title: Electrophysiological characteristics of left atrial diverticulum in patients with atrial fibrillation: electrograms, impedance and clinical implications.
abstract: BACKGROUND
  Left atrial diverticulum (LAD) is not rare in patients with atrial fibrillation (AF). Recent reports focused on its morphology however data on its electrophysiological characteristics are lacking. Our study aims to investigate the electrogram and impedance features of LAD.
  
  
  METHODS
  This study included 24 patients (mean age, 58.5 ± 10.7 years) with LAD undergoing catheter ablation for AF and 24 gender-and-age-matched individuals without LAD as controls. A bipolar LAD electroanatomic map was acquired in sinus rhythm from all study participants. Points were acquired for diverticulum in the LAD group and for corresponding areas in the control group. Electrogram deflections were counted, bipolar voltage and impedance were measured for each point, and average ∆ impedance and highest ∆ impedance were calculated.
  
  
  RESULTS
  A total of 234 points were collected in the two groups. In the LAD vs. control group, median (Q1, Q3) of electrogram deflections was 6 (5, 7) and 4 (4, 5) (P<0.0001), respectively, voltage was not significantly different (1.58 ± 0.68 mV vs. 1.28 ± 0.65 mV, P=0.10), and average ∆ impedance was significantly higher in the LAD group (19.5 ± 9.0 Ω vs 3.9 ± 1.7 Ω, P<0.0001). A cut-off value of 9.5 Ω for ∆ impedance predicted LAD with sensitivity, specificity, and positive and negative predictive values of 83.5%, 92.8%, 92.1% and 84.9%, respectively.
  
  
  CONCLUSIONS
  Electrogram was more fractionated and impedance was higher at LAD than in corresponding areas without LAD, which might help to differentiate LAD during catheter ablation for AF.
authors.affiliation: Department of Cardiology, Beijing Military Region General Hospital of PLA, Beijing, China. Electronic address: happytanchen@126.com.
authors.forename: Chen
authors.initials: C
authors.lastname: Tan
authors.affiliation: Department of Radiology, Beijing Military Region General Hospital of PLA, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.affiliation: Department of Cardiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
authors.forename: Xingpeng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Cardiology, Beijing Military Region General Hospital of PLA, Beijing, China.
authors.forename: Xuehong
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Cardiology, Beijing Military Region General Hospital of PLA, Beijing, China.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Cardiology, Beijing Military Region General Hospital of PLA, Beijing, China.
authors.forename: Junyu
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Cardiology, Beijing Military Region General Hospital of PLA, Beijing, China.
authors.forename: Junxia
authors.initials: J
authors.lastname: Li
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*; D016279:Atrial Function, Left; D018780:Body Surface Potential Mapping / Q000379:methods*; D004240:Diverticulum / Q000175:diagnosis* / Q000503:physiopathology*; D017097:Electric Impedance; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Atrial fibrillation; Catheter ablation; Electroanatomic mapping; Impedance; Left atrial diverticulum