AIMS: Radiofrequency catheter ablation of typical atrial flutter is one of the most frequent indications for catheter ablation in electrophysiology laboratories today. Clinical utility of electroanatomic mapping systems on treatment results and resource utilization compared with conventional ablation has not been systematically investigated in a prospective multicenter study. METHODS AND RESULTS: In this prospective, randomized multicenter study, the results of catheter ablation to cure typical atrial flutter using conventional ablation strategy were compared with electroanatomically guided mapping and ablation (Carto). Primary endpoints of the study were procedure duration and fluoroscopy exposure time, secondary endpoints were acute success rate, recurrence rate, and resource utilization. A total of 210 patients (169 men, 41 women, mean age 63 +/- 10 years) with documented typical atrial flutter were included in the study. Acute ablation success, that is, demonstration of bidirectional isthmus block, was achieved in 99 of 105 patients (94%) in the electroanatomically guided ablation group and in 102 of 105 patients (97%) in the conventional ablation group (P > 0.05). Total procedure duration was comparable between both study groups (99 +/- 57 minutes vs 88 +/- 54 minutes, P > 0.05). Fluoroscopy exposure time was significantly shorter in the electroanatomically guided ablation group (7.7 +/- 7.3 minutes vs 14.8 +/- 11.9 minutes; P <0.05). Total recurrence rate of typical atrial flutter at 6 months of follow-up was comparable between the 2 groups (respectively for the CARTO and conventional group 6.6% vs 5.7%, P > 0.05). The material costs per procedure in the electroanatomically guided and conventional groups (NaviStar DS vs Celsius DS) was 3035 euro (USD 3,870) and 2133 euro (USD 2,720), respectively. CONCLUSIONS: This multicenter study documented that cavotricuspid isthmus ablation to cure typical atrial flutter was highly effective and safe, both in the conventional and the electroanatomically guided ablation group. The use of electroanatomical mapping system significantly reduced the fluoroscopy exposure time by almost 50%, however, at the expense of increased cost of the procedure.