title: Platelet activation and microvascular injury in patients with ST-segment elevation myocardial infarction.
abstract: BACKGROUND
  Dual antiplatelet therapy reduces the risk of thrombotic complications after primary percutaneous coronary intervention (PCI).
  
  
  OBJECTIVE
  To assess whether inhibition of platelet function attenuates microvascular damage in patients with ST-segment elevation myocardial infarction (STEMI).
  
  
  METHODS
  We studied 83 STEMI patients treated with primary PCI. Platelet aggregation was measured on admission (ADM) and 4 days later (D4) by light transmission aggregometry after stimulation with 0.5 mM of arachidonic acid and after stimulation with 5 and 20 μM of adenosine diphosphate (ADP) on treatment with dual antiplatelet therapy with aspirin and clopidogrel. Platelet-neutrophil aggregate (PNA) and platelet-monocyte aggregate (PMA) were analysed by flow cytometry. Contrast-enhanced magnetic resonance imaging was performed 2-4 days after STEMI to detect the area of perfusion defect at rest and to determine the size of microvascular obstruction. Microvascular obstruction was expressed as a percentage of infarct area.
  
  
  RESULTS
  Perfusion defect at rest was found in 56 (67.5%) patients whereas microvascular obstruction in 63 (75.9%) patients. Patients with perfusion defect at rest had on admission a significantly higher level of both PMA (7.0 vs. 4.5%, p = 0.004) and PNA (4.1 vs. 2.2%, p = 0.016), however there were no significant differences at D4. Platelet aggregation after stimulation with 5 μM of ADP on ADM was correlated (r = 0.37, p = 0.004) with microvascular obstruction area. Moreover, the higher the concentration of PMA(ADM) (r = 0.31, p = 0.016), PNA(ADM) (r = 0.34, p = 0.006) and PM(AD4) (r = 0.35, p = 0.005) the larger the size of microvascular obstruction. Infarct size (β = 0.43, 95% CI 0.19 to 0.67, p 〈 0.0001), TIMI < 3 after PCI (β = -0.27, 95% CI -1.90 to -0.11, p = 0.015) and PMA(D4) (β = 0.21, 95% CI 0.13 to 1.86, p = 0.032) independently influenced the size of microvascular obstruction (R2 = 0.60, p 〈 0.0001).
  
  
  CONCLUSIONS
  Excessive platelet activation during reperfusion in STEMI patients despite dual antiplatelet therapy is associated with greater microvascular impairment.
authors: Centre for Interventional Treatment of Cardiovascular Diseases, The John Paul II Hospital, Kraków, Poland. jzalewski@szpitaljp2.krakow.pl
authors: Jarosław
authors: J
authors: Zalewski
authors: Monika
authors: M
authors: Durak
authors: Piotr
authors: P
authors: Lech
authors: Grzegorz
authors: G
authors: Gajos
authors: Anetta
authors: A
authors: Undas
authors: Jadwiga
authors: J
authors: Nessler
authors: Agnieszka
authors: A
authors: Rosławiecka
authors: Krzysztof
authors: K
authors: Zmudka
mesh_terms: D000077144:Clopidogrel; D015897:Comorbidity; D017023:Coronary Angiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D055909:Magnetic Field Therapy; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D015425:Myocardial Reperfusion; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D012307:Risk Factors; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D057772:Vascular System Injuries / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control*
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine