The relationship between the P wave and local atrial electrogram in predicting conduction block during catheter ablation of cavo-tricuspid isthmus-dependent atrial flutter
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The endpoint for radiofrequency catheter ablation (RFA) of cavo-tricuspid isthmus (CTI)-dependent atrial flutter (AFL) is complete conduction block along the CTI. The purpose of this study is to evaluate the utility of the temporal relationship between the P wave and the local atrial electrograms in determining complete CTI block.
RFA of CTI was performed in 125 patients (age 63 ± 11 years). During pacing from the coronary sinus (CS), the intervals from the peak of the P wave (Ppeak) in lead V1 to the second component of the local atrial electrogram (A2) along the ablation line (Ppeak-A2) and from the end of the P wave (Pend) to A2 (Pend-A2) were investigated before and after complete block in the first 100 patients (training set). In the next 25 patients (validation set), Ppeak-A2 and Pend-A2 intervals were prospectively assessed to determine CTI block.
The mean Ppeak-A2 and Pend-A2 immediately before complete block were − 15±24 and − 39±23 ms compared to 49 ± 17 and 21 ± 16 ms after CTI block (P < 0.0001). Ppeak-A2 ≥ 20 ms and Pend-A2 ≥ 0 ms predicted CTI block with 98% sensitivity and 95% specificity and 96% sensitivity and 100% specificity, respectively. In the validation set, the positive and negative predictive values of Ppeak-A2 ≥ 20 ms or Pend-A2 ≥ 0 ms were 100 and 96%, respectively. The diagnostic accuracy was 98%.
During pacing from the CS, the temporal relationship between the P wave in lead V1 and A2 is a simple and reliable indicator of complete block during RFA of CTI-AFL.
KeywordsAtrial flutter Catheter ablation Cavo-tricuspid isthmus
Compliance with ethical standards
All patients provided informed written consent. The study protocol was approved by the Institutional Review Board.
Conflict of interest
The authors declare that they have no conflict of interest.
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