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Acute Coronary Syndrome: Angina, Emergency Medicine

Basics

Description

- 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

- Chest pain: - Substernal pressure, heaviness, tightness, burning or squeezing - Radiates to neck, jaw, left shoulder, or arm

- "Levine Sign"Ł: 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

- New ST changes or T-wave inversion suspicious for UA - T-wave flattening or biphasic T-waves - ÔëĄ1 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

- Aspirin: 325 mg PO (chewed) or 81 mg Ś 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 ╬╝g/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

- 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

- Glycoprotein IIb/IIIa inhibitors: Primary benefit en route to cath - Eptifibatide (Integrilin): 180 ╬╝g/kg bolus IV over 1-2 min, then 2 ╬╝g/kg/min up to 72 hr - Tirofiban (Aggrastat): 0.4 ╬╝g/kg/min for 30 min, then 0.1 ╬╝g/kg/min for 48-108 hr - Abciximab (Reopro): 0.25 mg/kg IV bolus, then 0.125 ╬╝g/kg/min, maximum dose 10 ╬╝g/min for 12 hr - Bilvalirudin, fondaparinux

  • 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 activityClass II: Slight limitation of normal activity with angina occurring with walking, climbing stairs, or emotional stressClass III: Severe limitation of ordinary physical activity with angina when walking 1-2 blocks on level surface or climbing 1 flight of stairsClass 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 onsetIncrease in frequency, duration or lower threshold for symptomsAt rest
  • UA associated with increased risk of transmural myocardial infarction and cardiac death

Etiology

  • Cardiac risk factors:AgeMen >35 yrPostmenopausal in womenHypercholesterolemiaDMHTNSmoking
  • Atherosclerotic narrowing of coronary vesselsStable angina: Chronic and leads to imbalance of blood flow during exertionUA: 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 squeezingRadiates to neck, jaw, left shoulder, or arm
  • Poorly localized, visceral pain
  • Anginal equivalents include:DyspneaEpigastric discomfortWeaknessDiaphoresisNausea/vomitingAbdominal painSyncope
  • Symptoms usually reproduced by exertion, eating, cold exposure, emotional stress
  • Symptoms not usually positional or pleuritic
  • Usually relieved with rest or nitroglycerinRelief 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
  • 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"Ł: Clenched fist over chest, classic finding
  • BP often elevated during symptoms
  • Physical exam often uninformativeoccasional S3/S4,mitral regurgitation or new murmur (papillary muscle dysfunction)diminished peripheral pulses

Essential Workup

ECG: á

  • Standard 12 leadIdeally 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 availableIf normal or unchanged, serial ECGs every 10-30 min
  • New ST changes or T-wave inversion suspicious for UAT-wave flattening or biphasic T-wavesÔëĄ1 mm ST depression 80 msec from the J point, is characteristic in UACan see evidence of old ischemia, strain or infarct, such as old TWI, Q-wave, ST depressionSingle ECG for acute MI is about 60% sensitive and 90% specific
  • ECG can also be helpful to diagnose other causes of chest painPericarditis: Diffuse ST elevations, then TW inversions and pulse rate depressionPulmonary 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

Diagnosis Tests & 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 elevationsCK-MB peaks 12-24 hr, return to baseline in 2-3 daysTroponin 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 nonrevealingMay show cardiomegaly, or pulmonary edema, CHF suggests UA or MIMay 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"Ł 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/Surgery

  • Exercise stress testing:Not appropriate if active chest pain with moderate to high likelihood of ischemiaImaging stress test (sestamibi, thallium, or echo) if baseline ECG abnormalitiesEarly 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 ischemiaCoronary artery spasmCoronary artery embolusCongenital coronary diseaseCoronary dissectionValvular disease: AS, AI, pulmonary stenosis, mitral stenosisCongenital 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 Ś 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 sublingual5-10 ╬╝g/min IV USE NON-PVC tubing, titrating to effect1-2 in of nitro pasteHold 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
  • Morphine4 mg IV, titrate to relief of pain assuming no respiratory depression and SBP >90
  • Consider beta blockerMetoprolol: 25-50 mg PO or 5 mg IV q5-15min for refractory HTN and tachycardiaContraindicated in reactive airway disease, active CHF, bradycardia, hypotension, heart block, cocaine useDoes not necessarily need to be given while patient is in ED, suggested benefit within 24 hrs of AMI

Second Line

Anticoagulation á

  • Does not alter mortalityConsider conferring with cardiology prior to anticoagulationHeparin: 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 cathEptifibatide (Integrilin): 180 ╬╝g/kg bolus IV over 1-2 min, then 2 ╬╝g/kg/min up to 72 hrTirofiban (Aggrastat): 0.4 ╬╝g/kg/min for 30 min, then 0.1 ╬╝g/kg/min for 48-108 hrAbciximab (Reopro): 0.25 mg/kg IV bolus, then 0.125 ╬╝g/kg/min, maximum dose 10 ╬╝g/min for 12 hrBilvalirudin, fondaparinux
  • Patients at risk for high risk for bleeding include the elderly, female, anemic, chronic renal failure

Follow-Up

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

Followup Recommendations

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

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 áH, Anderson áJL, 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 áJA, Hockberger áRS, Walls áRM, eds. Rosens Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, PA: Mosby Elsevier; 2010.
  • Mistry áNF, Vesely áMR. Acute coronary syndromes: From the emergency department to the cardiac care unit. Clinics. 2012;30:617-627.
  • Swap áC, Nagurney áJT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294:2623-2949.

See Also (Topic, Algorithm, Electronic Media Element)

  • ACS Myocardial Infarction
  • ACS Coronary Vasospasm
  • Cardiac Testing

Codes

ICD9

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

ICD10

  • I20.0 Unstable angina
  • I20.1 Angina pectoris with documented spasm
  • I20.9 Angina pectoris, unspecified
  • I24.9 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)