Catheter ablation of typical atrial flutter - A randomized comparison of 2methods for determining complete bidirectional isthmus block

Background-Complete bidirectional isthmus conduction block (CBIB) was initi ally assessed by sequential detailed activation mapping at both sides of th e ablation line during proximal coronary sinus and anteroinferior right atr ium pacing. Mapping only the ablation line ("on-site" atrial potential anal ysis) was recently reported as a means of CBIB identification. The study wa s designed to compare these 2 techniques prospectively regarding the diagno sis of CBIB. Methods and Results-In 76 consecutive patients (mean age, 63.4 +/- 10.5 yea rs), typical atrial flutter ablation was performed using either the activat ion mapping technique (group I) or on-site atrial potential analysis (group II). Criteria for CBIB using on-site atrial potential analysis was the rec ording of parallel, widely spaced double atrial potentials along the ablati on line. The CBIB criterion was retrospectively searched using the alternat ive technique at the end of the procedure. In successful patients, the mean radiofrequency delivery duration was longer in group II (845 +/- 776 versu s 534 +/- 363 s; P=0.03). On-site, clear-cut, widely spaced double atrial p otentials and activation mapping suggesting CBIB were concomitantly observe d in only 47 patients (54%), and ambiguous/atypical double potentials were recorded in 31 patients (39%). Conclusions-Although feasible, the on-site atrial potential analysis seemed to be inferior to the classic activation mapping technique, mainly because of the ambiguity of electrogram interpretation along the ablation line, Ho wever, when combined with the activation mapping technique, it provided add itional information regarding isthmus conduction properties in some cases. Therefore, optimally, both methods should be used concomitantly.