title: Resistance to platelet antiaggregants: an important cause of very late thrombosis of drug eluting stents? Observations from five cases.
abstract: BACKGROUND
  Very late thrombosis of drug eluting stents is a rare complication that might be triggered by resistance to platelet antiaggregants (PAAs).
  
  
  OBJECTIVE
  Following an initial case where clinical data strongly suggested resistance to PAAs, we carried out a prospective systematic analysis of platelet aggregation in four subsequent cases of late thrombosis.
  
  
  METHODS
  Resistance to aspirin was investigated with the PFA-100 test employing a collagen-epinephrine cartridge (Platelet Function Analyzer; Dade Behring). Resistance to clopidogrel was determined by flow cytometry of intraplatelet vasodilator-stimulated phosphoprotein (VASP) phosphorylation.
  
  
  RESULTS
  All four cases showed resistance to either aspirin or clopidogrel, and two cases showed dual resistance to both of these PAAs.
  
  
  CONCLUSIONS
  Analysis of platelet function in a patient with late stent thrombosis is useful and may allow adaptation of subsequent patient management. The value of monitoring platelet function after implantation of a drug eluting stent should be evaluated in prospective studies.
authors.affiliation: Service de cardiologie et urgences cardiologiques, Centre hospitalier universitaire de Grenoble.
authors.forename: G
authors.initials: G
authors.lastname: Barone-Rochette
authors.forename: O
authors.initials: O
authors.lastname: Ormezzano
authors.forename: B
authors.initials: B
authors.lastname: Polack
authors.forename: G
authors.initials: G
authors.lastname: Vanzetto
authors.forename: B
authors.initials: B
authors.lastname: Bertrand
authors.forename: J
authors.initials: J
authors.lastname: Machecourt
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000494:pharmacology*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D000077144:Clopidogrel; D003328:Coronary Thrombosis / Q000209:etiology* / Q000401:mortality; D004351:Drug Resistance; D054855:Drug-Eluting Stents / Q000009:adverse effects*; D005260:Female; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D008875:Middle Aged; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D010979:Platelet Function Tests; D011446:Prospective Studies; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D005343:Fibrinolytic Agents; D008840:Microfilament Proteins; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D000098662:Vasodilator-Stimulated Phosphoprotein; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin