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Introduction: This prospective, single-arm, crossover pharmacodynamic study assessed the effect of Bayer® low-dose enteric-coated aspirin 81 mg tablets (LD EC-ASA) (Bayer AG, Leverkusen, North Rhine-Westphalia, Germany) compared to Vazalore® low-dose phospholipid-aspirin liquid-filled 81 mg capsules (LD PL-ASA) (PLx Pharma Inc., Sparta, NJ, USA) on platelet reactivity with respect to aspirin reaction units (ARU). Methods: Forty-seven healthy volunteers were recruited. Platelet function was evaluated with the VerifyNow™ ARU assay (Werfen, Bedford, MA, USA) and assessed post-initiation of Bayer® LD EC-ASA daily for 14 days, with a washout period of 28 days, followed by Vazalore® LD PL-ASA daily for 14 days, again followed by ARU testing. Results: Participants on LD EC-ASA had a mean ARU score of 426, with 19.1% of participants having an ARU > 550; patients on LD PL-ASA derived a mean ARU score of 435, with 14.9% achieving an ARU > 550. There were no significant differences in aspirin resistance (ARU > 550) according to the formulation (Bayer® LD EC-ASA vs. Vazalore® LD PL-ASA) used. Aspirin resistance was independent of ethnicity regardless of the formulation used. In addition, there were no significant associations between body surface area (BSA) and Bayer® LD EC-ASA ARU value (p value 0.788) or Vazalore® LD PL-ASA ARU value (p value 0.477). No patients experienced any serious adverse events or treatment-emergent adverse events. Conclusions: There were no significant differences in aspirin resistance between Bayer® LD EC-ASA and Vazalore® LD PL-ASA. This dedicated pharmacodynamic study could potentially be informative and applicable for Trinidadian patients on dual antiplatelet therapy (DAPT). Further studies are required to confirm these exploratory findings. Trial Registration: ClinicalTrials.gov identifier, NCT06228820, prospectively registered 1/18/2024. [ABSTRACT FROM AUTHOR]

Background: Concomitant use of clopidogrel and proton pump inhibitor (PPI) is common, but PPI may reduce the antiplatelet effects of clopidogrel in patients undergoing percutaneous coronary intervention (PCI). We evaluated the impact of PPI use on clinical outcomes in post-PCI patients, by incorporating P2Y12 reaction unit (PRU) and CYP2C19 genotyping results. Methods: From a multicenter registry of patients who underwent PCI with drug-eluting stent implantation and received clopidogrel-based dual antiplatelet therapy (DAPT), patients who were prescribed a PPI at the time of PCI (PPI users) were compared to those who were not (non-users). The primary outcome included all-cause death, myocardial infarction, stent thrombosis, or cerebrovascular accident at 12 months. Major bleeding (Bleeding Academic Research Consortium [BARC] types 3–5) and gastrointestinal (GI) bleeding (BARC types 3–5) were important secondary outcomes. The adjusted outcomes were compared using a 1:1 propensity-score (PS) matching and competing risk analysis. Results: Of 13,160 patients, 2,235 (17.0%) were prescribed PPI, with an average age of 65.4 years. PPI users had higher on-treatment PRU levels than non-users. After PS matching, the primary outcome occurred in 51 patients who were PPI users (cumulative incidence, 4.7%) and 41 patients who were non-users (cumulative incidence, 3.7%; log-rank p = 0.27). In carriers of both CYP2C19 loss-of-function alleles, PPI use was linked to an increased risk of the primary outcome (hazard ratio, 3.22; 95% confidence interval, 1.18–8.78). The incidence of major bleeding and GI bleeding (BARC types 3–5) was comparable between PPI users and non-users in the PS-matched cohort. Conclusions: In post-PCI patients receiving clopidogrel-based DAPT, PPI use was not linked to an increased risk of adverse cardiac and cerebrovascular events, but there was a small but significant increase in on-treatment PRU. Future research using a more individualized approach would further elucidate these interactions and guide evidence-based clinical practices. [ABSTRACT FROM AUTHOR]

Abstract Background Concomitant use of clopidogrel and proton pump inhibitor (PPI) is common, but PPI may reduce the antiplatelet effects of clopidogrel in patients undergoing percutaneous coronary intervention (PCI). We evaluated the impact of PPI use on clinical outcomes in post-PCI patients, by incorporating P2Y12 reaction unit (PRU) and CYP2C19 genotyping results. Methods From a multicenter registry of patients who underwent PCI with drug-eluting stent implantation and received clopidogrel-based dual antiplatelet therapy (DAPT), patients who were prescribed a PPI at the time of PCI (PPI users) were compared to those who were not (non-users). The primary outcome included all-cause death, myocardial infarction, stent thrombosis, or cerebrovascular accident at 12 months. Major bleeding (Bleeding Academic Research Consortium [BARC] types 3–5) and gastrointestinal (GI) bleeding (BARC types 3–5) were important secondary outcomes. The adjusted outcomes were compared using a 1:1 propensity-score (PS) matching and competing risk analysis. Results Of 13,160 patients, 2,235 (17.0%) were prescribed PPI, with an average age of 65.4 years. PPI users had higher on-treatment PRU levels than non-users. After PS matching, the primary outcome occurred in 51 patients who were PPI users (cumulative incidence, 4.7%) and 41 patients who were non-users (cumulative incidence, 3.7%; log-rank p = 0.27). In carriers of both CYP2C19 loss-of-function alleles, PPI use was linked to an increased risk of the primary outcome (hazard ratio, 3.22; 95% confidence interval, 1.18–8.78). The incidence of major bleeding and GI bleeding (BARC types 3–5) was comparable between PPI users and non-users in the PS-matched cohort. Conclusions In post-PCI patients receiving clopidogrel-based DAPT, PPI use was not linked to an increased risk of adverse cardiac and cerebrovascular events, but there was a small but significant increase in on-treatment PRU. Future research using a more individualized approach would further elucidate these interactions and guide evidence-based clinical practices.

Abstract Introduction This prospective, single-arm, crossover pharmacodynamic study assessed the effect of Bayer® low-dose enteric-coated aspirin 81 mg tablets (LD EC-ASA) (Bayer AG, Leverkusen, North Rhine-Westphalia, Germany) compared to Vazalore® low-dose phospholipid-aspirin liquid-filled 81 mg capsules (LD PL-ASA) (PLx Pharma Inc., Sparta, NJ, USA) on platelet reactivity with respect to aspirin reaction units (ARU). Methods Forty-seven healthy volunteers were recruited. Platelet function was evaluated with the VerifyNow™ ARU assay (Werfen, Bedford, MA, USA) and assessed post-initiation of Bayer® LD EC-ASA daily for 14 days, with a washout period of 28 days, followed by Vazalore® LD PL-ASA daily for 14 days, again followed by ARU testing. Results Participants on LD EC-ASA had a mean ARU score of 426, with 19.1% of participants having an ARU > 550; patients on LD PL-ASA derived a mean ARU score of 435, with 14.9% achieving an ARU > 550. There were no significant differences in aspirin resistance (ARU > 550) according to the formulation (Bayer® LD EC-ASA vs. Vazalore® LD PL-ASA) used. Aspirin resistance was independent of ethnicity regardless of the formulation used. In addition, there were no significant associations between body surface area (BSA) and Bayer® LD EC-ASA ARU value (p value 0.788) or Vazalore® LD PL-ASA ARU value (p value 0.477). No patients experienced any serious adverse events or treatment-emergent adverse events. Conclusions There were no significant differences in aspirin resistance between Bayer® LD EC-ASA and Vazalore® LD PL-ASA. This dedicated pharmacodynamic study could potentially be informative and applicable for Trinidadian patients on dual antiplatelet therapy (DAPT). Further studies are required to confirm these exploratory findings. Trial Registration ClinicalTrials.gov identifier, NCT06228820, prospectively registered 1/18/2024.

Abstract This study evaluated the association of atherogenic index of plasma (AIP) with platelet reactivity and clinical outcomes according to acute myocardial infarction (AMI). The composite of 3-year adverse outcomes of all-cause death, myocardial infarction, and cerebrovascular accident was evaluated in 10,735 patients after successful percutaneous coronary intervention with drug-eluting stents. AIP was defined as the base 10 logarithm of the ratio of triglyceride to high-density lipoprotein cholesterol concentration. High platelet reactivity (HPR) was defined as ≥ 252 P2Y12 reactivity unit. An increase of AIP (per-0.1 unit) was related to the decreased risk of HPR [odds ratio (OR) 0.97, 95% confidence interval (CI) 0.96–0.99; P = 0.001] in non-AMI patients, not in AMI patients (OR 0.98, 95% CI 0.96–1.01; P = 0.138). The HPR was associated with the increased risk of composite outcomes in both non-AMI and AMI patients (all-P

This study evaluated the association of atherogenic index of plasma (AIP) with platelet reactivity and clinical outcomes according to acute myocardial infarction (AMI). The composite of 3-year adverse outcomes of all-cause death, myocardial infarction, and cerebrovascular accident was evaluated in 10,735 patients after successful percutaneous coronary intervention with drug-eluting stents. AIP was defined as the base 10 logarithm of the ratio of triglyceride to high-density lipoprotein cholesterol concentration. High platelet reactivity (HPR) was defined as ≥ 252 P2Y12 reactivity unit. An increase of AIP (per-0.1 unit) was related to the decreased risk of HPR [odds ratio (OR) 0.97, 95% confidence interval (CI) 0.96–0.99; P = 0.001] in non-AMI patients, not in AMI patients (OR 0.98, 95% CI 0.96–1.01; P = 0.138). The HPR was associated with the increased risk of composite outcomes in both non-AMI and AMI patients (all-P < 0.05). AIP levels were not independently associated with the risk of composite outcomes in both patients with non-AMI and AMI. In conclusion, an inverse association between AIP and the risk of HPR was observed in patients with non-AMI. This suggests that the association between plasma atherogenicity and platelet reactivity may play a substantial role in the development of AMI. Trial registration: NCT04734028. [ABSTRACT FROM AUTHOR]

AbstractFluid shear plays a key role in hemostasis and thrombosis, and the purpose of this study was to investigate the effect of shear gradient change rate (SGCR) on platelet reactivity and von Willebrand factor (vWF) activity and its mechanism. In this study, we developed a set of microfluidic chips capable of generating different shear gradients and simulated the shear rate distribution in the flow field by COMSOL Multiphysics software. Molecular markers of platelet activation (P-selectin, activated GPIIb/IIIa, phosphatidylserine exposure, and monocyte-platelet aggregate formation) were analyzed by flow cytometry. Platelet aggregation induced by shear gradient was studied by a microfluidic experimental platform, and plasma vWF ristocetin cofactor (vWF: RCO) activity was investigated by flow cytometry. The expression of p-Akt was studied by Western blotting. The results showed that the faster the SGCR, the higher the expression of platelet p-Akt, and the stronger the platelet reactivity and vWF activity. This indicates that fluid shear stress can activate platelets and vWF in a shear gradient-dependent manner through the PI3K/AKT signal pathway, and the faster the SGCR, the more significant the activation effect.

Background: Psoriasis is a chronic, inflammatory, immune-mediated disease with a specific cutaneous presentation. Increased platelet aggregation has been observed in patients with extensive psoriatic lesions. The aim of this study was to evaluate the clinical factors affecting platelet reactivity in patients with an exacerbation of psoriasis. Methods: This was a prospective, single-center, observational study, enrolling patients hospitalized for an aggravation of psoriasis. Enrolled patients underwent single platelet function testing with light transmission aggregometry on the first morning of hospitalization. Results: 120 patients were enrolled in the study. Of the compared subgroups, women had higher maximal platelet aggregation (MPA) than men (77% vs. 72%; p = 0.03), and those with BMIs < 25 kg/m2 showed higher platelet reactivity compared to subjects with BMIs ≥ 25 kg/m2 (75% vs. 73%; p = 0.02). There was a positive correlation between MPA and platelet count (r = 0.27; p < 0.01), as well as C-reactive protein concentration (r = 0.20; p = 0.03), while a negative correlation was observed with total cholesterol (r = −0.24; p = 0.01) and triglycerides (r = −0.30; p < 0.01). A two-step analysis based on multidimensional models with random effects revealed that every increase in the platelet count by 103/μL led to an increase in MPA by 0.07% (R2 = 0.07; p < 0.01), and an increase in triglycerides' concentration by 1 mg/dL was related to a reduction in MPA by 0.05% (R2 = 0.07; p < 0.01). Conclusions: The increased platelet reactivity observed in patients with psoriasis appears to be multifactorial and related to several clinical and laboratory features. Further research is warranted to put these findings into a clinical perspective. [ABSTRACT FROM AUTHOR]

Introduction: Patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) require dual antiplatelet therapy (DAPT). However, the response to treatment can vary considerably. Certain platelet microRNAs (miRs) are suspected to predict DAPT response and influence platelet function. This study aimed to analyze selected miRs' expressions and compare them among patients treated with different P2Y12 inhibitors while assessing their association with platelet activity and turnover parameters. Materials and methods: We recruited 79 ACS patients post-PCI treated with clopidogrel, ticagrelor, or prasugrel, along with 18 healthy volunteers. Expression levels of miR-126-3p, miR223-3p, miR-21-5p, miR-197-3p, and miR-24-3p, as well as immature platelet fraction (IPF) and ADP-induced platelet reactivity, were measured and compared between groups. Results: Analyses revealed significantly lower expressions of miR-126-3p, miR-223-3p, miR-21-5p, and miR-197-3p in patients treated with ticagrelor, compared to clopidogrel (fold changes from −1.43 to −1.27, p-values from 0.028 to 0.048). Positive correlations were observed between platelet function and the expressions of miR-223-3p (r = 0.400, p = 0.019) and miR-21-5p (r = 0.423, p = 0.013) in patients treated with potent drugs. Additionally, miR-24-3p (r = 0.411, p = 0.012) and miR-197-3p (r = 0.333, p = 0.044) showed correlations with IPF. Conclusions: The identified platelet miRs hold potential as biomarkers for antiplatelet therapy. (ClinicalTrials.gov number, NCT06177587). [ABSTRACT FROM AUTHOR]

Background Although age and body mass index (BMI) significantly affect platelet reactivity units and clinical outcomes after percutaneous coronary intervention, there are limited data on the relationship between high on‐treatment platelet reactivity (HPR) and clinical outcomes on age and BMI differences. Thus, we investigated the association of HPR with clinical outcomes according to age and BMI. Methods and Results The study analyzed 11 714 patients who underwent platelet function tests after percutaneous coronary intervention. The primary end point was the occurrence of major adverse cardiac and cerebrovascular events (MACCEs), whereas the secondary end point was major bleeding. HPR was defined as platelet reactivity units ≥252. Patients were categorized by age (22.6 kg/m2). Patients 22.6 kg/m2 had increases in MACCEs (adjusted HR, 1.387 [95% CI, 1.140–1.688]; P=0.001). No differences were shown in major bleeding. Conclusions HPR was linked to an increase in MACCEs or a decrease in major bleeding in patients after percutaneous coronary intervention, depending on age and BMI. This study is the first to observe that clinical outcomes in patients with HPR after percutaneous coronary intervention may vary based on age and BMI. Because the study is observational, the results should be viewed as hypothesis generating and emphasize the need for randomized clinical trials.

AbstractBackground/objective Type 2 diabetes is a major risk factor for atherosclerotic disease. It is well agreed that the reactivity of diabetic platelets is increased but how platelet reactivity regulates is unknown. In our laboratory, density separated platelets have been investigated extensively and high- and low-density platelets circulate in an activated state. The density distribution of circulating platelets is altered in diabetes type 2 as well. We hypothesize that such platelets modify whole blood (WB) in vitro α-thrombin-evoked (10 μM/mL) activity in type 2 diabetes. Thus, the study aims to identify features of circulating normal-sized density subpopulations affecting whole blood (WB) platelet reactivity in type 2 diabetes.Patients and methods Patients with type 2 diabetes (n = 16) were enrolled. Their normal-sized platelets were divided into density subfractions (n = 16) using continuous polyvinylpyrrolidone-coated silica (Percoll™) gradients (density span, 1.090–1.040 kg/L) containing prostaglandin E1. The proportions (%) of such density-separated platelets expressing lysosomal-associated membrane protein 1 (LAMP-1) were analyzed using a flow cytometer. Further, determinations of WB ɑ-thrombin-evoked (10 U/mL) surface LAMP-1 (an assessment of lysosomal release), the fibrinogen (αIIbβ3) receptor activity, annexin V (binds to exposed membrane phosphatidylserine), and mitochondrial transmembrane potentials (an estimate of organelle integrity) were performed. Surface LAMP-1 expressions of individual normal-sized platelet density subpopulations were stratified into equal-sized groups (n = 2) depending on reactivity, as judged from the ɑ-thrombin-induced WB activity markers.Results With some exceptions, the proportion of normal-sized circulating platelets showing spontaneous LAMP-1 was strongly associated with WB ɑ-thrombin-evoked (10 U/mL) surface LAMP-1 and αIIbβ3 receptor activity. LAMP-1-expressing normal-sized platelets also displayed inverse associations with WB ɑ-thrombin-induced surface annexin V and mitochondrial damage, which are features of procoagulant platelets.Conclusions From the current descriptive work only involving type 2 diabetes, it is impossible to judge whether the findings are features of the disease or if they occur in healthy individuals as well. However, the study describes LAMP-1 expressing subpopulations of circulating normal-sized platelets that associate with WB α-thrombin (10 U/mL) responses in vitro. Increased proportions of such platelets induced lysosomal release and αIIbβ3 receptor activity, whereas lower proportions promoted WB agonist-induced procoagulant platelet creation. It is to hypothesize that the new described regulatory mechanism could in the future offer a possibility to influence platelet behavior in type 2 diabetes.Key messagesLysosomal exocytosis of circulating platelets influences reactivity, as determined by agonist-induced platelet reactions in vitroThus, the low release of lysosomes by normal-sized platelets in vivo increases agonist-evoked procoagulant platelet production.Higher lysosomal exocytosis of circulating normal-sized platelets promotes platelet aggregation and secretion.

Exercise training (ET) can lower platelet reactivity in patients with cardiovascular risk factors. However, the effects of ET on platelet reactivity in higher-risk patients is unknown. The aim of this study was to evaluate the effects of ET on platelet reactivity in patients with recent myocardial infarction (MI). Ninety patients were randomly assigned 1 month post-MI to the intervention (patients submitted to a supervised ET program) or control group. All patients were on dual antiplatelet therapy (DAPT). Platelet reactivity by VerifyNow-P2Y12 (measured by P2Y12 reaction units - PRUs) test was determined at baseline and at the end of 14 ± 2 weeks of follow-up at rest (primary endpoint), and multiplate electrode aggregometry (MEA) adenosine diphosphate (ADP) and aspirin (ASPI) tests were performed immediately before and after the maximal cardiopulmonary exercise test (CPET) at the same time points (secondary endpoints). Sixty-five patients (mean age 58.9 ± 10 years; 73.8% men; 60% ST elevation MI) completed follow-up (control group, n = 31; intervention group, n = 34). At the end of the follow-up, the mean platelet reactivity was 172.8 ± 68.9 PRUs and 166.9 ± 65.1 PRUs for the control and intervention groups, respectively (p = .72). Platelet reactivity was significantly increased after the CPET compared to rest at the beginning and at the end of the 14-week follow-up (among the intervention groups) by the MEA-ADP and MEA-ASPI tests (p < .01 for all analyses). In post-MI patients on DAPT, 14 weeks of supervised ET did not reduce platelet reactivity. Moreover, platelet reactivity was increased after highintensity exercise (ClinicalTrials.gov: NCT02958657; https://clinicaltrials.gov/ct2/show/NCT02958657). [ABSTRACT FROM AUTHOR]

Type 2 diabetes is a major risk factor for atherosclerotic disease. It is well agreed that the reactivity of diabetic platelets is increased but how platelet reactivity regulates is unknown. In our laboratory, density separated platelets have been investigated extensively and high- and low-density platelets circulate in an activated state. The density distribution of circulating platelets is altered in diabetes type 2 as well. We hypothesize that such platelets modify whole blood (WB) in vitro α-thrombin-evoked (10 μM/mL) activity in type 2 diabetes. Thus, the study aims to identify features of circulating normal-sized density subpopulations affecting whole blood (WB) platelet reactivity in type 2 diabetes. Patients with type 2 diabetes (n = 16) were enrolled. Their normal-sized platelets were divided into density subfractions (n = 16) using continuous polyvinylpyrrolidone-coated silica (Percoll™) gradients (density span, 1.090–1.040 kg/L) containing prostaglandin E1. The proportions (%) of such density-separated platelets expressing lysosomal-associated membrane protein 1 (LAMP-1) were analyzed using a flow cytometer. Further, determinations of WB ɑ-thrombin-evoked (10 U/mL) surface LAMP-1 (an assessment of lysosomal release), the fibrinogen (αIIbβ3) receptor activity, annexin V (binds to exposed membrane phosphatidylserine), and mitochondrial transmembrane potentials (an estimate of organelle integrity) were performed. Surface LAMP-1 expressions of individual normal-sized platelet density subpopulations were stratified into equal-sized groups (n = 2) depending on reactivity, as judged from the ɑ-thrombin-induced WB activity markers. With some exceptions, the proportion of normal-sized circulating platelets showing spontaneous LAMP-1 was strongly associated with WB ɑ-thrombin-evoked (10 U/mL) surface LAMP-1 and αIIbβ3 receptor activity. LAMP-1-expressing normal-sized platelets also displayed inverse associations with WB ɑ-thrombin-induced surface annexin V and mitochondrial damage, which are features of procoagulant platelets. From the current descriptive work only involving type 2 diabetes, it is impossible to judge whether the findings are features of the disease or if they occur in healthy individuals as well. However, the study describes LAMP-1 expressing subpopulations of circulating normal-sized platelets that associate with WB α-thrombin (10 U/mL) responses in vitro. Increased proportions of such platelets induced lysosomal release and αIIbβ3 receptor activity, whereas lower proportions promoted WB agonist-induced procoagulant platelet creation. It is to hypothesize that the new described regulatory mechanism could in the future offer a possibility to influence platelet behavior in type 2 diabetes. Lysosomal exocytosis of circulating platelets influences reactivity, as determined by agonist-induced platelet reactions in vitro Thus, the low release of lysosomes by normal-sized platelets in vivo increases agonist-evoked procoagulant platelet production. Higher lysosomal exocytosis of circulating normal-sized platelets promotes platelet aggregation and secretion. [ABSTRACT FROM AUTHOR]

Background. Antiplatelet therapy is the cornerstone of treatment for patients presenting with acute coronary syndrome (ACS) treated with percutaneous coronary intervention (PCI). Some patients may not respond to such therapy adequately, which is associated with a greater risk of ischemic events. Reticulated platelets are the youngest, largest, and most active platelet subtype. They have been initially shown to be associated with an increased risk of cardiovascular (CV) events and increased platelet activity. Objectives. The aim of the presented study was to evaluate whether the immature platelet fraction (IPF) reflects the response to antiplatelet treatment in invasively managed ACS patients. Materials and methods. This prospective study enrolled ACS patients treated with PCI and dual antiplatelet therapy (DAPT) comprising acetylsalicylic acid (ASA) and clopidogrel or ticagrelor. In all patients, venous blood was collected within 24 h after the procedure. Platelet parameters were measured, including IPF using the Sysmex hematological analyzer and adenosine diphosphate (ADP)-induced platelet reactivity using the Multiplate® Analyzer. Results. A total of 108 patients were enrolled, including 62 with ST-segment elevation ACS (STE-ACS) and 46 with non-ST-segment elevation ACS (NSTE-ACS). Of them, 20.4% had diabetes mellitus, 26.9% had a history of MI and 59.2% of smoking. Spearman's correlation analysis demonstrated that higher IPF and immature platelet count (IPC) values are associated with increased ADP-induced platelet reactivity (respectively: rho = 0.387, 95% confidence interval (95% CI): 0.101-0.615, p = 0.008; and rho = 0.458, 95% CI: 0.185-0.666, p = 0.001) in NSTE-ACS but not in STE-ACS patients. Conclusions. Immature platelet count and IPF may be valuable markers of platelet activity in patients with NSTE-ACS treated invasively and receiving DAPT (ClinicalTrials.gov No. NCT06177587). [ABSTRACT FROM AUTHOR]

Abnormal lipid profile, increased glucose level, and elevated body weight are traditional cardiometabolic risk factors; however, the role of platelets in the development of cardiovascular disease (CVD) is increasingly being highlighted. The aim of this study was to select platelet-related parameters (non-genetic molecular and routine laboratory measurements) that may be associated with increased cardiovascular risk among healthy populations. We evaluated the level of platelet indices, platelet-based inflammatory markers, platelet reactivity parameters, and platelet reactive oxygen species (ROS) generation in relation to selected cardiometabolic risk factors. We noted the association between total cholesterol and LDL cholesterol with platelet aggregation and platelet ROS generation. We found the relationship between triglycerides, glucose, and body mass index with the relatively new multi-inflammatory indices (MII-1 and MII-3). Moreover, we noticed that the mean platelet volume-to-lymphocyte ratio in healthy subjects is not a good source of information about platelets and inflammation. We also highlighted that platelet-to-HDL-cholesterol ratio may be a promising prognostic cardiometabolic indicator. The association between platelet-related (especially molecular) and cardiometabolic parameters requires further research. However, the goal of this study was to shed light on the consideration of platelets as a non-traditional cardiovascular risk factor and a crucial element in identifying individuals at high-risk of developing CVD in the future. [ABSTRACT FROM AUTHOR]

Lipoprotein(a) [Lp(a)] is an independent, genetically determined, and causal risk factor for cardiovascular disease. Laboratory data have suggested an interaction of Lp(a) with platelet function, potentially caused by its interaction with platelet receptors. So far, the potential association of Lp(a) with platelet activation and reactivity has not been proven in larger clinical cohorts. This study analyzed intrinsic platelet reactivity before loading with clopidogrel 600 mg and on-treatment platelet reactivity tested 24 h following loading in patients undergoing elective coronary angiography. Platelet reactivity was tested by optical aggregometry following stimulation with collagen or adenosine diphosphate as well as by flow cytometry. Lp(a) levels were directly measured in all patients from fresh samples. The present analysis included 1912 patients. Lp(a) levels ranged between 0 and 332 mg/dl. There was a significant association of rising levels of Lp(a) with a higher prevalence of a history of ischemic heart disease (p

Abstract Background Diabetes mellitus (DM) is associated with thrombogenicity, clinically manifested with atherothrombotic events after percutaneous cutaneous intervention (PCI). This study aimed to investigate association between DM status and platelet reactivity, and their prognostic implication in PCI-treated patients. Methods The Platelet function and genoType-Related long-term Prognosis-Platelet Function Test (PTRG-PFT) cohort was established to determine the linkage of platelet function test (PFT) with long-term prognosis during dual antiplatelet therapy including clopidogrel in patients treated with drug-eluting stent (DES). We assessed platelet reactivity using VerifyNow and ‘high platelet reactivity (HPR)’ was defined as ≥ 252 P2Y12 reaction unit (PRU). Major adverse cardiac and cerebrovascular event (MACCE) was a composite of all-cause death, myocardial infarction, stent thrombosis or stroke. Results Between July 2003 and Aug 2018, DES-treated patients with available PFT were enrolled (n = 11,714). Diabetic patients demonstrated significant higher levels of platelet reactivity (DM vs. non-DM: 225.7 ± 77.5 vs. 213.6 ± 79.1 PRU, P

The key role played by platelets in the atherosclerosis physiopathology, especially in the acute setting, is ascertained: they are the main actors during thrombus formation and, thus, one of the major investigated elements related to atherothrombotic process involving coronary arteries. Platelets have been studied from different points of view, according with the technology advances and the improvement in the hemostasis knowledge achieved in the last years. Morphology and reactivity constitute the first aspects investigated related to platelets with a significant body of evidence published linking a number of their values and markers to coronary artery disease and cardiovascular events. Recently, the impact of genetics on platelet activation has been explored with promising findings as additional instrument for patient risk stratification; however, this deserves further confirmations. Moreover, the interplay between immune system and platelets has been partially elucidated in the last years, providing intriguing elements that will be basic components for future research to better understand platelet regulation and improve cardiovascular outcome of patients. [ABSTRACT FROM AUTHOR]

Background: Diabetes mellitus (DM) is associated with thrombogenicity, clinically manifested with atherothrombotic events after percutaneous cutaneous intervention (PCI). This study aimed to investigate association between DM status and platelet reactivity, and their prognostic implication in PCI-treated patients. Methods: The Platelet function and genoType-Related long-term Prognosis-Platelet Function Test (PTRG-PFT) cohort was established to determine the linkage of platelet function test (PFT) with long-term prognosis during dual antiplatelet therapy including clopidogrel in patients treated with drug-eluting stent (DES). We assessed platelet reactivity using VerifyNow and 'high platelet reactivity (HPR)' was defined as ≥ 252 P2Y12 reaction unit (PRU). Major adverse cardiac and cerebrovascular event (MACCE) was a composite of all-cause death, myocardial infarction, stent thrombosis or stroke. Results: Between July 2003 and Aug 2018, DES-treated patients with available PFT were enrolled (n = 11,714). Diabetic patients demonstrated significant higher levels of platelet reactivity (DM vs. non-DM: 225.7 ± 77.5 vs. 213.6 ± 79.1 PRU, P < 0.001) and greater prevalence of HPR compared to non-diabetic patients (38.1% vs. 32.0%, P < 0.001). PRU level and prevalence of HPR were significantly associated with insulin requirement and HbA1c level, as well as diabetic status. DM status and HPR phenotype had a similar prognostic implication, which showed the synergistic clinical impact on MACCE. Association between PRU level and MACCE occurrence seemed higher in diabetic vs. non-diabetic patients. In non-DM patients, HPR phenotype did not significantly increase the risk of MACCE (adjusted hazard ratio [HRadj]: 1.073; 95% confidence interval [CI]: 0.869–1.325; P = 0.511), whereas HPR was an independent determinant for MACCE occurrence among diabetic patients (HRadj: 1.507; 95% CI: 1.193–1.902; P < 0.001). Conclusion: The levels of on-clopidogrel platelet reactivity are determined by diabetic status and the severity of DM. In addition, HPR phenotype significantly increases the risk of MACCE only in diabetic patients. Clinical trial registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT04734028. [ABSTRACT FROM AUTHOR]

[Display omitted] [ABSTRACT FROM AUTHOR]

The degree of platelet inhibition in patients undergoing dual antiplatelet therapy (DAPT) affects cardiovascular outcomes after acute coronary syndromes (ACS) and/or percutaneous coronary intervention. Our aim was to search for correlates of residual ex vivo platelet reactivity and circulating soluble P-selectin (sP-selectin), an index of in vivo platelet activation, in patients being treated by DAPT with ticagrelor. Adenosine diphosphate (ADP)-induced platelet aggregability (by multiple electrode aggregometry) and plasma sP-selectin were estimated in 62 stable post-ACS subjects (46 men and 16 women; mean age: 64 ± 10 years; 30 with type 2 diabetes (T2DM)) undergoing maintenance DAPT with ticagrelor and aspirin. These patients did not exhibit heart failure or other relevant coexistent diseases except for properly controlled T2DM, mild renal insufficiency, and hypertension. We also assessed this in 64 subjects on clopidogrel-based DAPT matched for age, sex, and T2DM status. ADP-induced platelet aggregation was below the optimal levels (190–460 arbitrary units (AU) * min) in most patients receiving ticagrelor-based DAPT, especially in those with below-median (<1.9 mmol/L) serum concentrations of low-density lipoprotein cholesterol (LDL-c) (128 ± 61 vs. 167 ± 73 AU * min for below-median and above-median LDL-c, respectively, p = 0.025). In contrast, platelet reactivity did not differ by LDL-c on clopidogrel-based DAPT (246 ± 101 vs. 268 ± 108 AU * min for below-median and above-median LDL-c, respectively, p > 0.4). Plasma sP-selectin was found to be unrelated to serum LDL-c when receiving DAPT with ticagrelor (p > 0.4) or clopidogrel (p > 0.8). In conclusion, our preliminary observational study suggests the association of lower residual ex vivo platelet aggregability with better LDL-c control in patients undergoing ticagrelor-based maintenance DAPT, which does not appear to be reflected by plasma sP-selectin. Whether the serum LDL-c level should be considered among the factors affecting the degree of platelet inhibition for those treated with ticagrelor-based DAPT needs to be investigated in larger studies. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is a chronic, inflammatory, immune-mediated disease with a specific cutaneous presentation. Increased platelet aggregation has been observed in patients with extensive psoriatic lesions. The aim of this study was to evaluate the clinical factors affecting platelet reactivity in patients with an exacerbation of psoriasis. Methods: This was a prospective, single-center, observational study, enrolling patients hospitalized for an aggravation of psoriasis. Enrolled patients underwent single platelet function testing with light transmission aggregometry on the first morning of hospitalization. Results: 120 patients were enrolled in the study. Of the compared subgroups, women had higher maximal platelet aggregation (MPA) than men (77% vs. 72%; p = 0.03), and those with BMIs < 25 kg/m2 showed higher platelet reactivity compared to subjects with BMIs ≥ 25 kg/m2 (75% vs. 73%; p = 0.02). There was a positive correlation between MPA and platelet count (r = 0.27; p < 0.01), as well as C-reactive protein concentration (r = 0.20; p = 0.03), while a negative correlation was observed with total cholesterol (r = −0.24; p = 0.01) and triglycerides (r = −0.30; p < 0.01). A two-step analysis based on multidimensional models with random effects revealed that every increase in the platelet count by 103/μL led to an increase in MPA by 0.07% (R2 = 0.07; p < 0.01), and an increase in triglycerides’ concentration by 1 mg/dL was related to a reduction in MPA by 0.05% (R2 = 0.07; p < 0.01). Conclusions: The increased platelet reactivity observed in patients with psoriasis appears to be multifactorial and related to several clinical and laboratory features. Further research is warranted to put these findings into a clinical perspective.

Spontaneous reperfusion, seen in ∼20% of patients with ST-segment elevation myocardial infarction (STEMI), manifests as normal epicardial flow in the infarct-related artery, with or without ST-segment resolution, before percutaneous coronary intervention (PCI). The drivers mediating this are unknown. The authors sought to relate spontaneous reperfusion to the thrombotic profile. In a prospective study, blood from STEMI patients (n = 801) was tested pre-PCI to assess in vitro , point-of-care, occlusion times (OT) and endogenous lysis times (LT). Spontaneous reperfusion was defined as infarct-related artery Thrombolysis In Myocardial Infarction flow grade 3 before PCI. Patients were followed for major cardiovascular events (death, myocardial infarction, or stroke). Spontaneous reperfusion was associated with a longer OT (435 seconds vs 366 seconds; P < 0.001) and a shorter LT (1,257 seconds vs 1,616 seconds; P < 0.001), lower troponin, and better left ventricular function. LT was superior to OT for predicting spontaneous reperfusion (area under the curve for LT: 0.707; 95% CI: 0.661-0.753; area under the curve for OT: 0.629; 95% CI: 0.581-0.677). Among patients with spontaneous reperfusion, those with complete, vs partial ST-segment resolution, had a longer OT (P = 0.002) and a shorter LT (P < 0.001). Spontaneous reperfusion was unrelated to clinical characteristics or pain-to-angiography times. Over 4 years, patients with spontaneous reperfusion experienced fewer major adverse cardiovascular events than those without (4.1% vs 10.6%; P = 0.013), especially in those with both spontaneous reperfusion and complete ST-segment resolution (1.5% vs 10.1%; P = 0.029). We demonstrate a novel hematological signature in STEMI patients with spontaneous reperfusion, namely, decreased platelet reactivity and faster endogenous fibrinolysis, relating to smaller infarcts and improved survival. This finding indicates a role for modulating thrombotic status early after STEMI onset, to facilitate spontaneous reperfusion and improve outcomes. [Display omitted] [ABSTRACT FROM AUTHOR]

Exercise training (ET) can lower platelet reactivity in patients with cardiovascular risk factors. However, the effects of ET on platelet reactivity in higher-risk patients is unknown. The aim of this study was to evaluate the effects of ET on platelet reactivity in patients with recent myocardial infarction (MI). Ninety patients were randomly assigned 1 month post-MI to the intervention (patients submitted to a supervised ET program) or control group. All patients were on dual antiplatelet therapy (DAPT). Platelet reactivity by VerifyNow-P2Y12 (measured by P2Y12 reaction units – PRUs) test was determined at baseline and at the end of 14 ± 2 weeks of follow-up at rest (primary endpoint), and multiplate electrode aggregometry (MEA) adenosine diphosphate (ADP) and aspirin (ASPI) tests were performed immediately before and after the maximal cardiopulmonary exercise test (CPET) at the same time points (secondary endpoints). Sixty-five patients (mean age 58.9 ± 10 years; 73.8% men; 60% ST elevation MI) completed follow-up (control group, n = 31; intervention group, n = 34). At the end of the follow-up, the mean platelet reactivity was 172.8 ± 68.9 PRUs and 166.9 ± 65.1 PRUs for the control and intervention groups, respectively (p = .72). Platelet reactivity was significantly increased after the CPET compared to rest at the beginning and at the end of the 14-week follow-up (among the intervention groups) by the MEA-ADP and MEA-ASPI tests (p

Prostacyclin (PGI2) analogues (epoprostenol, treprostonil, iloprost) are the cornerstone of pulmonary arterial hypertension (PAH) treatment. PGI2 analogues inhibit platelet reactivity, but their impact on coagulation and fibrinolysis parameters has not been elucidated. We compared platelet reactivity, thrombin generation, clot permeation, and lysis properties in patients with PAH treated with PGI2 analogues (n = 20) and those not receiving PGI2 analogues (n = 20). Platelet reactivity was lower in patients treated with PGI2 analogues, compared to the control group, as evaluated with arachidonic acid (ASPI), adenosine diphosphate (ADP), and thrombin receptor-activating peptide-6 (TRAP) tests (p = .009, p = .02, p = .007, respectively). In the subgroup analysis, both treprostinil and epoprostenol decreased platelet reactivity to the similar extent. There were no differences regarding thrombin generation, clot permeation, and lysis parameters in patients receiving and not receiving PGI2 analogues (p ≥ .60 for all). In the subgroup analysis, there were no differences regarding coagulation and fibrinolysis parameters between treprostinil, epoprostenol, and no PGI2 analogues. To conclude, patients with PAH treated with PGI2 analogues have reduced platelet reactivity, but similar clot formation and lysis parameters, compared to patients not receiving PGI2 analogues. Further randomized clinical trials are required to confirm these findings.

MicroRNAs (miRNAs) are small, non-coding RNAs, able to regulate cellular functions by induction of mRNA degradation and post-transcriptional repression of gene expression. Platelets are the major source of circulating miRNAs, with significant regulatory potential on cardiovascular pathophysiology and other diseases. MiRNAs have been shown to modify the expression of platelet proteins, which influence the platelets reactivity. Circulating miRNAs can be determined from plasma, serum, or whole blood, and they can be used as diagnostic and prognostic biomarkers as well as therapeutic targets including cardiovascular diseases (CVDs). Herein, we present original results from bioinformatic analyses, which identified top 22 platelet-related miRNAs including hsa-miR-320a, hsa-miR-16-5p, hsa-miR-106a-5p, hsa-miR-320b, hsa-miR-15a-5p, hsa-miR-15b-5p, hsa-miR-195-5p, hsa-miR-92a-3p as widely involved in platelet reactivity and associated diseases, including CVDs, Alzheimer’s and cerebrovascular diseases, cancer and hypertension. Analysis focused on the identification of the highly regulatory targets shared between those miRNAs identified 43 of them. Best ranked genes associated with overall platelet activity and most susceptible for noncoding regulation were PTEN, PIK3R1, CREB1, APP, and MAPK1. Top targets also strongly associated with CVDs were VEGFA, IGF1, ESR1, BDNF, and PPARG. Top targets associated with other platelet-related diseases including cancer identified in our study were TP53, KRAS, and CCND1. The most affected pathways by top miRNAs and top targets included diseases of signal transduction by Growth Factor Receptors (GDFRs) and second messengers, platelet activation, signaling, and aggregation, signaling by VEGF, MAPK family signaling cascades, and signaling by Interleukins. Terms specific only for platelet-related miRNAs included coronary artery disease, platelet degranulation, and neutrophil degranulation, while for the top platelet-related genes it was Estrogen Signaling Receptor (ESR) mediated signaling, extra-nuclear estrogen signaling, and endometriosis. Our results show the novel features of platelet physiology and may provide a basis for further clinical studies focused on platelet reactivity. They also show in which aspects miRNAs can be promising biomarkers of platelet-related pathological processes.

Abstract Aims Acute myocardial infarction (AMI) is associated with left ventricular remodelling (LVR), which leads to progressive heart failure. Platelets play a pivotal role in promoting systemic and cardiac inflammatory responses during the complex process of myocardial wound healing or repair following AMI. This study aimed to investigate the impact of platelet reactivity immediately after primary percutaneous coronary intervention (PCI) on LVR in AMI patients with ST‐segment (STEMI) and non‐ST‐segment elevation (NSTEMI). Methods and results This prospective, single‐centre, observational study included 182 patients with AMI who underwent primary PCI (107 patient with STEMI and 75 patients with NSTEMI). Patients were administered a loading dose of aspirin plus prasugrel before the procedure, and platelet reactivity was assessed using the VerifyNow P2Y12 assay immediately after PCI. Echocardiography was performed before discharge and during the chronic phase (8 ± 3 months after discharge). LVR was defined as a relative ≥20% increase in left ventricular end‐diastolic volume index (LVEDVI). LVR in chronic phase was found in 34 patients (18.7%) whose platelet reactivity was significantly higher than those without LVR (259.6 ± 61.5 and 213.1 ± 74.8 P2Y12 reaction units [PRU]; P = 0.001). The occurrence of LVR did not differ between patients with STEMI and patients with NSTEMI (21.5% and 14.7%; P = 0.33). The optimal cut‐off value of platelet reactivity for discriminating LVR was ≥245 PRU. LVEDVI significantly decreased at chronic phase in patients without high platelet reactivity (

Mass cytometry (CyTOF) is a new technology that allows the investigation of protein expression at single cell level with high resolution. While several protocols are available to investigate leukocyte expression, platelet staining and analysis with CyTOF have been described only from whole blood. Moreover, available protocols do not allow sample storage but require fresh samples to be obtained, processed, and measured immediately. We provide a structured and reproducible method to stain platelets from platelet-rich plasma to study thrombocyte protein expression and reactivity using mass cytometry. With our method, it is possible to acquire a large number of events allowing deep bioinformatic investigation of platelet expression heterogeneity. Integrated in our protocol is also a previously established freezing protocol that allows the storage of stained samples and to delay their measurement. Finally, we provide a structured workflow using different platelet stimulators and a freely available bioinformatic pipeline to analyze platelet expression. Our protocol unlocks the potential of CyTOF analysis for studying platelet biology in health and disease.

Several studies report elevated blood platelet activation and altered platelet count in COVID-19 patients, but the role of the SARS-CoV-2 spike protein in this process remains intriguing. Additionally, there is no data that anti-SARS-CoV-2 neutralizing antibodies (nAb) may attenuate spike protein activity toward blood platelets. Our results indicate that under in vitro conditions, the spike protein increased the collagen-stimulated aggregation of isolated platelets and induced the binding of vWF to platelets in ristocetin-treated blood. The spike protein also significantly reduced collagen- or ADP-induced aggregation or decreased GPIIbIIIa (fibrinogen receptor) activation in whole blood, depending on the presence of the anti-spike protein nAb. Our findings suggest that studies on platelet activation/reactivity in COVID-19 patients or in donors vaccinated with anti-SARS-CoV-2 and/or previously-infected COVID-19 should be supported by measurements of spike protein and IgG anti-spike protein antibody concentrations in blood. [ABSTRACT FROM AUTHOR]

Transcription factors bind promoter or regulatory sequences of a gene to regulate its rate of transcription. However, they are also detected in anucleated platelets. The transcription factors RUNX1, GATA1, STAT3, NFκB, and PPAR have been widely reported to play key roles in the pathophysiology of platelet hyper-reactivity, thrombosis, and atherosclerosis. These nontranscriptional activities are independent of gene transcription or protein synthesis but their underlying mechanisms of action remain poorly defined. Genetic and acquired defects in these transcription factors are associated with the production of platelet microvesicles that are known to initiate and propagate coagulation and to promote thrombosis. In this review, we summarize recent developments in the study of transcription factors in platelet generation, reactivity, and production of microvesicles, with a focus on non-transcriptional activities of selected transcription factors. [ABSTRACT FROM AUTHOR]

Background: The clinical and prognostic implications of platelet reactivity (PR) testing in a P2Y12-inhibitor naïve population are poorly understood. Objectives: This explorative study aims to assess the role of PR and explore factors that may modify elevated mortality risk in patients with altered PR. Methods: Platelet ADP-induced CD62P and CD63 expression were measured by flow-cytometry in 1520 patients who were referred for coronary angiography in the Ludwigshafen Risk and Cardiovascular Health Study (LURIC). Results: High- and Low-platelet reactivity to ADP were strong predictors of cardiovascular and all-cause mortality and risk equivalent to the presence of coronary artery disease. (High platelet reactivity 1.4 [95% CI 1.1–1.9]; Low platelet reactivity: 1.4 [95% CI 1.0–2.0]). Relative weight analysis indicated glucose control (HbA1c), renal function ([eGFR]), inflammation (high-sensitive C-reactive protein [hsCRP]) and antiplatelet therapy by Aspirin as consistent mortality risk modifiers in patients with Low- and High-platelet reactivity. Pre-specified stratification of patients by risk modifiers HbA1c (<7.0%), eGFR (>60 mL/min/1.73 m2) and CRP (<3 mg/L) was associated with a lower mortality risk, however irrespective of platelet reactivity. Aspirin treatment was associated with reduced mortality in patients with high platelet reactivity only (p for interaction: 0.02 for CV-death [<0.01 for all-cause mortality]. Conclusions: Cardiovascular mortality risk in patients with High- and Low platelet reactivity is equivalent to the presence of coronary artery disease. Targeted glucose control, improved kidney function and lower inflammation are associated with reduced mortality risk, however independent of platelet reactivity. In contrast, only in patients with High-platelet reactivity was Aspirin treatment associated with lower mortality. [ABSTRACT FROM AUTHOR]

Introduction: Despite therapy, patients operated using a cardiopulmonary bypass demonstrate increased platelet aggregation, which rebounds to above preoperative levels. The aim of the study was to test the interaction between platelet reactivity/activation and selected inflammatory markers in the post-operative period. Material and methods: In total, 103 patients with non-ST elevation acute coronary syndrome (NSTE-ACS) who were not eligible for percutaneous coronary interventions (PCI), and required urgent revascularization, were included. Platelet reactivity was measured using the PFA-100 platelet analyser, multiple electrode aggregometry, and was expressed as a novel platelet reactivity score (PRS). Patients were divided using their PRS scores into high platelet relativity or low platelet reactivity subgroups (HPR or LPR). Platelet basal activation was measured using immunoassays for soluble P-selectin and soluble CD40L. We measured high-sensitivity C-reactive protein (CRP), and used immunoassays for tumour necrosis factor α (TNF-α) and interleukin 6 (IL-6) as inflammation markers. Results: Significant differences between HPR and LPR groups were found for CRP (mg/l): 81.5 vs. 44.6, p < 0.02; and TNF-α (pg/l): 3.51 vs. 2.37, p < 0.02. A significant association was found between CRP, TNF-α, IL-6 and platelet reactivity (platelet reactivity score). Cohen's k showed: CRP = 0.49, p < 0.0001, TNF-α = 0.37, p < 0.002. Perioperative myocardial infarction and rhythm disturbances occurred more frequently in the high platelet reactivity group: 7 (16.3%) vs. 2 (3.3%), p < 0.04, and 9 (20.9%) vs. 4 (6.7%), p < 0.04, respectively. Conclusions: Inflammatory parameters CRP and TNF-α are strongly associated with platelet reactivity (expressed as PRS) in cardiopulmonary bypass graft patients. Platelet hyperreactivity in the early post-operative period combined with a systemic inflammatory state correlates with a higher risk of post-operative rhythm disturbances and myocardial infarction. [ABSTRACT FROM AUTHOR]

Bleeding events in patients with acute coronary syndrome (ACS) are a risk factor for adverse outcomes, including mortality. We investigated the association of growth differentiation factor (GDF)-15, an established predictor of bleeding complications, with on-treatment platelet reactivity in ACS patients undergoing coronary stenting receiving prasugrel or ticagrelor. Platelet aggregation was measured by multiple electrode aggregometry (MEA) in response to adenosine diphosphate (ADP), arachidonic acid (AA), thrombin receptor-activating peptide (TRAP, a protease-activated receptor-1 (PAR-1) agonist), AYPGKF (a PAR-4 agonist) and collagen (COL). GDF-15 levels were measured using a commercially available assay. GDF-15 correlated inversely with MEA ADP (r = −0.202, p = 0.004), MEA AA (r = −0.139, p = 0.048) and MEA TRAP (r = −0.190, p = 0.007). After adjustment, GDF-15 was significantly associated with MEA TRAP (β = −0.150, p = 0.044), whereas no significant associations were detectable for the other agonists. Patients with low platelet reactivity in response to ADP had significantly higher GDF-15 levels (p = 0.005). In conclusion, GDF-15 is inversely associated with TRAP-inducible platelet aggregation in ACS patients treated with state-of-the-art antiplatelet therapy and significantly elevated in patients with low platelet reactivity in response to ADP. [ABSTRACT FROM AUTHOR]

Newly produced immature platelets are larger, contain higher amounts of residual RNA, and are more reactive than mature platelets. Flow cytometry using the SYTO-13 dye is a method for the subdivision of immature platelets from mature platelets based on the labelling of intracellular platelet RNA, enabling the simultaneous investigation of the reactivity of each platelet population. This method provides detailed information on several aspects of platelet physiology using a combination of platelet surface markers and agonists. Currently, no standardized protocol exists across laboratories. Here, we describe a flow cytometry protocol in detail to investigate platelet reactivity and its relation to platelet maturity. We analyzed 20 healthy individuals with the protocol and compared the platelet subpopulation with the highest SYTO-13 labelling (in the first quintile, "SYTO-high") corresponding to the most immature platelets (highest RNA content) with the platelet subpopulation with the lowest SYTO-13 labelling (in the fifth quintile, "SYTO-low") corresponding to the mature platelets with the lowest RNA content. SYTO-high platelets had overall significantly increased platelet reactivity compared with that of SYTO-low platelets. The presented method may be a valuable research tool for the analysis of platelet reactivity and its relation to platelet maturity. [ABSTRACT FROM AUTHOR]

Exercise training (ET) can lower platelet reactivity in patients with cardiovascular risk factors. However, the effects of ET on platelet reactivity in higher-risk patients is unknown. The aim of this study was to evaluate the effects of ET on platelet reactivity in patients with recent myocardial infarction (MI). Ninety patients were randomly assigned 1 month post-MI to the intervention (patients submitted to a supervised ET program) or control group. All patients were on dual antiplatelet therapy (DAPT). Platelet reactivity by VerifyNow-P2Y12 (measured by P2Y12 reaction units – PRUs) test was determined at baseline and at the end of 14 ± 2 weeks of follow-up at rest (primary endpoint), and multiplate electrode aggregometry (MEA) adenosine diphosphate (ADP) and aspirin (ASPI) tests were performed immediately before and after the maximal cardiopulmonary exercise test (CPET) at the same time points (secondary endpoints). Sixty-five patients (mean age 58.9 ± 10 years; 73.8% men; 60% ST elevation MI) completed follow-up (control group, n = 31; intervention group, n = 34). At the end of the follow-up, the mean platelet reactivity was 172.8 ± 68.9 PRUs and 166.9 ± 65.1 PRUs for the control and intervention groups, respectively (p =.72). Platelet reactivity was significantly increased after the CPET compared to rest at the beginning and at the end of the 14-week follow-up (among the intervention groups) by the MEA-ADP and MEA-ASPI tests (p <.01 for all analyses). In post-MI patients on DAPT, 14 weeks of supervised ET did not reduce platelet reactivity. Moreover, platelet reactivity was increased after high-intensity exercise (ClinicalTrials.gov: NCT02958657; ). What is the context? Platelet reactivity is reduced after exercise training in healthy individuals and patients with cardiovascular risk factors, but the effect in higher-risk patients is unknown. High-intensity exercise in untrained individuals increases platelet reactivity. The effect of dual antiplatelet therapy in inhibiting exercise-induced hyperreactivity is poorly understood. What's new? Exercise training did not reduce platelet reactivity in post-myocardial infarction patients. High-intensity exercise increased platelet reactivity in post-myocardial infarction patients on dual antiplatelet therapy. Exercise training did not attenuate the exercise-induced increase in platelet reactivity. What's the impact? The study suggests that strenuous exercise, if indicated, should be applied carefully to patients with high risk of recurrent ischemic events, even if on optimal medical therapy and after being trained. [ABSTRACT FROM AUTHOR]

The interaction of platelets with steroid hormones is poorly investigated. Age is one of the factors that increase the risk of pathological platelet reactivity and thrombosis. The aim of this study was to assess whether there were associations between platelet reactivity and plasma cortisol levels in volunteers aged 60–65 years. For this purpose, impedance aggregometry in whole blood measured after arachidonic acid, collagen, or ADP stimulation was used to estimate platelet reactivity and mass spectrometry was used to measure peripheral plasma cortisol concentration. Statistically significant negative correlations were observed between cortisol concentration and platelet reactivity in response to arachidonic acid and ADP, but not to collagen. The presented results suggest for the very first time that cortisol is a new endogenous modulator of platelet reactivity in the elderly population. [ABSTRACT FROM AUTHOR]

Background and Objectives: Dual antiplatelet therapy (DAPT) is essential in the treatment of patients with acute coronary syndrome (ACS). The objective of this study was to evaluate the effectiveness of antiplatelet medication in our practice and to investigate the factors that influence it. Materials and Methods: A prospective cohort observational study was conducted, in which 193 patients with ACS were enrolled. The patients were stented in the catheterization laboratory between May 2019 and October 2020, before and during the COVID-19 pandemic, and were receiving DAPT. Their platelet functions were tested using a Multiplate Analyzer. In addition to this, clinical data, demographics, laboratory tests, and cardiovascular risk factors were also analyzed. Results: 43.46% of the patients treated with aspirin were found to be resistant to it. This phenomenon was more common in men (48.17% vs. 31.48%, p = 0.036), and it was associated with being under the age of 50 (OR: 2.08; 95% CI: 1.11–3.90) and weighing over 70 kg (OR: 3.00; 95% CI: 1.21–7.40). Most of the patients treated with clopidogrel were in the optimal treatment window, while about half of the patients treated with ticagrelor had an exaggerated pharmacological response. Among the laboratory parameters, leukocytosis and platelet count were found to be determinants of platelet reactivity for both the aspirin and ticagrelor treatments. Conclusions: Many patients treated with antiplatelet agents are outside of the treatment window. The results obtained showed that low doses of gastro-resistant aspirin tablets are ineffective, and their efficacy can be influenced by various clinical and laboratory factors. Patients receiving ticagrelor have significantly reduced platelet reactivity, influenced only by certain laboratory indicators. The pandemic significantly influenced the results of the platelet aggregation tests only in patients treated with clopidogrel. [ABSTRACT FROM AUTHOR]

Background: Chronic renal failure (CKD) is associated with the presence of increased platelet reactivity and lower clinical benefit of clopidogrel. Ticagrelor has a more favorable pharmacodynamic and pharmacokinetic profile compared to clopidogrel, which has translated into better clinical outcomes in patients with acute coronary syndrome (ACS). We conducted a prospective mechanistic cohort study in order to investigate the impact of renal failure on the pharmacokinetics and pharmacodynamics of ticagrelor in patients with acute ACS. Methods: Patients were divided into two groups based on their estimated renal clearances (eGFR ≥ 60 mL/min and eGFR

BackgroundMetabolic abnormalities are associated with the occurrence, severity, and poor prognosis of coronary artery disease (CAD), some of which affect the antiplatelet efficacy of clopidogrel. Free fatty acids (FFAs) is a biomarker for metabolic abnormalities, and elevated FFAs is observed among CAD patients. Whether FFAs enhances residual platelet reactivity induced by adenosine diphosphate (ADP) while using clopidogrel was unknown. The purpose of our study is exploring the issue.MethodCurrent study included 1,277 CAD patients using clopidogrel and used logistic regression to detect whether the higher level of FFAs is associated with high residual platelet reactivity (HRPR). We additionally performed subgroup and sensitivity analyses to evaluate the stability of the results. We defined HRPR as ADP-induced platelet inhibition rate (ADPi) 47 mm.Results486 patients (38.1%) showed HRPR. The proportion of HRPR among patients with higher FFAs (>0.445 mmol/L) is greater than among patients with lower FFAs (46.4% vs. 32.6%, P 0.445 mmol/L) is independently associated with HRPR (adjusted OR = 1.745, 95% CI, 1.352–2.254). After subgroup and sensitivity analyses, the results remained robust.ConclusionThe higher level of FFAs enhances residual platelet reactivity induced by ADP and is independently associated with clopidogrel HRPR.

Introduction: Patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) require dual antiplatelet therapy (DAPT). However, the response to treatment can vary considerably. Certain platelet microRNAs (miRs) are suspected to predict DAPT response and influence platelet function. This study aimed to analyze selected miRs’ expressions and compare them among patients treated with different P2Y12 inhibitors while assessing their association with platelet activity and turnover parameters. Materials and methods: We recruited 79 ACS patients post-PCI treated with clopidogrel, ticagrelor, or prasugrel, along with 18 healthy volunteers. Expression levels of miR-126-3p, miR223-3p, miR-21-5p, miR-197-3p, and miR-24-3p, as well as immature platelet fraction (IPF) and ADP-induced platelet reactivity, were measured and compared between groups. Results: Analyses revealed significantly lower expressions of miR-126-3p, miR-223-3p, miR-21-5p, and miR-197-3p in patients treated with ticagrelor, compared to clopidogrel (fold changes from −1.43 to −1.27, p-values from 0.028 to 0.048). Positive correlations were observed between platelet function and the expressions of miR-223-3p (r = 0.400, p = 0.019) and miR-21-5p (r = 0.423, p = 0.013) in patients treated with potent drugs. Additionally, miR-24-3p (r = 0.411, p = 0.012) and miR-197-3p (r = 0.333, p = 0.044) showed correlations with IPF. Conclusions: The identified platelet miRs hold potential as biomarkers for antiplatelet therapy. (ClinicalTrials.gov number, NCT06177587).

Abstract Background The prevalence and the role of CYP2C19 gene mutations concerning recurrent Cardiovascular Events (CVEs) among patients treated with clopidogrel is still controversial especially among Arab people. Therefore, this review aimed to determine the frequency of CYP2C19 polymorphic alleles among the Arab population and to investigate the efficacy of clopidogrel as an antiplatelet drug among those carrying different variants of this gene. Methodology Two authors independently searched in PubMed, Google Scholar, and EMBASE databases at any year for studies related to the role of CYP2C19 gene on the prognosis of patients with CVEs treated with clopidogrel. The review included Arab people who were genotyped to determine the frequency of CYP2C19 genotypes and alleles (the qualitative part). Concerning the quantitative part (meta-analysis), only patients who previously had CVEs and using clopidogrel as secondary prophylaxis had been included. The Newcastle Ottawa Scale for non-randomizes Studies was utilized to consider the risk of bias among included studies. We analyzed the data using odds ratio at 95% confidence interval and the quality of evidence of each outcome measure was judged using GRADE approach. Results The current study revealed that 4% of Arabs reported in the included studies are homozygous, and 25% are heterozygous for the CYP2C19*2 allele. While 3% and 18.5% of them are homozygous and heterozygous of CYP2C19*17 alleles, respectively. A significant increased risk of recurrent CVEs by about threefold was associated with CYP2C19*2 or CYP2C19*3 allele carriers (OR = 3.32, CI = 1.94–5.67, and OR = 3.53, CI = 1.17–10.63, respectively). However, no significant increased risk among carriers of CYP2C19*17 mutation (OR = 0.80, (CI = 0.44–1.44) was documented. Conclusion The present study revealed that Arabs carrying CYP2C19*2 and CYP2C19*3 alleles could be at increased risk of decreasing the antiplatelet efficacy of clopidogrel and an alternative drug should be prescribed for those patients to avoid recurrent CVEs. However, few available studies were included in the quantitative part of the analysis and further studies with large sample size are recommended to confirm our results.

Endovascular aortic repair (EVAR) an alternative to open surgical repair of thoracoabdominal aortic aneurysm (TAAA). The effect of EVAR on platelet reactivity is unknown. We prospectively determined the effect of branched EVAR (bEVAR) on platelet reactivity in patients with TAAA, and evaluated the predictive value of preoperative platelet reactivity for post-operative bleeding in 50 consecutive patients undergoing elective bEVAR (mean age 70.9 ± 5.7 years, 66% male). Blood samples were collected within 24 hours before bEVAR, after bEVAR and at hospital discharge. Platelet reactivity was assessed with impedance aggregometry using ASPI, ADP and TRAP tests. Platelet reactivity decreased within 24 hours after bEVAR compared to the measurement before bEVAR in all tests (p ≤ 0.04), with a further decrease in hospital discharge in the ADP test (p = .004). Twenty-three patients experienced post-operative bleeding complications (transfusion ≥2 red blood cell [RBC] units). Preoperative platelet reactivity below the cutoff value of 30 AUC units predicted post-operative bleeding with 78% sensitivity and 59% specificity (p = .045). In the multivariable analysis, platelet reactivity was the only independent predictor of postoperative bleeding (OR 6.507, 95% CI 1.227–34.506, p = .028). We conclude that platelet reactivity decreases following bEVAR of TAAA and is a strong and independent predictor for postoperative bleeding complications.

Abstract Background In patients with type 2 diabetes mellitus (T2DM) an association between severe hypoglycaemic episodes and the risk of cardiovascular (CV) morbidity and mortality has been previously established. Methods We aimed to investigate the influence of hypoglycaemia on several diabetes-related and platelet-related miRNAs selected based on bioinformatic analysis and literature search, including hsa-miR-16, hsa-miR-34a, hsa-miR-129-2, hsa-miR-15a, hsa-miR-15b, hsa-miR-106a, miR-223, miR-126. Selected miRNAs were validated by qRT-PCR in 14 patients with T2DM on metformin monotherapy, without established CV disease and antiplatelet therapy during a stepwise hypoglycaemic clamp experiment and a follow-up 7 days after the clamp event. In order to identify which pathways and phenotypes are associated with validated miRNAs we performed target prediction on genes expressed with high confidence in platelets. Results Circulating levels of miR-106a-5p, miR-15b, miR-15a, miR-16-5p, miR-223 and miR-126 were increased after euglycaemic clamp followed by hypoglycaemic clamp, each with its distinctive time trend. On the contrary, miR-129-2-3p, miR-92a-3p and miR-34a-3p remained unchanged. MiR-16-5p was negatively correlated with interleukin (IL)-6, intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM) (p = 0.002, p

While previous reports showed ADP-induced platelet reactivity to be an independent predictor of bleeding after PCI in stable patients, this has never been investigated in patients with cardiogenic shock. The association of bleeding events with respect to ADP-induced platelet aggregation was investigated in patients undergoing primary PCI for acute myocardial infarction complicated by cardiogenic shock and with available on-treatment ADP-induced platelet aggregation measurements. Out of 233 patients, 74 suffered from a severe BARC3 or higher bleed. ADP-induced platelet aggregation was significantly lower in patients with BARC≥3 bleedings (p