Scope of Application
This guideline is intended for physicians working in EDs or chest pain evaluation units.

Inclusion Criteria
This guideline is intended for adult patients (>18 years) presenting to the emergency department with undifferentiated chest pain or other complaints or conditions that are suspicious for non–ST-elevation acute coronary syndromes.

Exclusion Criteria 
This guideline is not intended for pediatric patients or adults who receive a diagnosis of non–ST-elevation acute coronary syndrome incidentally. For example, atypical presentations of an acute coronary syndrome such as individuals presenting with only dyspnea or with an alteration in mental status, are generally excluded from the scope of this work. Also, myocardial infarction (ie, ST-elevation acute coronary syndrome) diagnosed on arrival to the emergency department is excluded.

Critical Questions

1. In adult patients without evidence of ST-elevation acute coronary syndrome, can initial risk stratification be used to predict a low rate of 30-day major adverse cardiac events?
   
   Level B Recommendations:
   
   In adult patients without evidence of ST-elevation acute coronary syndrome, the History, ECG, Age, Risk factors, Troponin (HEART) score can be used as a clinical prediction instrument for risk stratification. A low score (≤3) predicts a 30-day major adverse cardiac event miss rate within a range of 0% to 2%.
   
   Level C Recommendations:
   
   In adult patients without evidence of ST-elevation acute coronary syndrome, other risk-stratification tools, such as Thrombolysis in Myocardial Infarction (TIMI), can be used to predict a rate of a 30-day major adverse cardiac event.
   
   
   
2. In adult patients with suspected acute non–ST-elevation acute coronary syndromes, can troponin testing within 3 hours of emergency department presentation be used to predict a low rate of 30-day major adverse cardiac events?
   
   Level C Recommendations:
   
   (1) In adult patients with suspected acute non–ST-elevation acute coronary syndrome, conventional troponin testing at 0 and 3 hours among low-risk acute coronary syndrome patients (defined by HEART score 0 to 3) can predict an acceptable low rate of 30-day major adverse cardiac events.
   
   (2) A single high-sensitivity troponin result below the level of detection on arrival to the emergency department, or a negative serial high-sensitivity troponin result at 0 and 2 hours is predictive of a low rate of major adverse cardiac events.
   
   (3) In adult patients with suspected acute non–ST-elevation acute coronary syndrome who are determined to be low risk based on validated accelerated diagnostic pathways that include a nonischemic ECG result and negative serial high-sensitivity troponin testing results both at presentation and at 2 hours can predict a low rate of 30-day major adverse cardiac events allowing for an accelerated discharge pathway from the emergency department.
   
   
   
3. In adult patients with suspected acute non–ST-elevation acute coronary syndromes in whom acute myocardial infarction has been excluded, does further diagnostic testing (eg, provocative, stress test, computed tomography [CT] angiography) for acute coronary syndrome prior to discharge reduce 30-day major adverse cardiac events?
   
   Level B Recommendations:
   
   Do not routinely use further diagnostic testing (coronary CT angiography, stress testing, myocardial perfusion imaging) prior to discharge in low-risk patients in whom acute myocardial infarction has been ruled out to reduce 30-day major adverse cardiac events.
   
   Level C Recommendations:
   
   Arrange follow-up in 1 to 2 weeks for low-risk patients in whom myocardial infarction has been ruled out. If no follow-up is available, consider further testing or observation prior to discharge (Consensus recommendation).
   
   
   
4. Should adult patients with acute non–ST-elevation myocardial infarction receive immediate antiplatelet therapy in addition to aspirin to reduce 30-day major adverse cardiac events?
   
   Level C Recommendations:
   
   P2Y12 inhibitors and glycoprotein IIb/IIIa inhibitors may be given in the emergency department or delayed until cardiac catheterization.

Disclaimer
Recommendations offered in this policy are not intended to represent the only diagnostic and management options that the emergency physician should consider. ACEP recognizes the importance of the individual physician's judgment and patient preferences.