A 26-year-old woman in her first pregnancy presented with persistent atrial tachycardia (AT). AT was resistant to medications, cardioversions, and the first attempt of catheter ablation. Two months after delivery she developed severe systolic dysfunction and circulatory collapse. Emergent catheter ablation was performed with the support of percutaneous cardiopulmonary bypass and intraaortic balloon pump. The AT originated in the apex of the right atrial appendage (RAA). Repeated attempts at ablation were unsuccessful, prompting surgical RAA resection, which terminated the tachycardia and improved the cardiac function. Histological examination of resected RAA provided insights into mechanism of resistance to catheter ablation.