Comparison Between the Octaray and Pentaray Catheters in Patients Undergoing Ablation for Atrial Tachycardia.

This is a randomized open-label cross-over trial including consecutive patients undergoing ablation for atrial tachycardia of the left and right atrium. The sample-sizes of the left (N=20) and right (N=20) atrium will be equal. Half of the eligible patients with either left or right atrium AT will be randomized to undergo Coherent Mapping with Pentaray catheter first followed by Coherent Mapping with the Octaray catheter. The other half will undergo initial Coherent Mapping with the Octaray catheter followed by Pentaray catheter. This way all study participants (total N=40) will undergo the Coherent Mapping with both catheters (Figure 1). Only the second map created with either Octaray (n active arm left atrium =10 and n active arm right atrium =10) or Pentaray (n control arm left atrium =10 and n control arm right atrium =10) will be used for the subsequent ablation procedure.

The main outcome of the trial is the performance of the Coherent Mapping quality (electrograms per map) with Octaray catheter versus Pentaray catheter for left and right atrium, separately. A map will be considered complete when the fill threshold reach 5 mm for the entire surface area of the left or right atrium, that is the interpolation between points will be \<5 mm as previously reported. The high- and low-pass filters settings will be harmonized between the catheters. The following data will be collected: 1) number of electrograms per map; 2) Voltage based signal-to-noise ratio (vSNR),17 calculated as the ratio between the mean of the peak-to-peak amplitude of the true local bipolar atrial signals and the mean of the SD of the peak-to-peak of all other signals considered as far-field or ambient lab noise; 3) electrograms acquisition rate (i.e., the acquired number of points per minute of mapping); 4) electrograms acquisition density (i.e., the acquired number of electrograms per cm2 of the left or right atrium); 5) number of electrograms acquired per beat; 6) the total ablation and fluoroscopy times; 7) acute mapping success rate, defined as termination of AT at the target region; 8) number of entrainments attempted and the best post-pacing interval value at the ablation site when available. Successful entrainment is sometimes not possible (i.e., focal AT) and some investigator may prefer not to entrain. Therefore, the decision to use entrainment and the number of entrainment attempts will be left to the discretion of the operator.