Immature platelets and platelet reactivity in patients with acute ST-segment Elevation Myocardial Infarction using whole blood flow cytometry with SYTO-13 staining.

Reduced effect of antiplatelet therapy has been reported in patients with ST-segment elevation myocardial infarction (STEMI). Multiple factors may concur to explain this, including increased amount of highly reactive immature platelets. To investigate the association between immature platelets and reactivity determined with multicolour flow cytometry using the SYTO-13 dye in STEMI patients. We conducted an observational study of 59 patients with acute STEMI. Blood samples were obtained within 24 h after admission and after loading doses of dual antiplatelet therapy. For comparison, samples were obtained from 50 healthy individuals. Immature platelets and platelet reactivity were investigated using multicolour flow cytometry including the SYTO-13 dye that binds to platelet RNA and thus provides a method for subdividing platelets into immature and mature platelets. Additionally, we assessed platelet aggregation, serum-thromboxane B 2 levels and standard immature platelet markers. Immature platelets were more reactive than mature platelets in both STEMI patients and healthy individuals (p -values < 0.05). STEMI patients had lower platelet aggregation and thromboxane B 2 levels than healthy individuals. We found a positive association between automatically determined immature platelet markers and CD63 expression on activated platelets (Spearman's rho: 0.27 to 0.58, p -values < 0.05). Our study shows that immature platelets identified with a multicolour flow cytometric method using the SYTO-13 dye are more reactive than mature platelets in patients with acute STEMI and in healthy individuals. The presence of immature platelets may be important for the overall platelet reactivity, which may have implications for the effect of antiplatelet therapy. We included 59 patients diagnosed with acute ST-segment elevation myocardial infarction (STEMI) and 50 healthy individuals. Following blood sampling, we utilized whole blood multicolor flow cytometry, incorporating the SYTO-13 dye, which binds to platelet RNA. This approach allows us to subdivide platelets into immature and mature, enabling a comprehensive assessment of platelet reactivity across distinct platelet subpopulations. [Display omitted] • Reduced effect of antiplatelet therapy is observed in acute STEMI patients. • Immature platelets may influence platelet reactivity and the effect of antiplatelet therapy. • Results provided by a multicolour flow cytometric method using the SYTO-13 dye. • Immature platelets were more reactive than mature platelets in STEMI patients. • This study emphasizes the importance of immature platelets for the overall platelet reactivity. [ABSTRACT FROM AUTHOR]