Ticagrelor induces more potent platelet reactivity (PR) inhibition with reduced interindividual variability compared to clopidogrel. Although on-clopidogrel PR was shown to correlate with ischemia and bleeding events, data regarding PR from ticagrelor and the outcomes are lacking.

We aimed to determine the association between PR after a ticagrelor loading dose (LD), assessed by the vasodilator-stimulated phosphoprotein index (VASP), and thrombotic and bleeding events in patients with acute coronary syndrome (ACS) treated by percutaneous coronary intervention (PCI).

We performed a prospective, multicenter observational study on patients treated with PCI for ACS. The VASP index was used to assess PR after ticagrelor LD. The primary endpoint was the link between major adverse cardiovascular events (MACE) and PR.

Among the included 530patients with ACS, 185 (34.5%) were admitted for ST elevation myocardial infarction. We observed high potency and limited interindividual variability after the ticagrelor LD (VASP 19.1±16.6%). At 1month, 21 (3.8%) MACE and 29 (5.5%) bleedings Academic Research Consortium≥2events were recorded. Neither MACE nor bleeding were associated with PR (P=0.34and p=0.78 respectively). However, there was a strong association between PR and the occurrence of definite acute stent thrombosis (P=0.03). PR was the only factor associated with acute definite stent thrombosis.

In patients receiving a ticagrelor LD while undergoing PCI for ACS, PR using the VASP does not predict MACE or bleeding, but it is significantly associated with the occurrence of definite acute ST.