What is the management approach for Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Management of Non-ST-Elevation Myocardial Infarction (NSTEMI)

Immediately administer aspirin 162-325 mg (non-enteric formulation, chewed or oral) upon presentation, initiate parenteral anticoagulation, admit to a monitored unit, and perform risk stratification to determine whether an early invasive strategy (angiography within 24-48 hours) or conservative approach is appropriate. 1, 2

Immediate Initial Management (First Hours)

• Administer aspirin 162-325 mg immediately as a non-enteric formulation, either chewed or taken orally, regardless of prior aspirin use 3, 1, 2

• Admit to a monitored unit with continuous cardiac rhythm monitoring for at least 24 hours to detect arrhythmias 1, 2

• Provide supplemental oxygen only if arterial oxygen saturation is <90%; routine oxygen is not indicated 1, 2

• Administer sublingual or intravenous nitroglycerin for ongoing ischemic chest pain, but avoid if:

  • Systolic blood pressure <90 mmHg or ≥30 mmHg below baseline 3
  • Severe bradycardia (<50 bpm) or tachycardia (>100 bpm without heart failure) 3
  • Right ventricular infarction 3
  • Phosphodiesterase inhibitor use within 24 hours (sildenafil) or 48 hours (tadalafil) 3

• Initiate beta-blocker therapy (oral preferred over intravenous) to reduce myocardial oxygen demand by decreasing heart rate, blood pressure, and contractility, unless contraindications exist 1, 2

• Consider morphine sulfate intravenously only for uncontrolled ischemic chest discomfort despite nitroglycerin 2

Antiplatelet Therapy

Aspirin

• Continue aspirin 75-162 mg daily indefinitely after the initial loading dose 1, 2, 4
• After stent placement, use 162-325 mg daily for 1 month (bare-metal stent), 3 months (sirolimus-eluting stent), or 6 months (paclitaxel-eluting stent), then reduce to 75-162 mg daily 3

P2Y12 Inhibitor Selection

• Add a P2Y12 receptor inhibitor to aspirin for 12 months unless contraindicated or high bleeding risk 1, 4

• Preferred agents (in order of preference):

  • Ticagrelor: Loading dose 180 mg, then 90 mg twice daily—recommended regardless of invasive or conservative strategy 1, 4
  • Prasugrel: Loading dose 60 mg, then 10 mg daily (reduce to 5 mg daily if age ≥75 years or weight <60 kg)—only for patients undergoing PCI who are P2Y12 inhibitor-naïve 4
  • Clopidogrel: Loading dose 300-600 mg, then 75 mg daily—use only when ticagrelor or prasugrel are unavailable, not tolerated, or contraindicated 4, 5

• Critical clopidogrel caveat: Patients who are CYP2C19 poor metabolizers have reduced conversion to active metabolite and diminished antiplatelet effect; consider genetic testing and alternative P2Y12 inhibitor if identified 5

• Avoid concomitant omeprazole or esomeprazole with clopidogrel as they significantly reduce its antiplatelet activity 5

Anticoagulant Therapy

• Administer parenteral anticoagulation to all NSTEMI patients in addition to antiplatelet therapy 1, 2, 4, 6

Anticoagulant Options:

• Unfractionated heparin (UFH): Continue for at least 48 hours or until discharge if given before angiography 3, 2, 4
• Enoxaparin: Continue for duration of hospitalization, up to 8 days, if given before angiography 3, 2, 4
• Fondaparinux: Continue for duration of hospitalization, up to 8 days, if given before angiography 3, 2, 4
• Bivalirudin: Either discontinue or continue at 0.25 mg/kg/hour for up to 72 hours at physician's discretion 3

Risk Stratification and Management Strategy Selection

Early Invasive Strategy (Angiography Within 24-48 Hours) - Indicated For:

• Refractory angina despite medical therapy 1, 2, 4
• Hemodynamic instability or cardiogenic shock 1, 2, 4
• Electrical instability (ventricular arrhythmias) 1, 2, 4
• Elevated cardiac biomarkers (troponin positive) 1, 2, 4
• High GRACE or TIMI risk score 1, 2, 4

Conservative Strategy - Appropriate For:

• Lower-risk patients without ongoing ischemia 2, 4
• Significant comorbidities where invasive risks outweigh benefits 2, 4
• If conservative strategy selected: Perform stress testing if no recurrent symptoms, heart failure, or serious arrhythmias develop 3

Post-Angiography Management

If PCI Selected:

• Continue aspirin 3, 2
• Administer P2Y12 inhibitor loading dose if not given before angiography (clopidogrel 300-600 mg or ticagrelor 180 mg) 3, 2
• Administer intravenous GP IIb/IIIa inhibitor (abciximab, eptifibatide, or tirofiban) for troponin-positive and high-risk patients if not started before angiography 3
• Discontinue anticoagulant therapy after uncomplicated PCI 3
• Continue dual antiplatelet therapy: For bare-metal stents, at least 1 month (ideally up to 1 year); for drug-eluting stents, at least 1 year in patients not at high bleeding risk 3

If CABG Selected:

• Continue aspirin 3, 2
• Discontinue clopidogrel 5-7 days before elective CABG 3, 2
• Discontinue prasugrel at least 7 days before surgery 4
• Discontinue ticagrelor at least 5 days before surgery 4
• Discontinue GP IIb/IIIa inhibitors (eptifibatide or tirofiban) 4 hours before CABG 3
• Manage anticoagulation: Continue UFH; discontinue enoxaparin 12-24 hours before CABG; discontinue fondaparinux 24 hours before CABG; discontinue bivalirudin 3 hours before CABG 3

If Medical Management Selected:

• Continue aspirin 3, 2
• Administer P2Y12 inhibitor loading dose if not given before angiography 3, 2
• Discontinue intravenous GP IIb/IIIa inhibitor if started previously 3
• Continue anticoagulation: UFH for at least 48 hours or until discharge; enoxaparin or fondaparinux for duration of hospitalization up to 8 days 3

Long-Term Management and Risk Assessment

• Measure left ventricular ejection fraction (LVEF) in all patients 3, 2, 4

• If LVEF ≤0.40: Consider diagnostic angiography 3, 2, 4

• If LVEF >0.40: Perform stress testing 3, 2, 4

• If stress test shows high risk: Proceed to diagnostic angiography 3

• If stress test shows low risk: Prepare for discharge with appropriate medications 3

Secondary Prevention Medications:

• ACE inhibitors: Initiate for patients with heart failure, LV dysfunction (LVEF <0.40), hypertension, or diabetes 1, 2, 4
• ARBs: Use for ACE inhibitor-intolerant patients 1, 2
• Beta-blockers: Continue indefinitely in all NSTEMI patients without contraindications 4
• High-intensity statin therapy: Initiate regardless of baseline LDL levels 2

Long-Term Anticoagulation (If Atrial Fibrillation or Other Indication):

• Triple therapy (DOAC + aspirin + clopidogrel) for up to 1 month (typically 1 week or until hospital discharge) 6
• Dual therapy (DOAC + clopidogrel) for up to 1 year 6
• DOAC monotherapy thereafter 6

Critical Contraindications and Pitfalls

• Never administer NSAIDs (except aspirin) during hospitalization—associated with increased mortality, reinfarction, hypertension, heart failure, and myocardial rupture 3, 1, 2

• Never give immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade 3, 1, 2

• Avoid intravenous ACE inhibitors within the first 24 hours due to hypotension risk (exception: refractory hypertension) 3, 2

• Do not administer intravenous beta blockers to patients with contraindications, signs of heart failure, low-output state, or cardiogenic shock risk factors 3

• Fibrinolytic therapy is contraindicated in NSTEMI patients without ST-segment elevation 3

• Platelet transfusions may be less effective if given within 4 hours of clopidogrel loading dose or 2 hours of maintenance dose 5