STEMI / Acute Coronary Syndrome – Quick Consult
Last Updated / Reviewed: October 2024

Key History
Key Physical Exam
Risk Factors for MI/ACS
Differential Diagnosis
Diagnostic Testing
Clinical Risk and Safety Pearls

Key History

  • Classic: substernal chest pain radiating to left arm, neck, jaw
  • Associated symptoms of shortness of breath, diaphoresis, nausea or vomiting
  • Atypical presentations: 1/3 of patients do not have chest pain on presentation—especially women, diabetics and elderly
  • Pain onset typically crescendo vs. sudden
  • Pain onset usually with exertion, although may occur at rest
  • Dizziness
  • Dyspnea
  • Elderly patients and diabetics may present only with nausea, vomiting, diaphoresis or dyspnea
  • Fatigue
  • Impending sense of doom, anxiety
  • Indigestion
  • Pain can vary in intensity
  • Pain in arms, shoulder, epigastrium or neck
  • Palpitations
  • Posture changes or breathing does not change the intensity of the pain
  • Sensation described as squeezing, burning, heaviness, tightness, band around chest, or stabbing
  • Syncope
  • Vague discomfort
  • Weakness
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Key Physical Exam

  • Typically normal
  • Cold clammy skin
  • Hypertension or hypotension
  • May find signs of abnormal lipid metabolism—xanthelasma, xanthoma
  • May find signs of diffuse vascular disease—diminished peripheral pulses, carotid bruit
  • New systolic ejection murmur—if papillary muscle ruptured
  • Peripheral or central cyanosis
  • S4 heart sound
  • Signs of congestive heart failure
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Risk Factors for MI/ACS

  • CAD
  • Diabetes
  • Family history (especially of MI or acute coronary syndrome (ACS) before age 55)
  • Cocaine use
  • HTN
  • Hyperlipidemia
  • Smoking
  • Obesity
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Differential Diagnosis

Cardiopulmonary Abdominal Infectious
  • Cholecystitis
  • Cholelithiasis
  • Esophageal rupture
  • Esophagitis
  • Gastritis
  • Gastroesophageal reflux
  • Hiatal hernia
  • Mallory-Weiss syndrome
  • Pancreatitis
  • Peptic ulcer disease
Musculoskeletal Other
  • Costochondritis
  • Pleurisy
  • Anxiety disorder

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Diagnostic Testing

  • ECG Criteria for Acute MI:
    • STEMI: New ST elevation at the J point in at least 2 contiguous leads of ≥2 mm (0.2 mV) in men or ≥1.5 mm (0.15 mV) in women in leads V2-V3, and/or of ≥1 mm (0.1 mV) in other contiguous chest leads or the limb leads
    • Posterior MI: New ST depression in ≥2 precordial leads (V1-V4)
  • LBBB with Acute MI (Sgarbossa or Modified Sgarbossa Criteria):
    • ST elevation ≥1 mm and concordant with the QRS complex (5 points)
    • ST depression ≥1 mm in lead V1, V2, or V3 (3 points)
    • ST elevation ≥5 mm and discordant with the QRS complex (2 points) (Modified criteria replaces this 5 mm criterion with a proportion: ST elevation/S-wave amplitude of ≤ -0.25)
  • Troponin is the preferred biomarker for diagnosis of MI.
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Clinical Risk and Safety Pearls

  • Failure to diagnose myocardial infarction is one of the leading causes of litigation against medical practitioners.
  • Consider atypical presentations in women, elderly and diabetic patients.
  • Cardiac risk factors are not helpful to predict acute MI for the patient presenting with acute chest pain.
  • Beware the non-specific ECG. The non-specific change may be a normal variant or a new ECG change indicating the presence of ACS.
  • Do not use a GI cocktail as a test to rule out the presence of ACS.
  • Do not use the failure to respond to nitroglycerin as a test to rule out the presence of ACS.
  • Intermediate or indeterminate troponin levels are not normal. Repeat the test or get a cardiology consult.
  • Always view old ECGs for comparison if available.
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Brown JC, Gerhardt TE, Kwon E. Risk Factors for Coronary Artery Disease. [Updated 2023 Jan 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554410/.

Carrillo X, Curós A, Muga R, et al. Acute coronary syndrome and cocaine use: 8-year prevalence and inhospital outcomes. Eur Heart J. 2011 May;32(10):1244-50. doi: 10.1093/eurheartj/ehq504. Epub 2011 Jan 24. PMID: 21266375.

Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. Volume 144, Number 22. https://doi.org/10.1161/CIR.0000000000001029.

Kawamoto KR, Davis MB, Duvernoy CS. Acute Coronary Syndromes: Differences in Men and Women. Curr Atheroscler Rep. 2016 Dec;18(12):73. doi: 10.1007/s11883-016-0629-7. PMID: 27807732.

Mehta LS, Beckie TM, DeVon HA, et al. Acute myocardial infarction in women: A scientific statement from the American Heart Association. Circulation. 2016;133(9):916-947.

Singh A, Museedi AS, Grossman SA. Acute Coronary Syndrome. [Updated 2023 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459157/.

Wahrenberg A, Magnusson PK, et al. Family history of coronary artery disease is associated with acute coronary syndrome in 28,188 chest pain patients. Eur Heart J Acute Cardiovasc Care. 2020 Oct;9(7):741-747. doi: 10.1177/2048872619853521. Epub 2019 May 24. PMID: 31124704.

This is intended solely as reference material and is not a recommendation for any specific patient. The practitioner must rely upon his or her own professional judgment and medical decision-making to determine whether it is relevant in a particular case. Materials are derived from medical and nursing texts, medical literature and national guidelines and should not be considered complete or authoritative. Users must rely on specific patient presentation, experience and judgment when utilizing any of the information contained herein relative to an actual patient.
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