There are several competing theories about whether (and how) PPIs enhance the risk of major adverse cardiovascular events (MACE) amongst individuals with a history of ACS.[5–10] A leading hypothesis is that PPIs compete for and inhibit the clopidogrel-activating hepatic isoenzyme, CYP2C19, thereby interfering with clopidogrel’s capacity to prevent clot formation in subjects at risk for coronary thrombosis and myocardial infarction (MI).[11]. Here, CYP2C19 is linked to myocardial infarction.