BACKGROUND

Platelet glycoprotein (GP) IIb/IIIa receptors are involved in platelet aggregation and acute thrombus formation. Changes in the expression of GP IIb/IIIa receptors are an important but little-explored aspect of antiplatelet therapy. Understanding these changes may be particularly relevant for elucidating the mechanisms and effects of GP IIb/IIIa antagonist therapy, and may help to establish methods to identify patients most likely to benefit from the use of GP IIb/IIIa blockade, or those especially prone to its thrombotic complications. The aim of this study was to evaluate the influence of common cardiovascular risk factors on the expression of GP IIb/IIIa receptors in patients with ST-segment-elevation myocardial infarction (STEMI) who received antiplatelet treatment under primary percutaneous coronary intervention (PCI).

MATERIALS AND METHODS

The study group consisted of 30 patients with STEMI who underwent PCI and who received antiplatelet treatment with aspirin (acetylsalicylic acid), a loading dose of clopidogrel and, if necessary, abciximab. The expression of platelet GP receptors was estimated by measuring the changes in the number of platelet antigens: CD41a (GP IIb/IIIa) and CD61 (GP IIIa). The assessments were performed in whole blood and on isolated platelets before and up to 24 hours after initiation of the antiplatelet therapy. The relationships between expression of platelet GP receptors and risk factors such as hypertension, smoking, diabetes mellitus, dyslipidemia, and family history of cardiovascular disease were examined using statistical analyses.

RESULTS

Before antiplatelet treatment, non-smokers had more receptors than smokers when antigen numbers were measured in whole blood. After treatment, the number of CD41a antigens present on isolated platelets significantly increased in non-smokers and in patients without dyslipidemia (p = 0.05). At the same time, the number of CD61 antigens increased in all patients except for those with diabetes. In patients without hypertension, the number of CD61 antigens (whole-blood measurement) increased considerably, and the difference between the patients with and without hypertension was significant (p = 0.01). The results of the study revealed that, after the treatment, the numbers of CD61 antigens were higher in patients without dyslipidemia and lower in patients with dyslipidemia compared with the results obtained from the preceding measurements. These different numbers of CD61 antigens significantly distinguished these two groups of patients from each other (p = 0.01).

CONCLUSION

Non-smokers with STEMI have significantly higher expression of GP IIb/IIIa and IIIa receptors than do smokers. Up to 24 hours after the start of antiplatelet treatment, the number of GP IIb/IIIa receptors on the platelet surface did not depend on common cardiovascular risk factors such as hypertension, diabetes, smoking, and dyslipidemia. Patients without hypertension and without dyslipidemia tended to have more of only one component of the GP IIb/IIIa complex (i.e. GP IIIa, as represented by the antigen CD61) than the patients with these risk factors.