AIMS:We describe a new strategic stepwise mapping approach for fast and accurate identification and ablation of ectopic atrial foci using an electroanatomic mapping system.METHODS AND RESULTS:Mapping procedures started with the acquisition of four points at the superior/septal part of the tricuspid annulus. According to this activation sequence, maps were continued towards the right atrial free wall if relatively early activation was shown at the superior part of the initial map or towards the triangle of Koch and, if necessary, to the left atrium, in cases of relatively early activation at the septum. High density mapping and detailed electrogram analysis only of the target area allowed identification and ablation of 34 foci in 30 of the 32 studied consecutive patients. A small number of mapping points were sufficient within a procedure time of 90 +/- 41 min for right 148 +/- 68 min and for left sided foci and a total fluoroscopy time of 9.6 +/- 7.2 min and 24.8 +/- 16.4 min respectively. Sixteen foci were located at the right free wall, eight at the left free wall, and 10 at the right or left side of the septum.CONCLUSION:Strategic electroanatomic mapping with fast identification of the area of tachycardia origin and high density mapping only of this target area allowed fast and successful localization and ablation of right and left free wall and septal ectopic atrial foci.

Background —Radiofrequency catheter ablation within the tricuspid annulus–inferior caval vein isthmus can cure typical atrial flutter. The target for ablation, 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 typical atrial flutter were prospectively randomized to receive isthmus ablation using conventional fluoroscopy for catheter navigation (group I, n=24) or electromagnetic mapping (group II, n=26). Complete bidirectional isthmus block was verified with double potential mapping. If complete isthmus block could not be achieved after 20 radiofrequency pulses or 25 minutes of fluoroscopy, the patients were switched to the other group. Eight patients from group I (33%) but only 1 patient from group II (4%) were switched. Overall, complete isthmus block was achieved in 47 of 50 patients (94%). The overall 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 <0.0001). The fluoroscopy time needed for isthmus mapping was 17.7±6.5 minutes in group I and 0.2±0.3 minutes in group II ( P <0.0001). Conclusions —Electromagnetic mapping during the induction of linear lesions for 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.