What is the appropriate management for a patient presenting with Acute Coronary Syndrome (ACS) non-ST-elevation myocardial infarction (nstemi)?

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

All NSTEMI patients require immediate dual antiplatelet therapy (aspirin plus ticagrelor preferred), parenteral anticoagulation, high-intensity statin therapy, and risk-stratified invasive coronary angiography within 2-72 hours depending on clinical presentation. 1, 2

Immediate Assessment and Diagnosis

• Obtain 12-lead ECG within 10 minutes of presentation to confirm non-ST-elevation pattern 3
• Measure high-sensitivity troponin at 0 and 1 hour using validated algorithm, or at 0 and 3 hours if 1-hour protocol unavailable 1
• Initiate continuous cardiac monitoring for arrhythmia detection 3
• Perform echocardiography to assess left ventricular function and exclude mechanical complications 1
• Calculate GRACE score for risk stratification to determine timing of invasive strategy 1

Risk-Stratified Timing of Invasive Strategy

Very High-Risk (Immediate angiography <2 hours): 1

• Hemodynamic instability or cardiogenic shock
• Recurrent or ongoing chest pain refractory to medical treatment
• Life-threatening arrhythmias or cardiac arrest
• Mechanical complications of MI
• Acute heart failure with refractory angina or ST-segment deviation

High-Risk (Early angiography <24 hours): 1, 2

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

Intermediate-Risk (Invasive strategy <72 hours): 1

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

Immediate Antiplatelet Therapy

Aspirin: 1, 4, 3

• Loading dose: 150-325 mg orally immediately
• Maintenance: 75-100 mg daily indefinitely (81 mg daily when combined with ticagrelor) 1

P2Y12 Inhibitor (choose one): 1, 2

• Ticagrelor (preferred for moderate-to-high risk patients): 180 mg loading dose, then 90 mg twice daily for 12 months, regardless of invasive or conservative strategy 1, 2
• Prasugrel: 60 mg loading dose, then 10 mg daily (reduce to 5 mg daily if age ≥75 years or weight <60 kg), only after coronary anatomy is known and PCI planned, contraindicated if prior stroke/TIA 1
• Clopidogrel: 300-600 mg loading dose, then 75 mg daily, reserved for patients who cannot receive ticagrelor or prasugrel, or who require oral anticoagulation 1

The 2014 AHA/ACC guidelines suggest it is reasonable to use ticagrelor in preference to clopidogrel for patients undergoing early invasive or ischemia-guided strategy, while the 2015 ESC guidelines more strongly recommend ticagrelor for all moderate-to-high risk patients with elevated troponin. 1

Parenteral Anticoagulation (Choose One)

For patients managed medically or awaiting angiography: 1, 4, 2

• Fondaparinux (preferred for conservative management): 2.5 mg subcutaneously once daily, best efficacy-safety profile 1, 4
  • Critical caveat: Must add UFH or bivalirudin during PCI due to catheter thrombosis risk 1, 4
• Enoxaparin: 1 mg/kg subcutaneously every 12 hours (reduce to 1 mg/kg once daily if CrCl <30 mL/min), with optional 30 mg IV loading dose 1, 4, 2
• Unfractionated heparin: 60 IU/kg IV bolus (max 4000 IU), then 12 IU/kg/hour infusion (max 1000 IU/hour), adjusted to aPTT 1.5-2.5 times control 1, 4

For patients proceeding directly to PCI: 1, 2

• Bivalirudin: 0.10 mg/kg loading dose, then 0.25 mg/kg/hour infusion until angiography/PCI, with provisional GP IIb/IIIa inhibitor use only 1

Continue anticoagulation for duration of hospitalization or until PCI performed, up to 48-72 hours for medical management. 1, 4

Glycoprotein IIb/IIIa Inhibitors

Routine upstream GP IIb/IIIa inhibitors are NOT recommended due to increased bleeding without ischemic benefit. 2

Selective use may be considered: 1, 5, 6, 5

• In intermediate-to-high risk patients (positive troponin) during PCI with provisional use only 1
• Eptifibatide: 180 mcg/kg IV bolus, then 2 mcg/kg/min infusion (reduce to 1 mcg/kg/min if CrCl <50 mL/min), with second 180 mcg/kg bolus 10 minutes after first for PCI patients 5
• Tirofiban: Dosing per FDA label, demonstrated 32% risk reduction in composite endpoint of death, MI, or refractory ischemia at 7 days in PRISM-PLUS trial 6

High-Intensity Statin Therapy

Initiate immediately upon admission regardless of baseline cholesterol levels: 1, 2, 3

• Target LDL-C <1.8 mmol/L (<70 mg/dL) 1
• Atorvastatin 80 mg daily is the evidence-based high-intensity regimen 1
• Provides plaque stabilization and anti-inflammatory effects beyond LDL lowering 2
• Continue indefinitely for secondary prevention 1

Additional Acute Medical Management

Beta-blockers: 1, 4, 3

• Initiate early in patients without contraindications (heart failure, hypotension, bradycardia, heart block) 4
• Particularly important if LVEF ≤40% 1, 3

Nitrates: 4

• For ongoing chest pain, uncontrolled hypertension, or signs of heart failure 4

ACE inhibitors or ARBs: 1, 3

• Recommended for patients with LVEF ≤40%, heart failure, hypertension, or diabetes 1, 3
• ARBs for ACE inhibitor-intolerant patients 1

Aldosterone blockade (eplerenone): 1

• For post-MI patients already on ACE inhibitor and beta-blocker with LVEF ≤35% and either diabetes or heart failure, without significant renal dysfunction 1

Post-Revascularization and Long-Term Management

Dual antiplatelet therapy: 1, 4, 2, 3

• Continue aspirin plus P2Y12 inhibitor (ticagrelor or clopidogrel) for 12 months after PCI unless excessive bleeding risk 1, 4
• After 12 months, transition to aspirin monotherapy indefinitely 4, 3

If clopidogrel used and CABG planned: 1

• Discontinue clopidogrel 5 days prior to scheduled surgery 1

Special Populations

Renal impairment (CrCl <60 mL/min): 1, 4

• Adjust anticoagulant doses: enoxaparin to 1 mg/kg once daily if CrCl <30 mL/min 1, 4
• Eptifibatide infusion reduced to 1 mcg/kg/min if CrCl <50 mL/min 5

Elderly patients (≥75 years): 4

• Apply same diagnostic and therapeutic strategies 4
• Reduce prasugrel dose to 5 mg daily if used 4

Patients requiring oral anticoagulation (e.g., atrial fibrillation): 4

• Triple therapy (aspirin + clopidogrel + oral anticoagulant) for acute phase only (up to 1 week) 4
• Transition to dual therapy with oral anticoagulant plus clopidogrel (not ticagrelor or prasugrel) after acute phase, continue for up to 12 months 4, 7
• Then oral anticoagulant monotherapy thereafter 7

Critical Contraindications

Fibrinolytic therapy is contraindicated in NSTEMI and causes harm. 1

Prasugrel should not be administered until coronary anatomy is known. 1