title: Evidence of increased platelet reactivity in the first six months after acute ST segment elevation myocardial infarction.
abstract: BACKGROUND
  Platelets play a crucial role in the pathogenesis of acute coronary syndromes. Accordingly, previous studies showed increased platelet reactivity on admission in these patients. In this study we assessed platelet reactivity at short-medium term follow-up in patients with ST-segment elevation acute myocardial infarction (STEMI).
  
  
  METHODS
  Fifty-nine patients (58 ± 11 years, 45 men), treated with primary angioplasty, were studied 1 month after STEMI. Thirty-five patients were retested at 6 months. Twenty matched patients with stable coronary artery disease served as controls. Platelet reactivity was assessed by flow cyometry at rest and at peak exercise, with and without adenosine diphosphate (ADP) stimulation, by measuring monocyte-platelet aggregates (MPAs) and glycoprotein IIb/IIIa (CD41) expression in the MPA gate, and CD41 and fibrinogen receptor (PAC-1) expression in the platelet gate.
  
  
  RESULTS
  Compared to controls, basal MPAs and CD41 in the MPA gate were higher in STEMI patients both at 1 month (p = 0.001 and p = 0.002, respectively) and at 6 months (p = 0.03 and p = 0.01, respectively). Basal CD41 and PAC-1 expression was also higher in STEMI patients at the two assessments compared to controls (P<0.001 for both). Exercise induced a similar increase in platelet reactivity in patients and controls. ADP induced a higher increase in CD41 platelet expression in STEMI patients compared to controls both at 1 and 6 months (P < 0.001).
  
  
  CONCLUSIONS
  Platelet reactivity is increased in the first 6 months after STEMI. The persistence of increased platelet reactivity in this time period may play a role in the early recurrence of coronary events after STEMI.
authors.affiliation: Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Roma, Italy.
authors.forename: Giancarla
authors.initials: G
authors.lastname: Scalone
authors.forename: Ilaria
authors.initials: I
authors.lastname: Coviello
authors.forename: Lucy
authors.initials: L
authors.lastname: Barone
authors.forename: Irma
authors.initials: I
authors.lastname: Battipaglia
authors.forename: Cristina
authors.initials: C
authors.lastname: Aurigemma
authors.forename: Giulia
authors.initials: G
authors.lastname: Careri
authors.forename: Gaetano
authors.initials: G
authors.lastname: Pinnacchio
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Tarzia
authors.forename: Gaetano Antonio
authors.initials: GA
authors.lastname: Lanza
authors.forename: Filippo
authors.initials: F
authors.lastname: Crea
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood*; D001792:Blood Platelets / Q000502:physiology*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood*; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D010976:Platelet Count