The association between clopidogrel and 2-oxo-clopidogrel plasma levels and the long-term clinical outcome after acute myocardial infarction

Background and objectives: A significant number of ischemic events occur after acute myocardial infarction (MI), even when adhering to dual antiplatelet therapy including aspirin and clopidogrel. The aim of our study was to investigate the association between the concentration of the pro-drug clopidogrel and its intermediary metabolite 2-oxo-clopidogrel plasma as well as demographic and clinical factors, and the long-term clinical outcome in patients with their first acute MI, ST-elevation myocardial infarction (STEMI) or non-ST-elevation myocardial infarction NSTEMI, treated with percutaneous coronary intervention (PCI). Materials and methods: This study included 172 consecutive patients with their first acute MI, 88 STEMI, and 84 NSTEMI, treated with Pa On the third day of hospitalization, blood samples were collected from each patient to measure the concentration of clopidogrel and its metabolite 2-oxo-clopidogrel using the UHPLC-DAD-MS method. The following clinical outcomes were registered during the 28-month follow-up: mortality from cardiovascular causes, nonfatal MI, nonfatal stroke, and hospitalization for urgent myocardial revascularization or heart failure. Results: Lower dose-adjusted clopidogrel concentrations (p < 0.05) were measured in NSTEMI patients with a composite of the hard clinical endpoint events of cardiovascular mortality, non-fatal MI, or a nonfatal stroke. During the follow-up, there was a 3.4 times higher risk of hard clinical endpoint events (p < 0.05) for each unit decrement of the dose-adjusted clopidogrel plasma concentration. Lower dose-adjusted concentrations of clopidogrel in these patients were associated with lower left ventricular ejection fraction (p < 0.001), and fentanyl (p < 0.001) and pantoprazole administration (p < 0.01) during the acute phase of MI. Conclusion: In patients with acute MI treated with PCI, lower dose-adjusted clopidogrel and dose-adjusted 2-oxo-clopidogrel plasma concentrations were associated with an increased risk of ischemic events.