Abstract： @@ Radiofrequency (RF) ablation of the critical isthmus between the tricuspid annulus and the inferior vena cava is commonly used to treat typical atrial flutter (AFL).1 This has become the first line therapy in Europe and in the US due to its high success rate and significant improvement in quality of life compared with conventional medical therapy.2 Sizeable lesions are required to achieve persistent bidirectional conduction block (BCB), which is the best endpoint to ensurelong-term success.3,4 Cooling the ablation electrode by irrigation has been shown to prevent both overheating of the electrode-tissue interface and impedance rise during RF delivery, allowing greater power delivery and larger,deeper lesion.5 Recent studies showed that pain-free cryoablation was comparable to RF ablation regardingthe short and long-term clinical success rate and safety.6However, no studies have shown that cryoablation is superior to the irrigation RF ablation. In this study, we compared the efficacy and safety of cryoablation with the irrigation radiofrequency ablation technologies for typical AFL.