Case Presentation An 86-year-old woman with a previous history of paroxysmal atrial fibrillation was referred for atypical atrial flutter (AFL) ablation. She had never been submitted to catheter ablation before. The transthoracic echocardiogram revealed a left ventricular ejection fraction of 65%, a mildly dilated left atrium (42mm) and moderate mitral regurgitation. The baseline 12-lead ECG exhibited positive F waves in V1 and the lower limb leads, isoelectric F waves in DI and negative F wave in aVL. () Given the […]