Diagnostics

• Indicated for every patient with suspected ACS (best initial test)

• Findings:

  • ECG changes in STEMI

  • ECG changes in NSTEMI/unstable angina

• Compare with previous ECGs (if available).

Consider serial ECGs if the initial ECG is negative or inconclusive, as ECG findings are dynamic and signs of ischemia can appear or disappear within minute

• CBC, BMP, coagulation panel

• Anemia may exacerbate myocardial ischemia. Thrombocytopenia and/or coagulopathies may affect management options, e.g., the use of anticoagulants.

• Troponin: all patients at arrival (see also “Cardiac biomarkers”)

  • Repeat interval

    • Conventional assay: 3–6 hours

    • High-sensitivity troponin (hscTn): 1–3 hours

  • Interpretation alongside clinical findings

    • STEMI/NSTEMI: elevation > 99thpercentile PLUS change ≥ 20% on repeat testing

    • Unstable angina: no detectable elevation

TTE is generally not necessary and should not delay reperfusion therapy. However, it may be a helpful study in patients with atypical symptoms or if the diagnosis is unclear.

• Indications include:

  • Cardiogenic shock

  • Infarct-like symptoms but inconclusive ECG findings

  • Evaluation for complications of myocardial infarction

• Findings

  • Wall motion abnormalities

  • Decreased LV function

  • Signs of different conditions that cause chest pain