ACLS Provider: Course

Acute Coronary Syndromes (ACS) Algorithm

Acute Coronary Syndromes (ACS) refer to a spectrum of conditions caused by sudden, reduced blood flow to the heart muscle. This includes unstable angina, non–ST-elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI). Prompt recognition and early intervention are critical — timely management can prevent full cardiac arrest and improve survival and long-term outcomes. The ACLS ACS algorithm focuses on early symptom recognition, rapid evaluation, medication administration, and preparing for reperfusion therapy when appropriate.

Recognition of ACS

Patients experiencing ACS may present with:

  • Chest discomfort: Pressure, heaviness, squeezing, or pain that may radiate to the jaw, neck, shoulders, arms, or back.
  • Shortness of breath: Often accompanying or preceding chest pain.
  • Diaphoresis, nausea, or lightheadedness: Particularly common in women and elderly patients.
  • Silent symptoms: Especially in diabetics or elderly patients, ACS may present without classic chest pain — monitor for unexplained fatigue, syncope, or sudden dyspnea.

If ACS is suspected, initiate the algorithm immediately. Time is myocardium.

Immediate Actions (Prehospital or First Response)

  • Ensure airway, breathing, circulation (ABCs). Administer oxygen if SpO2 is <94% or if the patient is in respiratory distress.
  • Attach monitor/defibrillator and obtain a 12-lead ECG within 10 minutes of first medical contact.
  • Initiate IV access and begin appropriate medications:
    • Aspirin: 160–325 mg, chewed unless contraindicated
    • Nitroglycerin: Sublingual or spray every 5 minutes as needed (hold if hypotensive or using PDE-5 inhibitors)
    • Morphine: Consider for chest pain unrelieved by nitro, if not hypotensive
  • Be prepared to manage cardiac arrest if the patient deteriorates.

ECG Interpretation and Decision Pathway

  • STEMI: ST-segment elevation ≥1 mm in two or more contiguous leads, or new LBBB with symptoms
    • Activate cardiac cath lab or prepare for fibrinolysis immediately
    • Goal: PCI within 90 minutes of first medical contact (FMC)
  • NSTEMI or Unstable Angina: No ST elevation, but ECG changes (e.g., ST depression, T-wave inversion) and/or positive cardiac biomarkers
    • Admit for monitoring, cardiology evaluation, and serial troponins
    • Continue medical therapy — beta-blockers, anticoagulants, antiplatelets
  • Normal ECG but symptoms persist:
    • Do not dismiss — ACS may still be present
    • Repeat ECGs, monitor closely, obtain biomarkers

Reperfusion and Transport

If STEMI is confirmed and PCI is not available within 90 minutes, consider fibrinolytic therapy within 30 minutes of arrival unless contraindicated. Transport the patient to a PCI-capable facility as early as possible, even if fibrinolytics are given.

Summary

  • Recognize symptoms early — chest pain, SOB, diaphoresis, or “silent” presentations
  • Obtain a 12-lead ECG within 10 minutes of first medical contact
  • Initiate MONA-based therapy: Morphine, Oxygen, Nitroglycerin, Aspirin
  • Determine STEMI vs NSTEMI/UA and initiate appropriate interventions
  • Ensure rapid transport to a PCI-capable center for definitive treatment