Local electrogram assessment of unidirectional isthmus block is sufficient to predict the acute and long-term success of cavo-tricuspid isthmus ablation.

BACKGROUND: This study investigated whether a minimal approach to typical atrial flutter ablation using an 8 mm tip catheter with a 150 W generator with only the documentation of clockwise block by means of local criteria predicts a good long-term outcome. METHODS: Seventy patients underwent typical atrial flutter ablation. A multipolar catheter was inserted into the coronary sinus (CS) and an 8 mm tip ablation catheter was used to ablate and map the isthmus. The ablation line was performed in the posteroseptal region. The clockwise block was confirmed by recording a corridor of double potentials along the line and by counterclockwise activation of the portion of the isthmus just beyond the lesion line as demonstrated by measuring the conduction times during CS pacing. RESULTS: In case of block, the mean distance between the two split atrial electrograms was 129 +/- 31 ms. Acute isthmus block was achieved in all 70 patients. The median of the radiofrequency pulses was 10 (range 1-36). No immediate or late complications were noted. The long-term follow-up (19.5 +/- 4 months) revealed recurrence of typical atrial flutter in 2 cases (2.8%). CONCLUSIONS: Our results demonstrate that the acute success rate following typical atrial flutter isthmus ablation using an 8 mm tip catheter with a 150 W generator is high. No complications occurred. Moreover, the documentation of just the clockwise isthmus block using a minimal approach according to local electrogram criteria is a good predictor of the long-term success.