Partial inhibition of platelet thromboxane A2 synthesis by aspirin is associated with myonecrosis in patients with ST-segment elevation myocardial infarction.
Am J Cardiol
; 99(1): 19-25, 2007 Jan 01.
Article
em En
| MEDLINE
| ID: mdl-17196455
ABSTRACT
Heterogeneity in response to aspirin (ASA) treatment, or "aspirin resistance," could be of importance in patients with ST-segment elevation myocardial infarction (STEMI). Decreased effects of ASA in platelets could be due to partial inhibition of cyclo-oxygenase-1 (COX-1) or to COX-1-independent mechanisms. We evaluated the effect of ASA treatment in patients with STEMI for (1) platelet thromboxane A(2) (TXA(2)) synthesis, (2) platelet recruitment elicited by TXA(2)-dependent and -independent mechanisms, and (3) a possible association of these aspects of platelet reactivity with serum markers of myonecrosis. We studied 62 ASA-treated patients within 48 hours of onset of the acute event and 69 ASA-free and 10 ASA-treated controls. TXA(2) synthesis and platelet recruitment (fluid-phase proaggregate activity of cell-free releasate) were assessed after collagen stimulation (1 micro g/ml) of whole blood. Partial inhibition of TXA(2) by ASA was found in 21 patients (34%). This was associated with significant increases in troponin T, creatine kinase-MB mass, creatine kinase, and recruiting activity versus 41 patients with blocked TXA(2) production. This was independent of fibrinolysis, and platelet COX-2 expression was not augmented. TXA(2) blockade was achieved after subsequent daily treatments or platelet incubation with ASA in vitro, suggesting lower sensitivity of COX-1 to ASA. In addition, 28 patients (45%) had an abnormally increased recruiting activity despite TXA(2) blockade, which was also associated with increased myonecrosis. In conclusion, ASA resistance, elicited by TXA(2)-dependent and TXA(2)-independent mechanisms, was prevalent in patients with STEMI. This study describes, for the first time, the association of partial platelet TXA(2) inhibition with myonecrosis.
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Base de dados:
MEDLINE
Assunto principal:
Tromboxano A2
/
Plaquetas
/
Inibidores da Agregação Plaquetária
/
Aspirina
/
Infarto do Miocárdio
Tipo de estudo:
Observational_studies
/
Risk_factors_studies
Limite:
Adult
/
Aged
/
Aged80
/
Female
/
Humans
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Male
/
Middle aged
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article