Description

• 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

Etiology

• 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

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

• “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

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

• 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

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

• 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

Disposition

• 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

Follow-Up Recommendations

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

See Also

• ACS Myocardial Infarction
• ACS Coronary Vasospasm
• Cardiac Testing