 Despite its high efficacy, the RFA of atrial flutter can be sometimes very difficult. The most difficulties are done by anatomical differences in patients. 3, 4 In the area of CTI, the rudimentary Eustachian valve can be present, which can hide the effective ablation of the CI tissue. Moreover, deep pouches can be present in the TI area, which, if unrecognized, can present the area of insufficient ablation. Both of them, Eustachian valve or pouches, are not visible by fluoroscopy. In rare cases, a complete block in the CTI are is not achieved, typically due to some anatomical difficulties. Furthermore, this anatomical obstacles can lead to prolonged fluoroscopy time to find the location of conduction in CTI rea, more RF energy delivery and prolonged procedure time. Longer ablation time increases the risk of ablation such as right atrial perforation. Next possible anatomical obstacle is the right coronary artery which can effective prevent sufficient ablation due to its cooling effect. 5 Intracardiac echocardiography ICE is done by using intracardiac echo probe. The probe is inserted in the right atrium, which allows the visualizing of the CTI area. 6, 7 ICE is used for AF ablation in some centers, but its effect has never been validated in the randomized study. The aim of our study is to assess whether routine use of ICE can lead to decrease fluoroscopy time, decrease need for RFA delivery i.e. number of ablations and a decrease procedure time. On the other hand, the safety endpoint will be to assess whether a routine use of ICE is not associated with higher rate of complications. We hypothesize, the use of ICE will shorten fluoroscopy, ablation and procedural time without increased number of complication 