• Pain:
  • Pressure, tightness, or heaviness
  • Substernal, epigastric
  • +/− radiation to arm, jaw, back
  • More likely nonpositional, nonpleuritic, nonreproducible on palpation
• Nausea, vomiting
• Diaphoresis
• Cough
• Dyspnea
• Anxiety
• Lightheadedness
• Syncope
• Recent cocaine or amphetamine use
• Family history of coronary disease
• Atypical presentations common, especially in women, diabetics, and the elderly

• Pallor or diaphoresis
• Hypertension or hypotension
• Arrhythmias
• S4 gallop
• Physical exam is often normal

• Cardiac markers:
  • Troponins: Specific indicators of myocardial infarction, rise within 2-4 hr after MI, peak at 1-2 d, and return to normal in about 10 d
  • Creatine kinase (CK): Rises within 3-4 hr, peaks at 18-24 hr, subsides at 3-4 d; isoenzyme CK-MB more specific for cardiac origin
  • Myoglobin: Rises within 1-6 hr, returns to baseline within 24 hr, highly sensitive but very nonspecific
  • LDH: Rises within 24 hr, peaks at 3-6 d, returns to baseline at 8-12 d
• CBC
• Serum electrolytes including magnesium
• PT/PTT/INR for patients on warfarin
• NT-proBNP: Higher levels correlate with increased mortality in NSTEMI patients

• ECG:
  • ST-segment depression or transient elevation indicates increased risk.
  • T-wave inversion in regional patterns does not increase risk but helps differentiate cardiac pain from noncardiac pain.
  • Deep (>2 mm) precordial T-wave inversion suggests cardiac ischemia.
• CXR:
  • To assess heart size, pulmonary edema/congestion, or identify other causes of chest pain
• Echo (often not part of ED evaluation):
  • To identify wall motion abnormalities and assess ventricular function
• Radionuclide studies (if conservative management; often not part of ED evaluation):
  • Sestamibi scan: Identify viable myocardium
  • Technetium 99: Identify recently infarcted myocardium

Coronary angiography (+/− PCI), typically as an inpatient, depending on patient's risk profile and comorbidities

• Aspirin 162-325 mg PO per day
• β-Blockers:
  • Atenolol: Start 5 mg IV over 5 min, then 5 mg IV 10 min later, then 50-100 mg PO per day (1-2 hr after IV doses)
  • Esmolol: 100 mcg/kg/min IV infusion (titrate by increasing 50 mcg/kg/min q15min until effect—to max. dose 300 mcg/kg/min)
  • Metoprolol: Start 5 mg IV q5min × 3, after 15 min begin 25-50 mg PO BID
  • Propranolol: 0.5-1 mg IV then 40-80 mg PO q6-8h
• Clopidogrel: 300-600 mg PO × 1, then 75 mg/d
• Heparins:
  • Enoxaparin: 1 mg/kg SC q12h, can give 30-mg IV bolus before SC dose (caution in patients with renal dysfunction) or
  • Unfractionated heparin: 60-U/kg IV bolus then 12-U/kg/hr infusion (max. bolus 4,000 units, max. infusion rate 1,000 U/hr) (goal is a PTT 50-75 s)
• Morphine sulfate: 1-5 mg IV q5-30min PRN pain
• Nitroglycerin: 0.3-0.6 mg SL or 0.4 mg by spray q5min followed by IV infusion beginning at 10-20 mcg/min if pain persists (max. dose 200 mcg/min)
• GP IIb/IIIa inhibitors:
  • Eptifibatide: 180-mcg/kg IV bolus then 2-mcg/kg/min infusion for 72-96 hr
  • Tirofiban: 0.4 mcg/kg/min IV × 30 min, then 0.1 mcg/kg/min infusion for 12-24 hr

• Calcium channel blockers:
  • Diltiazem: Start 0.25-mg/kg IV bolus, then 0.35 mg/kg IV after 15 min if needed then 30 mg PO q6h: immediate release
  • Verapamil: Start 5-10 mg IV, repeat after 30 min if needed, then 80-160 mg PO q8h: immediate release
• ADP blocker:
  • Ticagrelor: 180 mg PO × 1 at time of PCI or no later than 1 hr post-PCI, then 90 mg PO BID
  • Prasugrel: 60 mg PO × 1 at time of PCI or no later than 1 hr post-PCI, then 10 mg/d
• Lorazepam: 1-2 mg IV PRN anxiety
• Anticoagulation (instead of unfractionated heparin or enoxaparin):
  • Fondaparinux: 2.5 mg SC once a day or
  • Bivalirudin (only prior to PCI): 0.75-mg/kg IV bolus, then 1.75 mg/kg/hr IV for up to 4 hr, then 0.2 mg/kg/hr IV for up to 20 hr

• All patients with positive cardiac biomarkers, high risk for adverse outcomes by clinical prediction rules (TIMI, GRACE, PURSUIT, HEART), or significant clinical probability of acute coronary syndrome undergoing consideration for urgent or early invasive management 12-24 hr after presentation
• Intensive care unit for monitoring unstable patients.

Only those who are ruled out for acute coronary syndrome/non-Q-wave infarction can be safely sent home.