Abstract
Focal atrial tachycardia arising from the right atrial appendage (RAAT) may be misdiagnosed as sinus tachycardia. The electrocardiogram from this case demonstrates a negative notched P-wave in leads V(1) and V(2) during RAAT compared with a beat of sinus rhythm. RAAT was confirmed and eliminated with mapping and ablation. (Level of Difficulty: Advanced.).