What is the initial treatment for Non-ST-Elevation Myocardial Infarction (NSTEMI) in the Emergency Room (ER)?

Initial Emergency Room Treatment for NSTEMI

Administer aspirin 162-325 mg immediately (non-enteric, chewed or oral) upon presentation, admit to a monitored unit with continuous cardiac rhythm monitoring for at least 24 hours, initiate anticoagulation, and add a P2Y12 inhibitor (preferably ticagrelor) to aspirin for dual antiplatelet therapy. 1, 2, 3

Immediate Actions Upon Presentation

Aspirin Administration

• Give aspirin 162-325 mg immediately as a non-enteric formulation, either chewed or taken orally, regardless of prior aspirin use 1, 3
• Continue aspirin 75-162 mg daily indefinitely after the initial loading dose 2, 3

Monitoring and Admission

• Admit all NSTEMI patients to a monitored unit (intermediate care or telemetry) with continuous cardiac rhythm monitoring for at least 24 hours to detect arrhythmias 1, 2, 3
• Obtain 12-lead ECG within 10 minutes of first medical contact 1
• Measure cardiac troponin (preferably high-sensitivity) on admission with results available within 60 minutes, and repeat at 1-3 hours if using high-sensitivity assays 1

Oxygen Therapy

• Administer supplemental oxygen ONLY if arterial oxygen saturation is <90%, respiratory distress, or other high-risk features of hypoxemia are present 1, 2, 3
• Do not give routine oxygen to normoxic patients, as benefit has never been demonstrated 1

Anti-Ischemic Therapy

Nitroglycerin

• Administer sublingual or intravenous nitroglycerin for ongoing ischemic chest pain 2, 3
• Contraindications include: systolic blood pressure <90 mmHg or ≥30 mmHg below baseline, severe bradycardia (<50 bpm), tachycardia (>100 bpm without heart failure), right ventricular infarction, or phosphodiesterase inhibitor use within 24 hours (sildenafil/vardenafil) or 48 hours (tadalafil) 3

Beta-Blockers

• Initiate oral beta-blocker therapy (preferred over intravenous) within the first 24 hours to reduce myocardial oxygen demand by decreasing heart rate, blood pressure, and contractility 2, 3
• Do not administer intravenous beta-blockers to patients with signs of heart failure, low-output state, cardiogenic shock risk factors, or other contraindications 3

Antiplatelet Therapy

Dual Antiplatelet Therapy (DAPT)

• Add a P2Y12 receptor inhibitor to aspirin for 12 months unless contraindicated or at high bleeding risk 2, 3
• Ticagrelor is the preferred P2Y12 inhibitor: loading dose 180 mg, then 90 mg twice daily, regardless of invasive or conservative strategy 1, 2, 3

Alternative P2Y12 Inhibitors

• Clopidogrel (loading dose 300-600 mg, then 75 mg daily) is an alternative if ticagrelor is contraindicated or unavailable 1, 2
• Prasugrel (60 mg loading dose, then 10 mg daily) may be used at the time of PCI if coronary anatomy is known, but is contraindicated in patients with prior stroke/TIA, age ≥75 years (except high-risk situations), or weight <60 kg 1, 4

Timing Considerations for P2Y12 Inhibitors

• For patients undergoing early invasive strategy, upstream administration of ticagrelor or clopidogrel before diagnostic angiography is appropriate 1, 2
• For prasugrel specifically, do not administer until coronary anatomy is established in UA/NSTEMI patients, as no clear benefit was observed with early administration and bleeding risk increased 4

GP IIb/IIIa Inhibitors

• Consider adding a GP IIb/IIIa inhibitor (eptifibatide or tirofiban preferred over abciximab for upstream use) in high-risk patients, particularly those with elevated troponins or diabetes 1
• Abciximab is indicated only if there is no appreciable delay to angiography and PCI is likely to be performed 1

Anticoagulation Therapy

Parenteral Anticoagulation

• Administer parenteral anticoagulation to all NSTEMI patients in addition to antiplatelet therapy 2, 3
• Unfractionated heparin (UFH) should be continued for at least 48 hours or until discharge if given before diagnostic angiography 2, 3
• Enoxaparin should be continued for the duration of hospitalization, up to 8 days, if given before angiography 3
• For dialysis patients, bivalirudin or UFH are preferred anticoagulants, as bivalirudin does not require renal dosing and has less bleeding risk 5

Risk Stratification and Management Strategy

Early Invasive Strategy Indications

• Perform coronary angiography within 24-48 hours for patients with: 2, 3
  • Refractory angina or ongoing ischemia
  • Hemodynamic instability
  • Electrical instability (life-threatening arrhythmias)
  • Elevated cardiac biomarkers (troponin)
  • High GRACE or TIMI risk score
  • Left ventricular ejection fraction (LVEF) ≤0.40

Immediate Invasive Strategy

• Patients with ongoing myocardial ischemia or hemodynamic compromise should undergo immediate coronary angiography irrespective of ECG or biomarker findings 1
• In cases of ongoing ischemia, place defibrillator patches until urgent revascularization is performed 1

Conservative Strategy

• A conservative (non-invasive) strategy is appropriate for lower-risk patients without ongoing ischemia or significant comorbidities where invasive risks outweigh benefits 3
• For conservative strategy patients, add clopidogrel to aspirin and anticoagulant therapy for at least 1 month and ideally up to 1 year 1

Critical Contraindications and Pitfalls

Medications to Avoid

• Do not administer NSAIDs (except aspirin) during hospitalization due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 2, 3
• Do not give immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade 2, 3
• Avoid intravenous ACE inhibitors within the first 24 hours due to hypotension risk (exception: refractory hypertension) 3
• Fibrinolytic therapy is contraindicated in NSTEMI patients without ST-segment elevation 3

Special Populations

• In patients <60 kg receiving prasugrel, consider lowering maintenance dose to 5 mg daily due to increased bleeding risk 4
• For dialysis patients, recognize increased bleeding risk and adjust medication doses based on creatinine clearance using the Cockroft-Gault formula 5
• Do not use low-molecular-weight heparins or fondaparinux without proper dose adjustment in severe renal dysfunction 5

Additional Laboratory and Diagnostic Work

• Obtain serum creatinine, hemoglobin, hematocrit, platelet count, blood glucose, and INR (if on warfarin) on admission 1
• Assess lipid profile in the early phase of admission if NSTE-ACS is confirmed 1
• Measure LVEF in all patients 3