title: Clinical validation and comparison of alternative methods for evaluation of entrainment mapping.
abstract: BACKGROUND
  Measuring the postpacing interval (PPI) and correcting for the tachycardia cycle length (TCL) is an important entrainment response (ER). However, it may be impossible to measure PPI due to electrical noise on the mapping catheter. To overcome this problem, 2 alternative methods for the assessment of ER have been proposed: N+1 difference (N+1 DIFF) and PPIR method. PPI-TCL difference (PPI-TCL) correlates very well with ER assessed by new methods, but the agreement with PPI-TCL was established only in relation to PPIR method. Moreover, it is not known which of these methods is superior in the assessment of ER.
  
  
  METHODS
  We analyzed 155 episodes of ER in 21 patients with heterogeneous reentrant arrhythmias. ER was estimated by PPI-TCL and by both alternative methods. Agreement between methods was assessed by means of the Bland-Altman test, kappa coefficient (kappa), and correlation coefficient (r). Finally, a mathematical comparison of the alternative methods was performed.
  
  
  RESULTS
  The agreement between PPI-TCL and alternative methods was very good. For N+1 DIFF the mean difference was -1.86 +/- 7.31 ms; kappa = 0.9; r = 0.98; for PPIR method the mean difference was -1.46 +/- 7.65 ms; kappa = 0.92; r = 0.99. Agreement between both alternative methods was also very high: the mean difference of 0.5 +/- 6.6 ms; kappa = 0.89; r = 0.99. The analysis of the equations used for calculation of ER by these methods revealed that essentially they were mathematically equivalent.
  
  
  CONCLUSIONS
  Each of the alternative methods may be used for evaluation of ER when PPI-TCL cannot be assessed directly. Results obtained by both alternative methods are comparable.
authors.affiliation: Institute of Cardiology, Warsaw, Poland. pderejko@yahoo.com
authors.forename: Paweł
authors.initials: P
authors.lastname: Derejko
authors.forename: Łukasz J
authors.initials: ŁJ
authors.lastname: Szumowski
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
authors.forename: Hany
authors.initials: H
authors.lastname: Dimitri
authors.forename: Paweł
authors.initials: P
authors.lastname: Kuklik
authors.forename: Andrzej
authors.initials: A
authors.lastname: Przybylski
authors.forename: Piotr
authors.initials: P
authors.lastname: Urbanek
authors.forename: Ewa
authors.initials: E
authors.lastname: Szufladowicz
authors.forename: Robert
authors.initials: R
authors.lastname: Bodalski
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sacher
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
authors.forename: Franciszek
authors.initials: F
authors.lastname: Walczak
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D054139:Tachycardia, Reciprocating / Q000175:diagnosis* / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome