KEY WORDS: AHA Scientific Statements acute myocardial infarction non ST-elevation myocardial infarction performance measures quality indicators quality measures ST-elevation myocardial infarction 16 Appendix A. STEMI and NSTEMI Performance Measures Performance Measures for Use in Patients With Inpatient STEMI and NSTEMI Inpatient Measures Short Title: PM-1: Aspirin at Arrival PM-1: AMI: Aspirin Received at Arrival Measure Description: Percentage of patients, age 18 y, hospitalized with AMI who received aspirin within 24 h before or after hospital arrival. Numerator Patients with AMI who have received aspirin within 24 h before or after hospital arrival Denominator All patients with AMI Denominator Exclusions Patients age <18 y Patients who leave against medical advice on day of or day after arrival Patients who die during hospitalization on day of or day after arrival Patients who are on comfort measures/hospice only documented on day of or day after arrival Patients who are transferred to another hospital for inpatient care on day of or day after arrival Patients received in transfer from the inpatient, outpatient, or ED of another facility Patients discharged on day of or day after arrival Denominator Exceptions Documentation of a medical reason for not prescribing aspirin at arrival (eg, aspirin allergy or intolerance, oral anticoagulant therapy as prearrival medication, active bleeding) Patient currently enrolled in a clinical trial precluding the use of aspirin in its protocol (eg, trials of triple versus dual therapy in atrial fibrillation patients) Measurement Period Encounter Sources of Data Medical record or other database (eg, administrative, clinical, registry) Attribution Measure reportable at the facility or provider level Care Setting Inpatient Rationale Coronary heart disease with atherosclerotic plaque disruption (eg, rupture, erosion, ulceration) and superimposed platelet-rich thrombus formation are the main pathophysiological mechanisms causing MI (type 1 or spontaneous MI). 