title: Factors influencing the level of circulating procoagulant microparticles in acute pulmonary embolism.
abstract: BACKGROUND
  Flow cytometry has shown levels of platelet-derived microparticles (PMPs) and endothelial-derived microparticles (EMPs) to be elevated in deep-vein thrombosis. Cardiovascular risk factors can also contribute to hypercoagulability due to circulating procoagulant microparticles (CPMPs).
  
  
  OBJECTIVE
  To investigate in a case-control study the respective contribution of pulmonary embolism and cardiovascular risk factors to the level of hypercoagulability due to CPMPs.
  
  
  METHODS
  CPMP, PMP and EMP levels were measured in 45 consecutive patients (age 67.9 +/- 11.6 years; 66.7% men) admitted to an intensive care unit for acute pulmonary embolism (APE), 45 healthy control subjects with no history of venous thromboembolism or vascular risk factors (Controls(noCVRFs)), and 45 patients with cardiovascular risk factors (Controls(CVRFs)). APE was diagnosed by spiral computed tomography or scintigraphy. CPMP levels were assessed using a prothrombinase assay on platelet-depleted plasma (results expressed as nmol/L equivalent).
  
  
  RESULTS
  CPMP levels were higher in APE patients than in Controls(noCVRFs) (medians 4.7 vs 3.2 nmol/L, interquartile ranges [IQRs] 2.9-11.1 vs 2.3-4.6 nmol/L; p=0.02). Similar results were reported for PMPs (medians 2.2 vs 1.9 nmol/L, IQRs 1.7-5.8 vs 1.4-2.4 nmol/L; p=0.02), whereas EMP levels were not significantly different. However, CPMP procoagulant activity was not significantly different in APE patients and Controls(CVRFs).
  
  
  CONCLUSIONS
  CPMPs and PMPs were significantly elevated in APE patients vs Controls(noCVRFs), but this correlation was not significant when APE patients were compared with Controls(CVRFs). Our observations highlight the importance of adjusting for the presence of cardiovascular risk factors in conditions in which microparticle levels are raised.
authors.affiliation: Cardiology Department, Saint-Antoine University and Medical School, Assistance Publique-Hôpitaux de Paris, université Pierre-et-Marie-Curie, 75571 Paris cedex 12, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Bal
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ederhy
authors.forename: Emanuele
authors.initials: E
authors.lastname: Di Angelantonio
authors.forename: Florence
authors.initials: F
authors.lastname: Toti
authors.forename: Fatiha
authors.initials: F
authors.lastname: Zobairi
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Dufaitre
authors.forename: Catherine
authors.initials: C
authors.lastname: Meuleman
authors.forename: Ziad
authors.initials: Z
authors.lastname: Mallat
authors.forename: Franck
authors.initials: F
authors.lastname: Boccara
authors.forename: Alain
authors.initials: A
authors.lastname: Tedgui
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Freyssinet
authors.forename: Ariel
authors.initials: A
authors.lastname: Cohen
mesh_terms: D000208:Acute Disease; D000368:Aged; D001777:Blood Coagulation; D001792:Blood Platelets / Q000473:pathology*; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology* / Q000473:pathology; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000473:pathology*; D016009:Chi-Square Distribution; D042783:Endothelial Cells / Q000473:pathology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000097:blood* / Q000000981:diagnostic imaging / Q000473:pathology*; D011877:Radionuclide Imaging; D018570:Risk Assessment; D012307:Risk Factors; D019851:Thrombophilia / Q000097:blood / Q000209:etiology* / Q000473:pathology; D036542:Tomography, Spiral Computed