OBJECTIVE Both ablation catheters with irrigated system and 8mm tip-catheters have shown to be more effective for typical atrial flutter radiofrequency (RF) ablation when compared to conventional 4 mm tip catheter. The purpose of this prospective study was to compare the efficiency of radiofrequency catheter ablation (RFA) of the cavotricuspid isthmus using a new type of open irrigation-tip catheter versus 8 mm tip-catheters to eliminate atrial flutter (AFL). METHODS Sixty consecutive patients, matched for age, presence of cardiopathy, atrial dimensions and comorbidity, underwent RF ablation of cavotricuspid isthmus (CTI) for the treatment of typical atrial flutter, using an open irrigated tip catheter - Surround Flow™ - (N.=30) or an 8-mm-tip catheter (N.=30). The RF pulses were applied point-by-point for 30 seconds, with power limited at 35 w for the irrigated catheter and by temperature control (60/70 w) for the 8-mm catheter. RESULTS The CTI block was successfully performed in 100% of cases. There was no significant difference with regard to ablation parameters, such as total time of RF ablation (608±324 vs. 556±244 s, P=0.79), number of RF applications (12±8 vs. 10±5, P=0.56), total procedure duration (86.4±23.6 vs. 78.1±22.5 min, P=0.58) and time of fluoroscopy (12±6 vs. 14±6 min, P=0.25) and periprocedural complications (1 groin hematoma in the 8 mm group). During follow-up of 11.6 months on average, one patient in the 8 mm group had recurrence of typical atrial flutter. CONCLUSIONS Efficacy and safety of CTI ablation was comparable between both techniques (open irrigated catheter and 8mm tip catheter). The ablation parameters were comparable and homogeneous between the two groups.