title: Variability in post-pacing intervals predicts global atrial activation pattern during tachycardia.
abstract: BACKGROUND
  Knowledge of the global atrial activation pattern is critical to ablation of an atrial arrhythmia. We hypothesized that the variability in post-pacing intervals (PPIs) with pacing at different cycle lengths (CLs) from the same pacing site, regardless of distance to the circuit, can be used to identify atrial activation patterns during tachycardia.
  
  
  RESULTS
  Consecutive patients referred for ablation of organized atrial arrhythmias were included (n = 28, 31 total tachycardias). The variability in PPIs (PPIV) was calculated by comparing the difference in PPIs after overdrive pacing with 5-second trains 10, 20, and 30 ms shorter than the tachycardia cycle length (TCL). The global activation pattern was defined as circuitous (macroreentrant atrial circuit) or centrifugal (focal origin with centrifugal radiation) by electroanatomic mapping. Except for one case, all pacing was performed from the proximal coronary sinus bipole. Circuitous tachycardias (n = 17, all macro-reentrant) exhibited minimal variability with pacing at 10 ms and 30 ms shorter than TCL (6.0 +/- 2.5 ms), whereas centrifugal tachycardias (n = 14, 8 microreentrant) displayed a high degree of variability (56.5 +/- 20.6 ms). Rank sum analysis of PPIV suggests that the two groups are indeed distinct (P < 0.001). Using PPIV cutoffs of <or=10 ms and >or=30 ms, circuitous and centrifugal activation patterns could be distinguished with a high degree of sensitivity (94% circuitous, 92.8% centrifugal) and 100% specificity.
  
  
  CONCLUSIONS
  Our data support the use of PPIV to rapidly and accurately predict the global activation pattern during atrial arrhythmia.
authors.affiliation: Texas Heart Institute, St. Luke's Episcopal Hospital, Houston, Texas, USA.
authors.forename: Ilyas K
authors.initials: IK
authors.lastname: Colombowala
authors.forename: Ali
authors.initials: A
authors.lastname: Massumi
authors.forename: Abdi
authors.initials: A
authors.lastname: Rasekh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Saeed
authors.forename: Jie
authors.initials: J
authors.lastname: Cheng
authors.forename: Bita
authors.initials: B
authors.lastname: Fakhri
authors.forename: Mossaab
authors.initials: M
authors.lastname: Shuraih
authors.forename: Mehdi
authors.initials: M
authors.lastname: Razavi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D013612:Tachycardia, Ectopic Atrial / Q000503:physiopathology* / Q000628:therapy*; D013997:Time Factors