What is the immediate management for a patient presenting with Acute Coronary Syndrome (ACS) Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Immediate Management of NSTEMI

Administer aspirin 162-325 mg (non-enteric-coated, chewable) immediately upon presentation, followed by a P2Y12 inhibitor (ticagrelor 180 mg loading dose preferred), and initiate parenteral anticoagulation with either enoxaparin, fondaparinux, or unfractionated heparin—then perform risk stratification to determine timing of coronary angiography. 1, 2, 3

Immediate Antiplatelet Therapy

Aspirin:

• Give non-enteric-coated, chewable aspirin 162-325 mg immediately to all patients without contraindications 1
• Continue maintenance dose 81 mg daily indefinitely 1, 2
• Enteric-coated formulations should be avoided initially due to delayed absorption 1

P2Y12 Inhibitor Selection:

• Ticagrelor is the preferred agent (180 mg loading, then 90 mg twice daily) for all moderate-to-high risk NSTEMI patients regardless of management strategy 2, 3
• Ticagrelor provides more potent and consistent platelet inhibition than clopidogrel 3
• Clopidogrel (300-600 mg loading, 75 mg daily) is indicated when ticagrelor is contraindicated or when oral anticoagulation is required 2
• Prasugrel should NOT be given until coronary anatomy is known 2, 4
• In patients with aspirin allergy or intolerance, use clopidogrel loading dose followed by maintenance dosing 1

Immediate Parenteral Anticoagulation

All NSTEMI patients require parenteral anticoagulation in addition to dual antiplatelet therapy from the time of diagnosis. 1, 2, 3

Anticoagulant Options:

• Enoxaparin: 1 mg/kg subcutaneous every 12 hours (reduce to 1 mg/kg once daily if creatinine clearance <30 mL/min); optional 30 mg IV loading dose 1
• Fondaparinux: 2.5 mg subcutaneous once daily—has the best efficacy-safety profile for conservative management 1, 3
  • Critical caveat: If patient receives fondaparinux and subsequently undergoes PCI, must give single bolus of unfractionated heparin at time of PCI to prevent catheter thrombosis 1, 2
• Unfractionated heparin: 60 IU/kg IV bolus (maximum 4000 IU) followed by 12 IU/kg/hour infusion (maximum 1000 IU/hour), adjusted to aPTT per hospital protocol 1
• Bivalirudin: 0.10 mg/kg loading dose followed by 0.25 mg/kg/hour—only for patients managed with early invasive strategy 1

Risk Stratification and Timing of Angiography

Risk stratification determines the urgency of invasive coronary angiography, as higher-risk patients derive greater mortality benefit from earlier revascularization. 3

Immediate Invasive Strategy (<2 hours): Proceed immediately to catheterization if ANY of the following are present: 2, 3

• 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 deviation

Early Invasive Strategy (<24 hours): Perform coronary angiography within 24 hours if ANY of the following: 2, 3

• Rise or fall in cardiac troponin compatible with MI
• Dynamic ST- or T-wave changes (≥0.5 mm)
• GRACE score >140

Invasive Strategy (<72 hours): Perform angiography within 72 hours if intermediate-risk criteria present: 2

• Diabetes mellitus
• Renal insufficiency (eGFR <60 mL/min/1.73 m²)
• GRACE score 109-140

Anti-Ischemic Therapy

Nitroglycerin:

• Administer sublingual or IV nitroglycerin for ongoing chest pain 3
• Contraindications: Systolic BP <90 mmHg, >30 mmHg below baseline, severe bradycardia <50 bpm, tachycardia >100 bpm without heart failure, or recent phosphodiesterase inhibitor use 3

Beta-Blockers:

• Initiate early in patients without contraindications (heart failure, hypotension, bradycardia, heart block) 3
• Reduces mortality in NSTEMI patients 2

High-Intensity Statin Therapy

Initiate high-intensity statin therapy immediately upon admission and continue indefinitely. 1, 3

• Statins reduce recurrent ischemic events through plaque stabilization and anti-inflammatory effects beyond LDL lowering 3
• Target LDL-C <70 mg/dL (<1.8 mmol/L) 1
• Atorvastatin 80 mg or equivalent high-intensity statin should be used 1

ACE Inhibitors/ARBs

Initiate within 24 hours in patients with: 1, 3

• LVEF ≤40%
• Heart failure
• Diabetes
• Hypertension
• Chronic kidney disease

Dosing considerations:

• Start with short-acting ACE inhibitor (captopril or enalapril) in patients at increased risk of hypotension or renal dysfunction 1
• ARBs are recommended for patients intolerant to ACE inhibitors 1

Special Populations and Dosing Adjustments

Elderly patients (≥75 years):

• Prasugrel generally not recommended due to increased bleeding risk; if used, reduce to 5 mg daily 4
• Adjust antithrombotic dosing based on renal function and bleeding risk 3

Low body weight (<60 kg):

• Consider reducing prasugrel maintenance dose to 5 mg daily due to increased bleeding risk 4

Renal impairment:

• Enoxaparin: reduce to 1 mg/kg once daily if CrCl <30 mL/min 1
• Use low- or iso-osmolar contrast if angiography performed 3

Duration of Dual Antiplatelet Therapy

Continue aspirin plus P2Y12 inhibitor for 12 months unless excessive bleeding risk, then transition to aspirin monotherapy indefinitely. 1, 2, 3

• This duration balances ischemic event reduction against bleeding risk 3