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Cardiology & Acute Coronary Syndromes

Acute Coronary Syndrome (ACS) Triage Pathway

When a patient presents with acute substernal chest discomfort suspicious for myocardial ischemia:

flowchart TD
    Presentation["Acute Chest Pain / Anginal Equivalent"] --> ECG["Stat 12-Lead ECG within 10 Minutes"]


    ECG --> STEMI{"ST Elevation or New LBBB?"}
    STEMI -- Yes --> CathLab["STEMI: Immediate Coronary Angiography (PCI within 90 min; Fibrinolysis if >120 min transfer)"]
    STEMI -- No --> NSTEMI["NSTE-ACS: Check Serial High-Sensitivity Troponins"]


    NSTEMI --> TropPositive{"Troponin Elevated?"}
    TropPositive -- Yes --> NSTE_MI["NSTEMI: Dual Antiplatelet + Anticoagulation + Early Invasive Cath (<24 hr)"]
    TropPositive -- No --> UnstableAngina["Unstable Angina: Risk Stratify (TIMI / GRACE score)"]

Initial Medical Management (MONA BASH)

  1. Aspirin: 325 mg chewed immediately (reduces mortality).
  2. P2Y12 Inhibitor: Ticagrelor (180 mg) or Clopidogrel (600 mg).
  3. Anticoagulation: Unfractionated Heparin (preferred if urgent PCI planned) or Enoxaparin / Fondaparinux.
  4. Sublingual Nitroglycerin: For ischemic pain relief (contraindicated if SBP < 90 mmHg, RV infarction, or phosphodiesterase-5 inhibitor use within 24–48 hours).
  5. Beta-Blocker: Oral Metoprolol within 24 hours (avoid IV push if signs of acute heart failure, bradycardia, or cardiogenic shock risk).
  6. High-Intensity Statin: Atorvastatin 80 mg daily regardless of baseline LDL.

High-Yield Contrasting Presentations

Key Differential Contrast

Aortic Dissection vs Acute Myocardial Infarction

Clinical Feature Acute Aortic Dissection Acute Myocardial Infarction (AMI) Discriminating Clue
Pain Character Sudden, tearing/ripping pain radiating to the back/interscapular area Pressure, squeezing, crushing substernal heaviness Instant maximal intensity at onset favors dissection
Physical Exam Clue Pulse deficit, asymmetric BP (>20 mmHg difference between arms), new aortic regurgitation murmur Diaphoresis, S4 gallop, signs of pulmonary congestion Asymmetric pulses are pathognomonic for Type A dissection
Diagnostic Test of Choice CT Angiography of Chest/Abdomen (or TEE if hemodynamically unstable) 12-Lead ECG + High-Sensitivity Troponin Never give heparin/fibrinolytics if dissection is suspected
Emergency Management IV Beta-blockers (Esmolol/Labetalol) to HR < 60 & SBP 100-120 mmHg; Emergent Surgery for Type A Aspirin, P2Y12 inhibitor, Heparin, Emergent PCI Anticoagulation in dissection leads to fatal pericardial tamponade or exsanguination