Selection of P2Y12 antagonist, treatment initiation, and predictors of high on-treatment platelet reactivity in a “Real World” registry

- The availability of three P2Y12 antagonists creates the option for individualizing therapy.
- Selection of P2Y12 antagonists reflects strengths and limitations of the new agents.
- Safety is the most important aspect in choosing new agents for an individual patient.
- Pretreatment was rare in an institution with a short time to coronary angiography.
- Platelet characteristics are related to high residual reactivity after new agents.

ObjectiveThe present study aimed to compare characteristics related to selection of a P2Y12 antagonist, investigate initiation of therapy with new-generation drugs, and identify predictors of high on-treatment platelet reactivity (HTPR) in patients with acute coronary syndrome treated with stent percutaneous coronary intervention (PCI).Methods and ResultsData from 589 patients in the LAPCOR (Laboratory AntiPlatelet efficacy and Clinical Outcome Registry; ClinicalTrials.gov Identifier: NCT02264912) registry was analyzed. P2Y12 receptor antagonist efficacy was measured by VASP phosphorylation 24 ± 4 hours after a loading dose of clopidogrel (600 mg, N = 407), prasugrel (60 mg, N = 106), or ticagrelor (180 mg, N = 76) and expressed by platelet reactivity index (PRI). HTPR was defined as PRI ≥ 50%. Patients treated with prasugrel were significantly younger and had significantly higher hemoglobin levels than those who received clopidogrel or ticagrelor, while chronic kidney disease was significantly more prevalent in the ticagrelor group. Almost all invasively managed patients given new-generation drugs received a loading dose after coronary angiography. Mean residual PRI and HTPR were significantly higher after clopidogrel (44.2 ± 23.1% and 42.2%, respectively) vs. prasugrel (17.7 ± 18.0% and 9.4%, respectively) or ticagrelor (18.8 ± 17.0% and 7.9%, respectively; all p < 0.001). Among multiple variables tested, HTPR in patients treated with the new agents significantly related only to platelet count (p = 0.014) and mean platelet volume (p = 0.03).ConclusionSafety is the most important aspect under consideration in choosing new agents for an individual patient. Other than platelet count and mean platelet volume, factors known as predictors of higher platelet reactivity, did not influence the efficacy of new-generation P2Y12 receptor antagonists.