The ESC NSTEMI and STEMI guidelines
1,2 and an ACCF/ACG/AHA consensus document
3 recommend treatment with proton pump inhibitors (PPIs) in patients treated with dual antiplatelet treatment (DAPT) during the initial phase of an acute coronary syndrome (ACS) (ESC Class 1A recommendation), particularly in patients with a history of GI bleeding or peptic ulcer. Several studies have raised concerns that many PPIs, especially omeprazole, might diminish the antiplatelet effects of clopidogrel, most likely through inhibition of CYP2C19 and, consequently, the conversion of clopidogrel into its active metabolite.
4,5