RADIOFREQUENCY CATHETER ABLATION OF ATRIAL TACHYCARDIAS

Atrial tachycardias are frequently unresponsive to medical therapy. Hi s bundle ablation has been proposed as a palliative treatment to treat symptoms and prevent development of tachycardia-mediated cardiomyopat hy. Experience with catheter ablation directed at the atrial origin of the tachycardia remains limited. We reviewed the initial success rate and long-term follow-up of radiofrequency ablation of atrial tachycar dias. Thirty-six patients underwent electrophysiologic study and radio frequency ablation of atrial tachycardias, excluding atrial flutter. T he suspected mechanism of the clinical arrhythmia was automatic in 16 patients, intraatrial reentrant in 15, sinoatrial reentrant in 3, and unknown in 2. One or two ablation catheters with a 4 mm distal electro de were used to find (1) the earliest local atrial activation time com pared to P-wave onset in the bipolar recording mode and (2) a QS patte rn in the unipolar mode. When two ablation catheters were used, an enc ircling approach was taken. Pace-mapping during sinus rhythm and entra inment techniques were occasionally used for mapping. Tachycardia rose from the right atrium in 33 of 36 patients and from the left atrium i n the remaining three. Three patients showed multiple foci during the procedure. Successful ablation was obtained in 31 (86%) of 36 patients , with a median of two radiofrequency applications (range 1 to 32) at 10 to 50 W for 10 to 60 seconds. Failure occurred in 5 patients (inclu ding the 3 patients with multiple atrial foci). Late follow-up (18 +/- 15 months) showed recurrence of atrial tachycardia in 2 patients, eac h of whom underwent a successful second ablation. Emergence of another atrial tachycardia was noted in 2 other patients, and an uncommon atr ial flutter was noted in 1 patient with repaired atrial septal defect. No late sinus or atrioventricular nodal dysfunction were observed. In conclusion, radiofrequency catheter ablation is a safe and reasonable alternative for atrial tachycardias that do not respond to drugs. How ever, as previously suggested by the surgical experience, the success rate of ablation appears less satisfactory in patients with multiple s ites of origin of ectopic atrial tachycardia.