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

Initial Management of NSTEMI

Immediately administer aspirin 162-325 mg orally (non-enteric coated), initiate parenteral anticoagulation with unfractionated heparin or enoxaparin, add a P2Y12 inhibitor (preferably ticagrelor 180 mg loading dose), admit to a monitored unit, and perform risk stratification to determine timing of invasive strategy within 24 hours. 1, 2, 3

Immediate Stabilization and Monitoring

• Admit the patient to a monitored unit with continuous cardiac rhythm monitoring for at least 24 hours to detect life-threatening arrhythmias and electrical instability 2, 3
• Administer supplemental oxygen only if arterial oxygen saturation is <90%—routine oxygen in normoxic patients should be avoided 2, 3
• Give sublingual or intravenous nitroglycerin for ongoing ischemic chest pain, unless systolic blood pressure is <90 mmHg, severe bradycardia or tachycardia is present, right ventricular infarction is suspected, or phosphodiesterase inhibitor use occurred within 24-48 hours 2
• Consider morphine sulfate intravenously (2-4 mg with increments of 2-8 mg at 5-15 minute intervals) for uncontrolled ischemic chest discomfort despite nitroglycerin, but use cautiously as it may delay P2Y12 inhibitor absorption 2, 3

Antiplatelet Therapy

Aspirin

• Administer aspirin 162-325 mg orally immediately upon presentation (non-enteric coated for faster absorption) 1, 2, 3, 4
• Continue aspirin 75-100 mg daily indefinitely for secondary prevention 1, 2, 3
• The maintenance dose of aspirin when used with ticagrelor should be 81 mg daily 1

P2Y12 Inhibitor Selection

• Add a P2Y12 inhibitor before diagnostic angiography (upstream administration) 1, 2
• Ticagrelor is preferred over clopidogrel for patients undergoing early invasive or ischemia-guided strategy: 180 mg loading dose, then 90 mg twice daily 1, 2, 3, 4
• Clopidogrel 600 mg loading dose (or 300 mg if conservative strategy), then 75 mg daily, is an alternative if ticagrelor is contraindicated 1, 3
• Prasugrel 60 mg loading dose should be given promptly after coronary anatomy is defined and a decision is made to proceed with PCI, not before angiography in NSTEMI patients 1, 5
• For prasugrel, do not administer until coronary anatomy is known because it is contraindicated in patients with prior stroke/TIA and should be avoided if urgent CABG is likely 1, 5
• Continue P2Y12 inhibitor for at least 12 months regardless of whether a stent was placed 1, 2, 3, 4

Critical Prasugrel Considerations

• Prasugrel is contraindicated in patients with prior stroke or TIA (Class III: Harm) 1, 5
• Consider lowering prasugrel maintenance dose to 5 mg daily in patients weighing <60 kg due to increased bleeding risk 1, 5
• Prasugrel is generally not recommended in patients ≥75 years of age except in high-risk situations (diabetes or prior MI) 5

Anticoagulation Therapy

• Initiate parenteral anticoagulation immediately in all patients in addition to antiplatelet therapy 1, 2, 3, 4

Agent Selection

• Enoxaparin 1 mg/kg subcutaneously every 12 hours (reduce to 1 mg/kg once daily if creatinine clearance <30 mL/min), continued for duration of hospitalization or until PCI 1, 3
• Unfractionated heparin: 60 IU/kg IV bolus (maximum 4000 IU) followed by 12 IU/kg/hour infusion (maximum 1000 IU/hour), adjusted per aPTT, continued for 48 hours or until PCI 1, 3
• Fondaparinux 2.5 mg subcutaneously daily for duration of hospitalization or until PCI—preferred for conservative strategy due to lower bleeding risk 1, 3
• If fondaparinux is used and PCI is performed, add unfractionated heparin or bivalirudin during PCI due to risk of catheter thrombosis 1, 3
• Bivalirudin 0.10 mg/kg loading dose followed by 0.25 mg/kg/hour (only for early invasive strategy) until angiography or PCI 1, 3

Critical Anticoagulation Pitfalls

• Do not switch between anticoagulants as this increases bleeding risk 3
• Fondaparinux alone is insufficient during PCI—must add UFH 3

Risk Stratification and Management Strategy

Immediate/Urgent Invasive Strategy (<2 hours)

Indicated for patients with: 1, 2, 3

• Refractory or recurrent angina despite medical therapy
• Hemodynamic instability or cardiogenic shock
• Life-threatening arrhythmias or cardiac arrest
• Mechanical complications of MI
• Acute heart failure with ongoing ischemia

Early Invasive Strategy (within 12-24 hours)

Indicated for initially stabilized high-risk patients with: 1, 2, 3, 4

• Elevated cardiac troponin with high-risk features
• Dynamic ST-segment or T-wave changes
• High GRACE score (>140) or TIMI score (≥3)
• Diabetes mellitus
• Renal insufficiency (eGFR <60 mL/min/1.73m²)
• Left ventricular ejection fraction <40%
• Recent PCI or prior CABG

Conservative (Ischemia-Guided) Strategy

• May be considered for low-to-intermediate risk patients who are initially stabilized without high-risk features 1, 3
• Not recommended for patients with extensive comorbidities (hepatic, renal, pulmonary failure, cancer) where revascularization risks outweigh benefits 1

Glycoprotein IIb/IIIa Inhibitor Considerations

• Eptifibatide or tirofiban may be added upstream in very high-risk patients with elevated troponin, diabetes, or significant ST-segment depression who are not at high bleeding risk 1, 2
• Abciximab should not be administered upstream (only at time of PCI if needed) 1, 2
• Routine upstream GP IIb/IIIa inhibitors are not recommended due to increased bleeding risk without clear reduction in ischemic events 3

Additional Pharmacotherapy

Beta-Blockers

• Initiate beta-blocker therapy within 24 hours unless contraindicated (acute heart failure, hemodynamic instability, heart block, active bronchospasm) 1, 2, 3
• Continue indefinitely for secondary prevention 1, 2
• In patients with moderate or severe LV dysfunction, use gradual titration 1

ACE Inhibitors/ARBs

• Start ACE inhibitor within 24 hours for patients with heart failure, LV dysfunction (LVEF <40%), hypertension, or diabetes 1, 2, 3, 4
• Continue indefinitely 1, 4
• Use ARB for ACE inhibitor-intolerant patients with clinical or radiological signs of heart failure and LVEF <40% 1, 3

Statins

• Initiate high-intensity statin therapy immediately (atorvastatin 80 mg or rosuvastatin 40 mg) regardless of baseline LDL cholesterol 2, 3

Critical Medications to Avoid

• NSAIDs (except aspirin) are contraindicated during hospitalization due to increased mortality, reinfarction, hypertension, heart failure, and myocardial rupture risk 2, 3
• Immediate-release dihydropyridine calcium channel blockers (nifedipine) should not be used without adequate beta-blockade 2, 3
• Intravenous fibrinolytic therapy is contraindicated in NSTEMI (Class III: Harm) 1
• Avoid omeprazole and esomeprazole with clopidogrel due to reduced antiplatelet effect; use other PPIs if gastroprotection is needed 2

Timing Considerations for Invasive Strategy

• Do not delay angiography in high-risk patients for "medical stabilization"—early invasive approach within 24 hours reduces ischemic events 2, 3
• For NSTEMI patients, prasugrel loading should be delayed until coronary anatomy is defined to avoid excessive bleeding if urgent CABG is needed 1, 5
• In a trial of 4033 NSTEMI patients, no clear benefit was observed when prasugrel was given before angiography compared to at time of PCI, but bleeding risk increased with early administration 5