Background: Recently radiofrequency (RF) catheter ablation (CA) of atrial tachycardia (AT) showed to be highly effective with a low incidence of compliance. Aim of our study was to report the results and follow-up of RFCA of drug-refractory AT in 59 consecutive patients (pts).
Methods: Two mapping techniques were used to localize the ablation site of AT: the earliest atrial activation and the pace-mapping. Traumatic interruption of AT was used to verify the ablation site identified by the previous procedures. Moreover we evaluated the sensitivity, specificity and the positive predictive value of the three mapping techniques.
Results: AT was successfully treated in 55/59 (93.2%) pts with a mean of 4.0 +/- 3.8 (range 1-16) RF pulses for patient. The mean procedure time was 185.2 +/- 48.5 min with a mean rx-time of 41.5 +/- 21.3 min. An interval between the onset of the intracavitary atrial deflection and the onset of the P-wave, during atrial tachycardia, (AP interval) > or = 30 ms and pace-mapping concordant sequence were highly sensitive (90.9% and 89.1%) but less specific (49.2% and 33.9%) in identifying the site of ablation. By using atrial tachycardia traumatic interruption combined with the AP interval > 30 ms or the pace-mapping concordant sequence we obtained a specificity of 78.7% and 77.0% respectively and a positive predictive value of 48.0% and 46.8% respectively. Four recurrences (7.3%) were observed during a mean follow-up of 23.4 +/- 13.3 months. In the 22 (37.3%) pts with dilated cardiomyopathy, chest Xr and echocardiography showed a significant decrease of cardiothoracic index (0.56 +/- 0.08 pre ablation, 0.43 +/- 0.07 post ablation, p < 0.001) and end-diastolic diameter (64 +/- 8 mm pre ablation, 52 +/- 8 mm post ablation, p < 0.001) and a significant improvement of left ventricular ejection fraction (37 +/- 9% pre ablation, 48 +/- 11% post ablation, p < 0.05).
Conclusion: The RFCA of AT was effective and safe. Moreover we observed a hemodynamic improvement in patients with reduced ejection fraction and increased cardiac volumes. An AP interval > or = 30 ms and the pace-mapping concordant sequence were reliable features to predict the outcome of the ablation procedure. Traumatic ablation of atrial tachycardia improved the specificity and the positive predictive value of these two mapping techniques and was able to predict the response to radiofrequency with a high specificity.