- Adult patients admitted to cardiac units at MGH with a primary admission diagnosis of ACS (eligible patients must meet World Health Organization criteria for myocardial infarction or criteria for unstable angina [new-onset angina within 2 months, exacerbation of previous angina with rest pain or with minimal exercise, or angina within 2 weeks of MI]). ACS diagnosis will be clarified with the inpatient care team and adjudicated by co-investigator cardiologist Dr. Januzzi as needed.