Stent thrombosis in a patient with high on-treatment platelet reactivity despite ticagrelor treatment

We describe, to the best of our knowledge, the first incidence of stent thrombosis in a patient treated with ticagrelor, who exhibited high on-treatment platelet reactivity (HTPR) according to platelet reactivity testing. He was on clopidrogel and tested for platelet reactivity using the VerifyNow P2Y12 assay. The test showed a PRU of 249 and only 12% platelet inhibition. The patient was then switched to ticagrelor, with a loading dose of 180 mg given. The patient had stent thrombosis three weeks later with an acute myocardial infarction (MI). The patient had good platelet inhibition when started on Ticagrelor treatment (PRU=33), but had HTPR when the stent thrombosis occurred three weeks later (PRU=339).