Abstract
BACKGROUND: Postsurgical atrial flutter constitutes a significant portion of atypical atrial flutter. Its activation sequence is complex and exhibits significant individual variation. CASE SUMMARY: A 76-year-old woman with a history of atrial septal defect repair was admitted for atrial flutter. Although initial mapping suggested a focal atrial tachycardia originating from the left anterior wall, complex signal identification revealed previously overlooked prolonged low-amplitude fragmented potentials within the map. This unveiled a macro-re-entrant circuit around the right superior pulmonary vein. After radiofrequency ablation at the critical fragmented potential site, sinus rhythm was restored. DISCUSSION: In this case, the final mapping diagnosis markedly differed from the initial interpretation, highlighting the critical importance of precisely identifying the key slow conduction zone. TAKE-HOME MESSAGES: Tachycardias after cardiac surgery are predominantly atypical atrial flutter. Detailed mapping and meticulous analysis are paramount for successful ablation of complex tachycardias.