title: A simple algorithm for defining the mechanism and the chamber of origin in atrial tachycardias.
abstract: BACKGROUND
  Although macroreentrant atrial tachycardia (MRAT) and focal atrial tachycardia (FAT) can be successfully cured by catheter ablation, the proper diagnosis and treatment of these arrhythmias can still be challenging.
  
  
  OBJECTIVE
  The objective of this study is to develop an algorithm allowing rapid diagnosis of the mechanism and the chamber of origin of atrial tachycardia based on intracardiac catheter recordings from the right atrium and the coronary sinus (CS).
  
  
  METHODS
  A 2-stepped algorithm was designed: (1) The time of biatrial activation expressed as a percentage of the tachycardia cycle length served to discriminate FAT from MRAT. (2) In FAT, the direction of activation of the CS catheter and the earliest atrial activation were used to define the chamber of origin. In MRAT, the time of right atrium activation was determined or entrainment was used at different sites. Thirty-two intracardiac recordings were reviewed off-line after the algorithm by 4 electrophysiologists blinded to the mechanism and the chamber of origin. The results of their analysis were compared with the intraoperative diagnosis.
  
  
  RESULTS
  The algorithm correctly identified 11 (100%) of 11 FATs and 19 (90.4%) of 21 MRATs. The site of origin was correctly identified in 8 (72.7%) of 11 FATs and in 20 of 21 (95.2%) MRATs. The site of origin was misidentified in 3 FATs, all arising from the CS ostium.
  
  
  CONCLUSIONS
  This algorithm allows rapid discrimination between FAT and MRAT. The chamber of origin is detected with a high accuracy in MRAT. However, the earliest atrial activation taken as an isolated event is not a good predictor for the chamber of origin in FAT arising from the ostium of the CS.
authors.affiliation: Department of Clinical Cardiac Electrophysiology and Cardiac Pacing, Gottsegen Gyorgy Hungarian Institute of Cardiology, H-1096 Budapest, Hungary.
authors.forename: Tchavdar Nikolov
authors.initials: TN
authors.lastname: Shalganov
authors.forename: Radu
authors.initials: R
authors.lastname: Vatasescu
authors.forename: Dora
authors.initials: D
authors.lastname: Paprika
authors.forename: Laszlo
authors.initials: L
authors.lastname: Kornyei
authors.forename: Jozsef
authors.initials: J
authors.lastname: Vanyi
authors.forename: Laszlo
authors.initials: L
authors.lastname: Geller
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Szilagyi
authors.forename: Vassil Borislavov
authors.initials: VB
authors.lastname: Traykov
authors.forename: Tosho Lukanov
authors.initials: TL
authors.lastname: Balabanski
authors.forename: Tamas
authors.initials: T
authors.lastname: Szili-Torok
mesh_terms: D000465:Algorithms; D018780:Body Surface Potential Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013612:Tachycardia, Ectopic Atrial / Q000145:classification* / Q000175:diagnosis*