Activation mapping of focal atrial tachycardia: the impact of the method for estimating activation time.
OBJECTIVE
Different methods can be used to estimate activation time during the mapping of focal atrial tachycardia. The present study aimed to compare activation maps generated by three widely used methods of determining activation time.


METHODS
Fourteen patients (mean age 48 +/- 17 years) with focal atrial tachycardia were investigated. Mapping was performed with the CARTO system. All patients underwent successful ablation. Local activation time was successively defined as the peak amplitude (Bi-peak), the steepest downslope (Bi-dslope), and the onset (Bi-on) of the bipolar electrograms.


RESULTS
The three methods of activation time determination were highly correlated with one another but generated foci with different locations. The distances between the foci generated by the different methods were 4.36 +/- 4.91 mm (Bi-peak-Bi-dslope), 7.21 +/- 5.11 mm (Bi-peak-Bi-on), and 7.21 +/- 5.87 mm (Bi-dslope-Bi-on) (p = 0.26). Also, the three methods generated foci with different diameters: 3.13 +/- 2.17 mm for Bi-peak, 2.81 +/- 0.78 for Bi-dslope, and 2.54 +/- 0.14 mm for Bi-on (p = 0.60). However, the foci tended to cluster within relatively wide regions of low-amplitude fractionated electrograms. The surface of these regions was 3.81 +/- 2.34 cm(2) (Bi-peak), 3.38 +/- 2.12 cm(2) (Bi-dslope), and 4.76 +/- 3.01 cm(2) (Bi-on) (p = 0.34).


CONCLUSIONS
The three methods of activation time determination, although highly correlated with one another, may generate foci of different sizes and in different locations. However, the foci tend to cluster within relatively large areas of low-amplitude fractionated electrograms. These findings suggest a sizeable atrial region with particular electrophysiological proprieties and raise the possibility of an anatomical substrate of the tachycardia. During mapping, this region can be roughly delineated by all three methods of activation time estimation. However, details concerning the activation pattern within the region and the location of the focus vary among the methods.
Department of Cardiology, University Hospital Linköping, 581 85 Linköping, Sweden. ioan.liuba@liu.se
Ioan
I
Liuba
Håkan
H
Walfridsson
D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013612:Tachycardia, Ectopic Atrial / Q000175:diagnosis* / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult