title: Assessment of platelet function in acute ischemic stroke patients previously treated with aspirin.
abstract: BACKGROUND
  Platelet inhibition measured by platelet function tests could be critical to understand the reasons for early recurrence and to guide therapeutic recommendations. We assess the platelet function during the acute phase of ischemic stroke in patients pretreated with aspirin who continue their treatment with aspirin only, are started on clopidogrel only, or add clopidogrel to aspirin.
  
  
  METHODS
  Sixty-four patients were taking aspirin before the stroke. Depending on the administered antiplatelet, 3 groups were defined: ASA: patients who continued on aspirin orally or intravenous acetylsalicylate of lysine, n = 30; CLO: patients who discontinued aspirin and were started on clopidogrel, n = 16; and ASA + CLO: patients who were prescribed both aspirin and clopidogrel, n = 10. Collagen-induced thromboxane A2 (TXA2) synthesis, ADP (adenosine diphosphate)-induced aggregation, and occlusion time (PF-100) were measured.
  
  
  RESULTS
  CLO group only had a marked elevation of TXA2 (17.44 ± 15.62 ng/mL, P = .000) and a shortening of the platelet function analyzer (PFA)-100 closure time (157.13 ± 88 seconds, P = .047) compared with the other 2 groups (ASA: TXA2, .62 ± 1.59 ng/mL; ASA + CLO: TXA2 1.79 ± 4.59 ng/mL). They achieved a small (13%) but significant reduction of ADP-induced aggregation (87.00 ± 23.06 mm, P = .008) compared with the ASA group (102.82 ± 22.38 seconds).
  
  
  CONCLUSIONS
  Stopping aspirin intake within the first 72 hours of the acute stroke drastically increases TXA2 synthesis. During the same time window, the freshly prescribed clopidogrel manages to reduce the ADP-induced aggregation only slightly (13%). This study offers analytic proof that the common practice of replacing aspirin with clopidogrel does not leave stroke patients fully protected during the first days after an ischemic stroke. Possible solutions could be to preserve aspirin during a few days or to use loading doses of clopidogrel at hospital admission.
authors.affiliation: Department of Neurology, Hospital Universitari La Fe, Valencia, Spain. Electronic address: aidalagom@gmail.com.
authors.forename: Aida
authors.initials: A
authors.lastname: Lago
authors.affiliation: Department of Neurology, Hospital Universitari La Fe, Valencia, Spain.
authors.forename: Vera
authors.initials: V
authors.lastname: Parkhutik
authors.affiliation: Department of Neurology, Hospital Universitari La Fe, Valencia, Spain.
authors.forename: Jose Ignacio
authors.initials: JI
authors.lastname: Tembl
authors.affiliation: Research Center, Hospital Universitari La Fe, Valencia, Spain.
authors.forename: Juana
authors.initials: J
authors.lastname: Vallés
authors.affiliation: Research Center, Hospital Universitari La Fe, Valencia, Spain.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Santos
authors.affiliation: Research Center, Hospital Universitari La Fe, Valencia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Moscardó
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000008:administration & dosage* / Q000009:adverse effects; D015415:Biomarkers / Q000097:blood; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002545:Brain Ischemia / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D000077144:Clopidogrel; D057915:Drug Substitution; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D010979:Platelet Function Tests; D011237:Predictive Value of Tests; D020521:Stroke / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D013928:Thromboxane A2 / Q000097:blood; D013988:Ticlopidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D010975:Platelet Aggregation Inhibitors; D013928:Thromboxane A2; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin
keywords: Antiplatelet; aspirin; clopidogrel; ischemic stroke