ROLE OF CATHETER-INDUCED MECHANICAL TRAUMA IN LOCALIZATION OF TARGET SITES OF RADIOFREQUENCY ABLATION IN AUTOMATIC ATRIAL TACHYCARDIA

Objectives. We compared the efficacy of two different mapping techniqu es in identifying the ablation site for atrial tachycardia. Moreover, we evaluated the additive positive predictive value of mechanical inte rruption of atrial tachycardia to reduce the number of ineffective rad iofrequency applications. Background. Radiofrequency catheter ablation has been suggested as a highly effective technique to treat drug resi stant atrial tachycardia. However, irrespective of the mapping techniq ue utilized, success was most often achieved with a large number of ra diofrequency applications. Methods. Forty-five patients with atrial ta chycardia underwent radiofrequency catheter ablation. Mapping techniqu es included identification of earliest atrial activation and pace-mapp ing concordant sequence. Results. Atrial tachycardia was successfully treated in 42 (93.3%) of 45 patients with a mean of 3.9 radiofrequency pulses/patient. An interval between the onset of the intracavitary at rial deflection and the onset of the P wave during atrial tachycardia (AP interval) greater than or equal to 30 ms (p < 0.001) and pace-mapp ing concordant sequence (p = 0.01) mere all significant predictors of outcome. An AP interval greater than or equal to 30 ms and a pace-mapp ing concordant sequence were highly sensitive (92.8%, 95% confidence i nterval [CI] 80.5% to 98.5%; 85.7%, 95% Ct 71.5% to 94.6%, respectivel y) but less specific (47.8%, 95% CI 37.9% to 58.2%; 36.8%, 95% CI 27.6 % to 47.2%, respectively) in identifying the site of ablation. By usin g atrial tachycardia mechanical interruption combined with the AP inte rval >30 ms or the pace-mapping concordant sequence, we obtained a spe cificity of 76.5% (95% CI 66.4% to 84.0%) and 73.5% (95% CI 63.2% to 8 1.4%), respectively, and a positive predictive value of 49.2% and 44.6 %, respectively. Conclusions. An AP interval greater than or equal to 30 ms and a pace-mapping concordant sequence were reliable mapping fea tures for predicting the outcome of the ablation procedure. Mechanical interruption of atrial tachycardia improved the specificity and posit ive predictive value of these two mapping techniques.