title: Reduced apelin levels in lone atrial fibrillation.
abstract: OBJECTIVE
  Apelin is an endogenous peptide hormone that appears to have a physiological role in counter-regulation of the angiotensin and vasopressin systems. This peptide has been reported to be down-regulated in subjects with acute heart failure, but has not been studied in other cardiovascular conditions. We studied apelin levels in 73 subjects with lone atrial fibrillation (AF).
  
  
  RESULTS
  Study subjects had electrocardiographic evidence of paroxysmal or chronic AF and a structurally normal heart on echocardiography. Subjects were excluded if they had a history of coronary artery disease, rheumatic heart disease, cardiomyopathy, significant valvular disease, hyperthyroidism, or antecedent hypertension. Controls were recruited from a healthy outpatient population. Plasma apelin levels were determined using a commercially available immunoassay. Seventy-three subjects with lone AF and 73 healthy controls were enrolled and studied. Mean levels of apelin were significantly lower in subjects with lone AF when compared with controls (307 vs. 648 pg/mL, P<0.00005).
  
  
  CONCLUSIONS
  Reduced apelin levels were observed in this homogenous population of lone AF subjects and may represent an underlying diathesis predisposing to this common arrhythmia.
authors.affiliation: Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Boston, MA, USA.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Ellinor
authors.forename: Adrian F
authors.initials: AF
authors.lastname: Low
authors.forename: Calum A
authors.initials: CA
authors.lastname: Macrae
mesh_terms: D001281:Atrial Fibrillation / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002908:Chronic Disease; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis
chemical_list: D015415:Biomarkers; D036341:Intercellular Signaling Peptides and Proteins; C495200:apelin-12 peptide