Electromagnetic versus fluoroscopic mapping of the inferior isthmus for ablation of typical atrial flutter - A prospective randomized study

Background-Radiofrequency catheter ablation within the tricuspid annulus-in ferior caval vein isthmus can cure typical atrial flutter. The target for a blation, nonetheless, is relatively wide, and standard ablation procedures may require significant exposure to radiation. Methods and Results-A total of 50 patients (mean age, 58+/-11 years) with t ypical atrial flutter were prospectively randomized to receive isthmus abla tion using conventional fluoroscopy for catheter navigation (group I, n=24) or electromagnetic mapping (group TT, n=26). Complete bidirectional isthmu s block was verified with double potential mapping. If complete isthmus blo ck could not be achieved after 20 radiofrequency pulses or 25 minutes of fl uoroscopy, the patients were switched to the other group. Eight patients fr om group I (33%) but only 1 patient from group II (4%) were switched. Overa ll, complete isthmus block was achieved in 47 of 50 patients (94%). The ove rall fluoroscopy time, including the placement of the diagnostic catheters, was 22.0+/-6.3 minutes in group I and 3.9+/-1.5 minutes in group II (P<0.0 001). The fluoroscopy time needed for isthmus mapping was 17.7+/-6.5 minute s in group I and 0.2+/-0.3 minutes in group II (P<0.0001). Conclusions-Electromagnetic mapping during the induction of linear lesions fur the ablation of atrial flutter permitted a highly significant reduction in exposure to fluoroscopy while maintaining high efficacy, and it allowed the time required for fluoroscopy to be reduced to levels anticipated for diagnostic electrophysiological studies.