  OBJECTIVE
  This study aimed to develop a magnetocardiography (MCG)-based algorithm using a novel adaptive spatial filter to differentiate between VAs originating from the aortic sinus cusp (ASC-VAs) and those originating from the right ventricular outflow tract (RVOT-VAs).
  
  
  METHODS
  This study comprised 51 patients with an OT-VA as the target of catheter ablation. An algorithm was developed by correlating MCG findings with the successful ablation site. The arrhythmias were classified as RVOT-VAs or ASC-VAs. Three parameters were obtained from 3-dimensional MCG imaging: depth of the origin of the OT-VA in the anteroposterior direction; distance between the earliest atrial activation site, that is, sinus node, and the origin of the OT-VA; and orientation of the arrhythmia propagation at the QRS peak. The distance was indexed to the patient's body surface area (in mm/m2).
  
  
  RESULTS
  Origins of ASC-VAs were significantly deeper (81 ± 6 mm/m(2) vs. 68 ± 8 mm/m(2); P < .01) and farther from the sinus node (55 ± 9 mm/m2 vs. 41 ± 9 mm/m(2); P < .01) than those of RVOT-VAs. ASC-VA propagation had a tendency toward rightward axis. Receiver operating characteristic analyses determined that the depth of the origin was the most powerful predictor, with a sensitivity of 90% and a specificity of 73% (area under the curve = 0.90; P < .01). Discriminant analysis combining all 3 parameters revealed the accuracy of the localization to be 94%.
  
  
  CONCLUSIONS
  This MCG-based algorithm appeared to precisely discriminate ASC-VAs from RVOT-VAs. Further investigation is required to validate the clinical value of this technique.
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Systems Design & Engineering, Tokyo Metropolitan University, Hachioji, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Shiga
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan. Electronic address: kentaroyo@nifty.com.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Central Research Laboratory, Hitachi Ltd, Kokubunji, Japan.
authors.forename: Kuniomi
authors.initials: K
authors.lastname: Ogata
authors.affiliation: Central Research Laboratory, Hitachi Ltd, Kokubunji, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kandori
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Inaba
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nakazawa
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Sekiguchi
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Fukui, Yoshida-gun, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tada
authors.affiliation: Department of Systems Design & Engineering, Tokyo Metropolitan University, Hachioji, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sekihara
authors.affiliation: Cardiovascular Division, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aonuma
mesh_terms: D000465:Algorithms; D017115:Catheter Ablation / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D053798:Magnetocardiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012372:ROC Curve; D012189:Retrospective Studies; D012850:Sinus of Valsalva / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000601:surgery
keywords: Aortic sinus cusp; Catheter ablation; Magnetocardiography; Premature ventricular contraction; Right ventricular outflow tract; Spatial filter