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

NSTEMI Treatment

Administer aspirin 162-325 mg immediately (chewed or non-enteric formulation), initiate dual antiplatelet therapy with ticagrelor (180 mg loading dose, then 90 mg twice daily), add parenteral anticoagulation (unfractionated heparin or enoxaparin), admit to a monitored unit, and proceed with early invasive strategy (angiography within 24 hours) for high-risk patients or immediate invasive strategy (<2 hours) for very high-risk patients. 1, 2, 3

Immediate Management (First Hours)

Antiplatelet Therapy

• Aspirin 162-325 mg immediately as a non-enteric formulation, either chewed or taken orally, regardless of prior aspirin use 1, 3
• Continue aspirin 75-100 mg daily indefinitely 1, 2
• Add ticagrelor as the preferred P2Y12 inhibitor: 180 mg loading dose, then 90 mg twice daily, regardless of invasive or conservative strategy 1, 2
• Alternative P2Y12 inhibitors if ticagrelor unavailable or contraindicated:
  • Prasugrel (60 mg loading dose, 10 mg daily; 5 mg daily if age ≥75 years or weight <60 kg) for P2Y12-naïve patients proceeding to PCI 1
  • Clopidogrel (300-600 mg loading dose, 75 mg daily) only when prasugrel or ticagrelor cannot be used 1, 4
• Continue P2Y12 inhibitor for 12 months unless excessive bleeding risk 1, 2

Anticoagulation

• Initiate parenteral anticoagulation immediately in all patients, in addition to antiplatelet therapy 1, 2, 5
• Unfractionated heparin (UFH): Continue for at least 48 hours or until discharge if given before angiography 1, 2, 5
• Enoxaparin: Continue for duration of hospitalization, up to 8 days, if given before angiography 1, 5
• Fondaparinux: Continue for duration of hospitalization, up to 8 days; must add UFH bolus during PCI to prevent catheter thrombosis 1, 5
• Avoid switching between anticoagulants as this increases bleeding risk 5

Supportive Care

• Admit to monitored unit with continuous cardiac rhythm monitoring for at least 24 hours to detect arrhythmias 1, 2
• Supplemental oxygen only if arterial oxygen saturation <90%; routine oxygen is not indicated 1, 2, 3
• Sublingual or IV nitroglycerin for ongoing ischemic chest pain (0.4 mg every 5 minutes for 3 doses, then assess need for IV) 1, 2
  • Contraindications: Systolic BP <90 mmHg or ≥30 mmHg below baseline, severe bradycardia (<50 bpm) or tachycardia (>100 bpm without heart failure), right ventricular infarction, phosphodiesterase inhibitor use within 24 hours (sildenafil) or 48 hours (tadalafil) 1, 3
• Oral beta-blocker within first 24 hours unless signs of heart failure, low-output state, increased cardiogenic shock risk, or contraindications (PR interval >0.24s, second/third-degree heart block, active asthma) 1, 2
• Morphine sulfate IV for uncontrolled ischemic chest pain despite nitroglycerin, but only as adjunct to definitive ischemia management 1, 5

Risk Stratification and Timing of Invasive Strategy

Very High-Risk Criteria: Immediate Invasive Strategy (<2 hours)

• Hemodynamic instability or cardiogenic shock 1
• Recurrent or ongoing chest pain refractory to medical treatment 1
• Life-threatening arrhythmias or cardiac arrest 1
• Mechanical complications of MI 1
• Acute heart failure with refractory angina or ST deviation 1
• Recurrent dynamic ST- or T-wave changes, particularly with intermittent ST elevation 1

High-Risk Criteria: Early Invasive Strategy (<24 hours)

• Rise or fall in cardiac troponin compatible with MI 1, 2
• Dynamic ST- or T-wave changes (symptomatic or silent) 1
• GRACE score >140 1
• Elevated cardiac biomarkers 2, 5

Intermediate-Risk Criteria: Invasive Strategy (<72 hours)

• Diabetes mellitus 1
• Renal insufficiency (eGFR <60 mL/min/1.73 m²) 1
• LVEF <40% or congestive heart failure 1
• Early post-infarction angina 1
• Recent PCI or prior CABG 1
• GRACE risk score >109 and <140 1

Conservative Strategy

• Appropriate for lower-risk patients without ongoing ischemia or significant comorbidities where invasive risks outweigh benefits 2, 5, 3

Post-Angiography Management

If PCI Performed

• Continue aspirin indefinitely 1, 2, 5
• Administer P2Y12 inhibitor loading dose if not given before angiography 1, 2, 5
• Continue dual antiplatelet therapy for 12 months 1, 2

If CABG Planned

• Continue aspirin 1, 5
• Discontinue clopidogrel 5-7 days before elective CABG 1, 5
• Discontinue ticagrelor 5 days before elective CABG 5
• Discontinue prasugrel at least 7 days before CABG 5

If Medical Management Selected

• Continue aspirin 1, 5
• Administer clopidogrel loading dose if not given before angiography 1, 5

Long-Term Management and Secondary Prevention

Cardiac Function Assessment

• Measure left ventricular ejection fraction (LVEF) in all patients 2, 5, 3
• If LVEF ≤0.40, consider diagnostic angiography 2, 5
• If LVEF >0.40, consider stress test 5

Pharmacotherapy

• ACE inhibitors for patients with heart failure, LV dysfunction (LVEF <0.40), hypertension, or diabetes; initiate within first 24 hours if pulmonary congestion or LVEF ≤0.40 present 1, 2, 5
• ARBs for ACE inhibitor-intolerant patients with heart failure or LVEF ≤0.40 1, 2, 5
• Beta-blockers continued indefinitely in all NSTEMI patients without contraindications 2, 3
• High-intensity statin therapy regardless of baseline LDL levels 2, 5, 3

Patients Requiring Long-Term Anticoagulation

• Triple antithrombotic therapy (oral anticoagulant preferably DOAC + aspirin + clopidogrel) for shortest duration possible, typically 1 week to 1 month 5, 6
• Dual therapy (DOAC + clopidogrel) for up to 1 year 5, 6
• DOAC monotherapy thereafter 5, 6
• Target INR 2.0-3.0 if warfarin used 5

Critical Contraindications and Pitfalls

Absolute Contraindications

• NSAIDs (except aspirin) during hospitalization: increased mortality, reinfarction, hypertension, heart failure, and myocardial rupture 1, 2, 3
• Fibrinolytic therapy in NSTEMI patients without ST-segment elevation 3
• Routine upstream GP IIb/IIIa inhibitors when coronary anatomy unknown: increased bleeding without ischemic benefit 1, 5

Avoid These Practices

• Immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade 2, 3
• IV ACE inhibitors within first 24 hours (except refractory hypertension): increased hypotension risk 3
• IV beta-blockers in patients with heart failure signs, low-output state, or cardiogenic shock risk factors 3
• Omeprazole or esomeprazole with clopidogrel: significantly reduces clopidogrel's antiplatelet activity 4
• Routine pre-treatment with P2Y12 inhibitor when coronary anatomy unknown and early invasive management planned 1

Special Considerations

• CYP2C19 poor metabolizers (2% of White, 4% of Black, 14% of Chinese patients): clopidogrel forms less active metabolite; consider alternative P2Y12 inhibitor 4
• Renal impairment: Adjust anticoagulation dosing; UFH preferred in severe renal impairment or end-stage renal disease 5
• Hepatic impairment: UFH preferred as it can be monitored with aPTT and does not undergo hepatic metabolism 5