Effects of Ticagrelor, Prasugrel, or Clopidogrel on Endothelial Function and Other Vascular Biomarkers: A Randomized Crossover Study

Incidence and pattern of urgent revascularization in acute coronary syndromes treated with ticagrelor or prasugrel

BACKGROUND

The ISAR-REACT 5 trial compared the efficacy and safety of ticagrelor and prasugrel in patients with ACS managed invasively. The present study sought to investigate the impact of ticagrelor and prasugrel on the incidence and pattern of urgent revascularization in acute coronary syndromes (ACS) patients undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS

This post-hoc analysis of the ISAR-REACT 5 trial included all ACS patients who underwent PCI. The primary endpoint for this analysis was the incidence of urgent revascularization at 12-month follow-up. Secondary outcome was the pattern of urgent revascularization procedures (namely, urgent target vessel/non-target vessel revascularization - TVR/NTVR). Among 3,377 ACS patients who underwent PCI, 1,676 were assigned to ticagrelor and 1,701 to prasugrel before PCI. After 12 months, the incidence of urgent revascularization was higher among patients assigned to ticagrelor as compared to prasugrel (6.8% vs. 5.2%; hazard ratio [HR] = 1.32, 95% confidence interval [CI] 1.00-1.75; p = 0.051), mostly attributable to significantly more urgent NTVR in the ticagrelor group (3.8% vs. 2.4%; HR = 1.62 [1.09-2.41]; p = 0.017). The risk of urgent TVR did not differ between treatment groups (3.3% vs. 3.0%; HR = 1.13 [0.77-1.65]; p = 0.546).

CONCLUSIONS

In ACS patients treated with PCI, the cumulative rate of urgent revascularizations after 12 months is higher with ticagrelor compared to prasugrel, due to a significant increase in urgent revascularizations involving remote coronary vessels.

Ticagrelor potentiates cardioprotection by remote ischemic preconditioning: the ticagrelor in remote ischemic preconditioning (TRIP) randomized clinical trial

OBJECTIVE

Remote ischemic preconditioning (RIPC) reduces periprocedural myocardial injury (PMI) after percutaneous coronary intervention (PCI) through various pathways, including an adenosine-triggered pathway. Ticagrelor inhibits adenosine uptake, thus may potentiate the effects of RIPC. This randomized trial tested the hypothesis that ticagrelor potentiates the effect of RIPC and reduces PMI, assessed by post-procedural troponin release.

METHODS

Patients undergoing PCI for non-ST elevation acute coronary syndromes were 1:1 randomized to ticagrelor (TG-Group) or clopidogrel (CL-Group). Within each treatment, patients were 1:1 randomized to a RIPC (RIPC-Group) or a control group (CTRL-Group). The primary endpoint was the difference between post- and pre-procedural troponin at 24 h following PCI, termed deltaTnI.

RESULTS

During a 12-month period, 138 patients were included in the study (34 in the CL-CTRL group, 34 in the TG-CTRL group, 35 in the CL-RIPC group, and 35 in the TG-CTRL group). There was a significant difference in deltaTnI between the study groups [ TG-RIPC:0.04 (0-0.16), CL-CTRL:0.10 (0.03-0.43), CLRIPC:0.11 (0.03-0.89), and TG-CTRL:0.24 (0.06-0.47); p = 0.007]. Eight patients (22.9%) in the TG-RIPC group developed type 4a myocardial infarction (MI), compared to 14 (40%) in the CL-RIPC group, 13 (38.2%) in the CL-CTRL group, and 19 (55.9%) in the TG-CTRL group (p = 0.048). A significant interaction between antiplatelet group allocation and RIPC on deltaTnI was observed [F (1,134) = 7.509; p = 0.007]. In multivariate analysis, the interaction between RIPC and ticagrelor treatment was independently associated with a lower incidence of Type 4a MI.

CONCLUSION

Our results demonstrate an interaction between ticagrelor and RIPC, which may potentiate the cardioprotective effects of RIPC during PCI by reducing PMI.

Effect of pentoxifylline on endothelial dysfunction, oxidative stress and inflammatory markers in STEMI patients

Aim: ST-elevation myocardial infarction (STEMI) patients suffer higher mortality and adverse outcomes linked to endothelial dysfunction (ED). Methods: 43 patients were randomized to pentoxifylline (PTX) 400 mg thrice daily (n = 22) or placebo (n = 21). Soluble vascular cell adhesion molecule-1, malondialdehyde, interleukin-1 (IL-1), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-α (TNF-α) were assessed at baseline and 2 months. Results: After 2 months, no significant difference was observed in markers' levels between the 2 groups. However, a within-group comparison revealed a statistically significant change in hs-CRP in the PTX group (10.057 (9.779-10.331) versus 9.721 (6.102-10.191)), p = 0.032. Conclusion: PTX for 2 months in STEMI patients was safe and well-tolerated but had no significant detectable effect on ED, oxidative stress or inflammatory markers. Clinical Trial Registration: NCT04367935 (ClinicalTrials.gov).

Clinical Impact of Dyspnea after Ticagrelor Treatment and the Effect of Switching to Clopidogrel in Patients with Myocardial Infarction

BACKGROUND

 Dyspnea is frequent during ticagrelor-based dual antiplatelet therapy (DAPT) for acute myocardial infarction (AMI). However, its clinical characteristics or management strategy remains uncertain.

METHODS

 The study assessed 2,617 AMI patients from the Ticagrelor versus Clopidogrel in Stabilized Patients with AMI (TALOS-AMI) trial. Dyspnea during 1-month ticagrelor-based DAPT and following DAPT strategies with continued ticagrelor or de-escalation to clopidogrel from 1 to 12 months were evaluated for drug adherence, subsequent dyspnea, major adverse cardiovascular events (MACE), and bleeding events.

RESULTS

 Dyspnea was reported by 538 patients (20.6%) during 1 month of ticagrelor-based DAPT. Adherence to allocated DAPT over the study period was lower in the continued ticagrelor arm than the de-escalation to clopidogrel, particularly among the dyspneic population (81.1% vs. 91.5%, p < 0.001). Among ticagrelor-treated patients with dyspnea, those switched to clopidogrel at 1 month had a lower frequency of dyspnea at 3 months (34.3% vs. 51.7%, p < 0.001) and 6 months (25.5% vs. 38.4%, p = 0.002) than those continued with ticagrelor. In patients with dyspnea in their 1-month ticagrelor-based DAPT, de-escalation was not associated with increased MACE (1.3% vs. 3.9%, hazard ratio [HR]: 0.31, 95% confidence interval [CI]: 0.08-1.11, p = 0.07) or clinically relevant bleeding (3.2% vs. 6.2%, HR: 0.51, 95% CI: 0.22-1.19, p = 0.12) at 1 year.

CONCLUSION

 Dyspnea is a common side effect among ticagrelor-based DAPTs in AMI patients. Switching from ticagrelor to clopidogrel after 1 month in AMI patients may provide a reasonable option to alleviate subsequent dyspnea in ticagrelor-relevant dyspneic patients, without increasing the risk of ischemic events (NCT02018055).

Off-Target Effects of P2Y12 Receptor Inhibitors: Focus on Early Myocardial Fibrosis Modulation

Several studies have demonstrated that, beyond their antithrombotic effects, P2Y12 receptor inhibitors may provide additional off-target effects through different mechanisms. These effects range from the preservation of endothelial barrier function to the modulation of inflammation or stabilization of atherosclerotic plaques, with an impact on different cell types, including endothelial and immune cells. Many P2Y12 inhibitors have been developed, from ticlopidine, the first thienopyridine, to the more potent non-thienopyridine derivatives such as ticagrelor which may promote cardioprotective effects following myocardial infarction (MI) by inhibiting adenosine reuptake through sodium-independent equilibrative nucleoside transporter 1 (ENT1). Adenosine may affect different molecular pathways involved in cardiac fibrosis, such as the Wnt (wingless-type)/beta (β)-catenin signaling. An early pro-fibrotic response of the epicardium and activation of cardiac fibroblasts with the involvement of Wnt1 (wingless-type family member 1)/β-catenin, are critically required for preserving cardiac function after acute ischemic cardiac injury. This review discusses molecular signaling pathways involved in cardiac fibrosis post MI, focusing on the Wnt/β-catenin pathway, and the off-target effect of P2Y12 receptor inhibition. A potential role of ticagrelor was speculated in the early modulation of cardiac fibrosis, thanks to its off-target effect.

The effect of ticagrelor on coronary microvascular function after PCI in patients with ACS compared to clopidogrel: A systematic review and meta-analysis

BACKGROUND

The function of coronary microcirculation is an important factor in predicting the prognosis of patients with acute coronary syndrome (ACS) who receive percutaneous coronary intervention (PCI) therapy. Ticagrelor, a type of oral P2Y12 inhibitor, is widely prescribed to ACS patients and can improve prognosis compared to clopidogrel. However, the efficacy of ticagrelor on coronary microcirculation, compared to clopidogrel, remains unclear. The objective of this meta-analysis was to determine the efficacy of ticagrelor on coronary microcirculation.

METHODS

The PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov databases were comprehensively searched to identify studies until November 2022. Data was pooled using the fixed effects model or random effects model based on the level of heterogeneity. Sensitivity analyses were performed to measure the effects of potential confounders.

RESULTS

After screening, 16 trials with a total of 3676 participants were ultimately included in the analysis. The meta-analysis revealed that compared to clopidogrel, patients receiving ticagrelor exhibited a more significant reduction in the IMR (WMD: -6.23, 95% CI: -8.41 to -4.04), a reduction in the cTFC (WMD: -1.88; 95% CI: -3.32 to -0.45), and greater increases in CFR (WMD: 0.38; 95% CI: 0.18 to 0.57), MBG (RR 1.29, 95% CI 1.12 to 1.48), and TIMI (RR 1.03, 95% CI 1.00 to 1.06).

CONCLUSION

Our findings suggest that, compared to clopidogrel, ticagrelor has a significant effect in reducing coronary microcirculatory resistance, enhancing coronary blood flow reserve, and improving myocardial perfusion.

Early Effects of Ticagrelor Versus Clopidogrel on Peripheral Endothelial Function After Non-ST-Elevation Acute Coronary Syndrome and Assessment of Its Relationship With Coronary Microvascular Function

Peripheral endothelial dysfunction is an independent predictor of adverse long-term prognosis after acute coronary syndrome. Data are lacking on the effects of oral P2Y12-inhibitors on peripheral endothelial function in non-ST-elevation acute coronary syndrome (NSTEACS). Furthermore, the relation between peripheral endothelial function and invasive indexes of coronary microvascular function in NSTEACS is unclear. Between March 2018 and July 2020, hospitalized patients with NSTEACS were randomized (1:1) to ticagrelor or clopidogrel. Peripheral endothelial function was assessed with brachial artery flow-mediated vasodilation (FMD). Invasive indexes of coronary microvascular function were obtained using an intracoronary pressure-temperature sensor-tipped wire. In 70 patients included, mean age was 58.6 years, 78.6% (n = 55) were male and 20% (n = 14) had diabetes mellitus. Compared with clopidogrel, ticagrelor significantly improved FMD (14.2 ± 5.4% vs 8.9 ± 5.3%, p <0.001) after a median treatment time of 41.2 hours. The FMD was significantly correlated with the index of microcirculatory resistance (IMR) measured in the infarct-related artery (r = -0.38, p = 0.001), with a stronger correlation found in those who did not have percutaneous coronary intervention (r = -0.52, p = 0.03). Using receiver operating characteristic curve analysis, an FMD of 8.2% identified an IMR of >34 as the threshold, with 77.6% sensitivity and 52.4% specificity. In patients who did not have a percutaneous coronary intervention, an FMD of 11.49% identified an IMR of >34 with 84.6% sensitivity and 80% specificity. In conclusion, ticagrelor significantly improved peripheral endothelial function compared with clopidogrel in patients with NSTEACS. There was a significant correlation between brachial artery FMD and IMR of the infarct-related artery.

Clinical and Pre-Clinical Pharmacokinetics and Pharmacodynamics of Bentracimab

Antiplatelet agents are among the most frequently used medications in cardiovascular medicine. Although in patients with atherosclerotic disease manifestations, in particular those treated by percutaneous coronary intervention, antiplatelet agents are beneficial for the prevention of ischemic events, they inevitably increase the risk of bleeding. Furthermore, 5-15% of patients treated by percutaneous coronary intervention may need a surgical procedure within 2 years, creating challenges to safe and effective antiplatelet drug management. Importantly, major spontaneous or procedural-related bleedings are associated with increased hospital admission, length, costs, and poor prognosis. Although the effects of other antithrombotic therapies, such as direct oral anticoagulants, can be reversed by approved specific agents, there are no approved reversal agents for any antiplatelet drugs. The fact that many antiplatelet agents, such as aspirin and thienopyridines (i.e., clopidogrel and prasugrel), bind irreversibly to their targets represents a challenge for the development of a drug-specific reversal agent. In contrast, ticagrelor is a non-thienopyridine with a plasma half-life of 7-9 h that reversely binds the P2Y₁₂ receptor producing potent signaling blockage. In 2015, bentracimab (also known as PB2452 or MEDI2452), a neutralizing monoclonal antibody fragment that binds free plasma ticagrelor and its major active metabolite, was identified. This systematic overview provides a comprehensive summary of the drug development program of bentracimab, focusing on its pharmacodynamic, pharmacokinetic, and safety profiles.

Thrombogenicity and endothelial progenitor cells function during Acute myocardial infarction - comparison of Prasugrel versus Ticagrelor

BACKGROUND

Thrombin generation (TG), platelet function and circulating endothelial progenitor cells (EPCs) have an important role in the pathophysiology of coronary artery disease (CAD). To date, the effect of novel P2Y₁₂ inhibitors on these aspects has mostly been studied in the sub-acute phase following myocardial infarction.

OBJECTIVES

Comparing the effects of prasugrel and ticagrelor on TG and EPCs in the acute phase of ST-segment elevation myocardial infarction (STEMI).

METHODS

STEMI patients were randomized to either ticagrelor or prasugrel treatment. TG, platelet reactivity and EPCs were evaluated prior to P2Y₁₂ inhibitor loading dose (T0), and one day following (T1).

RESULTS

Between December 2018 - July 2021, 83 consecutive STEMI patients were randomized to ticagrelor (N = 42) or prasugrel (N = 41) treatment. No differences were observed at T0 for all measurements. P2Y₁₂ reactivity units (PRU) at T1 did not differ as well (prasugrel 13.2 [5.5-20.8] vs. ticagrelor 15.8 [4.0-26.3], p = 0.40). At T1, prasugrel was a significantly more potent TG inhibitor, with longer lag time to TG initiation (7.7 ± 7.5 vs. 3.9 ± 2.1 min, p < 0.01), longer time to peak (14.1 ± 12.6 vs. 8.3 ± 9.7 min, p = 0.03) and a lower endogenous thrombin potential (AUC 2186.1 ± 1123.1 vs. 3362.5 ± 2108.5 nM, p < 0.01). Furthermore, EPCs measured by percentage of cells expressing CD34 (2.6 ± 4.1 vs. 1.1 ± 1.1, p = 0.01) and CD133 (2.3 ± 1.8 vs. 1.4 ± 1.5, p = 0.01) and number of colony forming units (CFU, 2.1 ± 1.5 vs. 1.1 ± 1.0, p < 0.01) were significantly higher in the prasugrel group.

CONCLUSION

Among STEMI patients, prasugrel as compared to ticagrelor was associated with more potent TG inhibition and improved EPCs count and function.

The developmental journey of therapies targeting purine receptors: from basic science to clinical trials

Since the discovery of ATP as an extracellular signalling molecule in 1972, purinergic signalling, mediated by extracellular purines and pyrimidines has been identified in virtually all mammalian tissues and is implicated in regulating fundamental cellular processes. In recent years, there has been an increasing focus on the pathophysiology and potential therapeutic interventions based on purinergic signalling. A vast range of compounds targeting purine receptors are in clinical development, and many more are in preclinical studies, which highlights the fast growth in this research field. As a tribute to Professor Geoffrey Burnstock's legacy in purinergic signalling, we present here a brief review of compounds targeting purine receptors that are in different stages of clinical trials. The review highlights the 50-year journey from basic research on purinergic receptors to clinical applications of therapies targeting purine receptors.

Endothelial biomarkers and platelet reactivity on ticagrelor versus clopidogrel in patients after acute coronary syndrome with and without concomitant type 2 diabetes: a preliminary observational study

BACKGROUND

Pleiotropic effects have been implicated in clinical benefits of ticagrelor compared to thienopyridine P2Y₁₂ antagonists. There are conflicting data regarding effects of ticagrelor vs. thienopyridine P2Y₁₂ blockers on endothelial function. Our aim was to compare endothelial biomarkers and their relations with platelet reactivity in real-world patients after acute coronary syndrome (ACS) on maintenance dual antiplatelet therapy (DAPT) with ticagrelor or clopidogrel stratified by diabetes status.

METHODS

Biochemical indices of endothelial dysfunction/activation and platelet reactivity by multiple electrode aggregometry were compared in 126 stable post-ACS subjects (mean age: 65 ± 10 years, 92 men and 34 women), including patients with (n = 61) or without (n = 65) coexistent type 2 diabetes (T2DM) on uneventful maintenance DAPT with either ticagrelor (90 mg b.d.) or clopidogrel (75 mg o.d.) in addition to low-dose aspirin. Exclusion criteria included a complicated in-hospital course, symptomatic heart failure, left ventricular ejection fraction < 40% and relevant coexistent diseases except for well-controlled diabetes, mild renal insufficiency or hypertension.

RESULTS

Clinical characteristics were similar in patients on ticagrelor (n = 62) and clopidogrel (n = 64). The adenosine diphosphate-induced platelet aggregation and circulating soluble P-selectin (sP-selectin) were decreased in ticagrelor users irrespective of T2DM status (p < 0.001 and p < 0.01 for platelet reactivity and sP-selectin, respectively). Plasma levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) were lower in T2DM subjects on ticagrelor vs. clopidogrel (758 ± 162 vs. 913 ± 217 µg/L, p < 0.01). In contrast, plasma sVCAM-1 was similar in non-diabetic patients on ticagrelor and clopidogrel (872 ± 203 vs. 821 ± 210 µg/L, p > 0.7). The concentrations of sE-selectin, monocyte chemoattractant protein-1 and asymmetric dimethylarginine did not differ according to the type of P2Y₁₂ antagonist regardless of T2DM status. Platelet reactivity was unrelated to any endothelial biomarker in subjects with or without T2DM.

CONCLUSIONS

Our preliminary findings may suggest an association of ticagrelor-based maintenance DAPT with favorable endothelial effects compared to clopidogrel users in stable post-ACS patients with T2DM. If proven, this could contribute to more pronounced clinical benefits of ticagrelor in diabetic subjects.

P2Y12 Inhibitor Monotherapy after Percutaneous Coronary Intervention

In patients with acute and chronic coronary artery disease undergoing percutaneous coronary intervention (PCI), dual antiplatelet therapy (DAPT) has been the cornerstone of pharmacotherapy for the past two decades. Although its antithrombotic benefit is well established, DAPT is associated with an increased risk of bleeding, which is independently associated with poor prognosis. The improvement of the safety profiles of drug-eluting stents has been critical in investigating and implementing shorter DAPT regimens. The introduction into clinical practice of newer generation oral P2Y₁₂ inhibitors such as prasugrel and ticagrelor, which provide more potent and predictable platelet inhibition, has questioned the paradigm of standard DAPT durations after coronary stenting. Over the last five years, several trials have assessed the safety and efficacy of P2Y₁₂ inhibitor monotherapy after a short course of DAPT in patients treated with PCI. Moreover, ongoing studies are testing the role of P2Y₁₂ inhibitor monotherapy immediately after PCI in selected patients. In this review, we provide up-to-date evidence on the efficacy and safety of P2Y₁₂ inhibitor monotherapy after a short period of DAPT compared to DAPT in patients undergoing PCI as well as outcomes associated with P2Y₁₂ inhibitor monotherapy compared to aspirin for long-term prevention.

Efficacy of ticagrelor compared to clopidogrel in improving endothelial function in patients with coronary artery disease: a systematic review

BACKGROUND

Ticagrelor and clopidogrel are antiplatelet drugs that act by binding to the adenosine diphosphate P2Y12 receptor. Previous studies have compared between them regarding the endothelial function effect.

OBJECTIVES

This systematic review aims to summarize the evidence comparing the efficacy of ticagrelor vs. clopidogrel in improving endothelial function in patients with coronary artery disease (CAD).

METHODS

In August 2021, the Scopus, PubMed, Web of Science, and Cochrane library were searched systematically for eligible trials. We included randomized controlled trials that compared the efficacy of ticagrelor vs. clopidogrel in improving endothelial function in patients with CAD.

RESULTS

Seven trials (n = 511) were included in our systematic review. Ticagrelor resulted in a greater elevation of the level of progenitor cells CD34+ KDR+ and CD34+ 133+ (P = 0.036 and P = 0.019, respectively), with a lower rate of endothelial cell apoptosis rate (P < 0.001). Moreover, ticagrelor showed superiority regarding nitric oxide, radical oxygen species, and soluble P-selectin levels (P = 0.03, P = 0.02, and P = 0.019, respectively). Flow-mediated dilation findings differed between the studies (P = 0.004 vs. P = 0.39).

CONCLUSION

Ticagrelor appears to exert an additional improvement in endothelial function compared with clopidogrel in patients with coronary heart disease.

Assessment of myocardial salvage in patients with STEMI undergoing thrombolysis: ticagrelor versus clopidogrel

Background

In the setting of ST-segment elevation myocardial infarction (STEMI), the faster and stronger antiplatelet action of ticagrelor compared to clopidogrel, as well as its pleiotropic effects, could result in a greater degree of cardioprotection and final infarct size (FIS) limitation. The aim of our study was to comparatively evaluate the effect of ticagrelor and clopidogrel on myocardial salvage index (MSI) in STEMI patients undergoing thrombolysis.

Methods

Forty-two STEMI patients treated with thrombolysis were randomized to receive clopidogrel (n = 21) or ticagrelor (n = 21), along with aspirin. Myocardial area at risk (AAR) was calculated according to the BARI and the APPROACH jeopardy scores. FIS was quantified by cardiac magnetic resonance imaging (CMR) performed 5–6 months post-randomization. MSI was calculated as (AAR-FIS)/AAR × 100%. Primary endpoint of our study was MSI. Secondary endpoints were FIS and CMR-derived left ventricular ejection fraction (LVEF) at 5 –6 months post-randomization.

Results

By using the BARI score for AAR calculation, mean MSI was 52.25 ± 30.5 for the clopidogrel group and 54.29 ± 31.08 for the ticagrelor group (p = 0.83), while mean MSI using the APPROACH score was calculated at 51.94 ± 30 and 53.09 ± 32.39 (p = 0.9), respectively. Median CMR-derived FIS—as a percentage of LV—was 10.7% ± 8.25 in the clopidogrel group and 12.09% ± 8.72 in the ticagrelor group (p = 0.6). Mean LVEF at 5–6 months post-randomization did not differ significantly between randomization groups.

Conclusions

Our results suggest that the administration of ticagrelor in STEMI patients undergoing thrombolysis offer a similar degree of myocardial salvage, compared to clopidogrel.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02735-1.

Multi-Omics Signatures Link to Ticagrelor Effects on Vascular Function in Patients With Acute Coronary Syndrome

BACKGROUND

Long-term antiplatelet agents including the potent P2Y12 antagonist ticagrelor are indicated in patients with a previous history of acute coronary syndrome. We sought to compare the effect of ticagrelor with that of aspirin monotherapy on vascular endothelial function in patients with prior acute coronary syndrome.

METHODS

This was a prospective, single center, parallel group, investigator-blinded randomized controlled trial. We randomized 200 patients on long-term aspirin monotherapy with prior acute coronary syndrome in a 1:1 fashion to receive ticagrelor 60 mg BD (n=100) or aspirin 100 mg OD (n=100). The primary end point was change from baseline in brachial artery flow-mediated dilation at 12 weeks. Secondary end points were changes to platelet activation marker (CD41_62p) and endothelial progenitor cell (CD34/133) count measured by flow cytometry, plasma level of adenosine, IL-6 (interleukin-6) and EGF (epidermal growth factor), and multi-omics profiling at 12 weeks.

RESULTS

After 12 weeks, brachial flow-mediated dilation was significantly increased in the ticagrelor group compared with the aspirin group (ticagrelor: 3.48±3.48% versus aspirin: -1.26±2.85%, treatment effect 4.73 [95% CI, 3.85-5.62], P<0.001). Nevertheless ticagrelor treatment for 12 weeks had no significant effect on platelet activation markers, circulating endothelial progenitor cell count or plasma level of adenosine, IL-6, and EGF (all P>0.05). Multi-omics pathway assessment revealed that changes in the metabolism and biosynthesis of amino acids (cysteine and methionine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis) and phospholipids (glycerophosphoethanolamines and glycerophosphoserines) were associated with improved brachial artery flow-mediated dilation in the ticagrelor group.

CONCLUSIONS

In patients with prior acute coronary syndrome, ticagrelor 60 mg BD monotherapy significantly improved brachial flow-mediated dilation compared with aspirin monotherapy and was associated with significant changes in metabolomic and lipidomic signatures.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03881943.

The Effect of Ticagrelor on Endothelial Function Compared to Prasugrel, Clopidogrel, and Placebo: A Systematic Review and Meta-Analysis

Background/Objective

Endothelial dysfunction is associated with the long-term outcomes in patients with coronary artery disease (CAD). Recent evidence suggests that ticagrelor, a potent antiplatelet agent, improves endothelial function. However, several studies demonstrated contrasting results. The objective of this meta-analysis was to determine the efficacy of ticagrelor treatment on endothelial function.

Materials and Methods

A systematic literature study was conducted on databases including PubMed, Web of Science, EMBASE, Scopus, and the Cochrane Library. A historical search was performed for a reference list of the selected studies as of August 2021. The randomized controlled trials (RCTs) were assessed using the Cochrane tool. The weighted mean difference (WMD) 95% CI was treated as the overall effect size, and data were pooled using the fixed-effect model or random-effect model according to the heterogeneity. Subgroup and sensitivity analyses were performed to measure the effects of potential confounders.

Results

A total of 21 studies were included. The meta-analysis indicated that ticagrelor resulted in a significant increase of flow-mediated dilation (FMD) (WMD: 1.48; 95% CI: 0.36, 2.60), reactive hyperemia index (RHI) (WMD: 0.06; 95% CI: 0.00, 0.13), and circulating progenitor endothelial cells (CEPCs) (WMD: 13.84; 95% CI: 5.70, 21.98), and a reduction in the index of microvascular resistance (IMR) (WMD: −15.39; 95% CI: −25.11, −5.68).

Conclusion

Ticagrelor has a significant effect on some markers of endothelial function in patients with CAD. However, the results should be interpreted with caution due to the heterogeneity and limited studies.

Effects of Clopidogrel, Prasugrel and Ticagrelor on Microvascular Function and Platelet Reactivity in Patients With Acute Coronary Syndrome Undergoing Coronary Artery Stenting. A Randomized, Blinded, Parallel Group Trial

Aims: In this pre-specified analysis of the "endothelium, stent and antiplatelet therapy" study, we investigate the impact of antiplatelet therapies on microvascular function in patients undergoing stenting for an acute coronary syndrome. Methods and Results: Fifty-six patients [age: 63(55-67) years, males, 10 diabetics, 27 non-ST-elevation myocardial infarction] were randomized to receive clopidogrel, ticagrelor or prasugrel in form of oral loading 2 h before stenting followed by oral therapy. Investigators were blinded to the allocation. Laser-Doppler microvascular function and ADP-induced platelet aggregation capacity were measured at baseline, 2 h after oral antiplatelet loading, and 1 day, 1 week and 1 month after stenting during chronic therapy with the same antiplatelet agent. Platelet aggregation decreased in all groups 2 h after oral loading, with a significantly larger effect in the prasugrel group (P = 0.009). Similarly, prasugrel and ticagrelor loading was followed by an increase in microvascular reactive hyperemia (P = 0.007 and P = 0.042 compared to clopidogrel). This effect disappeared one day after coronary intervention, with a significant decrease in the prasugrel group (P = 0.026). Similarly, analysis of microvascular conductance showed a larger increase in the prasugrel group 2 h after loading (P = 0.022 among groups), and a decrease in all groups after stenting. Conclusions: Oral loading with prasugrel (and less consistently ticagrelor) is associated with improved microvascular function and stronger platelet inhibition in acute coronary syndrome patients. The microvascular effect was however lost 1 day after stenting and during subsequent follow-up. Further studies are necessary to clarify the the long-term effects and potential benefits of P2Y12 inhibitors on microvascular damage. ClINICALTRIALS.gov N°: NCT01700322 EUDRACT-N°: 2011-005305-73.

Long-Term Ticagrelor in Patients With Prior Coronary Stenting in the PEGASUS-TIMI 54 Trial

Background Coronary stent type and risk of stent thrombosis remain important factors affecting recommended duration of dual antiplatelet therapy. We investigated the efficacy and safety of long-term ticagrelor in patients with prior coronary stenting enrolled in the PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients with Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin-Thrombolysis in Myocardial Infarction 54) trial. Methods and Results Patients in PEGASUS-TIMI 54 had a myocardial infarction 1 to 3 year prior and were randomized 1:1:1 to ticagrelor 60 or 90 mg BID or placebo. The primary end point was a composite of cardiovascular death, myocardial infarction, or stroke (major adverse cardiovascular events). Stent thrombosis was prospectively adjudicated (Academic Research Consortium definition). Baseline characteristics were compared by most recent stent type (bare metal versus drug-eluting stent and first- versus later-generation drug-eluting stent). Treatment arms were compared using Cox proportional hazards models. Of 21 162 patients randomized, 80% (n=16 891) had prior coronary stenting. Following randomization, myocardial infarction was the most frequent ischemic event in patients with prior stenting in the placebo arm, occurring in 5.2% of patients (Type 1: 4.1%), followed by cardiovascular death (2.3%), stroke (1.7%), and stent thrombosis (0.9%). Ticagrelor_pooled reduced major adverse cardiovascular events (7.0% versus 8.0%; hazard ratio [HR], 0.85; 95% CI, 0.75-96) regardless of stent type (bare metal stent versus drug-eluting stent: p_interaction=0.767; first versus later generation: p_interaction=0.940). The rate of any stent thrombosis was numerically lower with ticagrelor_pooled (0.7% versus 0.9%; HR, 0.73; 95% CI, 0.50-1.05) and Thrombolysis in Myocardial Infarction major bleeding was increased (HR, 2.65; 95% CI, 1.90-3.68). Conclusions Long-term ticagrelor reduces major adverse cardiovascular events in patients with prior myocardial infarction and coronary stenting regardless of stent type, with the benefit driven predominantly by reduction in de novo events. Nonfatal major bleeding is increased with ticagrelor. Registration Information clinicaltrials.gov. Identifier: NCT01225562.

A review of the effects of ticagrelor on adenosine concentration and its clinical significance

BACKGROUND

Ticagrelor is an oral antiplatelet drug that can reversibly bind to the platelet P2Y12 receptor. Ticagrelor is metabolized mainly by CYP3A4 and produces a rapid blood concentration-dependent platelet inhibitory effect. Unlike other P2Y12 receptor antagonists, many clinical features of ticagrelor are not related to P2Y12 receptor antagonism.

PURPOSE

This review aims to gather existing literature on the clinical effects of ticagrelor after inhibiting adenosine uptake.

METHODOLOGY

The current study reviewed literature related to the effects of ticagrelor on adenosine metabolism. The review also examined the drug's biological effects and clinical characteristics to see how it could be used in a clinical setting.

RESULTS

Many studies have shown that ticagrelor can inhibit equilibrative nucleoside transporter 1 (ENT1). This inhibition leads to intracellular adenosine uptake, increased adenosine half-life and plasma concentration levels and an enhanced adenosine-mediated biological effect.

CONCLUSIONS

Based on the studies reviewed, it was found that ticagrelor essentially inhibits adenosine absorption of adenosine into cells through ENT1, which increases the concentration in the blood and subsequently increases the protection of the heart muscle by adenosine. It also prevents platelet aggregation, and extends the biological effects of coronary arteries. Moreover, it leads to a lower mortality rate in acute coronary syndrome (ACS) patients.

Ticagrelor or Prasugrel for Patients With Acute Coronary Syndrome Treated With Percutaneous Coronary Intervention: A Prespecified Subgroup Analysis of a Randomized Clinical Trial

Importance

It is unclear whether ticagrelor or prasugrel hydrochloride is superior for patients with acute coronary syndrome (ACS) treated with percutaneous coronary intervention (PCI).

Objective

To assess the safety and efficacy of ticagrelor vs prasugrel for patients with ACS treated with PCI.

Design, Setting, and Participants

A prespecified analysis was performed of a postrandomization subgroup of 3377 patients who presented with ACS and were treated with PCI in the investigator-initiated, multicenter, phase 4, open-label Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment 5 randomized clinical trial, conducted from September 1, 2013, to February 28, 2018. Statistical analysis was performed from September 1, 2020, to January 30, 2021. Analysis was performed according to the intention-to-treat principle.

Interventions

Patients were randomly assigned to a ticagrelor-based or prasugrel-based strategy. This analysis focuses on the subgroup of patients who underwent PCI that was formed after randomization.

Main Outcomes and Measures

The primary end point was a composite consisting of all-cause death, myocardial infarction, or stroke at 12 months. The safety end point was Bleeding Academic Research Consortium (BARC) type 3 to 5 bleeding.

Results

The ticagrelor group comprised 1676 patients (1323 men [78.9%]; mean [SD] age, 64.4 [12.0] years), and the prasugrel group comprised 1701 patients (1341 men [78.8%]; mean [SD] age, 64.7 [12.0] years). The primary end point occurred for 162 patients (9.8%) in the ticagrelor group and 120 patients (7.1%) in the prasugrel group (hazard ratio [HR], 1.41; 95% CI, 1.11-1.78; P = .005). Myocardial infarction occurred in 88 patients (5.3%) in the ticagrelor group compared with 55 patients (3.8%) in the prasugrel group (HR, 1.67; 95% CI, 1.19-2.34; P = .003). The safety end point, BARC type 3 to 5 bleeding, occurred in 84 of 1672 patients (5.3%) in the ticagrelor group and 78 of 1680 patients (4.9%) in the prasugrel group (HR; 1.10; 95% CI, 0.81-1.50; P = .54).

Conclusions and Relevance

Among patients presenting with ACS who were treated with PCI, the incidence of the primary composite end point occurred less frequently for patients who received prasugrel compared with those who received ticagrelor. The incidence of bleeding events was comparable between the 2 groups. These results suggest that, for patients presenting with ACS who undergo PCI, a prasugrel-based strategy is superior to a ticagrelor-based strategy. However, because these observations are based on a postrandomization subgroup, these findings should be regarded as hypothesis generating and dedicated randomized clinical trials may be warranted to confirm these findings.

Trial Registration

ClinicalTrials.gov Identifier: NCT01944800.

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.

Differential modulation of polyunsaturated fatty acids in patients with myocardial infarction treated with ticagrelor or clopidogrel

Untargeted metabolomics is used to refine the development of biomarkers for the diagnosis of cardiovascular disease. Myocardial infarction (MI) has major individual and societal consequences for patients, who remain at high risk of secondary events, despite advances in pharmacological therapy. To monitor their differential response to treatment, we performed untargeted plasma metabolomics on 175 patients from the platelet inhibition and patient outcomes (PLATO) trial treated with ticagrelor and clopidogrel, two common P₂Y₁₂ inhibitors. We identified a signature that discriminates patients, which involves polyunsaturated fatty acids (PUFAs) and particularly the omega-3 fatty acids docosahexaenoate and eicosapentaenoate. The known cardiovascular benefits of PUFAs could contribute to the efficacy of ticagrelor. Our work, beyond pointing out the high relevance of untargeted metabolomics in evaluating response to treatment, establishes PUFA metabolism as a pathway of clinical interest in the recovery path from MI.

We detect an extreme metabolomic signature of myocardial infarction (MI) in plasma

Polyunsaturated fatty acids (PUFAs) are upregulated in patients taking ticagrelor

PUFA metabolism is a pathway of clinical interest in the recovery path from MI

Data science methods detect biologically meaningful patterns in metabolite signals

Effects of clopidogrel vs. prasugrel vs. ticagrelor on endothelial function, inflammatory parameters, and platelet function in patients with acute coronary syndrome undergoing coronary artery stenting: a randomized, blinded, parallel study

AIMS

In a randomized, parallel, blinded study, we investigate the impact of clopidogrel, prasugrel, or ticagrelor on peripheral endothelial function in patients undergoing stenting for an acute coronary syndrome.

METHODS AND RESULTS

The primary endpoint of the study was the change in endothelium-dependent flow-mediated dilation (FMD) following stenting. A total of 90 patients (age 62 ± 9 years, 81 males, 22 diabetics, 49 non-ST elevation myocardial infarctions) were enrolled. There were no significant differences among groups in any clinical parameter. Acutely before stenting, all three drugs improved FMD without differences between groups (P = 0.73). Stenting blunted FMD in the clopidogrel and ticagrelor group (both P < 0.01), but not in the prasugrel group. During follow-up, prasugrel was superior to clopidogrel [mean difference 2.13, 95% confidence interval (CI) 0.68-3.58; P = 0.0047] and ticagrelor (mean difference 1.57, 95% CI 0.31-2.83; P = 0.0155), but this difference was limited to patients who received the study therapy 2 h before stenting. Ticagrelor was not significantly superior to clopidogrel (mean difference 0.55, 95% CI -0.73 to 1.82; P = 0.39). No significant differences were seen among groups for low-flow-mediated dilation. Plasma interleukin (IL)-6 (P = 0.02 and P = 0.01, respectively) and platelet aggregation reactivity in response to adenosine diphosphate (P = 0.002 and P = 0.035) were lower in the prasugrel compared to clopidogrel and ticagrelor group.

CONCLUSION

As compared to ticagrelor and clopidogrel, therapy with prasugrel in patients undergoing stenting for an acute coronary syndrome is associated with improved endothelial function, stronger platelet inhibition, and reduced IL-6 levels, all of which may have prognostic implications. This effect was lost in patients who received the study medication immediately after stenting.

EUDRACT-NO

2011-005305-73.

Revisiting the Evidence for Dipyridamole in Reducing Restenosis: A Systematic Review and Meta-analysis

ABSTRACT

Atherosclerosis remains a leading cause of morbidity and mortality, with revascularization remaining a cornerstone of management. Conventional revascularization modalities remain challenged by target vessel reocclusion-an event driven by mechanical, thrombotic, and proliferative processes. Despite considerable advancements, restenosis remains the focus of ongoing research. Adjunctive agents, including dipyridamole, offer a multitude of effects that may improve vascular homeostasis. We sought to quantify the potential therapeutic impact of dipyridamole on vascular occlusion. We performed a literature search (EMBASE and MEDLINE) examining studies that encompassed 3 areas: (1) one of the designated medical therapies applied in (2) the setting of a vascular intervention with (3) an outcome including vascular occlusion rates and/or quantification of neointimal proliferation/restenosis. The primary outcome was vascular occlusion rates. The secondary outcome was the degree of restenosis by neointimal quantification. Both human and animal studies were included in this translational analysis. There were 6,839 articles screened, from which 73 studies were included, encompassing 16,146 vessels followed up for a mean of 327.3 days (range 7-3650 days). Preclinical studies demonstrate that dipyridamole results in reduced vascular occlusion rates {24.9% vs. 48.8%, risk ratio 0.53 [95% confidence interval (CI) 0.40-0.70], I2 = 39%, P < 0.00001}, owing to diminished neointimal proliferation [standardized mean differences -1.13 (95% CI -1.74 to -0.53), I2 = 91%, P = 0.0002]. Clinical studies similarly demonstrated reduced occlusion rates with dipyridamole therapy [23.5% vs. 31.0%, risk ratio 0.77 (95% CI 0.67-0.88), I2 = 84%, P < 0.0001]. Dipyridamole may improve post-intervention vascular patency and mitigate restenosis. Dedicated studies are warranted to delineate its role as an adjunctive agent after revascularization.

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.

Performance of Plasma Adenosine as a Biomarker for Predicting Cardiovascular Risk

Adenosine boasts promising preclinical and clinical data supporting a vital role in modulating vascular homeostasis. Its widespread use as a diagnostic and therapeutic agent have been limited by its short half-life and complex biology, though adenosine-modulators have shown promise in improving vascular healing. Moreover, circulating adenosine has shown promise in predicting cardiovascular (CV) events. We sought to delineate whether circulating plasma adenosine levels predict CV events in patients undergoing invasive assessment for coronary artery disease. Patients undergoing invasive angiography had clinical data prospectively recorded in the Cardiovascular and Percutaneous ClInical TriALs (CAPITAL) revascularization registry and blood samples collected in the CAPITAL Biobank from which adenosine levels were quantified. Tertile-based analysis was used to assess prediction of major adverse cardiovascular events (MACE; composite of death, myocardial infarction, unplanned revascularization, and cerebrovascular accident). Secondary analyses included MACE subgroups, clinical subgroups and adenosine levels. There were 1,815 patients undergoing angiography who had blood collected with adenosine quantified in 1,323. Of those quantified, 51.0% were revascularized and 7.3% experienced MACE in 12 months of follow-up. Tertile-based analysis failed to demonstrate any stratification of MACE rates (log rank, P = 0.83), when comparing low-to-middle (hazard ratio (HR) 1.10, 95% confidence interval (CI) 0.68-1.78, P = 0.70) or low-to-high adenosine tertiles (HR 0.95, 95% CI 0.56-1.57, P = 0.84). In adjusted analysis, adenosine similarly failed to predict MACE. Finally, adenosine did not predict outcomes in patients with acute coronary syndrome nor in those revascularized or treated medically. Plasma adenosine levels do not predict subsequent CV outcomes or aid in patient risk stratification.

Effects of switching from clopidogrel to prasugrel at the chronic phase after coronary stenting on antiplatelet action and vascular endothelial function: Switch-Pras study

Compared to clopidogrel, prasugrel has a lower incidence of ischemic events following percutaneous coronary intervention (PCI) because of an early reduction during the acute phase in P2Y12 reaction units (PRU). The objective of this study was to compare the antiplatelet effect and vascular endothelial function of both drugs during the chronic phase after PCI. Patients who had undergone PCI and were confirmed to have no restenosis by follow-up coronary angiography under dual anti-platelet therapy with clopidogrel (75 mg/day) and aspirin (100 mg/day) were randomized to either continue clopidogrel or switch to prasugrel (3.75 mg/day). At baseline, prior to randomization we determined the CYP2C19 genotype. At the baseline and 24 weeks after randomization, the P2Y12 reactivity unit (PRU) was measured using the VerifyNow™ P2Y12 assay. Endothelial function was evaluated by flow-mediated vasodilation (FMD) and reactive hyperemia peripheral arterial tonometry (RH-PAT), while and circulating CD34+/CD133+/CD45^low progenitor cells were measured by flow cytometric analysis. Serum high-sensitivity C-reactive protein (hsCRP) level was also measured. The PRU was reduced significantly in the prasugrel group (P = 0.0008), especially in patients who were intermediate or poor metabolizers based on the CYP2C19 genotype (P < 0.0001). This reduction was not observed in the clopidogrel group. The number of CD34+/CD133+/CD45^low cells increased in the clopidogrel group (P = 0.008), but not in the prasugrel group. The hsCRP, FMD and reactive hyperemia index measured by RH-PAT did not change in either group. Prasugrel is potentially better than clopidogrel for preventing thrombotic events, although clopidogrel may have an advantage over prasugrel in terms of preventing atherosclerotic events. Proper use of thienopyridine drugs based on the CYP2C19 genotype has promising clinical potential.

Ticagrelor-Related Severe Dyspnoea: Mechanisms, Characteristic Features, Differential Diagnosis and Treatment

With a growing number of patients on ticagrelor therapy after stent implantation, we observe many cases of side effects of the drug, mostly dyspnoea and bradycardia. In our article we present 2 patients, in which the symptoms were particularly severe. Then we describe possible mechanisms of these complications, explain how to carry out differential diagnosis, discuss when to switch ticagrelor to other antiplatelet drug and finally we present the way to deal with the symptoms.

Ticagrelor Does Not Protect Against Endothelial Ischemia-Reperfusion Injury in Patients With Coronary Artery Disease

BACKGROUND

Ticagrelor is a recommended P2Y₁₂ receptor inhibitor after acute coronary syndrome (ACS). Its superiority has been suggested to rely on pleiotropic effects beyond platelet inhibition. Experimental studies indicate that ticagrelor may protect from ischemia-reperfusion injury but no data are available from such studies on patients. This study aimed to determine if chronic ticagrelor treatment protects against endothelial ischemia-reperfusion injury in patients with a previous ACS.

METHODS

Patients with a previous ACS were studied with flow mediated dilatation of the left brachial artery to determine the degree of endothelial ischemia-reperfusion injury before and after discontinuation of ticagrelor treatment, which had been continuous since 1 year. Each patient underwent 3 identical examinations. The first examination (Visit A) was at the end of ticagrelor treatment and the following 2 (Visit B and C) were after cessation of this treatment with an interval of 2 to 4 weeks.

RESULTS

Ischemia and reperfusion induced significant impairment of endothelial function at all 3 occasions (absolute decline in flow mediated dilatation 3.0% ± 0.7 at Visit A (P < 0.001), 1.9% ± 0.9 at Visit B (P < 0.05) and 1.9% ± 0.4 at Visit C (P < 0.0001)). However, there was no difference in the degree of endothelial ischemia-reperfusion injury or baseline endothelial function between the visits.

CONCLUSION

Chronic ticagrelor treatment in patients 1 year after an ACS does not protect against endothelial ischaemia-reperfusion injury. Nor is it associated with better basal endothelial function compared to after discontinuation of treatment.

Potential Therapeutic Applications of P2 Receptor Antagonists: From Bench to Clinical Trials

BACKGROUND

Extracellular purines and pyrimidines have important physiological functions in mammals. Purines and pyrimidines act on P1 and P2 purinergic receptors, which are widely expressed in the plasma membrane in various cell types. P2 receptors act as important therapeutic targets and are associated with several disorders, such as pain, neurodegeneration, cancer, inflammation, and thrombosis. However, the use of antagonists for P2 receptors in clinical therapy, with the exception of P2Y12, is a great challenge. Currently, many research groups and pharmaceutical companies are working on the development of specific antagonist molecules for each receptor subtype that could be used as new medicines to treat their respective disorders.

OBJECTIVE

The present review compiles some interesting findings on the application of P2 receptor antagonists in different in vitro and in vivo experimental models as well as the progress of advanced clinical trials with these compounds.

CONCLUSION

Despite all of the exciting results obtained on the bench, few antagonists of P2 receptors advanced to the clinical trials, and once they reach this stage, the effectiveness of the therapy is not guaranteed, as in the example of P2X7 antagonists. Despite this, P2Y12 receptor antagonists have a history of success and have been used in therapy for at least two decades to prevent thrombosis in patients at risk for myocardial infarctions. This breakthrough is the motivation for scientists to develop new drugs with antagonistic activity for the other P2 receptors; thus, in a matter of years, we will have an evolution in the field of purinergic therapy.

Platelet Inhibition, Endothelial Function, and Clinical Outcome in Patients Presenting With ST-Segment-Elevation Myocardial Infarction Randomized to Ticagrelor Versus Prasugrel Maintenance Therapy: Long-Term Follow-Up of the REDUCE-MVI Trial

Background

Off‐target properties of ticagrelor might reduce microvascular injury and improve clinical outcome in patients with ST‐segment–elevation myocardial infarction. The REDUCE‐MVI (Evaluation of Microvascular Injury in Revascularized Patients with ST‐Segment–Elevation Myocardial Infarction Treated With Ticagrelor Versus Prasugrel) trial reported no benefit of ticagrelor regarding microvascular function at 1 month. We now present the follow‐up data up to 1.5 years.

Methods and Results

We randomized 110 patients with ST‐segment–elevation myocardial infarction to either ticagrelor 90 mg twice daily or prasugrel 10 mg once a day. Platelet inhibition and peripheral endothelial function measurements including calculation of the reactive hyperemia index and clinical follow‐up were obtained up to 1.5 years. Major adverse clinical events and bleedings were scored. An intention to treat and a per‐protocol analysis were performed. There were no between‐group differences in platelet inhibition and endothelial function. At 1 year the reactive hyperemia index in the ticagrelor group was 0.66±0.26 versus 0.61±0.28 in the prasugrel group (P=0.31). Platelet inhibition was lower at 1 month versus 1 year in the total study population (61% [42%–81%] versus 83% [61%–95%]; P<0.001), and per‐protocol platelet inhibition was higher in patients randomized to ticagrelor versus prasugrel at 1 year (91% [83%–97%] versus 82% [65%–92%]; P=0.002). There was an improvement in intention to treat endothelial function in patients randomized to ticagrelor (P=0.03) but not in patients randomized to prasugrel (P=0.88). Major adverse clinical events (10% versus 14%; P=0.54) and bleedings (47% versus 63%; P=0.10) were similar in the intention‐to‐treat analysis in both groups.

Conclusions

Platelet inhibition at 1 year was higher in the ticagrelor group, without an accompanying increase in bleedings. Endothelial function improved over time in ticagrelor patients, while it did not change in the prasugrel group.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov/. Unique Identifier: NCT02422888.

Ticagrelor Increases SIRT1 and HES1 mRNA Levels in Peripheral Blood Cells from Patients with Stable Coronary Artery Disease and Chronic Obstructive Pulmonary Disease

Ticagrelor is a powerful P2Y₁₂ inhibitor with pleiotropic effects in the cardiovascular system. Consistently, we have reported that in patients with stable coronary artery disease (CAD) and concomitant chronic obstructive pulmonary disease (COPD) who underwent percutaneous coronary intervention (PCI), 1-month treatment with ticagrelor was superior in improving biological markers of endothelial function, compared with clopidogrel. The objective of this study was to investigate the mechanisms underlying these beneficial effects of ticagrelor by conducting molecular analyses of RNA isolated from peripheral blood cells of these patients. We determined mRNAs levels of markers of inflammation and oxidative stress, such as RORγt (T helper 17 cells marker), FoxP3 (regulatory T cells marker), NLRP3, ICAM1, SIRT1, Notch ligands JAG1 and DLL4, and HES1, a Notch target gene. We found that 1-month treatment with ticagrelor, but not clopidogrel, led to increased levels of SIRT1 and HES1 mRNAs. In patients treated with ticagrelor or clopidogrel, we observed a negative correlation among changes in both SIRT1 and HES1 mRNA and serum levels of Epidermal Growth Factor (EGF), a marker of endothelial dysfunction found to be reduced by ticagrelor treatment in our previous study. In conclusion, we report that in stable CAD/COPD patients ticagrelor positively regulates HES1 and SIRT1, two genes playing a protective role in the context of inflammation and oxidative stress. Our observations confirm and expand previous studies showing that the beneficial effects of ticagrelor in stable CAD/COPD patients may be, at least in part, mediated by its capacity to reduce systemic inflammation and oxidative stress.

Antithrombotic Therapy: Prevention and Treatment of Atherosclerosis and Atherothrombosis

Atherosclerosis is a multifactorial vascular disease that develops in the course of a lifetime. Numerous risk factors for atherosclerosis have been identified, mostly inflicting pro-inflammatory effects. Vessel injury, such as occurring during erosion or rupture of atherosclerotic lesions triggers blood coagulation, in attempt to maintain hemostasis (protect against bleeding). However, thrombo-inflammatory mechanisms may drive blood coagulation such that thrombosis develops, the key process underlying myocardial infarction and ischemic stroke (not due to embolization from the heart). In the blood coagulation system, platelets and coagulation proteins are both essential elements. Hyperreactivity of blood coagulation aggravates atherosclerosis in preclinical models. Pharmacologic inhibition of blood coagulation, either with platelet inhibitors, or better documented with anticoagulants, or both, limits the risk of thrombosis and may potentially reverse atherosclerosis burden, although the latter evidence is still based on animal experimentation.Patients at risk of atherothrombotic complications should receive a single antiplatelet agent (acetylsalicylic acid, ASA, or clopidogrel); those who survived an atherothrombotic event will be prescribed temporary dual antiplatelet therapy (ASA plus a P2Y12 inhibitor) in case of myocardial infarction (6-12 months), or stroke (<6 weeks), followed by a single antiplatelet agent indefinitely. High risk for thrombosis patients (such as those with peripheral artery disease) benefit from a combination of an anticoagulant and ASA. The price of gained efficacy is always increased risk of (major) bleeding; while tailoring therapy to individual needs may limit the risks to some extent, new generations of agents that target less critical elements of hemostasis and coagulation mechanisms are needed to maintain efficacy while reducing bleeding risks.

Comparison of the Effects of Ticagrelor and Clopidogrel on Microvascular Dysfunction in Patients With Acute Coronary Syndrome Using Invasive Physiologic Indices

Background:

Ticagrelor reduced the rate of myocardial infarction and death compared with clopidogrel in patients with acute coronary syndrome. However, little is understood about chronic treatment of ticagrelor on microvascular dysfunction. The objective of this study was to assess the impact of ticagrelor maintenance treatment on microvascular system and coronary flow in comparison with clopidogrel.

Methods:

This study was a nonblinded, open-label, parallel-group, prospective, randomized controlled trial that enrolled 120 patients with acute coronary syndrome requiring stent implantation. Patients were randomized into the ticagrelor (180 mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300 to 600 mg loading dose, 75 mg daily thereafter) group. The primary end point was coronary microvascular dysfunction as measured by an index of microcirculatory resistance (IMR) at 6 months after treatment.

Results:

The baseline clinical characteristics and physiological parameters, such as fractional flow reserve, coronary flow reserve, and IMR, did not differ between the ticagrelor and clopidogrel groups. Six-month follow-up physiological data showed that the IMR value was significantly lower in the ticagrelor group than the clopidogrel group (15.57±5.65 versus 21.15±8.39, P <0.01), and coronary flow reserve was higher in the ticagrelor group than in the clopidogrel group (3.85±0.72 versus 3.37±0.76, P <0.01). However, there was no difference in fractional flow reserve (0.87±0.08 versus 0.87±0.09, P =0.94) between the 2 groups. The improvement in IMR after 6 months of treatment was higher in the ticagrelor group ( P <0.01). Analyses of 223 nonculprit vessels of registered patients based on physiological results showed no differences in baseline fractional flow reserve (0.93±0.13 versus 0.92±0.09, P =0.58), coronary flow reserve (3.62±1.27 versus 3.51±1.24, P =0.16), or IMR (21.37±12.37 versus 24.19±21.08, P =0.22) or in follow-up fractional flow reserve (0.91±0.09 versus 0.91±0.08, P =0.67), coronary flow reserve (3.91±1.22 versus 3.75±1.16, P =0.36), or IMR (19.43±10.32 versus 21.52±18.90, P =0.34) between the 2 groups.

Conclusions:

Compared with clopidogrel, 6 months of ticagrelor therapy significantly improved microvascular dysfunction in acute coronary syndrome patients with stent implantation.

Clinical Trial Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02618733.

Evaluation of Plasma Adenosine as a Marker of Cardiovascular Risk: Analytical and Biological Considerations

Background

Adenosine is a ubiquitous regulatory molecule known to modulate signaling in many cells and processes vital to vascular homeostasis. While studies of adenosine receptors have dominated research in the field, quantification of adenosine systemically and locally remains limited owing largely to technical restrictions. Given the potential clinical implications of adenosine biology, there is a need for adequately powered studies examining the role of plasma adenosine in vascular health. We sought to describe the analytical and biological factors that affect quantification of adenosine in humans in a large, real‐world cohort of patients undergoing evaluation for coronary artery disease.

Methods and Results

Between November 2016 and April 2018, we assessed 1141 patients undergoing angiography for evaluation of coronary artery disease. High‐performance liquid chromatography was used for quantification of plasma adenosine concentration, yielding an analytical coefficient of variance (CV_a) of 3.2%, intra‐subject variance (CV_i) 35.8% and inter‐subject variance (CV_g) 56.7%. Traditional cardiovascular risk factors, medications, and clinical presentation had no significant impact on adenosine levels. Conversely, increasing age (P=0.027) and the presence of obstructive coronary artery disease (P=0.026) were associated with lower adenosine levels. Adjusted multivariable analysis supported only age being inversely associated with adenosine levels (P=0.039).

Conclusions

Plasma adenosine is not significantly impacted by traditional cardiovascular risk factors; however, advancing age and presence of obstructive coronary artery disease may be associated with lower adenosine levels. The degree of intra‐ and inter‐subject variance of adenosine has important implications for biomarker use as a prognosticator of cardiovascular outcomes and as an end point in clinical studies.

DT-678 inhibits platelet activation with lower tendency for bleeding compared to existing P2Y12 antagonists

The novel clopidogrel conjugate, DT-678, is an effective inhibitor of platelets and thrombosis in preclinical studies. However, a comparison of the bleeding risk with DT-678 and currently approved P2Y12 antagonists has yet to be determined. The objective of this study was to evaluate the bleeding tendency of animals treated with clopidogrel, ticagrelor, and DT-678. Ninety-one New Zealand white rabbits were randomized to one of 13 treatment groups (n = 7). Platelet activation was assessed by flow cytometry and light transmission aggregometry before and after the administration of various doses of DT-678, clopidogrel, and ticagrelor. Tongue template bleeding times were also measured before and after drug treatment. Treatment with P2Y12 receptor antagonists caused a dose-dependent reduction in markers of platelet activation (P-selectin and integrin αIIbβ3) and aggregation in response to adenosine diphosphate stimulation. At the same doses required for platelet inhibition, clopidogrel and ticagrelor significantly prolonged bleeding times, while DT-678 did not. DT-678 and the FDA-approved P2Y12 antagonists clopidogrel and ticagrelor are effective inhibitors of platelet activation and aggregation. However, unlike clopidogrel and ticagrelor, DT-678 did not prolong bleeding times at equally effective antiplatelet doses. The results suggest a more favorable benefit/risk ratio for DT-678 and potential utility as part of a dual antiplatelet therapy regimen.

Effect of Ticagrelor Versus Clopidogrel on Aortic Stiffness in Patients With Coronary Artery Disease

Background

We compared the acute and midterm effect of ticagrelor versus clopidogrel on aortic stiffness.

Methods and Results

We studied 117 patients in a randomized, assessor‐blinded, parallel‐group trial. The acute effect of ticagrelor was studied in 58 patients randomized (1:1) to receive a loading dose of clopidogrel (600 mg) or ticagrelor (180 mg). Carotid‐femoral pulse wave velocity (cfPWV) was measured before, 3, and 24 hours after the loading dose. The midterm effect (30‐day treatment period) was studied in 59 subjects who underwent percutaneous coronary intervention and were randomized to either clopidogrel (75 mg, OD) or ticagrelor (90 mg BID). cfPWV was measured before and at 30 days of treatment. Circulating markers of inflammation and endothelial function were measured at all study points. Repeated‐measures analysis showed a significant main effect for treatment (P=0.03), with the ticagrelor showing a reduction in cfPWV after treatment. cfPWV at 24 hours was significantly lower in the ticagrelor group compared with the clopidogrel group (P=0.017) (maximal response reduction by 0.42±0.26 m/s). At 30 days, cfPWV decreased in the ticagrelor group, whereas there was no change with clopidogrel (−0.43±0.57 versus 0.12±0.14 m/s, P=0.004). There were no significant changes in both the acute and midterm study period in the pro‐inflammatory and endothelial function parameters.

Conclusions

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02071212. Ticagrelor decreases cfPWV for 24 hours after the loading dose and at 1 month post–percutaneous coronary intervention compared with clopidogrel. Considering that aortic stiffness is an independent predictor of cardiovascular events, this finding may have clinical implications regarding the beneficial effect of ticagrelor.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02071212.

Ticagrelor Does Not Improve Endothelial Dysfunction in Stable Survivors of Acute Coronary Syndrome

Background:

Ticagrelor is an intriguing antiplatelet agent with a potentially beneficial impact on endothelial dysfunction and confers a mortality benefit beyond 1 month after acute coronary syndrome (ACS). However, little data exist on whether ticagrelor improves endothelial dysfunction in stable patients who survive the acute period and receive guideline-directed medical therapy.

Methods and Results:

This study is a prospective, randomized, parallel, open-labeled study that enrolled 30-day survivors of non-ST-segment elevation ACS (NSTE-ACS). Forty patients with NSTE-ACS were randomly assigned to ticagrelor or clopidogrel groups. The primary end point was the change in the percentage brachial artery flow-mediated dilation (baFMD) from baseline. Baseline characteristics were not different between the 2 groups. The median time from the stent implantation to screening was 269 days. After 30 days of study medication administration, the change in the percentage baFMD value was similar between the ticagrelor and clopidogrel groups (−0.08 [1.42] vs 0.30 [1.69], P = .66). There was no difference in the change in high-sensitive C-reactive protein (−0.61 [1.48] vs −0.01 [0.57], P = .28); however, the change in platelet inhibition significantly differed (P2Y12 reaction units, −140.5 [49.5] vs −3.9 [51.4], P < .001).

Conclusions:

This dual time point baFMD study demonstrated that treatment with ticagrelor was not superior to clopidogrel for improving endothelial dysfunction in stabilized patients with NSTE-ACS.

Novel Antiplatelet Therapies for Atherothrombotic Diseases

Antiplatelet therapies are an essential tool to reduce the risk of developing clinically apparent atherothrombotic disease and are a mainstay in the therapy of patients who have established cardiovascular, cerebrovascular, and peripheral artery disease. Strategies to intensify antiplatelet regimens are limited by concomitant increases in clinically significant bleeding. The development of novel antiplatelet therapies targeting additional receptor and signaling pathways, with a focus on maintaining antiplatelet efficacy while preserving hemostasis, holds tremendous potential to improve outcomes among patients with atherothrombotic diseases.