Acute Coronary Syndrome: Angina

Basics

Description

  • Chest discomfort, due to 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 with angina occurring with walking, climbing stairs, or emotional stress
    • Class III: Severe limitation of ordinary physical activity with angina when walking 1–2 blocks on level surface or climbing 1 flight of stairs
    • Class IV: Inability to carry on any physical activity without discomfort or angina symptoms occur at rest
  • Typically categorized as either 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
  • UA associated with increased risk of transmural myocardial infarction and cardiac death

Etiology

  • Cardiac risk factors:
    • Age
    • Men >35 yr
    • Postmenopausal in women
    • Hypercholesterolemia
    • DM
    • 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

Diagnosis

Signs and Symptoms

History
  • 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
    • Relief with nitroglycerin in nondiagnostic
  • Lasts more than a few minutes but <20 min
  • Considered stable angina if no changes in pattern of frequency of symptoms

Geriatric Considerations
  • Women, diabetics, ethnic minorities, and those >65 yr often present 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
    • occasional S3/S4,
    • mitral regurgitation or new murmur (papillary muscle dysfunction)
    • diminished peripheral pulses

Essential Workup

ECG:
  • Standard 12 lead
    • Ideally should be obtained and read within 10 min of presentation for patients with acute chest pain
  • Mostly helpful in detecting acute MI, less so UA
  • Compare to prior ECG if available
    • If normal or unchanged, serial ECGs every 10–30 min
  • New ST changes or T-wave inversion 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
    • 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 TW inversions and pulse rate depression
    • Pulmonary embolus S1Q3T3 pattern, unexplained tachycardia and signs of right heart strain

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

Diagnostic Tests and Interpretation

Lab
  • For stable angina, cardiac enzymes not indicated, but if history suspicious for acute MI, should obtain.
  • CK-MB and troponin I or T
    • <50% of patient with UA will have low level troponin elevations
    • CK-MB peaks 12–24 hr, return to baseline in 2–3 days
    • Troponin peaks in 12 hr, return to baseline 7–10 days
  • Hematocrit (anemia increases risk of ischemia)
  • Coagulation profile
  • Electrolytes, especially Cr and K+

Imaging
  • CXR:
    • Usually nonrevealing
    • May show cardiomegaly, or pulmonary edema, CHF suggests UA or MI
    • 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 in patient 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
  • Technetium Tc-99 sestamibi (rest): Radionucleotide whose uptake by myocardium is dependent on perfusion

Diagnostic Procedures/Other
  • Exercise stress testing:
    • Not appropriate if active chest pain with moderate to high likelihood of ischemia
    • Imaging stress test (sestamibi, thallium, or echo) if baseline ECG abnormalities
    • Early positive (within 3 min) concerning for UA
  • Coronary angiography:
    • Gold standard of 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

Treatment

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

First Line
  • Aspirin: 325 mg PO (chewed) or 81 mg × 4 (chewed)
  • In patients with aspirin allergy: Clopidogrel (Plavix) 300–600 mg PO, also consider prasugrel 60 mg PO or 180 mg PO 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 μg/min IV USE NON-PVC tubing, titrating to effect
    • 1–2 in of nitro paste
    • Hold for low BP (can severely drop BP)
    • Beware if pt has history of erectile dysfunction and use of phosphodiesterase inhibitors like sildenafil (Viagra) or tadalafil (Cialis) can last 48 hr
  • Morphine
    • 4 mg IV, titrate to relief of pain assuming no respiratory depression and SBP >90
  • Consider beta blocker
    • Metoprolol: 25—50 mg PO or 5 mg IV q5–15min for refractory HTN and tachycardia
    • Contraindicated in reactive airway disease, active CHF, bradycardia, hypotension, heart block, cocaine use
    • Does not necessarily need to be given while patient is in ED, suggested benefit within 24 hrs of AMI

Second Line
Anticoagulation
  • Does not alter mortality
    • Consider conferring with cardiology prior to 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 <30mL/min
  • Glycoprotein IIb/IIIa inhibitors: Primary benefit en route to cath
    • Eptifibatide (Integrilin): 180 μg/kg bolus IV over 1–2 min, then 2 μg/kg/min up to 72 hr
    • Tirofiban (Aggrastat): 0.4 μg/kg/min for 30 min, then 0.1 μg/kg/min for 48—108 hr
    • Abciximab (Reopro): 0.25 mg/kg IV bolus, then 0.125 μg/kg/min, maximum dose 10 μg/min for 12 hr
    • Bilvalirudin, fondaparinux
  • Patients at risk for high risk for bleeding include the elderly, female, anemic, chronic renal failure

Ongoing Care

Disposition

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 hospitalization for serial cardiac enzymes, ECG and stress testing/catheterization

Discharge Criteria
  • Patients with stable angina
  • Patients who are enzyme/stress testing or cath negative

Follow-Up Recommendations

Patients with stable angina or workup negative chest pain should follow up with their PCP or cardiologist within several days of ED visit.

Pearls and Pitfalls

  • History is the most important factor in differentiating unstable from stable angina or noncardiac pain
  • All patients with chest pain or symptoms concerning for a cardiac etiology should have an immediate ECG
  • It the initial ECG is normal or unchanged, do serial ECGs 10–30 min apart
  • A single set of negative cardiac enzymes may not rule out ACS in a patient with chest pain
  • Women, diabetics, ethnic minorities, and patients >65 yr require a low threshold for ACS workup as they often have atypical presentations

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.
  • Marx JA, Hockberger RS, Walls RM, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, PA: Mosby Elsevier; 2010.
  • Mistry NF, Vesely MR. Acute coronary syndromes: From the emergency department to the cardiac care unit. Clinics. 2012;30:617–627.
  • Swap C, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294:2623–2949.  [PMID:16304077]

See Also

  • ACS Myocardial Infarction
  • ACS Coronary Vasospasm
  • Cardiac Testing

Codes

ICD-9

  • 411.1 Intermediate coronary syndrome
  • 413.1 Prinzmetal angina
  • 413.9 Other and unspecified angina pectoris

ICD-10

  • Unstable angina
  • Angina pectoris with documented spasm
  • Angina pectoris, unspecified
  • Acute ischemic heart disease, unspecified

SNOMED

  • 194828000 Angina (disorder)
  • 233819005 Stable angina (disorder)
  • 4557003 Preinfarction syndrome (disorder)
  • 87343002 Prinzmetal angina (disorder)
  • 394659003 Acute coronary syndrome (disorder)

Authors

Shamai A. Grossman
Margaret J. Lin


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