Suspected Acute Coronary Syndrome

Initial Evaluation

• Suspect acute coronary syndrome (ACS) in patients presenting with typical symptoms of pressure-type chest pain originating in the retrosternal area with a duration of pain ≥ 10 minutes. Patients may present with a variety of symptoms.
• Refer patients with high-risk features (retrosternal chest pain/pressure, severe dyspnea, syncope/presyncope, or palpitations) immediately to the emergency department for evaluation of their symptoms (Strong recommendation).
• Perform the following tests as part of the initial evaluation
  • 12-lead electrocardiogram (ECG) within 10 minutes of patient arrival (Strong recommendation)
  • Cardiac troponin I or T at presentation (Strong recommendation)
  • If high sensitivity cardiac troponin test available use
    • rapid rule out protocol at 0 and 3 hours (Strong recommendation)
    • rapid rule out protocol at 0 and 1 hours if validated 0 hour/1 hour algorithm available (Strong recommendation)
    • repeat after 3-6 hours if first two tests are inconclusive (Strong recommendation)
  • If high sensitivity cardiac troponin not available, repeat cardiac troponin measurement 3-6 hours after symptom onset (Strong recommendation)
  • If patients present within 3 hours of symptom onset, repeat measurements at 3-6 hours after symptom onset.

Risk Stratification and Diagnosis

• Risk stratify patients (such as using GRACE, HEART or TIMI scores) with suspected acute coronary syndrome (ACS) (Strong recommendation).
  • Consider admission for all high-risk or intermediate-risk patients.
  • Consider observation for low-risk patients.
• A diagnosis of ST-elevation myocardial infarction (STEMI) is made by electrocardiogram (ECG).
  • Specific ECG criteria (in the absence of left ventricular hypertrophy or left bundle branch block [LBBB]) are a new ST elevation and either of:
    • ≥ 2 mm (0.2 millivolts [mV]) in men or ≥ 1.5 mm (0.15 mV) in women in leads V2-V3
    • ≥ 1 mm (0.1 mV) in 2 other contiguous chest leads or limb leads
  • See ST-elevation myocardial infarction (STEMI) for details on the management of these patients.
• A diagnosis of non-ST-elevation acute coronary syndrome (non-STE ACS) is made using multiple clinical criteria.
  • These include the absence of ECG criteria for STEMI and at least 1 of the following:
    • typical symptoms of ischemia
    • cardiac biomarkers (preferably cardiac troponin) have ≥ 1 value > 99th percentile of upper reference limit - if so, this is also called non-ST-elevation myocardial infarction (NSTEMI)
    • ECG shows new or presumed-new significant, or dynamic ST-segment T-wave changes, new LBBB, or pathological Q waves
    • imaging evidence of new loss of viable myocardium or new regional wall motion abnormality
    • identification of intracoronary thrombus by angiography or autopsy
  • See Acute coronary syndromes for details on the management of these patients.

Initial Management

All Patients With Suspected ACS

• Give aspirin 162-325 mg (chewed) to patients with suspected acute coronary syndrome (ACS) as soon as possible (Strong recommendation).
• If the patient is unable to take aspirin, give ticagrelor or clopidogrel (Strong recommendation).
• Give supplemental oxygen to patients with ACS only for arterial saturation < 90% and/or respiratory distress (Strong recommendation).

High- or Intermediate-risk Patients With Suspected ACS

• Give sublingual nitroglycerin 0.3-0.4 mg every 5 minutes for a total of 3 doses as needed for resolution of ischemic symptoms and then assess need for IV nitroglycerin (Strong recommendation).
• Use IV nitroglycerin in first 48 hours for patients with unstable angina/non-ST-elevation myocardial infarction for treatment of persistent ischemia, heart failure, or hypertension (Strong recommendation).
• Do not give nitrates (Strong recommendation)
  • if the patient has used a phosphodiesterase inhibitor for erectile dysfunction within 24 hours (sildenafil) or 48 hours (tadalafil)
  • if systolic blood pressure is < 90 mm Hg or ≥ 30 mm Hg below baseline, severe bradycardia (< 50 beats/minute), tachycardia (> 100 beats/minute) in absence of symptomatic heart failure, or right ventricular infarction
• Consider morphine sulfate IV if patient has ischemic chest discomfort despite treatment with maximally tolerated anti-ischemic medications (Weak recommendation).
• Add anticoagulant therapy (unfractionated heparin, enoxaparin, bivalirudin, or fondaparinux) to antiplatelet therapy as soon as possible after presentation for patients with highly likely or definite ACS (Strong recommendation).
• Add ticagrelor or clopidogrel (loading dose followed by daily maintenance dose) to aspirin and anticoagulant therapy as soon as possible after admission for patients with highly likely or definite ACS (Strong recommendation).

Low-risk Patients With Suspected ACS

• Consider observation in chest pain unit or telemetry unit with serial electrocardiogram (ECG) and cardiac troponin measurements at 3- to 6-hour intervals for symptomatic patients with normal initial ECG and cardiac troponin levels (Weak recommendation).
• Consider discharge of low-risk patients with referral for outpatient testing (Weak recommendation).