MPO and myocardial infarction: Brennan and colleagues (10) evaluated 604 consecutive patients presenting with chest pain to the emergency department and found that for all patients, increasing quartiles of MPO carried increased risk (4th quartile OR 4.7) of major adverse cardiac events (myocardial infarction, re-infarction, revascularization, and death) at 30 days and 6 months.