The object of this study was to assess the efficacy and risks of radiofrequency ablation of common atrial flutter and to determine the optimal site of ablation in a large population of patients. Three different methods were used to determine the site of ablation : the first was anatomical and electrophysiological whilst the two others were based essentially on anatomical landmarks for localising the critical zone of the reentry circuit. Recent studies report that radiofrequency ablation is effective in interrupting and preventing recurrences of common atrial flutter both by using anatomical and electrophysiological methods. Nevertheless, a larger series of patients was necessary to establish the efficacy and to determine the optimal site of ablation. A series of 110 consecutive patients with common atrial flutter resistant to antiarrhythmic drugs was studied. The site of ablation of the first 50 patients was determined using both anatomical landmarks and electrophysiological parameters. The anatomical zones were : zone 1, between the septal leaflet of the tricuspid valve and the orifice of the inferior vena cava; zone 2, between the septal leaflet of the tricuspid valve and the ostium of the coronary sinus, and zone 3 : between the orifice of the inferior vena cava and the ostium of the coronary sinus. The electrophysiological criterion was an endocavitary auriculogramme occurring during the plateau phase preceding the F wave of the flutter. In the next 30 patients, the efficacy of application of radiofrequency current along a single line situated in zone 1 (first 10 patients), zone 2 (second 10 patients) and zone 3 (last 10 patients), was studied. In the last 30 patients, radiofrequency current was applied in zone 1 alone, but repetitively. An energy of 12 to 30 watts was delivered for 60 to 90 seconds each time. The aim of ablation was interruption and non-inducibility of atrial flutter. Atrial flutter was interrupted and became non-inducible after a single session in 102 patients (93 %) and could not be interrupted in 8 patients (7 %). An average of 12 +/- 8 applications was necessary. After a follow-up of 28 +/- 8 months, flutter recurred in 18 patients (16 %); 14 of these patients underwent a second and third session of radiofrequency ablation with successful results. A retrospective analysis of the first 50 patients showed that the final site of ablation was in zone 1 in 39 %, zone 2 in 36 % and zone 3 in 25 % of patients. When lines of radiofrequency were applied in different zones, the success rates were 70 %, 40 % and 10 % for zones 1, 2 and 3 respectively. Repeated applications in zone 1 resulted in ablation of atrial flutter in 29 out of 30 patients. There were no complications. The authors conclude that ablation of common atrial flutter by radiofrequency current is a very successful and low risk procedure. The site where application is most successful is situated in the isthmus between the orifice of the inferior vena cava and the septal leaflet of the tricuspid valve. However, 16 % of patients require several sessions to obtain a permanent result because of recurrence. A longer follow-up is required to evaluate the long-term results of this technique.
