The continuing challenge of typical atrial flutter ablation: it is the anatomy! (Again)

Abstract

This editorial refers to ‘Anatomical variations of the right coronary artery may be a source of difficult block and conduction recurrence in catheter ablation of common-type atrial flutter’ by H.U. Klemm et al., on page 1608 Linear ablation of the inferior vena cava-tricuspid isthmus (CTI) has become the standard treatment for typical atrial flutter (AFL), the most common regular atrial tachycardia in clinical practice. The reasons for making the CTI the ablation target were its position as an obligatory path closing circular activation in the lower right atrium, its relative narrowness, good accessibility, and its safe distance to the atrioventricular junction. The accessibility of the CTI from the femoral vein approach did initially create expectations of an easy ablation procedure; however, 15–20% of cases pose a significant challenge, needing prolonged radiofrequency (RF) applications and long procedure times. Initial ablation procedures were performed during AFL, applying RF with electrodes 4 mm in length, a power limit of 50 W, and using AFL interruption and non-inducibility as the endpoints, and recurrence rates were 30–50%. When a bidirectional, persistent CTI block became the endpoint, recurrence rates fell to a mere 3–5%.1 The definition of CTI block as the ablation endpoint allowed performing ablation during sinus rhythm, improving catheter stability in some cases. Further progress was made by designing special catheter curves or using guiding sheaths to improve stability of the ablation electrode on the CTI, but the main breakthrough was the use of larger electrodes (8–10 mm in length) allowing the … *Corresponding author. Tel: +34 91 683 0781; fax: +34 91 624 7313, Email: fgarciacosio.hugf{at}salud.madrid.org