title: Atypical electrocardiographic features of cavotricuspid isthmus-dependent atrial flutter occurring during left atrial fibrillation ablation.
abstract: BACKGROUND
  Patients who have undergone percutaneous catheter ablation for atrial fibrillation (AF) may develop cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL), which can occur either spontaneously during left atrial (LA) ablation for AF or by induction from sinus rhythm during the procedure. The electrocardiographic (ECG) characteristics of CTI-dependent AFL occurring during LA ablation have not been described. The purpose of this study was to describe the ECG features of CTI-dependent AFL occurring during percutaneous LA catheter ablation for AF.
  
  
  RESULTS
  Of 223 patients presenting for first AF ablation at our institution between May 2004 and February 2008, 20 patients (9%) developed CTI-dependent AFL during LA ablation for AF. CTI-dependent AFL developed spontaneously in 4 patients (20%) and was induced in 16 patients (80%). Among these 20 patients, 3 (15%) had typical ECG patterns and 17 (85%) had atypical ECG patterns. Flutter waves in the inferior leads were biphasic in 10 patients (50%), downward in 3 patients (15%), positive in 3 patients (15%), and not fitting the above classifications in 4 patients (20%). There was no statistically significant association between AFL pattern and LA size, left ventricular ejection fraction, total ablation time, duration of prior AF, or type of prior AF.
  
  
  CONCLUSIONS
  A majority of patients with CTI-dependent AFL occurring during LA ablation have atypical ECG patterns. Biphasic flutter waves in the inferior leads are common ECG features, occurring in one-half of patients. Right atrial CTI-dependent AFL should be suspected even if the ECG appearance is atypical.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Janice Y
authors.initials: JY
authors.lastname: Chyou
authors.forename: Kathleen
authors.initials: K
authors.lastname: Hickey
authors.forename: Laurence
authors.initials: L
authors.lastname: Diamond
authors.forename: William
authors.initials: W
authors.lastname: Whang
authors.forename: Jose
authors.initials: J
authors.lastname: Dizon
authors.forename: Hasan
authors.initials: H
authors.lastname: Garan
authors.forename: Angelo
authors.initials: A
authors.lastname: Biviano
mesh_terms: D001281:Atrial Fibrillation / Q000150:complications / Q000601:surgery*; D001282:Atrial Flutter / Q000209:etiology* / Q000503:physiopathology*; D017115:Catheter Ablation / Q000009:adverse effects*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014261:Tricuspid Valve / Q000503:physiopathology / Q000601:surgery; D014682:Vena Cava, Inferior / Q000503:physiopathology / Q000601:surgery