Would you consider this an Non-ST-Elevation Myocardial Infarction (NSTEMI) and start heparin infusion in a patient with new ST depressions on lateral leads, negative troponins, and persistent chest pain?

Management of New ST Depressions with Negative Troponins and Persistent Chest Pain

This is NOT an NSTEMI by current diagnostic criteria, but represents high-risk unstable angina requiring immediate anticoagulation with heparin infusion. 1

Diagnostic Classification

Three negative troponins definitively exclude NSTEMI, as the diagnosis requires troponin elevation above the 99th percentile in addition to clinical evidence of ischemia. 2, 1 This patient meets criteria for unstable angina, which is a form of acute coronary syndrome that still requires aggressive medical therapy. 2

The new ST depressions on lateral leads during symptomatic episodes are particularly concerning:

• ST depressions ≥0.5 mm during chest pain strongly suggest acute ischemia and indicate very high likelihood of severe underlying coronary disease. 1
• The fact that these ST depressions are higher voltage than previous baseline changes makes them even more significant for active ischemia. 2
• Patients with ST-segment deviation have progressively greater mortality risk independent of troponin status. 1

Answer to Your Question: Start Heparin Infusion

YES, you should absolutely start heparin infusion. The European Society of Cardiology and American College of Cardiology recommend anticoagulation for ALL patients with unstable angina/NSTEMI, regardless of troponin status. 1, 2

Anticoagulation Options

Option 1: Unfractionated Heparin (UFH)

• Initial bolus: 60 IU/kg IV (maximum 4000 IU). 1
• Continuous infusion: 12 IU/kg/hour (maximum 1000 IU/hour). 1
• Target aPTT: 50-70 seconds (approximately 1.5-2 times control). 2, 3

Option 2: Low Molecular Weight Heparin (LMWH) - Preferred

• Enoxaparin is preferred over UFH unless CABG is planned within 24 hours. 1
• Enoxaparin has demonstrated advantages in non-ST-segment elevation ACS and offers convenience of subcutaneous dosing. 4

Complete Initial Medical Management Algorithm

1. Aspirin 162-325 mg orally immediately (if not already given). 1

2. Start anticoagulation with one of the regimens above. 1, 2

3. Add P2Y12 inhibitor: 2, 1

   • Ticagrelor 180 mg loading dose, then 90 mg twice daily (preferred for high-risk patients). 2
   • Alternative: Clopidogrel 300-600 mg loading dose, then 75 mg daily. 1

4. Beta-blocker if no contraindications (heart failure, hypotension, bradycardia). 2, 1

5. Nitrates (sublingual or IV) for ongoing chest pain. 2, 1

Risk Stratification: This is a HIGH-RISK Patient

Your patient meets multiple high-risk criteria requiring early invasive strategy (coronary angiography within 24 hours): 2, 1

High-risk features present:

• New ST depressions on ECG during symptomatic episodes. 2
• Persistent/recurrent chest pain despite medical therapy. 2
• Dynamic ECG changes (ST depressions worse than baseline). 2

The European Society of Cardiology specifically identifies patients with recurrent ischemia (recurrent chest pain or dynamic ST-segment changes, particularly ST-segment depression) as high-risk requiring early invasive evaluation. 2

Invasive Strategy Timing

Plan for coronary angiography within 24 hours. 2, 1 This patient does not meet criteria for immediate invasive strategy (<2 hours), which is reserved for hemodynamic instability, refractory chest pain despite maximal therapy, life-threatening arrhythmias, or acute heart failure. 2

However, the combination of new ST depressions and ongoing symptoms places this patient in the early invasive category (<24 hours). 2

Critical Pitfalls to Avoid

DO NOT give fibrinolytic therapy - this is absolutely contraindicated in isolated ST depression and may increase mortality. 2, 1 Fibrinolytic therapy is only indicated for ST-segment elevation or true posterior MI (which presents with specific patterns of ST depression in V1-V4 with upright T-waves). 2, 5

DO NOT dismiss these ST depressions as "non-specific" when they occur during symptomatic episodes and are worse than baseline. 1 This represents active ischemia requiring urgent intervention.

DO NOT withhold anticoagulation based on negative troponins alone - the ST depressions and ongoing symptoms mandate treatment as acute coronary syndrome. 1, 2

DO NOT crossover between UFH and LMWH - pick one anticoagulant and stick with it to avoid increased bleeding risk. 1

DO NOT delay angiography in this high-risk patient - plan for invasive evaluation within 24 hours. 2, 1

Additional Considerations

If the patient has refractory angina (ongoing chest pain despite the above medical therapy), consider adding a GP IIb/IIIa receptor inhibitor (eptifibatide or tirofiban) to bridge to angiography. 2, 6, 7 These agents have demonstrated benefit in high-risk patients with troponin elevation or high-risk anatomy, reducing death, MI, and need for urgent intervention. 6, 7

Monitor closely for recurrence of chest pain with repeat 12-lead ECG during symptomatic episodes, and watch for signs of hemodynamic instability (hypotension, pulmonary rales) which would upgrade to immediate invasive strategy. 2