title: Elevated M2-muscarinic and β1-adrenergic receptor autoantibody levels are associated with paroxysmal atrial fibrillation.
abstract: BACKGROUND
  Pathophysiologic mechanisms underlying lone atrial fibrillation (AF) have not been clearly demonstrated yet. Emerging evidence has indicated that autoimmunity may play a role in the development of AF. Relationship between serum anti-M2-muscarinic receptor autoantibody (anti-M2-R) and anti-β1-adrenergic receptor autoantibody (anti-β1-R) levels and lone paroxysmal atrial fibrillation (PAF) has not been investigated. We aimed to compare anti-M2-R and anti-β1-R levels between lone PAF patients and healthy control subjects.
  
  
  RESULTS
  75 patients with lone PAF (age: 52.80 ± 6.80 years, 53 % male) and 75 healthy control subjects (age: 53.30 ± 6.80 years, 54 % male) were enrolled in the study. Serum anti-M2-R and anti-β1-R levels were measured by ELISA and compared between two groups. Anti-M2-R [142.30 (77.65-400.00) vs. 69.00 (39.48-299.04) ng/mL; p < 0.001) and anti-β1-R [102.56 (65.18-348.41) vs. 44.17 (30.89-158.54) ng/mL; p < 0.001] levels were significantly higher in patients with lone PAF compared to healthy controls. Multivariate regression analysis showed that left atrial diameter (OR: 1.471, p < 0.001), hs-CRP(OR: 1.940, p < 0.001), anti-M2-R (OR: 1.158, p < 0.001) and anti-β1-R (OR: 1.296, p < 0.001) levels were independent predictors for the presence of lone PAF. Using a cut-off level of 101.83 ng/mL, anti-M2-R levels predicted presence of lone PAF with a sensitivity of 94.68 % and specificity of 81.33 %. Anti-β1-R levels predicted presence of lone PAF with a sensitivity of 92.00 % and specificity of 73.30 %, using a cut-off level of 72.16 ng/mL.
  
  
  CONCLUSIONS
  Our results demonstrated that higher serum anti-M2-R and anti-β1-R levels are associated with lone PAF. Autoantibodies related to autonomic system may play an important role in the development of lone AF.
authors.affiliation: Department of Cardiology, Hacettepe University Faculty of Medicine, 06100, Ankara, Turkey.
authors.forename: Muhammed U
authors.initials: MU
authors.lastname: Yalcin
authors.forename: Kadri M
authors.initials: KM
authors.lastname: Gurses
authors.forename: Duygu
authors.initials: D
authors.lastname: Kocyigit
authors.forename: Sacit Altug
authors.initials: SA
authors.lastname: Kesikli
authors.forename: Ahmet Hakan
authors.initials: AH
authors.lastname: Ates
authors.forename: Banu
authors.initials: B
authors.lastname: Evranos
authors.forename: Hikmet
authors.initials: H
authors.lastname: Yorgun
authors.forename: Mehmet L
authors.initials: ML
authors.lastname: Sahiner
authors.forename: Ergun B
authors.initials: EB
authors.lastname: Kaya
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Oto
authors.forename: Dicle
authors.initials: D
authors.lastname: Guc
authors.forename: Necla
authors.initials: N
authors.lastname: Ozer
authors.forename: Kudret
authors.initials: K
authors.lastname: Aytemir
mesh_terms: D001281:Atrial Fibrillation / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D043585:Receptor, Muscarinic M2 / Q000276:immunology*; D018342:Receptors, Adrenergic, beta-1 / Q000276:immunology*; D012307:Risk Factors; D014421:Turkey; D015854:Up-Regulation
chemical_list: C547787:ADRB1 protein, human; D001323:Autoantibodies; D015415:Biomarkers; C487078:CHRM2 protein, human; D043585:Receptor, Muscarinic M2; D018342:Receptors, Adrenergic, beta-1