title: Bi-atrial and right atrial activation times help to differentiate focal from macroreentrant right atrial tachycardias.
abstract: OBJECTIVE
  The objective was to study atrial activation intervals and their relation to the tachycardia cycle length (TCL) as electrophysiologic parameters differentiating focal (FAT) from macroreentrant atrial tachycardias (MRAT) originating in the right atrium.
  
  
  METHODS
  In 21 patients (8 men) with 30 successfully ablated right atrial tachycardias (15 focal) the endocardial activity during tachycardia was registered using multipolar catheters in the right atrium and the coronary sinus. Using this catheter configuration we measured the tachycardia cycle length (TCL), biatrial activation (BAA), right atrial activation (RAA), left atrial activation (LAA), as well as the proportion of those intervals to TCL. In 14 patients, the measurements were repeated in sinus rhythm as well. The diagnostic accuracy of the ratio of BAA to TCL was assessed.
  
  
  RESULTS
  TCL was longer, but all other intervals and ratios were significantly shorter in FAT compared to MRAT (P < 0.05 for all parameters, except for LAA - P = NS). During sinus rhythm, patients with MRAT had prolonged RAA (P = 0.003), but not BAA and LAA (P = NS), compared to patients with FAT. A discriminating value of 40% for the ratio of BAA to TCL, compared to 50% and 30%, was found to have the best sensitivity, specificity, positive and negative predictive values for MRAT, as well as for FAT.
  
  
  CONCLUSIONS
  BAA, RAA, LAA and their relation to the TCL are significantly shorter in FATs compared to MRATs arising from the right atrium. The ratio of BAA to TCL obtained using a simple 2-catheter configuration, allows a rapid and reliable differentiation between FAT and MRAT.
authors.affiliation: Cardiology Clinic, National Heart Hospital, 65 Koniovitsa Street, 1309 Sofia, Bulgaria. tchavdar.shalganov@gmail.com
authors.forename: Tchavdar N
authors.initials: TN
authors.lastname: Shalganov
authors.forename: Borislav B
authors.initials: BB
authors.lastname: Dinov
authors.forename: Vassil B
authors.initials: VB
authors.lastname: Traykov
authors.forename: Radu
authors.initials: R
authors.lastname: Vatasescu
authors.forename: Dora
authors.initials: D
authors.lastname: Paprika
authors.forename: Tocho L
authors.initials: TL
authors.lastname: Balabanski
authors.forename: Laszlo
authors.initials: L
authors.lastname: Geller
authors.forename: Tamas
authors.initials: T
authors.lastname: Szili-Torok