Antiplatelet efficacy of ticagrelor versus clopidogrel in Mediterranean patients with diabetes mellitus and chronic coronary syndromes: A crossover pharmacodynamic investigation

Introduction

Patients with diabetes mellitus (DM) have augmented platelet reactivity and diminished responsiveness to clopidogrel. Ticagrelor, a more potent P2Y12 inhibitor, is clinically superior to clopidogrel in acute coronary syndromes, although its role in chronic coronary syndromes (CCS) is still the subject of debate. The aim of this investigation was to compare the pharmacodynamic effectiveness of ticagrelor and clopidogrel in Mediterranean DM patients with CCS.

Materials and methods

In this prospective, randomized, crossover study, patients (n = 20) were randomized (1:1) to receive, on top of aspirin therapy, either ticagrelor 180 mg loading dose (LD)/90 mg maintenance dose (MD) b.i.d. or clopidogrel 600 mg LD/75 mg MD o.d. for 1 week in a crossover fashion with a 2–4 week washout period between regimens. Platelet function measurements were performed at 4 timepoints in each period (baseline, 2 h and 24 h after LD, and 1 week), including light transmission aggregometry (LTA, primary endpoint), VASP assay, Multiplate and VerifyNow P2Y12.

Results

The ticagrelor LD achieved greater platelet inhibitory effect than clopidogrel LD, assessed with LTA (20 μM ADP as agonist), at 2 h (34.9 ± 3.9% vs. 63.6 ± 3.9%; p < 0.001) and 24 h (39.4 ± 3.5% vs. 52.3 ± 3.8%; p = 0.014). After 1 week of therapy, platelet reactivity was again significantly inferior with ticagrelor compared to clopidogrel (30.7 ± 3.0% vs. 54.3 ± 3.0%; p < 0.001). The results were consistent with the other platelet function assays employed.

Conclusion

In Mediterranean patients with DM and CCS, ticagrelor provides a more potent antiplatelet effect than clopidogrel after the LD and during the maintenance phase of therapy.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT02457130].

Impact of COVID-19 disease on platelet reactivity and association with inflammatory parameters

Background

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the coronavirus disease 2019 (COVID-19) pandemic. Aside from the pulmonary manifestations, COVID-19 is associated with increased risk of venous and arterial thrombotic complications. The actual impact of SARS-CoV-2 infection on platelet reactivity and whether this is mediated by a hyperinflammatory status has not been fully elucidated to date.

Objective

To evaluate platelet reactivity in COVID-19 patients compared to healthy subjects and to assess the association between platelet reactivity and levels of inflammatory biomarkers among COVID-19 patients.

Methods

This prospective observational investigation included COVID-19 patients admitted into a tertiary care hospital and adult healthy volunteers, all of them not receiving any antiplatelet therapy. Subjects were classified in three groups: 1) Healthy subjects (HS group); 2) COVID-19 patients in a pulmonary phase (viral pneumonia and bilateral infiltrates) but without meeting criteria for systemic hyperinflammation (C19-Pulm group); and 3) COVID-19 patients in a hyperinflammation phase (C19-Infl group) meeting at least 2 of the following criteria: CRP>100mg/l, D-dimer >1000mcg/l, LDH>400U/l, ferritin>1000ng/ml, IL-6>70ng/l. Blood samples for platelet function testing and quantification of inflammatory parkers were collected at a single visit. Platelet function was measured with multiple electrode aggregometry using ADP (MEA-ADP, primary endpoint), arachidonic acid (AA) and thrombin receptor activating peptide (TRAP) as stimuli. Unadjusted analyses are presented.

Results

A total of 60 patients were included in the present investigation (20 in each group). A significantly greater platelet reactivity, measured with MEA-ADP, was observed in both groups of COVID-patients compared to healthy subjects (HS: 634,9±53,5, C19-Pulm: 919,9±53,5 and C19-Infl: 931,6±53,5 AU*min; p for C19-Pulm vs. HS <0,001, p for C19-Infl vs. HS <0,001, p for C19-Pulm vs. C19-Infl 0,878; Figure 1). Parallel findings were found when using AA as stimulus for platelet aggregation showing greater platelet aggregation in COVID-19 patients compared to healthy subjects, but numerical differences were not statistically significant when using TRAP. Among COVID-19 patients, when stratified by IL-6 levels splitted into tertiles, greater platelet reactivity was observed in patients with higher IL-6 concentrations (mid and upper tertile together) compared to those with values in the lower tertile, as assessed with MEA-ADP (lower tertile: 829,0±75,8, mid and upper tertile: 1028,7±56,2; p=0,043); a similar trend was observed with AA and TRAP as stimuli.

Conclusion

Patients with severe COVID-19 disease have greater platelet reactivity than healthy subjects. Increased IL-6 levels might be associated with the observed heightened platelet reactivity among COVID-19 patients.

Funding Acknowledgement

Type of funding sources: None.

Neurohormonal activation induces intracellular iron deficiency and mitochondrial dysfunction in cardiac cells

Background

Iron deficiency (ID) is common in patients with heart failure (HF) and is associated with poor outcomes, yet its role in the pathophysiology of HF is not well-defined. We sought to determine the consequences of HF neurohormonal activation in iron homeostasis and mitochondrial function in cardiac cells.

Methods

HF was induced in C57BL/6 mice by using isoproterenol osmotic pumps and embryonic rat heart-derived H9c2 cells were subsequently challenged with Angiotensin II and/or Norepinephrine. The expression of several genes and proteins related to intracellular iron metabolism were assessed by Real time-PCR and immunoblotting, respectively. The intracellular iron levels were also determined. Mitochondrial function was analyzed by studying the mitochondrial membrane potential, the accumulation of radical oxygen species (ROS) and the adenosine triphosphate (ATP) production.

Results

Hearts from isoproterenol-stimulated mice showed a decreased in both mRNA and protein levels of iron regulatory proteins, transferrin receptor 1, ferroportin 1 and hepcidin compared to control mice. Furthermore, mitoferrin 2 and mitochondrial ferritin were also downregulated in the hearts from HF mice. Similar data regarding these key iron regulatory molecules were found in the H9c2 cells challenged with neurohormonal stimuli. Accordingly, a depletion of intracellular iron levels was found in the stimulated cells compared to non-stimulated cells, as well as in the hearts from the isoproterenol-induced HF mice. Finally, neurohormonal activation impaired mitochondrial function as indicated by the accumulation of ROS, the impaired mitochondrial membrane potential and the decrease in the ATP levels in the cardiac cells.

Conclusions

HF characteristic neurohormonal activation induced changes in the regulation of key molecules involved in iron homeostasis, reduced intracellular iron levels and impaired mitochondrial function. The current results suggest that iron could be involved in the pathophysiology of HF.

Association of fractalkine with functional severity of heart failure and impact on clopidogrel efficacy in patients with ischemic heart disease

INTRODUCTION

Patients with heart failure (HF) display elevated levels of soluble fractalkine, a chemokine involved in inflammation processes, atherosclerosis and platelet activation. Further, fractalkine has been associated with reduced pharmacodynamic (PD) responsiveness to clopidogrel. The aim of this study was to investigate the association of fractalkine with the severity of HF and its impact on platelet activation and clopidogrel response in patients with coronary artery disease (CAD) with and without HF.

MATERIALS AND METHODS

This prospective PD study included 116 stable CAD patients on DAPT with aspirin and clopidogrel. Subjects were classified in two groups: patients with HF and reduced (<40%) left ventricular ejection fraction (HFrEF group, n = 56) and patients without HF (no HF group, n = 60). Clinical severity of HF was graded according to NYHA classification. Platelet function assays included vasodilator-stimulated phosphoprotein assay, multiple electrode aggregometry and light transmittance aggregometry. Fractalkine and P-selectin concentrations were determined by ELISA.

RESULTS

Fractalkine levels progressively increased with the severity of the disease in the HFrEF group (NYHA I: 471.2 ± 52.4 pg/ml, NYHA II: 500.5 ± 38.4 pg/ml, NYHA III: 638.9 ± 54.3 pg/ml, p for linear trend 0.023). Numerically higher concentrations of fractalkine were observed in the HFrEF group compared to the no HF group with borderline significance (p = 0.052). No significant differences in clopidogrel-induced platelet inhibition according to fractalkine values were observed in any of the groups.

CONCLUSIONS

Fractalkine levels were increased in patients with HFrEF and positively associated with the functional severity of the disease. No evident impact of fractalkine on clopidogrel PD efficacy was found.

Impact of mild hypothermia on platelet responsiveness to aspirin and clopidogrel: an in vitro pharmacodynamic investigation

The combination of percutaneous coronary intervention (PCI) and therapeutic hypothermia in comatose patients after cardiac arrest due to an acute coronary syndrome has been reported to be safe and effective. However, recent investigations suggest that hypothermia may be associated with impaired response to clopidogrel and greater risk of thrombotic complications after PCI. This investigation aimed to evaluate the effect of hypothermia on the pharmacodynamic response of aspirin and clopidogrel in patients (n = 20) with ST elevation myocardial infarction undergoing primary PCI. Higher platelet reactivity (ADP stimulus) was observed in samples incubated at 33 °C compared with those at 37 °C (multiple electrode aggregometry, 235.2 ± 31.4 AU×min vs. 181.9 ± 30.2 AU×min, p < 0.001; VerifyNow P2Y12, 172.9 ± 20.3 PRU vs. 151.0 ± 19.3 PRU, p = 0.004). Numerically greater rates of clopidogrel poor responsiveness were also observed at 33 °C. No differences were seen in aspirin responsiveness. In conclusion, mild hypothermia was associated with reduced clopidogrel-mediated platelet inhibition with no impact on aspirin effects.

CLINICAL RELEVANCE

Mild therapeutic hypothermia is associated with impaired response to clopidogrel therapy, which might contribute to increase the risk of thrombotic events in ACS comatose patients undergoing PCI.