title: Regulation of platelet glycoprotein VI (GPVI) surface expression and of soluble GPVI in patients with atrial fibrillation (AF) and acute coronary syndrome (ACS).
abstract: BACKGROUND
  The platelet collagen receptor glycoprotein VI (GPVI) mediates platelet adhesion to subendothelial matrix and thrombus formation in acute coronary syndrome (ACS). This study examined patients with both ACS and stable coronary artery disease (CAD), which presented with atrial fibrillation (AF) and sinus rhythm (SR).
  
  
  RESULTS
  We evaluated 992 patients with acute or stable CAD, and determined platelet surface expression of GPVI using flow cytometry. Seventy-eight patients presented with nonvalvular persistent AF. After 1:1 propensity score matching 156 matched cases with 78 pairs were obtained. Patients with AF and ACS showed a significantly decreased GPVI expression compared to patients with ACS and SR, whereas patients with stable angina pectoris (SA) presented with low level activation and no significant difference between SR and AF [mean fluorescence intensity (MFI) for ACS (SR Vs. AF): 20 +/- 6.3 Vs. 17.7 +/- 4.4; P = 0.023; SA (SR Vs. AF): 18.8 +/- 9.4 Vs. 18.1 +/- 6.1; P = 0.649]. In contrast, soluble GPVI was increased in ACS and AF accordingly [plasma GPVI (ng/ml) for ACS (SR Vs. AF): 1.4 +/- 0.8 Vs. 1.9 +/- 1.1; P = 0.038; SA (SR Vs. AF): 0.9 +/- 0.4 Vs. 1.1 +/- 0.5; P = 0.127].
  
  
  CONCLUSIONS
  Platelet GPVI surface expression is decreased in patients with AF and ACS compared to patients with SR and ACS. Nonvalvular AF is related to indices of chronic platelet activation and might be responsible for a down-regulation of GPVI receptor density on platelets, while soluble GPVI was increased in ACS and AF accordingly.
authors.affiliation: Medizinische Klinik III, Klinik für Kardiologie und Kreislauferkrankungen, Eberhard-Karls-Universität Tübingen, Tübingen, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Bigalke
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Stellos
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Weig
authors.forename: Tobias
authors.initials: T
authors.lastname: Geisler
authors.forename: Peter
authors.initials: P
authors.lastname: Seizer
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Kremmer
authors.forename: Oliver
authors.initials: O
authors.lastname: Pötz
authors.forename: Thomas
authors.initials: T
authors.lastname: Joos
authors.forename: Andreas E
authors.initials: AE
authors.lastname: May
authors.forename: Stephan
authors.initials: S
authors.lastname: Lindemann
authors.forename: Meinrad
authors.initials: M
authors.lastname: Gawaz
mesh_terms: D054058:Acute Coronary Syndrome / Q000378:metabolism*; D000368:Aged; D001281:Atrial Fibrillation / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism; D003324:Coronary Artery Disease / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*
chemical_list: D010980:Platelet Membrane Glycoproteins; C098341:platelet membrane glycoprotein VI