Clopidogrel Improves Systemic Endothelial Nitric Oxide Bioavailability in Patients With Coronary Artery Disease

Familial catamenial coronary spasms

Coronary artery spasms represent important causes of myocardial ischaemia and infarction in patients with non-obstructive coronary artery disease. They are notably seen in younger people and occur almost equally in men and women. Besides traditional risk factors (ie, smoking), female hormones might also play a role.We report of two young sisters who presented with myocardial infarction caused by catamenial coronary spasms (CS), that is, during menstruation. In one of these women, this resulted in heart failure with a severely reduced ejection fraction and ultimately a heart transplant because of intractable ventricular arrhythmias.CS might result from changing hormone levels (especially oestrogen) during menstruation. Increased awareness of the occurrence of catamenial CS is essential for diagnosis and consequent treatment with coronary vasodilators and/or specific oestrogen/progesterone regimens.

Superoxide Dismutase and Clopidogrel: A Potential Role in Peripheral Arterial Disease Treatment

Oxidative stress plays a crucial role in the pathogenesis of peripheral artery disease (PAD). This study aimed to investigate the effect of clopidogrel on oxidative stress in PAD patients. Seventy subjects were divided into three groups: PAD patients before treatment (B-PAD), PAD patients after treatment with clopidogrel (A-PAD), and healthy controls. Serum levels of superoxide dismutase (SOD), copper (Cu), zinc (Zn), manganese (Mn), and oxidized protein were measured. SOD activities were also determined. The results showed that SOD activities, and SOD specific activities were significantly decreased in PAD patients compared to healthy individuals. After treatment with clopidogrel, SOD activities, and SOD specific activities were continuously decrease in PAD patients. The SOD and oxidized protein concentrations were significantly increased in PAD patients compared to healthy individuals. After treatment with clopidogrel, the oxidized protein concentration was significantly decreased, while SOD concentration was significantly increased in PAD patients. These findings suggest that the treatment by clopidogrel stimulated the production of the enzyme but the ratio of active enzyme remained low. The decrease in oxidized protein can be explained by the treatment having antioxidant efficacy that may have compensated for the deficiency in enzyme activity and led to a decrease in oxidized protein. Additionally, the results of this study provide promising evidence that oxidative stress biomarkers including SOD concentration, T-SOD activity, Mn-SOD activity, and oxidized protein levels have potential utility in the diagnosis and management of PAD.

Antiplatelet therapy prior to COVID-19 infection impacts on patients mortality: a propensity score-matched cohort study

One of the major pathomechanisms of COVID-19 is the interplay of hyperinflammation and disruptions in coagulation processes, involving thrombocytes. Antiplatelet therapy (AP) by anti-inflammatory effect and inhibition of platelet aggregation may affect these pathways. The aim of this study was to investigate if AP has an impact on the in-hospital course and medium-term outcomes in hospitalized COVID-19 patients. The study population (2170 COVID-19 patients: mean ± SD age 60 ± 19 years old, 50% male) was divided into a group of 274 patients receiving any AP prior to COVID-19 infection (AP group), and after propensity score matching, a group of 274 patients without previous AP (non-AP group). Patients from the AP group were less frequently hospitalized in the intensive care unit: 9% vs. 15%, 0.55 (0.33-0.94), developed less often shock: 9% vs. 15%, 0.56 (0.33-0.96), and required less aggressive forms of therapy. The AP group had more coronary revascularizations: 5% vs. 1%, 3.48 (2.19-5.55) and strokes/TIA: 5% vs. 1%, 3.63 (1.18-11.2). The bleeding rate was comparable: 7% vs. 7%, 1.06 (0.54-2.06). The patients from the AP group had lower 3-month mortality: 31% vs. 39%, 0.69 (0.51-0.93) and didn't differ significantly in 6-month mortality: 34% vs. 41%, 0.79 (0.60-1.04). When analyzing the subgroup with a history of myocardial infarction and/or coronary revascularization and/or previous stroke/transient ischemic attack and/or peripheral artery disease, AP had a beneficial effect on both 3-month: 37% vs. 56%, 0.58 (0.40-0.86) and 6-month mortality: 42% vs. 57%, 0.63 (0.44-0.92). Moreover, the favourable effect was highly noticeable in this subgroup where acetylsalicylic acid was continued during hospitalization with reduction of in-hospital: 19% vs. 43%, 0.31 (0.15-0.67), 3-month: 30% vs. 54%, 044 (0.26-0.75) and 6-month mortality: 33% vs. 54%, 0.49 (0.29-0.82) when confronted with the subgroup who had acetylsalicylic acid suspension during hospitalization. The AP may have a beneficial impact on hospital course and mortality in COVID-19 and shouldn't be discontinued, especially in high-risk patients.

The role of platelet P2Y12 receptors in inflammation

Inflammation is a complex pathophysiological process underlying many clinical conditions. Platelets contribute to the thrombo-inflammatory response. Platelet P2Y12 receptors amplify platelet activation, potentiating platelet aggregation, degranulation and shape change. The contents of platelet alpha granules, in particular, act directly on leucocytes, including mediating platelet-leucocyte aggregation and activation via platelet P-selectin. Much evidence for the role of platelet P2Y12 receptors in inflammation comes from studies using antagonists of these receptors, such as the thienopyridines clopidogrel and prasugrel, and the cyclopentyltriazolopyrimidine ticagrelor, in animal and human experimental models. These suggest that antagonism of P2Y12 receptors decreases markers of inflammation with some evidence that this reduces incidence of adverse clinical sequelae during inflammatory conditions. Interpretation is complicated by pleiotropic effects such as those of the thienopyridines on circulating leucocyte numbers and of ticagrelor on adenosine reuptake. The available evidence suggests that P2Y12 receptors are prominent mediators of inflammation and P2Y12 receptor antagonism as a potentially powerful strategy in a broad range of inflammatory conditions. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Antioxidant Properties of Oral Antithrombotic Therapies in Atherosclerotic Disease and Atrial Fibrillation

The thrombosis-related diseases are one of the leading causes of illness and death in the general population, and despite significant improvements in long-term survival due to remarkable advances in pharmacologic therapy, they continue to pose a tremendous burden on healthcare systems. The oxidative stress plays a role of pivotal importance in thrombosis pathophysiology. The anticoagulant and antiplatelet drugs commonly used in the management of thrombosis-related diseases show several pleiotropic effects, beyond the antithrombotic effects. The present review aims to describe the current evidence about the antioxidant effects of the oral antithrombotic therapies in patients with atherosclerotic disease and atrial fibrillation.

Cardiovascular benefits of air purifier in patients with stable coronary artery disease: A randomized single-blind crossover study

Background

Exposure to PM_2.5 will accelerate the progression of cardiovascular diseases. Air purifier can reduce the PM_2.5 exposure and theoretically alleviate the influence of PM_2.5 on patients with stable coronary artery disease (SCAD). However, few studies of the protective effect showed significant results because the interferent effects of routine medication had not been taken into account. In order to explore the actual effect on patients with SCAD, we conducted a randomized single-blind crossover air purifier intervention trial.

Method

Levels of PM_2.5 exposure during intervention and cardiovascular indicators (inflammation, coagulation, plaque stability, and blood lipids) after intervention were detected, meanwhile the information of drug use was obtained by questionnaire. The kinds of drug used by more than 20% of the subjects were sorted out. And the influence of these drugs on cardiovascular indicators was summarized through literature review. Based on that, the drug use was included as a variable in linear mixed effects models that used to analyze the associations between PM_2.5 exposure reduction by air purifier and cardiovascular indicators.

Results

The result revealed that the interpretation contribution rate of drug use was more than that of PM_2.5 exposure. The level of C-reactive protein significantly decreased by 20.93% (95%CI: 6.56%, 33.10%), 23.44% (95%CI: 2.77%, 39.39%) and 24.11% (95%CI: 4.21%, 39.69%) on lag1, lag01 and lag02 respectively, while the level of high-density lipoprotein cholesterol significantly increased by 5.10% (95%CI: 0.69%, 9.05%), 3.71% (95%CI: 0.92%, 6.60%) and 6.48% (95%CI: 2.58%, 10.24%) respectively on lag0, lag1 and lag01 associated with an interquartile range decrease of 22.51 μg/m³ in PM_2.5 exposure.

Conclusion

The study shows positive effects of air purifier on SCAD, and also provides methodological reference for future related research.

Where the Action Is-Leukocyte Recruitment in Atherosclerosis

Atherosclerosis is the leading cause of death worldwide and leukocyte recruitment is a key element of this phenomenon, thus allowing immune cells to enter the arterial wall. There, in concert with accumulating lipids, the invading leukocytes trigger a plethora of inflammatory responses which promote the influx of additional leukocytes and lead to the continued growth of atherosclerotic plaques. The recruitment process follows a precise scheme of tethering, rolling, firm arrest, crawling and transmigration and involves multiple cellular and subcellular players. This review aims to provide a comprehensive up-to-date insight into the process of leukocyte recruitment relevant to atherosclerosis, each from the perspective of endothelial cells, monocytes and macrophages, neutrophils, T lymphocytes and platelets. In addition, therapeutic options targeting leukocyte recruitment into atherosclerotic lesions-or potentially arising from the growing body of insights into its precise mechanisms-are highlighted.

Clinical and pharmacological parameters determine relapse during clopidogrel treatment of acute coronary syndrome

The therapeutic efficacy of clopidogrel as an anti-platelet drug varies among individuals, being the mainstream hypothesis that its bioavailability depends on the individual genetic background and/or interactions with other drugs. A total of 477 patients receiving double anti-aggregation therapy with aspirin and clopidogrel, after suffering a first event, were followed for 1 year to record relapse, as a surrogate end point to measure their therapeutic response, as defined by presenting with an acute coronary event (unstable angina, STEMI, or NSTEMI), stent thrombosis/restenosis or cardiac mortality. Anthropometric, clinical and pharmacological variables along with CYP2C19 genotypes were analyzed for their association with the disease relapse phenotype. Only 75 patients (15%) suffered a relapse, which occurred during the first six months of therapy, with a peak at 4.5 months. An initial univariate analysis identified that patients in the relapse group were significantly older (67.4 ± 11.0 vs 61.6 ± 12.3 years old) and presented with diffuse coronary disease, insulin-dependent type 2 diabetes mellitus dyslipidemia, and arterial hypertension. A poor clinical response to the platelet anti-aggregation regime also occurred more frequently among patients taking, along with aspirin and clopidogrel, acenocoumarol and Calcium Channel Blockers, while no association was found according to CYP2C19 genotypes. A retrospective multivariate analysis indicated that patients belonging to the non-responder phenotype to treatment with aspirin and clopidogrel were older, presented with diffuse coronary disease, a group largely overlapping with type 2 insulin-dependent diabetes mellitus, and were taking dihidropyrimidinic calcium channel blockers. This article is protected by copyright. All rights reserved.

Effects of Monotherapy with Clopidogrel vs. Aspirin on Vascular Function and Hemostatic Measurements in Patients with Coronary Artery Disease: The Prospective, Crossover I-LOVE-MONO Trial

Objectives: To evaluate the effect of clopidogrel vs. aspirin monotherapy on vascular function and hemostatic measurement. Background: Monotherapy with P2Y₁₂ receptor inhibitor vs. aspirin can be a useful alterative to optimize clinical efficacy and safety in high-risk patients with coronary artery disease (CAD). Methods: We performed a randomized, open-label, two-period crossover study in stented patients receiving at least 6-month of dual antiplatelet therapy (DAPT). Thirty CAD patients with moderate-to-high ischemic risk were randomly assigned to receive either 75 mg of clopidogrel or 100 mg of aspirin daily for 4 weeks, and were crossed over to the other strategy for 4 weeks. Vascular function was evaluated with reactive hyperemia-peripheral arterial tonometry (RH-PAT) and brachial-ankle pulse wave velocity (baPWV). Hemostatic profiles were measured with VerifyNow and thromboelastography (TEG). The primary endpoint was the reactive hyperemia index (RHI) during clopidogrel or aspirin monotherapy. Results: Clopidogrel vs. aspirin monotherapy was associated with better endothelial function (RHI: 2.11 ± 0.77% vs. 1.87 ± 0.72%, p = 0.045), lower platelet reactivity (130 ± 64 vs. 214 ± 50 P2Y12 reaction unit [PRU], p < 0.001) and prolonged reaction time (TEG R: 5.5 ± 1.2 vs. 5.1 ± 1.1 min, p = 0.037). In multivariate analysis, normal endothelial function (RHI ≥ 2.1) was significantly associated with clot kinetics (TEG angle ≤ 68 degree) and ‘PRU ≤ 132’. ‘PRU ≤ 132’ was achieved in 46.2% vs. 3.8% during clopidogrel administration vs. aspirin monotherapy (odds ratio 21.4, 95% confidence interval 2.7 to 170.1, p < 0.001). Conclusions: In CAD patients, clopidogrel vs. aspirin monotherapy was associated with better endothelial function, greater platelet inhibition and lower coagulation activity, suggesting pleiotropic effects of clopidogrel on endothelial function and hemostatic profiles.

Supplementation of Lipoic Acid, Zinc and Clopidogrel Reduces Mortality Rate and Incidence of Ventricular Arrhythmia in Experimental Myocardial Infarction

Despite the significant advances in management of coronary heart diseases, myocardial infarction (MI) is still associated with a high mortality rate. The present study was planned to investigate the possible protective effects of the anti-oxidants lipoic acid and zinc sulfate as well as the anti-platelet clopidogrel on cardiac dysfunction in experimental isoproterenol (ISO)-induced MI, aiming at achieving useful means for protection and therapy against MI. Wistar rats of both sexes were allocated into five groups: control, untreated MI and MI pre-treated with lipoic acid, zinc, or clopidogrel. All rats were subjected to ECG recording and measurement of plasma levels of troponin I, creatine kinase-MB (CK-MB) unit, triglycerides and total cholesterol. The hearts were isolated and studied on Langendorff preparation for assessment of intrinsic cardiac activities. The results revealed that the percent mortality was markedly reduced upon pre-treatment and the total arrhythmia was also decreased except for the zinc pre-treated rats. The ST-segment elevation was significantly reduced and the plasma levels of CK-MB were only decreased in lipoic acid and clopidogrel pre-treated rats with variable hypolipidemic effect. Hearts of clopidogrel pre-treated rats showed augmented inotropic activity both basal and in response to β-adrenergic stimulation. While zinc pre-treated hearts revealed improved rate of contraction and increased myocardial flow rate. Overall, these results indicate that lipoic acid, zinc and clopidogrel were variably effective in modifying the ISO-induced MI insults and offered partial protection against experimental myocardial damage.

The effect of antiplatelet drug on coronary endothelial and microvascular function: comparison with ticagrelor and clopidogrel

BACKGROUND/AIMS

Coronary endothelial and microvascular function play important roles in cardiovascular disease. We aimed to evaluate the effect of ticagrelor on coronary artery function and tested the antiplatelet effect of low dose ticagrelor in East-Asian patients.

METHODS

Sixty-one consecutive patients with non-significant coronary disease were included in the study. Initially, patients were randomized in 1:1:1 ratio to receive drugs: ticagrelor 90 mg twice a day (bid; n = 22), ticagrelor 45 mg bid (n = 19) or clopidogrel 75 mg once a day (qd; n = 20) and then divided into two groups (ticagrelor vs clopidogrel) for evaluation of coronary artery function, and three groups for evaluation of antiplatelet function. Endothelial dysfunction was measured by coronary flow reserve (CFR), and changes in the levels of asymmetric dimethylarginine (ADMA), cluster of differentiation (CD) 40 ligand, and P-selectin. Microvascular function was evaluated as index of microvascular resistance (IMR). Platelet reactivity was assessed by VerifyNow P2Y12 assay.

RESULTS

The levels of CFR, ADMA, and CD 40 ligand were not different between the two groups. However, P-selectin was lower in the ticagrelor group compared with clopidogrel group. IMR was significantly lower in the ticagrelor group compared with clopidogrel group (median, 15.0 [interquartile range, 12.0 to 21.0] vs. 47.5 [23.0 to 67.5], p = 0.014). There was significant difference in platelet inhibition among the three groups (ticagrelor 90 mg bid vs. ticagrelor 45 mg bid vs. clopidogrel 75 mg qd; 85.57 ± 47.63 vs. 120.33 ± 51.09 vs. 256.42 ± 55.10, p < 0.001).

CONCLUSION

It is hypothesized that ticagrelor might ameliorate the coronary microvascular function. When compared with clopidogrel, low dose ticagrelor exhibited satisfactory antiplatelet effect in the present study.

Effect of Clopidogrel and Aspirin vs Aspirin Alone on Migraine Headaches After Transcatheter Atrial Septal Defect Closure: One-Year Results of the CANOA Randomized Clinical Trial

Importance

Adding clopidogrel to aspirin for 3 months after transcatheter atrial septal defect (ASD) closure results in a lower incidence of new-onset migraine attacks. However, the outcomes at 6- to 12-month follow-up (after clopidogrel cessation at 3 months) remain largely unknown.

Objective

To assess the incidence of migraine attacks at 6- and 12-month follow-up after transcatheter ASD closure.

Design, Setting, and Participants

This prespecified analysis of a randomized, double-blind clinical trial included patients with no prior history of migraine undergoing ASD closure from 6 university hospitals in Canada from December 2008 to November 2014. Patients were followed up at 3, 6, and 12 months, and a migraine headache questionnaire was administered at each time. Analysis began June 2019.

Interventions

Patients were randomized (1:1) to receive dual antiplatelet therapy (aspirin plus clopidogrel; n = 84) vs single antiplatelet therapy (aspirin plus placebo; n = 87) for 3 months following transcatheter ASD closure. After 3 months, only single antiplatelet therapy (aspirin) was pursued.

Main Outcomes and Measures

Incidence and severity of migraine attacks at 6- and 12-month follow-up.

Results

The mean (SD) age of the study population was 38 (12) years, with 106 women (62%). A total of 27 patients (15.8%) had new-onset migraine attacks within the 3 months following ASD closure (8 of 84 [9.5%] vs 19 of 87 [21.8%] in the initial clopidogrel and placebo groups, respectively; P = .03). After cessation of clopidogrel and aspirin monotherapy, the percentage of patients with migraine attacks decreased over time, with 8 (4.7%) and 4 patients (2.3%) continuing to have migraine attacks at 6 and 12 months, respectively (vs 3 months: P < .001). The severity of migraine attacks progressively decreased over time; no moderate or severe attacks occurred at 6 and 12 months (vs 3 months: P < .001). There were no differences between groups in the rate of migraine attacks at 6 months (initial clopidogrel group: 2 of 84 [2.4%]; initial placebo group: 6 of 87 [6.9%]; P = .28) and 12 months (initial clopidogrel group: 3 of 84 [3.6%]; initial placebo group: 1 of 87 [1.1%]; P = .36) after ASD closure. Only 2 patients (1.2%; 1 patient per group) presented with new-onset migraine attacks after 3 months.

Conclusions and Relevance

New-onset migraine attacks after ASD closure improved or resolved spontaneously within 6 to 12 months in most patients. No significant rebound effect was observed after clopidogrel cessation at 3 months. These results demonstrate a low rate of migraine events beyond 3 months following transcatheter ASD closure and support the early discontinuation of clopidogrel therapy if administered.

Trial Registration

ClinicalTrials.gov Identifier: NCT00799045.

Endothelium as a Therapeutic Target in Diabetes Mellitus: From Basic Mechanisms to Clinical Practice

Endothelium plays an essential role in human homeostasis by regulating arterial blood pressure, distributing nutrients and hormones as well as providing a smooth surface that modulates coagulation, fibrinolysis and inflammation. Endothelial dysfunction is present in Diabetes Mellitus (DM) and contributes to the development and progression of macrovascular disease, while it is also associated with most of the microvascular complications such as diabetic retinopathy, nephropathy and neuropathy. Hyperglycemia, insulin resistance, hyperinsulinemia and dyslipidemia are the main factors involved in the pathogenesis of endothelial dysfunction. Regarding antidiabetic medication, metformin, gliclazide, pioglitazone, exenatide and dapagliflozin exert a beneficial effect on Endothelial Function (EF); glimepiride and glibenclamide, dipeptidyl peptidase-4 inhibitors and liraglutide have a neutral effect, while studies examining the effect of insulin analogues, empagliflozin and canagliflozin on EF are limited. In terms of lipid-lowering medication, statins improve EF in subjects with DM, while data from short-term trials suggest that fenofibrate improves EF; ezetimibe also improves EF but further studies are required in people with DM. The effect of acetylsalicylic acid on EF is dose-dependent and lower doses improve EF while higher ones do not. Clopidogrel improves EF, but more studies in subjects with DM are required. Furthermore, angiotensin- converting-enzyme inhibitors /angiotensin II receptor blockers improve EF. Phosphodiesterase type 5 inhibitors improve EF locally in the corpus cavernosum. Finally, cilostazol exerts favorable effect on EF, nevertheless, more data in people with DM are required.

Clopidogrel plus Aspirin Use is Associated with Worse Long-Term Outcomes, but Aspirin Use Alone is Safe in Patients with Vasospastic Angina: Results from the VA-Korea Registry, A Prospective Multi-Center Cohort

Anti-platelet agents are commonly used in vasospastic angina (VA) patients with comorbidity like coronary artery disease. However, long-term clinical outcomes in the use of aspirin, clopidogrel or the two agents together have rarely been investigated in VA patients. In a prospective study, we enrolled 2960 patients who received coronary angiography and ergonovine provocation test at 11 university hospitals in Korea. Among them, 1838 patients were diagnosed either with definite (n = 680) or intermediate (n = 1212) VA, using the criteria of chest pain, ECG changes and ergonovine provocation test results. They were analyzed according to their use of aspirin, clopidogrel or both, or no anti-platelet agent at all. The primary outcome was time to composite events of death from any cause, acute coronary syndrome (ACS) and symptomatic arrhythmia during a 3-year follow-up. A primary composite outcome was significantly more common in the aspirin plus clopidogrel group, at 10.8% (14/130), as compared with the non-antiplatelet group, at 4.4% (44/1011), (hazard ratio [HR] 2.41, 95% confidence interval [CI], 1.32–4.40, p = 0.004). With regard to the person-time event rate, similar results were shown, with the highest rate in the aspirin plus clopidogrel user at 4.72/1000 person months (95% CI, 2.79–7.96, log-rank test for primary outcome p = 0.016). The person-time event of the ACS rate was also highest in that group, at 2.81 (95% CI, 1.46–5.40, log-rank test for ACS p = 0.116). Kaplan-Meier survival analysis demonstrated poor prognosis in primary outcomes and ACS in aspirin plus clopidogrel users (log-rank test, p = 0.005 and p = 0.0392, respectively). Cox-proportional hazard regression analysis, adjusting for age, sex, history of coronary heart disease, hypertension, diabetes, presence or not of definite spasm, use of calcium channel blocker, demonstrated that the use of aspirin plus clopidogrel is an independent risk for the primary outcome (HR 2.01, CI: 1.07–3.81, p = 0.031). The aspirin-alone group had a similar primary and individual event rate compared to the no-antiplatelet agent group (HR 0.96, CI, 0.59–1.55, p = 0.872). Smokers using aspirin plus clopidogrel had poorer outcomes than non-smokers, with HR 6.36 (CI 2.31–17.54, p = 0.045 for interaction). In conclusion, among VA patients, aspirin plus clopidogrel use is associated with a poor clinical outcome at 3 years, especially in ACS. Aspirin alone appears to be safe for use in those patients.

Targeting Early Atherosclerosis: A Focus on Oxidative Stress and Inflammation

Atherosclerosis is a chronic vascular inflammatory disease associated to oxidative stress and endothelial dysfunction. Oxidation of low-density lipoprotein (LDL) cholesterol is one of the key factors for the development of atherosclerosis. Nonoxidized LDL have a low affinity for macrophages, so they are not themselves a risk factor. However, lowering LDL levels is a common clinical practice to reduce oxidation and the risk of major events in patients with cardiovascular diseases (CVD). Atherosclerosis starts with dysfunctional changes in the endothelium induced by disturbed shear stress which can lead to endothelial and platelet activation, adhesion of monocytes on the activated endothelium, and differentiation into proinflammatory macrophages, which increase the uptake of oxidized LDL (oxLDL) and turn into foam cells, exacerbating the inflammatory signalling. The atherosclerotic process is accelerated by a myriad of factors, such as the release of inflammatory chemokines and cytokines, the generation of reactive oxygen species (ROS), growth factors, and the proliferation of vascular smooth muscle cells. Inflammation and immunity are key factors for the development and complications of atherosclerosis, and therefore, the whole atherosclerotic process is a target for diagnosis and treatment. In this review, we focus on early stages of the disease and we address both biomarkers and therapeutic approaches currently available and under research.

Monocyte-platelet aggregates affect local inflammation in patients with acute myocardial infarction

The local inflammatory response following acute myocardial infarction (AMI) is increasingly being recognized as a central factor determining infarct healing. Myocardial inflammation can be visualized in patients using fasting ¹⁸F-FDG PET/MRI. Although this novel biosignal correlates with long-term functional outcome, the corresponding cellular substrate is not well understood. Here we present a retrospective analysis of 29 patients with AMI who underwent revascularization, suggesting a connection between post infarction myocardial fasting ¹⁸F-FDG uptake, monocyte platelet aggregates (MPA), and P2Y₁₂ inhibition. In detail, patients with high MPA percentages of CD14^highCD16⁺ and CD14^lowCD16⁺ monocytes had significantly higher local ¹⁸F-FDG uptake (SUV_mean) in the infarcted myocardium than patients with low MPA (p < 0.05). Furthermore, there was an association of high MPA percentage in all monocyte subpopulations with deteriorating ΔLV-EF after 6 months (p < 0.01), which was confirmed in an extended analysis with additional 29 patients without PET/MRI data available. In this analysis, administration of Ticagrelor was associated with lower MPA percentage of CD14^high monocyte subpopulations than Clopidogrel (p < 0.01) or Prasugrel (p < 0.05). Taken together, the findings from this analysis suggest that platelet aggregability may affect monocyte extravasation into the infarcted myocardium and influence long-term functional outcome. P2Y₁₂ inhibition may intervene in this pathophysiologic process. Prospective studies are needed to further examine this important relationship.

Adenosine as a Marker and Mediator of Cardiovascular Homeostasis: A Translational Perspective

Adenosine, a purine nucleoside, is produced broadly and implicated in the homeostasis of many cells and tissues. It signals predominantly via 4 purinergic adenosine receptors (ADORs) - ADORA1, ADORA2A, ADORA2B and ADOosine signaling, both through design as specific ADOR agonists and antagonists and as offtarget effects of existing anti-platelet medications. Despite this, adenosine has yet to be firmly established as either a therapeutic or a prognostic tool in clinical medicine to date. Herein, we provide a bench-to-bedside review of adenosine biology, highlighting the key considerations for further translational development of this proRA3 in addition to non-ADOR mediated effects. Through these signaling mechanisms, adenosine exerts effects on numerous cell types crucial to maintaining vascular homeostasis, especially following vascular injury. Both in vitro and in vivo models have provided considerable insights into adenosine signaling and identified targets for therapeutic intervention. Numerous pharmacologic agents have been developed that modulate adenmising molecule.

Ticagrelor suppresses oxidized low‑density lipoprotein‑induced endothelial cell apoptosis and alleviates atherosclerosis in ApoE‑/‑ mice via downregulation of PCSK9

Although ticagrelor has been demonstrated to possess an anti-atherosclerosis (AS) effect, its underlying mechanism remains unclear. In the present study, it was investigated whether ticagrelor reduces oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell apoptosis, an initial step for the development of AS, and alleviates AS in apolipoprotein-E-deficient (ApoE^−/−) mice by inhibiting the expression of proprotein convertase subtilisin/kexin type 9 (PCSK9). The human endothelial cell line EAhy926 was treated with ox-LDL, ox-LDL + ticagrelor (40 µmol/l) and ox-LDL + ticagrelor (60 µmol/l) for 24 h. Cell apoptosis was detected using Annexin V-fluorescein isothiocyanate/propidium iodide staining. The expression levels of PCSK9, apoptosis-associated proteins and signaling pathways were determined by reverse transcription-quantitative polymerase chain reaction and western blotting. ApoE^−/− mice fed a high-fat diet were used to induce an AS model. After 20 weeks, ApoE^−/− mice were randomly assigned to receive saline or ticagrelor intragastrically for 10 days. The formation of atherosclerotic plaques was detected by hematoxylin and eosin staining. The expression of PCSK9 in the arterial tissues was measured by immunohistochemistry. The results demonstrated that treatment with ticagrelor was able to decrease ox-LDL-induced apoptosis in a concentration-dependent manner (40 µmol/l vs. ox-LDL, 17.58±2.66 vs. 27.25±5.54%; 60 µmol/l vs. ox-LDL, 12.26±1.54 vs. 27.25±5.54%). The mRNA and protein expression level of PCSK9 significantly decreased following treatment with ticagrelor, accompanied with upregulation of B-cell lymphoma (Bcl) 2 and downregulation of Bcl-2 associated X, apoptosis regulator, caspase-3, p38, phosphorylated-(p) p38, p-c-Jun N-terminal kinases (JNK), p-extracellular signal-regulated kinases and the ratio of p-JNK to JNK. Histological analysis of arterial tissues revealed ticagrelor markedly decreased the atherosclerotic plaque area and inhibited the expression of PCSK9. The present results suggested that ticagrelor may alleviate AS via downregulation of PCSK9-mediated endothelial cell apoptosis, which may be JNK-dependent.

Interaction between platelets and endothelium: from pathophysiology to new therapeutic options

Platelets were traditionally considered to purely have a role in the maintenance of haemostasis. Recently their role in vasomotor function, inflammation and atherosclerosis has been very well-recognized. Endothelium which was originally considered as a simple passive barrier, it is now viewed as an organ whose normal functioning is crucial for maintaining vascular health. When endothelial balance is disturbed, vascular disease initiates. Platelet interactions with endothelium have an important contribution in this process. Low-grade inflammation, endothelial dysfunction, and platelet hyper-reactivity are all independently associated with an increased risk of cardiovascular events. Older antiplatelet agents like aspirin and clopidogrel and newer more potent agents like prasugrel and ticagrelor have been proven effective in all the clinical spectrum of coronary artery disease patients. Current antiplatelet medications and especially newer generation P2Y12 inhibitor ticagrelor, offer clinical benefits not only due to their well-recognized antithrombotic effect, but also via the attenuation of platelet inflammatory action, impediment of P2Y12 activation effects in other cells and through other complex and sometimes undefined pathways. Future research is expected to better define platelet-endothelium interactions and the multiple impact of current antiplatelet therapy on them.

Potentiation of thrombus instability: a contributory mechanism to the effectiveness of antithrombotic medications

The stability of an arterial thrombus, determined by its structure and ability to resist endogenous fibrinolysis, is a major determinant of the extent of infarction that results from coronary or cerebrovascular thrombosis. There is ample evidence from both laboratory and clinical studies to suggest that in addition to inhibiting platelet aggregation, antithrombotic medications have shear-dependent effects, potentiating thrombus fragility and/or enhancing endogenous fibrinolysis. Such shear-dependent effects, potentiating the fragility of the growing thrombus and/or enhancing endogenous thrombolytic activity, likely contribute to the clinical effectiveness of such medications. It is not clear how much these effects relate to the measured inhibition of platelet aggregation in response to specific agonists. These effects are observable only with techniques that subject the growing thrombus to arterial flow and shear conditions. The effects of antithrombotic medications on thrombus stability and ways of assessing this are reviewed herein, and it is proposed that thrombus stability could become a new target for pharmacological intervention.

Ticagrelor, a P2Y12 antagonist, attenuates vascular dysfunction and inhibits atherogenesis in apolipoprotein-E-deficient mice

BACKGROUND AND AIMS

Ticagrelor reduces cardiovascular events in patients with acute coronary syndrome (ACS). Recent studies demonstrated the expression of P2Y12 on vascular cells including endothelial cells, as well as platelets, and suggested its contribution to atherogenesis. We investigated whether ticagrelor attenuates vascular dysfunction and inhibits atherogenesis in apolipoprotein E-deficient (apoe^-/-) mice.

METHODS

Eight-week-old male apoe^-/- mice were fed a western-type diet (WTD) supplemented with 0.1% ticagrelor (approximately 120 mg/kg/day). Non-treated animals on WTD served as control. Atherosclerotic lesions were examined by en-face Sudan IV staining, histological analyses, quantitative RT-PCR analysis, and western blotting. Endothelial function was analyzed by acetylcholine-dependent vasodilation using aortic rings. Human umbilical vein endothelial cells (HUVEC) were used for in vitro experiments.

RESULTS

Ticagrelor treatment for 20 weeks attenuated atherosclerotic lesion progression in the aortic arch compared with control (p < 0.05). Ticagrelor administration for 8 weeks attenuated endothelial dysfunction (p < 0.01). Ticagrelor reduced the expression of inflammatory molecules such as vascular cell adhesion molecule-1, macrophage accumulation, and lipid deposition. Ticagrelor decreased the phosphorylation of JNK in the aorta compared with control (p < 0.05). Ticagrelor and a JNK inhibitor ameliorated impairment of endothelium-dependent vasodilation by adenosine diphosphate (ADP) in wild-type mouse aortic segments. Furthermore, ticagrelor inhibited the expression of inflammatory molecules which were promoted by ADP in HUVEC (p < 0.001). Ticagrelor also inhibited ADP-induced JNK activation in HUVEC (p < 0.05).

CONCLUSIONS

Ticagrelor attenuated vascular dysfunction and atherogenesis through the inhibition of inflammatory activation of endothelial cells. These effects might be a potential mechanism by which ticagrelor decreases cardiovascular events in patients with ACS.

Peripheral revascularization attenuates the exercise pressor reflex and increases coronary exercise hyperemia in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with augmented blood pressure (BP) and impaired coronary blood flow responses to exercise, which may increase cardiovascular risk. We investigated the effects of leg revascularization on the BP and coronary blood flow responses to exercise in PAD. Seventeen PAD patients (11 men, 66 ± 2 yr) performed single-leg plantar flexion exercise 24 h before and 1 mo following leg revascularization. BP and heart rate (HR) were measured continuously, and rate pressure product (systolic BP × HR) was calculated as an index of myocardial oxygen demand. Coronary blood velocity was obtained by transthoracic Doppler echocardiography in 8/17 subjects. The mean BP response to plantar flexion exercise was attenuated by leg revascularization (pre-revascularization: 15 ± 4 vs. post-revascularization: 7 ± 3 mmHg, P = 0.025). The HR response to plantar flexion was also attenuated following leg revascularization (pre-revascularization: 9 ± 1 vs. post-revascularization: 6 ± 1 beats/min, P = 0.006). The change in coronary blood velocity with exercise was greater at the post-revascularization visit: 4 ± 1 vs. pre-revascularization: -1 ± 2 cm/s ( P = 0.038), even though the change in rate pressure product was not greater following revascularization in these subjects (pre-revascularization: 2,796 ± 871 vs. post-revascularization: 1,766 ± 378 mmHg·beats/min, P = 0.082). These data suggest that leg revascularization alters reflex control of BP, HR, and coronary blood flow in response to exercise in patients with PAD. NEW & NOTEWORTHY We found that peripheral revascularization procedures lowered exercise blood pressure and improved coronary blood flow in patients with peripheral arterial disease.

Clopidogrel in a combined therapy with anticancer drugs-effect on tumor growth, metastasis, and treatment toxicity: Studies in animal models

Clopidogrel, a thienopyridine derivative with antiplatelet activity, is widely prescribed for patients with cardiovascular diseases. In addition to antiplatelet activity, antiplatelet agents possess anticancer and antimetastatic properties. Contrary to this, results of some studies have suggested that the use of clopidogrel and other thienopyridines accelerates the progression of breast, colorectal, and prostate cancer. Therefore, in this study, we aimed to evaluate the efficacy of clopidogrel and various anticancer agents as a combined treatment using mouse models of breast, colorectal, and prostate cancer. Metastatic dissemination, selected parameters of platelet morphology and biochemistry, as well as angiogenesis were assessed. In addition, body weight, blood morphology, and biochemistry were evaluated to test toxicity of the studied compounds. According to the results, clopidogrel increased antitumor and/or antimetastatic activity of chemotherapeutics such as 5-fluorouracil, cyclophosphamide, and mitoxantrone, whereas it decreased the anticancer activity of doxorubicin, cisplatin, and tamoxifen. The mechanisms of such divergent activities may be based on the modulation of tumor vasculature via factors, such as transforming growth factor β1 released from platelets. Moreover, clopidogrel increased the toxicity of docetaxel and protected against mitoxantrone-induced toxicity, which may be due to the modulation of hepatic enzymes and protection of the vasculature, respectively. These results demonstrate that antiplatelet agents can be useful but also dangerous in anticancer treatment and therefore use of thienopyridines in patients undergoing chemotherapy should be carefully evaluated.

Platelets, inflammation and anti-inflammatory effects of antiplatelet drugs in ACS and CAD

Platelets play a pivotal role in chronic inflammation leading to progression of atherosclerosis and acute coronary events. Recent discoveries on novel mechanisms and platelet-dependent inflammatory targets underpin the role of platelets to maintain a chronic inflammatory condition in cardiovascular disease. There is strong and clinically relevant crosslink between chronic inflammation and platelet activation. Antiplatelet therapy is a cornerstone in the prevention and treatment of acute cardiovascular events. The benefit of antiplatelet agents has mainly been attributed to their direct anti-aggregatory impact. Some anti-inflammatory off-target effects have also been described. However, it is unclear whether these effects are secondary due to inhibition of platelet activation or are caused by direct distinct mechanisms interfering with inflammatory pathways. This article will highlight novel platelet associated targets that contribute to inflammation in cardiovascular disease and elucidate mechanisms by which currently available antiplatelet agents evolve anti-inflammatory capacities, in particular by carving out the differential mechanisms directly or indirectly affecting platelet mediated inflammation. It will further illustrate the prognostic impact of antiplatelet therapies by reducing inflammatory marker release in recent cardiovascular trials.

Ticagrelor mitigates ischaemia-reperfusion induced vascular endothelial dysfunction in healthy young males - a randomized, single-blinded study

AIMS

Animal data suggest that ticagrelor but not clopidogrel protects against tissue injury. It is unclear if this effect of ticagrelor is also detectable in humans. We studied the effect of ticagrelor and clopidogrel at standard clinical doses on endothelial dysfunction in an experimental model of forearm vascular ischaemia-reperfusion (IR) injury.

METHODS

In a randomized, single-blinded trial, 24 subjects underwent forearm blood flow (FBF) measurements in response to the endothelium-dependent vasodilator acetylcholine (ACh) and to glyceryltrinitrate (GTN; endothelium-independent) before and after a 20 min forearm ischaemia. FBF reactivity was assessed after an oral loading dose of ticagrelor or clopidogrel and after 14 days of regular intake of maintenance doses of the study medicines. In addition, the effect on platelet inhibition was evaluated using multiple electrode aggregometry.

RESULTS

ACh-induced vasodilation was impaired during reperfusion and not completely normalized by acute or chronic treatment with ticagrelor or clopidogrel (post- vs. pre-ischaemia). However, ticagrelor mitigated endothelial dysfunction compared to clopidogrel after loading (FBF ACh_AUC ratio post- vs. pre-ischaemia: 0.83 [0.70; 0.96] vs. 0.64 [0.56; 0.72]; P = 0.024) and after chronic administration (FBF ACh_AUC ratio: 0.86 [0.71; 1.00] vs. 0.66 [0.55; 0.77]; P = 0.027). As expected, GTN-induced vasodilation was not affected by ischaemia. Ticagrelor or clopidogrel treatment inhibited platelet activation to a similar degree.

CONCLUSION

Our data indicate that ticagrelor treatment exerts a greater vascular salutary effect than clopidogrel during reperfusion after an acute vascular occlusion. IR-induced vascular injury cannot be prevented completely by administration of these antiplatelet agents at standard clinical doses.

Prasugrel as opposed to clopidogrel improves endothelial nitric oxide bioavailability and reduces platelet-leukocyte interaction in patients with unstable angina pectoris: A randomized controlled trial

BACKGROUND

Platelet inhibition has been linked to improved endothelial function, a prognostic factor in coronary artery disease. Whether prasugrel, a potent platelet inhibitor, affects endothelial function remains unknown.

METHODS

This was a double-blind, randomized, active-controlled, parallel trial. Patients with unstable angina pectoris undergoing percutaneous coronary intervention (PCI) received either a daily dose of clopidogrel 75mg (n=23) or prasugrel 10mg (n=22). Flow-mediated dilation (FMD), circulating nitrate and nitrite, inflammatory markers and platelet-leukocyte aggregates (PLAs) were assessed the day after PCI and after 3months.

RESULTS

Baseline patient demographics were well matched between treatment groups. Prasugrel led to a significant improvement of FMD after 3months (9.01±3.64% vs. 6.65±3.24%, p=0.001). In contrast, no significant change was observed in the clopidogrel group (7.21±2.84% vs. 6.30±2.97%, p=0.187). Adjusted for baseline FMD, hyperlipidemia and statin use, the treatment effect on change in FMD favoured prasugrel by an absolute 1.97% (95% CI 0.29% to 3.66%, p=0.023). A significant reduction of plasma hsCRP, myeloperoxidase and neutrophil elastase and an increase of nitrate levels were noted in both treatment arms. Interestingly, only prasugrel significantly reduced sCD40 ligand and RANTES and increased nitrite levels. Prasugrel reduced the ADP-stimulated increase in PLAs by 40% (IR: 82 to 13), whereas clopidogrel revealed no such effect (1% increase (IR: 13 to 50) (p=0.01).

CONCLUSION

Prasugrel exhibits beneficial mid-term effects on endothelial nitric oxide bioavailability and inflammatory markers. (EudraCT number: 2009-015406-19).

Targeting Select Cellular Stress Pathways to Prevent Hyperglycemia-Related Complications: Shifting the Paradigm

Despite the advances made in preventing complications of diabetes, there is still substantial residual risk. Hence the need for developing new therapeutic agents that target the various facets of the pathogenesis of complications in people with diabetes. Traditionally four general biochemical pathways had been recognized as major contributors to glucotoxicity. These include the polyol pathway, the protein kinase C (PKC) pathway, glycosylation pathway, and oxidative stress. The latter has been proposed as a common impetus of the other pathways of glucotoxicity. More recently, the cross talk between oxidative stress and other recognized cellular stresses such as endoplasmic reticulum (ER), inflammatory, and mitochondrial stresses has emerged as an important additional mechanism of glucotoxicity. The observation that targeting oxidative stress with antioxidants has been associated with unfavorable clinical outcomes and the recognition that in cell cultures antioxidants may aggravate ER stress, suggests that selective targeting of individual cellular stresses may not be sufficient for preventing glucotoxicity. Future efforts should focus on developing therapeutic agents that can ameliorate cellular stress globally by simultaneously targeting the oxidative, ER, mitochondrial, and inflammatory stresses.

Therapeutic Targeting of Cellular Stress to Prevent Cardiovascular Disease: A Review of the Evidence

The availability of effective drugs targeting the major risk factors of cardiovascular disease (CVD) has reduced morbidity and mortality. Cumulative relative risk of CVD events can be reduced by 75 % with a combination of aspirin, a β-adrenoceptor antagonist (β-blocker), an HMG-CoA reductase inhibitor (statin), and an angiotensin-converting enzyme inhibitor. The principal pharmacodynamics of these drugs cannot explain the entirety of their cardioprotective action, as other drugs with similar pharmacologic targets have not been associated with favorable clinical effects. This raises the possibility that the cardioprotective drugs have a unique pleiotropic activity that contributes to their clinical efficacy. Recent data suggest that reducing cellular stress such as oxidative, inflammatory, and endoplasmic reticulum stress, might be a common denominator of the drugs with proven efficacy in reducing CVD risk. In this communication, the evidence in favor of this hypothesis is discussed, and ongoing trials with therapeutic agents targeting cellular stresses are reviewed.

Ticagrelor: Effects Beyond the P2Y12 Receptor

Platelet P2Y₁₂ receptor inhibitors are crucial in the treatment of patients with acute coronary syndrome or undergoing percutaneous coronary intervention. Ticagrelor is a reversibly binding, potent oral P2Y₁₂ inhibitor that also is a weak inhibitor of the equilibrative nucleoside transporter-1 pathway for cellular adenosine uptake. It is hypothesized that ticagrelor has clinically relevant "off-target" effects, independent of its effect on platelet aggregation and thrombosis. This review considers the pleiotropic effects of ticagrelor and some of the possible mechanisms related to these effects.

Platelet CD40L induces activation of astrocytes and microglia in hypertension

Studies have demonstrated separately that hypertension is associated with platelet activation in the periphery (resulting in accumulation and localized inflammatory response) and glial activation in the brain. We investigated the contribution of platelets in brain inflammation, particularly glial activation in vitro and in a rat model of hypertension. We found that HTN increased the expression of adhesion molecules like JAM-1, ICAM-1, and VCAM-1 on brain endothelium and resulted in the deposition of platelets in the brain. Platelet deposition in hypertensive rats was associated with augmented CD40 and CD40L and activation of astrocytes (GFAP expression) and microglia (Iba-1 expression) in the brain. Platelets isolated from hypertensive rats had significantly higher sCD40L levels and induced more prominent glial activation than platelets from normotensive rats. Activation of platelets with ADP induced sCD40L release and activation of astrocytes and microglia. Moreover, CD40L induced glial (astrocytes and microglia) activation, NFкB and MAPK inflammatory signaling, culminating in neuroinflammation and neuronal injury (increased apoptotic cells). Importantly, injection of ADP-activated platelets into normotensive rats strongly induced activation of astrocytes and microglia and increased plasma sCD40L levels compared with control platelets. On the contrary, inhibition of platelet activation by Clopidogrel or disruption of CD40 signaling prevented astrocyte and microglial activation and provided neuroprotection in both in vivo and in vitro conditions. Thus, we have identified platelet CD40L as a key inflammatory molecule for the induction of astrocyte and microglia activation, the major contributors to inflammation-mediated injury in the brain.

The Effect of Clopidogrel on the Response to Ischemia Reperfusion

Reperfusion in the setting of acute ischemia is essential in limiting tissue necrosis. However, reperfusion itself is associated with significant adverse effects. There is animal evidence that platelets play a role in the adverse effects of ischemia and reperfusion (IR) injury. We examined whether clopidogrel would have favorable effects on endothelial dysfunction induced by an episode of IR. Using a parallel design, we administered clopidogrel 600 mg or matching placebo to normal volunteers (n = 20) 24 hours before an episode of IR. Flow-mediated dilatation (FMD, radial artery) was assessed before and after 20 minutes of upper arm ischemia. Following IR, there was a highly significant decrease in FMD in the placebo group (7.6% ± 1.3% vs 3.4% ± 0.1%; P < .001). In the clopidogrel group, there was no change in FMD post-IR (8.3% ± 0.8% vs 7.1% ± 1.2%; P = not significant). Following IR, FMD in the placebo group was significantly smaller than that observed in the clopidogrel group ( P < .01). Ischemia and reperfusion caused no change in plasma levels of biomarkers of inflammation (intercellular adhesion molecule 1, chemokine ligand 5, and interleukin 6) in either group. Therefore, a single dose of clopidogrel given 24 hours prior to an episode of IR had protective effects, limiting the adverse effects of ischemia on endothelial function.

Impact of CYP2C19 Variants on Clinical Efficacy of Clopidogrel and 1-Year Clinical Outcomes in Coronary Heart Patients Undergoing Percutaneous Coronary Intervention

The impact of pharmacogenetic variants of cytochrome P450 2C19 (CYP2C19) on clopidogrel-mediated effects on platelet inhibition, inflammatory response and endothelial function, as well as risk of major adverse cardiovascular events (MACE), in coronary heart patients undergoing percutaneous coronary intervention (PCI) was investigated. To this end, we assessed the residual platelet aggregation rate (RPA), maximal aggregation rate (MAR) and plasma levels of sCD40L, sP-selectin, MMP-9, sVCAM-1 and sE-selectin after 24 h of PCI in 559 patients treated with clopidogrel and followed up for 1 year for evidence of MACE. CYP2C19^*2 and ^*3 variants were identified using a clopidogrel-sensitive gene detection kit. Our results showed higher RPA and MAR as well as increased sE-selectin, sCD40L, sP-selectin, MMP-9, and sVCAM-1 levels in CYP2C19 intermediate metabolizer (IM, CYP2C19^*1/^*2, or ^*1/^*3), poor metabolizer (PM, CYP2C19^*2/^*2, ^*2/^*3, or ^*3/^*3) and combined IM+PM groups, relative to those in extensive metabolizers (EM, CYP2C19^*1/^*1). In total, 519 patients completed 1 year of follow-up, among which 69 (13.3%) experienced MACE. The risk of MACE in CYP2C19 IM+PM patients was 2.664 times higher than that in CYP2C19 EM patients (OR = 2.664 (1.397–5.193), P = 0.004). The data suggest that CYP2C19^*2 and ^*3 variants modulate the drug efficacy of clopidogrel in coronary heart patients undergoing PCI and further enhance the risk of MACE. Accordingly, CYP2C19 pharmacogenetic profiling may be beneficial for coronary heart patients undergoing PCI to predict the efficacy of treatment with clopidogrel. We propose that IM and PM patients should benefit from treatment with higher clopidogrel doses to improve efficacy and reduce the incidence of MACE.

Clopidogrel Improves Skin Microcirculatory Endothelial Function in Persons With Heightened Platelet Aggregation

Background

Platelet activation can lead to enhanced oxidative stress, inflammatory response, and endothelial dysfunction. To quantify the effects of platelet inhibition on endothelial function, we assessed platelet activity of healthy persons before and after clopidogrel administration and evaluated its effects on endothelial function. We hypothesized that clopidogrel, by attenuating platelet activity, would result in enhanced endothelial function.

Methods and Results

Microcirculatory endothelial function was quantified by laser Doppler flowmetry (LDF) mediated by thermal hyperemia (TH) and postocclusive reactive hyperemia, respectively, in 287 and 241 relatively healthy and homogenous Old Order Amish persons. LDF and platelet aggregation measures were obtained at baseline and after 7 days of clopidogrel administration. Our primary outcome was percentage change in post‐ versus preclopidogrel LDF measures. Preclopidogrel TH‐LDF and platelet aggregation were higher in women than in men (P<0.001). Clopidogrel administration was associated with ≈2‐fold higher percentage change in TH‐LDF in participants with high versus low baseline platelet aggregation (39.4±10.1% versus 17.4±5.6%, P=0.03). Clopidogrel also increased absolute TH‐LDF measures in persons with high platelet aggregation (1757±766 to 2154±1055, P=0.03), with a more prominent effect in women (1909±846 to 2518±1048, P=0.001). There was no evidence that clopidogrel influenced postocclusive reactive hyperemia LDF measures.

Conclusions

The administration of clopidogrel in healthy persons with high baseline platelet aggregation results in improved TH‐induced microcirculatory endothelial function. These data suggest that clopidogrel may have a beneficial effect on microcirculatory endothelial function, presumably through antiplatelet activity, and may confer additional vascular benefits.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00799396.

Protective effects of ginseng extracts and common anti-aggregant drugs on ischaemia-reperfusion injury

OBJECTIVE

Ginseng is a traditional herbal medicinal product widely used for various types of diseases because of its cellular protective effects. Possible protective effects of ginseng were investigated in blood, cardiac and renal tissue samples and compared with common anti-aggregant agents in an animal ischaemia-reperfusion (I/R) model.

METHODS

Twenty rats were equally divided into four different groups as follows: control group (I/R-induced group without drug use), group I (acetylsalicylic acid-administered group), group II (clopidogrel bisulfate-administered group), group III (ginsenoside Rb1-administered group). For the groups assigned to a medication, peripheral I/R was induced by clamping the femoral artery one week after initiation of the specified medication. After reperfusion was initiated, cardiac and renal tissues and blood samples were obtained from each rat with subsequent analysis of nitrogen oxide (NOx), malondialdehyde (MDA), paraoxonase 1 (PON1) and prolidase.

RESULTS

NOx levels were similar in each group. Significant decrements were observed in serum PON1 levels in each group when compared with the control (p < 0.05). Serum MDA levels were significantly lower in groups II and III (p < 0.05). Ameliorated renal prolidase levels were detected in study groups (p < 0.05) and recovered cardiac prolidase levels were obtained in groups II and III (p < 0.05).

CONCLUSION

These findings indicate that ginseng extracts may have a potential beneficial effect in I/R injury. However, more comprehensive studies are required to clarify the hypothetical cardiac, renal and systemic protective effects in reperfusion-induced oxidative damage.

The influence of clopidogrel on ischemia diagnosed by myocardial perfusion stress testing

BACKGROUND

Clopidogrel is a platelet adenosine receptor antagonist which can influence coronary vascular tone and thus can potentially interfere with myocardial perfusion imaging. We investigated whether clopidogrel can hamper the diagnosis of ischemia in patients undergoing myocardial perfusion testing.

METHODS

Data from a database of 6349 myocardial perfusion stress tests were analyzed. Using a propensity analysis, patients who were taking clopidogrel were compared with patients not taking clopidogrel for the presence of reversible perfusion defects on myocardial single-photon emission computed tomography scans.

RESULTS

Of the 6349 tests, the stress technique was adenosine in 2713 patients and exercise in 3636. At the time of the stress test, 277 (4.3%) of the patients were taking clopidogrel. The odds ratio (OR) for patients taking clopidogrel to have a reversible perfusion defect was 2.75 (95% confidence interval [CI] 2.09-3.62; P < .01). After adjusting for the propensity to take clopidogrel, the OR was 1.06 (CI 0.76-1.49; P = .73) for patients undergoing adenosine stress tests and 1.60 (CI 0.85-3.00; P = .14) for patients undergoing exercise stress tests.

CONCLUSIONS

We found no evidence that the use of clopidogrel decreases the likelihood of ischemia on adenosine or exercise stress myocardial perfusion scans.

Similar Impact of Clopidogrel or Ticagrelor on Carotid Atherosclerotic Plaque Inflammation

BACKGROUND

Platelets play an important role in inflammation. Inhibitors of the P2Y₁₂ receptor, which is involved in platelet activation, may have a direct effect on carotid atherosclerotic plaque inflammation.

HYPOTHESIS

We compared the effects of clopidogrel and ticagrelor therapy for carotid atherosclerotic plaque inflammation using ¹⁸ F-fluorodeoxyglucose ( ¹⁸ FDG) positron emission tomography (PET) imaging.

METHODS

Fifty patients with acute coronary syndrome and ≥1 ¹⁸ FDG uptake in the carotid artery (target-to-background ratio [TBR] ≥1.6) were randomized to either clopidogrel or ticagrelor groups. Of these, 46 completed PET examinations at baseline and at 6 months. The primary endpoint was the percent change in TBR of the index vessel at the most diseased segment (MDS).

RESULTS

Baseline characteristics were similar between the 2 groups. At 6-month follow-up, low-density lipoprotein cholesterol and C-reactive protein significantly decreased in both groups (P < 0.001). The TBR of the index vessel and aorta significantly decreased in both groups (P < 0.01). The percent change in the MDS TBR of the index vessel was numerically but not significantly lower in the clopidogrel group than in the ticagrelor group (-9.5 ± 14.6% vs -13.5 ± 19.3%; P = 0.427). Likewise, the percent change in the whole-vessel TBR of the index vessel was not different between the 2 groups (P = 0.166). Similar findings were observed for changes in the MDS TBR (P = 0.412) or whole-vessel TBR of the aorta (P = 0.363).

CONCLUSIONS

Carotid atherosclerotic plaque inflammation significantly decreases to a similar degree following 6 months of either clopidogrel or ticagrelor treatment.

Effects of P2Y12 receptor antagonists beyond platelet inhibition--comparison of ticagrelor with thienopyridines

The effect and clinical benefit of P2Y12 receptor antagonists may not be limited to platelet inhibition and the prevention of arterial thrombus formation. Potential additional effects include reduction of the pro-inflammatory role of activated platelets and effects related to P2Y12 receptor inhibition on other cells apart from platelets. P2Y12 receptor antagonists, thienopyridines and ticagrelor, differ in their mode of action being prodrugs instead of direct acting and irreversibly instead of reversibly binding to P2Y12 . These key differences may provide different potential when it comes to additional effects. In addition to P2Y12 receptor blockade, ticagrelor is unique in having the only well-documented additional target of inhibition, the equilibrative nucleoside transporter 1. The current review will address the effects of P2Y12 receptor antagonists beyond platelets and the protection against arterial thrombosis. The discussion will include the potential for thienopyridines and ticagrelor to mediate anti-inflammatory effects, to conserve vascular function, to affect atherosclerosis, to provide cardioprotection and to induce dyspnea.

Soluble CD40 Ligand in Aspirin-Treated Patients Undergoing Cardiac Catheterization

Plasma soluble CD40 ligand (sCD40L) is mainly generated by cleavage of CD40L from the surface of activated platelets, and therefore considered a platelet activation marker. Although the predictive value of sCD40L for ischemic events has been demonstrated in patients with acute coronary syndromes (ACS), studies on the association of sCD40L with cardiovascular outcomes in lower risk populations yielded heterogeneous results. We therefore sought to investigate factors influencing sCD40L levels, and the predictive value of sCD40L for long-term ischemic events in unselected, aspirin-treated patients undergoing cardiac catheterization. sCD40L was determined by a commercially available enzyme-linked immunosorbent assay in 682 consecutive patients undergoing cardiac catheterization. Two-year follow-up data were obtained from 562 patients. Dual antiplatelet therapy with aspirin and clopidogrel was associated with significantly lower levels of sCD40L and lower platelet surface expressions of P-selectin and activated GPIIb/IIIa compared to aspirin monotherapy (all p≤0.01). Hypertension was linked to lower plasma concentrations of sCD40L, whereas female sex, increasing high-sensitivity C-reactive protein, and hematocrit were associated with higher sCD40L concentrations (all p<0.05). sCD40L levels were similar in patients without and with the primary endpoint in the overall study population (p = 0.4). Likewise, sCD40L levels did not differ significantly between patients without and with the secondary endpoints (both p≥0.4). Similar results were obtained when only patients with angiographically-proven coronary artery disease (n = 459), stent implantation (n = 205) or ACS (n = 125) were analyzed. The adjustment for differences in patient characteristics by multivariate regression analyses did not change the results. ROC curve analyses did not reveal cut-off values for sCD40L for the prediction of the primary or secondary endpoints. In conclusion, plasma sCD40L levels are reduced by antiplatelet therapy with clopidogrel, but not associated with long-term ischemic outcomes in unselected consecutive aspirin-treated patients undergoing cardiac catheterization.

The role of platelets in the recruitment of leukocytes during vascular disease

Besides their role in the formation of thrombus during haemostasis, it is becoming clear that platelets contribute to a number of other processes within the vasculature. Indeed, the integrated function of the thrombotic and inflammatory systems, which results in platelet-mediated recruitment of leukocytes, is now considered to be of great importance in the propagation, progression and pathogenesis of atherosclerotic disease of the arteries. There are three scenarios by which platelets can interact with leukocytes: (1) during haemostasis, when platelets adhere to and are activated on sub-endothelial matrix proteins exposed by vascular damage and then recruit leukocytes to a growing thrombus. (2) Platelets adhere to and are activated on stimulated endothelial cells and then bridge blood borne leukocytes to the vessel wall and. (3) Adhesion between platelets and leukocytes occurs in the blood leading to formation of heterotypic aggregates prior to contact with endothelial cells. In the following review we will not discuss leukocyte recruitment during haemostasis, as this represents a physiological response to tissue trauma that can progress, at least in its early stages, in the absence of inflammation. Rather we will deal with scenarios 2 and 3, as these pathways of platelet–leukocyte interactions are important during inflammation and in chronic inflammatory diseases such as atherosclerosis. Indeed, these interactions mean that leukocytes possess means of adhesion to the vessel wall under conditions that may not normally be permissive of leukocyte–endothelial cell adhesion, meaning that the disease process may be able to bypass the regulatory pathways which would ordinarily moderate the inflammatory response.

Clopidogrel response variability is associated with endothelial dysfunction in coronary artery disease patients receiving dual antiplatelet therapy

OBJECTIVES

Dual antiplatelet therapy with aspirin and a platelet P2Y12 ADP receptor antagonist is the cornerstone of treatment following percutaneous coronary intervention (PCI). Several clinical and genetic factors can cause suboptimal clopidogrel response. We examined the impact of endothelial dysfunction on clopidogrel response variability in subjects with stable coronary artery disease (CAD) after PCI.

METHODS

We consecutively enrolled 198 patients with stable CAD one month after successful PCI. All patients were receiving dual antiplatelet therapy (clopidogrel 75 mg and aspirin 100 mg/day). Platelet reactivity was measured by VerifyNow P2Y12 assay (Accumetrics, San Diego, CA). VerifyNow reports its results in P2Y12 reaction units (PRU) and the diagnostic cut-off value is 230. Endothelial function was evaluated by flow mediated dilation (FMD).

RESULTS

Patients with high on treatment platelet reactivity (32% of the study population), compared to subjects with low on treatment platelet reactivity, presented decreased FMD values (4.35 ± 2.22% vs. 5.74 ± 3.29%, p = 0.01). Moreover, an inverse association between endothelial function measurement and platelet reactivity (r = -0.24, p = 0.001) was found. Importantly, multivariate analysis after adjustment for age, gender and confounders revealed by the univariate analysis (left ventricle ejection fraction, body mass index, diabetes, dyslipidemia, coronary lesion number) showed that for every decrease in FMD by 1% there is an anticipated increased in the odds of patients to have HPR by 1.66 (95% CI 1.03-2.57, p = 0.037).

CONCLUSIONS

Endothelial dysfunction is associated with clopidogrel response variability in patients after PCI receiving dual antiplatelet therapy. These findings shed some light on the mechanisms affecting individual platelet response to antiplatelet therapy and may explain the non-straight forward association between clopidogrel dose, platelet inhibition and cardiovascular outcome.