What is the initial management for a patient with Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Initial Management of NSTEMI

All NSTEMI patients should receive immediate dual antiplatelet therapy (aspirin plus a P2Y12 inhibitor) combined with anticoagulation, followed by risk stratification to determine timing of invasive strategy. 1

Immediate Medical Therapy (Within Minutes of Presentation)

Antiplatelet Therapy

• Administer aspirin 162-325 mg loading dose immediately upon presentation, then continue 75-162 mg daily indefinitely. 1, 2
• Add a P2Y12 inhibitor: For high-risk patients not requiring urgent CABG, ticagrelor 90 mg twice daily or prasugrel 60 mg loading dose then 10 mg daily are preferred over clopidogrel. 1
• Clopidogrel 300-600 mg loading dose, then 75 mg daily is an acceptable alternative if ticagrelor or prasugrel are contraindicated or in post-surgical settings where bleeding risk is elevated. 1, 2, 3
• Important caveat: In UA/NSTEMI patients, the prasugrel loading dose should NOT be administered until coronary anatomy is established at angiography, as early administration increases bleeding risk without clear benefit if urgent CABG is needed. 4

Anticoagulation

• Initiate parenteral anticoagulation immediately with one of the following: 1, 2
  • Enoxaparin (LMWH) is preferred over unfractionated heparin unless renal failure is present or CABG is planned within 24 hours. 1
  • Unfractionated heparin with dose adjustment based on activated clotting time for patients with renal insufficiency. 5
  • Fondaparinux is preferred for conservative strategy due to lower bleeding risk. 6
• Continue anticoagulation for at least 48 hours or until revascularization is performed. 2

Anti-Ischemic Therapy

• Administer sublingual or intravenous nitroglycerin for ongoing ischemic chest pain unless contraindicated by systolic blood pressure <90 mmHg, severe bradycardia or tachycardia, right ventricular infarction, or recent phosphodiesterase inhibitor use within 24-48 hours. 6
• Start beta-blocker therapy to reduce myocardial oxygen demand unless contraindicated by signs of heart failure, low-output state, or risk factors for cardiogenic shock. 6
• Administer supplemental oxygen only if arterial oxygen saturation is <90% or if there are signs of respiratory distress or hypoxemia. 6

Monitoring

• Admit to a monitored unit with continuous cardiac rhythm monitoring for at least 24 hours to detect arrhythmias and electrical instability. 6

Risk Stratification and Invasive Strategy Selection

Immediate Invasive Strategy (Proceed Directly to Catheterization Laboratory)

An early invasive strategy is indicated (Class I) for patients with: 5

• Refractory angina despite maximal medical therapy
• Hemodynamic instability or cardiogenic shock
• Electrical instability (sustained ventricular arrhythmias)
• Mechanical complications of MI

Early Invasive Strategy (Within 12-24 Hours)

High-risk patients should undergo angiography within 12-24 hours if they have: 1, 2

• Elevated troponin levels (troponin T >0.01 ng/mL or troponin I >0.1 ng/mL)
• Dynamic ST-segment or T-wave changes
• TIMI risk score ≥3 or GRACE score >140
• LVEF <40%
• Diabetes mellitus
• Prior PCI or CABG
• Recurrent angina with ST-segment depression ≥0.05 mV

This is a Class I, Level of Evidence A recommendation for initially stabilized NSTEMI patients with elevated risk. 5

Conservative Strategy (Selective Invasive)

• For low-risk patients without the above features, an initially conservative strategy with selective invasive approach based on stress testing or recurrent symptoms may be considered (Class IIb). 5

Glycoprotein IIb/IIIa Inhibitors

• Eptifibatide or tirofiban should be used in high-risk UA/NSTEMI patients undergoing PCI (Class I recommendation). 5, 1
• Avoid routine upstream use (before angiography) as bleeding risk increases without clear benefit. 1

Additional Pharmacotherapy

• Initiate high-intensity statin therapy immediately regardless of baseline LDL cholesterol. 6, 1
• Start ACE inhibitors within 24 hours for patients with heart failure, left ventricular dysfunction (LVEF ≤0.40), hypertension, or diabetes. 6, 2
• Continue beta-blockers indefinitely for secondary prevention unless contraindicated. 6, 1

Critical Pitfalls to Avoid

Contraindicated Therapies

• Fibrinolytic therapy is absolutely contraindicated in all NSTEMI patients. Multiple trials (TIMI 11B, ISIS-2, GISSI 1) demonstrated no benefit and actually increased risk of MI. 5, 6

Medication Interactions

• Avoid omeprazole and esomeprazole with clopidogrel due to significantly reduced antiplatelet effect via CYP2C19 inhibition. 1, 3
• Avoid NSAIDs during hospitalization due to increased mortality, reinfarction, hypertension, heart failure, and myocardial rupture risk. 6
• Avoid immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade. 6

Strategy Selection Errors

• Do not delay invasive strategy in truly high-risk patients. The ISAR-COOL trial demonstrated that delayed invasive strategy (86 hours) had worse outcomes than very early strategy (2.4 hours). 1
• Do not proceed with early invasive strategy in patients with extensive comorbidities (e.g., liver or pulmonary failure, cancer) where risks outweigh benefits (Class III). 5
• Do not perform early invasive strategy in patients who will not consent to revascularization regardless of findings (Class III). 5

Dosing Considerations

• For patients <60 kg, consider lowering prasugrel maintenance dose to 5 mg daily due to increased bleeding risk. 4
• Adjust anticoagulant doses according to renal function. 6
• Closely monitor hemoglobin and platelet counts during antiplatelet and anticoagulant treatment. 6

Special Consideration: Type 2 NSTEMI

• If Type 2 NSTEMI is suspected (supply-demand mismatch rather than acute coronary thrombosis), the cornerstone of management is identifying and correcting the precipitating cause (e.g., anemia, tachyarrhythmias, hypotension). 6
• Do not routinely proceed to early invasive strategy in Type 2 NSTEMI as the pathophysiology is not acute coronary thrombosis. 6