Catheter ablation of atrial tachycardia originated from the left atrial epicardium

A patient was referred with frequent atrial tachycardia (AT) attacks. Activation mapping showed that the left atrium (LA) roof was earlier activated with a broad region, and right atrial activation was delayed. The far-field A wave corresponding to the pulmonary artery area was advanced with failed ablation. Therefore, the AT could be left atrial epicardial origin, which was further confirmed by the successful ablation at earliest activated site at the epicardium.