Randomized controlled trial protocol to investigate the antiplatelet therapy effect on extracellular vesicles (AFFECT EV) in acute myocardial infarction

Abstract

Activated platelets contribute to thrombosis and inflammation by the release of extracellular vesicles (EVs) exposing P-selectin, phosphatidylserine (PS) and fibrinogen. P2Y12 receptor antagonists are routinely administered to inhibit platelet activation in patients after acute myocardial infarction (AMI), being a combined antithrombotic and anti-inflammatory therapy. The more potent P2Y12 antagonist ticagrelor improves cardiovascular outcome in patients after AMI compared to the less potent clopidogrel, suggesting that greater inhibition of platelet aggregation is associated with better prognosis. The effect of ticagrelor and clopidogrel on the release of EVs from platelets and other P2Y12-exposing cells is unknown. This study compares the effects of ticagrelor and clopidogrel on (1) the concentrations of EVs from activated platelets (primary end point), (2) the concentrations of EVs exposing fibrinogen, exposing PS, from leukocytes and from endothelial cells (secondary end points) and (3) the procoagulant activity of plasma EVs (tertiary end points) in 60 consecutive AMI patients. After the percutaneous coronary intervention, patients will be randomized to antiplatelet therapy with ticagrelor (study group) or clopidogrel (control group). Blood will be collected from patients at randomization, 48 hours after randomization and 6 months following the index hospitalization. In addition, 30 age- and gender-matched healthy volunteers will be enrolled in the study to investigate the physiological concentrations and procoagulant activity of EVs using recently standardized protocols and EV-dedicated flow cytometry. Concentrations of EVs will be determined by flow cytometry. Procoagulant activity of EVs will be determined by fibrin generation test. The compliance and response to antiplatelet therapy will be assessed by impedance aggregometry. We expect that plasma from patients treated with ticagrelor (1) contains lower concentrations of EVs from activated platelets, exposing fibrinogen, exposing PS, from leukocytes and from endothelial cells and (2) has lower procoagulant activity, when compared to patients treated with clopidogrel. Antiplatelet therapy effect on EVs may identify a new mechanism of action of ticagrelor, as well as create a basis for future studies to investigate whether lower EV concentrations are associated with improved clinical outcomes in patients treated with P2Y12 antagonists.

Keywords:

• ADP receptors
• extracellular vesicles
• P2Y12 antagonists
• platelets
• ticagrelor

Acknowledgments

A. Gasecka and K.J. Filipiak acknowledge AstraZeneca/MedImmune for Externally Sponsored Scientific Research Grant in a form of ticagrelor for the study. E. van der Pol acknowledges funding from the Netherlands Organisation for Scientific Research – Domain Applied and Engineering Sciences (NWO-TTW), research program VENI 15924.

Declaration of interest

E. van der Pol is a cofounder and shareholder of Exometry BV. All other authors report no declarations of interest.

Additional information

Funding

The study is funded by Medical University of Warsaw (1WR\PM2\18). The sponsor is not involved in any procedure related with the protocol nor in the dissemination of the data. E. van der Pol is funded by the Netherlands Organisation for Scientific Research – Domain Applied and Engineering Sciences (NWO-TTW), research program VENI 15924.