Acute Coronary Syndrome: Angina



  • Chest discomfort, from imbalance of myocardial blood supply and oxygen requirements
  • Canadian Cardiovascular Society classification for angina:
    • Class I: No angina with ordinary physical activity
    • Class II: Slight limitation of normal activity as angina occurs when walking, climbing stairs, or with emotional stress
    • Class III: Severe limitation of ordinary physical activity as angina occurs on walking 1–2 blocks on level surface, climbing 1 flight of stairs
    • Class IV: Inability to carry on any physical activity without discomfort, as angina symptoms occur at rest
  • Typically categorized as stable or unstable
  • Stable angina: Predictable, with exertion, and improves with rest
  • Unstable angina (UA): New onset, increase in frequency, duration or lower threshold for symptoms, at rest, or >20 min
  • UA associated with increased risk of transmural myocardial infarction (MI) and cardiac death
  • New high-sensitivity cardiac biomarkers blurring boundaries between UA and NSTEMI


  • Cardiac risk factors:
    • Age
      • Men >35 yr
      • Postmenopausal in women
    • Hypercholesterolemia
    • HTN
    • Smoking
  • Atherosclerotic narrowing of coronary vessels:
    • Stable angina: Chronic and leads to imbalance of blood flow during exertion
    • UA: Acute disruption of plaque which can lead to worsening symptoms with exertion or at rest
  • Vasospasm: Prinzmetal angina, drug related (cocaine, amphetamines)
  • Microvascular angina or abnormal relaxation of vessels if diffuse vascular disease
  • Arteritis: Lupus, Takayasu disease, Kawasaki disease, rheumatoid arthritis
  • Anemia
  • Hyperbarism, carboxyhemoglobin elevation
  • Abnormal structure of coronaries: Radiation, aneurysm, ectasia


Signs and Symptoms

  • Chest pain:
    • Substernal pressure, heaviness, tightness, burning or squeezing
    • Radiates to neck, jaw, left shoulder, or arm
  • Poorly localized, visceral pain
  • Anginal equivalents include:
    • Dyspnea
    • Epigastric discomfort
    • Weakness
    • Diaphoresis
    • Nausea/vomiting
    • Abdominal pain
    • Syncope
  • Symptoms usually reproduced by exertion, eating, cold exposure, emotional stress
  • Symptoms not usually positional or pleuritic
  • Usually relieved with rest or nitroglycerin
  • For stable angina often lasts more than a few seconds but <20 min and no changes in pattern of frequency of symptoms

Geriatric Considerations
  • Women, diabetics, ethnic minorities, and those >65 yr often with atypical symptoms
  • Prognosis is worse for people with atypical symptoms

Physical Exam
  • “Levine sign”: Clenched fist over chest, classic finding
  • BP often elevated during symptoms
  • Physical exam often uninformative
  • Can look for S3/S4, papillary muscle dysfunction with mitral regurgitation or new murmur, diminished peripheral pulses

Essential Workup

  • ECG:
    • Standard 12 lead should be obtained and read within 10 min of presentation for patients with acute chest pain
    • Helpful in detecting acute MI, less so UA
    • Important to compare to prior ECG if available
    • New ST changes or TWI suspicious for UA:
      • T-wave flattening or biphasic T waves
      • ≤1-mm ST depression 80 msec from the J point, is characteristic in UA
      • Can see evidence of old ischemia, strain or infarct, such as old TWI, Q wave, ST depression
      • Serial ECGs helpful in distinguishing unstable from stable angina
      • A single ECG for acute MI is about 60% sensitive and 90% specific
    • ECG can also be helpful to diagnose other causes of chest pain:
      • Pericarditis: Diffuse ST elevations, then TWIs and pulse rate depression
      • Pulmonary embolus S1Q3T3 pattern, unexplained tachycardia, and signs of right heart strain

Patients with normal or nonspecific ECGs have a 1–5% incidence of AMI and 4–23% incidence of UA.

Diagnostic Tests and Interpretation

  • In stable angina, cardiac enzymes not indicated, but if history suspicious for acute MI, these should be obtained
  • CK-MB and troponin I or T:
    • High-sensitivity troponins changing positive threshold and timing of rule-out
    • CK-MB peaks 12–24 hr, return to baseline in 2–3 d
    • Troponin peaks in 12 hr, return to baseline 7–10 d
  • Hematocrit (anemia increases risk of ischemia)
  • Coagulation profile
  • Electrolytes, especially Cr and K+

  • CXR:
    • Usually nonrevealing
    • May show cardiomegaly, or pulmonary edema; CHF can be suggestive of UA
    • May be helpful in identifying other etiologies such as pneumonia, pneumothorax, or aortic dissection
  • Coronary CTA:
    • Good for low-risk patients with no known CAD to rule out ischemia as cause of pain if no coronary stenosis
    • “Triple rule-out” for ACS, PE, and aortic dissection
  • Bedside echo: To detect wall motion abnormalities and other etiologies of shock, pericardial effusion, pneumothorax
  • Tc-99 sestamibi (rest): Radionucleotide whose uptake by myocardium is dependent on perfusion

Diagnostic Procedures/Other
  • Exercise stress testing:
    • Not appropriate for active chest pain with moderate to high likelihood of ischemia
  • Imaging stress test (sestamibi, thallium, or echo) if baseline ECG abnormalities
  • Other imaging modalities including MRI, PET have also been used
  • Coronary angiography:
    • Gold standard for diagnosis for CAD

Differential Diagnosis

  • Anxiety and panic disorders
  • Aortic dissection
  • Biliary colic
  • Costochondritis
  • Esophageal reflux
  • Esophageal spasm
  • Esophagitis
  • GERD
  • Herpes zoster
  • Hiatal hernia
  • Mitral valve prolapse
  • Musculoskeletal chest pain
  • MI
  • Myocarditis
  • Nonatherosclerotic causes of cardiac ischemia:
    • Coronary artery spasm
    • Coronary artery embolus
    • Congenital coronary disease
    • Coronary dissection
    • Valvular disease: AS, AI, pulmonary stenosis, mitral stenosis
    • Congenital heart disease
  • Peptic ulcer disease
  • Pericarditis
  • Pneumonia
  • Psychogenic
  • Pneumothorax
  • Pulmonary embolism


Pre Hospital

  • IV access
  • Aspirin
  • Oxygen
  • Vital signs and oxygen saturation
  • Cardiac monitoring
  • 12-lead ECG, if possible
  • Sublingual nitroglycerin

Initial Stabilization/Therapy

  • IV access
  • Oxygen
  • Cardiac monitoring
  • Vital signs and continuous oxygen saturation

Ed Treatment/Procedures

  • All patients with chest pain in which cardiac ischemia is a consideration should receive an aspirin upon arrival to the ED
  • Sublingual nitroglycerin: If symptoms persist after 3 sublingual doses, suggestive of UA, AMI, or noncardiac etiology
  • Pain control
  • Anticoagulation


First Line Medication:
  • Aspirin: 325 mg or 81 mg × 4 PO (chewed)
  • In patients with aspirin allergy can give clopidogrel (Plavix) 300–600 mg PO, can also consider prasugrel 60 mg PO or ticagrelor
  • Dual antiplatelet therapy should be given to patients with UA at medium to high risk who have been selected to have invasive strategy such as catheterization or surgery
  • Nitroglycerin:
    • 0.4 mg sublingual
    • 5–10 mcg/min IV, titrating to effect
    • 1–2 in of nitro paste
    • Hold for low BP or if concern for preload dependence (RV infarct: Q in II, III, aVF; STE in right-sided V3, V4)
    • Beware if patient has history of erectile dysfunction and use of phosphodiesterase inhibitors like sildenafil (Viagra) or tadalafil (Cialis) in last 48 hr
  • Morphine:
    • 4 mg IV, titrate to relief of pain assuming no respiratory depression and SBP >90
  • Consider β-blocker:
    • Metoprolol: 25–50 mg PO or 5 mg IV q5–15min for refractory HTN and tachycardia
    • Contraindicated in active RAD, active CHF, bradycardia, hypotension, heart block, cocaine use
    • Does not necessarily need to be given in ED, suggested benefit within 24 hr of AMI

Second Line Medication:
  • Can vary by institution, recommend conferring with inpatient cardiologist regarding anticoagulation
  • Heparin: 60-U/kg IV bolus, then 12 U/kg/hr (goal PTT 50–70)
  • Enoxaparin: 1 mg/kg SC q12 or q24 if Cr clearance <30 mL/min
  • Glycoprotein IIb/IIIa inhibitors:
    • Eptifibatide (Integrilin): 180-ug/kg bolus IV over 1–2 min, then 2 ug/kg/min up to 72 hr
    • Tirofiban (Aggrastat): 0.4 ug/kg/min for 30 min, then 0.1 ug/kg/min for 48–108 hr
    • Abciximab (ReoPro): 0.25-mg/kg IV bolus, then 0.125 ug/kg/min
    • Bivalirudin, fondaparinux
  • Patients at high risk for bleeding include the elderly, female, anemic, CKD
  • For stable angina, management consists of preventative therapies including aspirin, blood pressure control (β-blocker, calcium channel blocker, long-acting nitrates) and lifestyle modification (weight loss, decreased fat/sugar intake, smoking cessation):
    • New antianginal medications including ranolazine may also be a part of management

Ongoing Care


Admission Criteria
  • Patients with UA require admission to the hospital
  • Early intervention with cardiac catheterization likely decreases mortality in patients with elevations in cardiac enzymes, persistent angina, or hemodynamic instability
  • Patients with unclear diagnosis likely would benefit from admission to ED observation unit or hospital admission for serial cardiac enzymes, ECG, and stress testing/catheterization

Discharge Criteria
Patients with stable angina

Follow-Up Recommendations

Patients with stable angina should follow up with their PCP and a cardiologist.

Pearls and Pitfalls

  • History is the most important factor in differentiating unstable from stable angina
  • All patients with chest pain or symptoms concerning for a cardiac etiology should have an immediate ECG, and serial ECGs are essential for ACS workup
  • A single set of negative cardiac enzymes may not rule out ACS in a patient with chest pain
  • Women, diabetics, ethnic minorities, and patients >64 yr require a low threshold for ACS workup as they often have atypical presentations
  • It is important to work with the inpatient cardiologist/interventionalist regarding anticoagulation regimen choice as this may vary by institution

Additional Reading

  • 2012 Writing Committee Members, Jneid H, Anderson JL, et al. 2012 ACCF/AHA focused update of the guideline for the management of patients with unstable angina/Non-ST-elevation myocardial infarction (updating the 2007 guideline and replacing the 2011 focused update): A report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation. 2012;126(7):857–910.
  • Long B, Koyfman A. Best clinical practice: Current controversies in the evaluation of low-risk chest pain with risk stratification aids. Part 1. J Emerg Med. 2016;51:668–676.
  • Long B, Koyfman A. Best clinical practice: Current controversies in the evaluation of low-risk chest pain with risk stratification aids. Part 2. J Emerg Med. 2017;52:43–51.
  • Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Mosby Elsevier; 2017.

See Also


Margaret J. Lin
Shamai A. Grossman

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