Platelet reactivity evaluated with the VASP assay following ticagrelor loading dose in acute coronary syndrome patients undergoing percutaneous coronary intervention

Abstract

Background: The level of platelet reactivity (PR) inhibition obtained after P2Y12-ADP receptor antagonist loading dose (LD) is associated with the ischemic and bleeding risk following percutaneous coronary intervention (PCI) in acute coronary syndromes (ACS).

Objective: We aimed to evaluate the level of PR inhibition achieved by a 180 mg LD of ticagrelor and the rate of high on-treatment platelet reactivity (HTPR) in ACS patients undergoing PCI.

Methods: We performed a multicentre prospective observational study enrolling ACS patients undergoing PCI. Patients were included if they were admitted for ST-elevation myocardial infarction or non ST-elevation ACS. To assess PR, a VASP index was measured at least 6 and within 24 hours following a 180 mg LD of ticagrelor. HTPR was defined as a VASP index ≥50%.

Results: One hundred and fifteen patients were included: 31.3% of STEMI, 49.6% of NSTEMI and 19.1% of unstable angina. Following ticagrelor LD the mean VASP index was 17±14%. However the response to ticagrelor was not uniform with a small inter-individual variability: inter quartile range: 7.6-22.8% and a rate of HTPR of 3.5%. A high number of patients, 65.6%, had a VASP index <16%. None of the baseline characteristics of the study population was associated with PR. In addition, PR was similar in STEMI, NSTEMI and unstable angina (p=0.9).

Conclusion: In ACS patients the level of PR inhibition achieved by a 180 mg loading dose of ticagrelor is not uniform and the rate of HTPR is 3.5%. A high proportion of patients exhibited a VASP index <16%.

Keywords: ACS; Acute coronary syndromes; HTPR; LD; LTPR; NSTEMI; On-treatment platelet reactivity; P2Y12-ADP receptor antagonist; PCI; PR; ST segment elevation myocardial infarction; STEMI; Ticagrelor; VASP; VASP index; Vasodilator-stimulated phosphoprotein; acute coronary syndrome; high on-treatment platelet reactivity; loading dose; low on-treatment platelet reactivity; non ST segment elevation myocardial infarction; percutaneous coronary intervention; platelet reactivity.