A Case of Roof‐Dependent Atrial Flutter With an Endocardial Narrow Channel Successfully Visualized by the Peak Frequency Analysis

Roof-dependent atrial flutter (AFL) can sometimes be challenging to treat with endocardial catheter ablation due to the thickness of the atrial myocardium and the separation of outer epicardial conductive fibers from the endocardial myocardium. This case highlights the utility of peak frequency (PF) analysis during the AFL, which can visualize a narrow endocardial channel and help physicians select an optimal therapeutic target to achieve a transmural line of block.