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Background and objective: One of the reasons for thrombosis in chronic heart failure (CHF) might be reactive forms of oxygen activating platelets. The aim of this study was to evaluate the effect of oxidant hypochlorous acid (HOCl) on platelet aggregation and dityrosine concentration in CHF patients and healthy controls. Materials and Methods: CHF patients (n = 67) and healthy (n = 31) were investigated. Heart echoscopy, 6-min walking test, complete blood count, platelet aggregation, and dityrosine concentration were performed. Platelet aggregation and dityrosine concentration were measured in plasma samples after incubation with different HOCl concentrations (0.15, 0.0778, and 0.0389 mmol/L). Results: Platelet aggregation without oxidant was lower (p = 0.049) in CHF patients than in controls. The spontaneous platelet aggregation with oxidant added was higher in CHF patients (p = 0.004). Dityrosine concentration was also higher (p = 0.032) in CHF patients. Platelet aggregation was the highest in samples with the highest oxidant concentration in both healthy controls (p = 0.0006) and in CHF patients (p = 0.036). Platelet aggregation was higher in NYHA III group in comparison to NYHA II group (p = 0.0014). Concentration of dityrosine was significantly higher in CHF samples (p = 0.032). The highest concentration of dityrosine was obtained in NYHA IV group samples (p < 0.05). Intensity of platelet aggregation, analyzed with ADP, was correlated with LV EF (r = 0.42, p = 0.007). Dityrosine concentration was correlated with NYHA functional class (r = 0.27, p < 0.05). Conclusions: The increase in platelet aggregation in CHF and healthy controls shows the oxidant effect on platelets. The increase in dityrosine concentration in higher NYHA functional classes shows a higher oxidative stress in patients with worse condition.

Introduction: Dual antiplatelet therapy (DAPT) of thienopyridines (ticagrelor or clopidogrel) and aspirin is recommended for patients with acute coronary syndromes for a period of 12 months after percutaneous coronary intervention (PCI) and stent implantation. Individual patients` genetic and non-genetic factors may determine bleeding and thrombosis during DAPT. As it was showed already, CYP4F2 rs2108622 may significantly affect antiplatelet treatment with clopidogrel. Our most recent data showed, that CYP4F2 rs3093135 TT variant carriers, users of ticagrelor, had lower platelet aggregation values than non-carriers. Aim: To determine the impact of CYP4F2 rs3093135 TT variant on bleeding and trombosis in patients treated with dual thienopyridine (ticagrelor or clopidogrel) and aspirin antiplatelet therapy after percutaneous coronary intervention (PCI) and stent implantation. Methods: This prospective study was carried out with the patients hospitalized with acute coronary syndromes at the Department of Cardiology of Hospital of Health Sciences, Lithuania between January 2013 till December 2016. All the patients received dual antiplatelet therapy (DAPT) with ticagrelor or clopidogrel and aspirin for at least of 6 months after PCI and stent implantation. From a total of (n=378) patients receiving DAPT, only the patients with CYP4F2 rs3093135 TT variant (n=33) were selected into this study. Bleeding was defined according to Bleeding Academic Research Consortium (BARC) classification. Results: From a total of 33 patients, carriers of CYP4F2 rs3093135 TT variant, 9 (27.3%) patients received ticagrelor and 24 (72.7%) were treated with clopidogrel. Only 2 patients who used ticagrelor had no bleeding events. Seven patients had type 1 or 2 bleeding according to BARC classification and one patient had a major type 3a gastrointestinal bleeding and required a blood tranfusion. The bleeding events were not documented in clop[...].