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

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

All patients with NSTEMI should receive immediate aspirin 162-325 mg (chewed or non-enteric formulation), be admitted to a monitored unit with continuous cardiac rhythm monitoring, and undergo risk stratification to determine whether an early invasive strategy (angiography within 24-48 hours) or conservative approach is appropriate, followed by dual antiplatelet therapy and long-term secondary prevention. 1, 2, 3

Immediate Initial Management (First 24 Hours)

Monitoring and Supportive Care

• Admit to monitored unit with continuous ECG monitoring for at least 24 hours to detect arrhythmias and ischemia 4, 1, 2
• Bed rest during the acute phase with ongoing chest pain 4
• Supplemental oxygen only if arterial oxygen saturation is <90% by pulse oximetry—routine oxygen is not indicated 4, 1, 2

Anti-Ischemic Therapy

Aspirin:

• 162-325 mg immediately as non-enteric formulation, chewed or taken orally 1, 2, 3
• Continue 75-162 mg daily indefinitely 1, 2, 3

Nitroglycerin:

• Sublingual NTG 0.4 mg every 5 minutes for up to 3 doses for ongoing ischemic chest pain 4
• Intravenous NTG for persistent ischemia, heart failure, or hypertension in first 48 hours 4
• Contraindications: systolic BP <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) 4, 2

Beta-Blockers:

• Initiate oral beta-blocker within first 24 hours to reduce myocardial oxygen demand by decreasing heart rate, blood pressure, and contractility 4, 1
• Do NOT give if: signs of heart failure, low-output state, increased risk for cardiogenic shock (age >70 years, systolic BP <120 mmHg, sinus tachycardia >110 bpm or heart rate <60 bpm), PR interval >0.24 seconds, second or third-degree heart block, active asthma, or reactive airway disease 4
• Avoid intravenous beta-blockers due to increased risk of cardiogenic shock 4

Morphine:

• Consider morphine sulfate IV for uncontrolled ischemic chest pain despite nitroglycerin or when acute pulmonary congestion/severe agitation is present 4, 3

Antiplatelet Therapy

Dual Antiplatelet Therapy (DAPT)

• Continue aspirin 75-162 mg daily indefinitely (Level of Evidence: A) 1, 2, 3
• Add P2Y12 inhibitor for 12 months unless contraindicated or high bleeding risk 1, 2

P2Y12 Inhibitor Selection:

• Ticagrelor is preferred: loading dose 180 mg, then 90 mg twice daily—recommended regardless of invasive or conservative strategy 1, 2
• Clopidogrel alternative: loading dose 300-600 mg, then 75 mg daily 3
• Discontinue clopidogrel 5-7 days before elective CABG (Level of Evidence: B) 3

Anticoagulant Therapy

All NSTEMI patients require parenteral anticoagulation in addition to antiplatelet therapy 1, 2, 3

Options:

• Unfractionated heparin (UFH): continue for at least 48 hours or until discharge if given before diagnostic angiography (Level of Evidence: A) 1, 2, 3
• Enoxaparin: continue for duration of hospitalization, up to 8 days, if given before angiography (Level of Evidence: A) 2, 3
• Fondaparinux: continue for duration of hospitalization, up to 8 days, if given before angiography (Level of Evidence: B) 3
• Bivalirudin: alternative option 3

Risk Stratification and Management Strategy Selection

Early Invasive Strategy (Angiography within 24-48 hours)

Indicated for patients with: 4, 1, 2, 3

• Refractory angina despite medical therapy
• Hemodynamic instability
• Electrical instability (sustained ventricular tachycardia/fibrillation)
• Elevated cardiac biomarkers (especially troponin)
• High GRACE or TIMI risk score
• Recurrent ischemia with ST-segment deviations ≥0.05 mV
• New or worsening heart failure symptoms, S3 gallop, or mitral regurgitation
• Left ventricular dysfunction (LVEF <0.40)

Conservative Strategy

Appropriate for: 4, 3

• Lower-risk patients without ongoing ischemia
• Patients with significant comorbidities where invasive risks outweigh benefits
• Requires noninvasive stress testing before discharge or shortly thereafter to identify patients who may benefit from revascularization 4

Post-Angiography Management

If PCI Performed:

• Continue aspirin (Level of Evidence: A) 1, 2, 3
• Administer P2Y12 inhibitor loading dose if not started before angiography (Level of Evidence: A) 1, 2, 3

If CABG Planned:

• Continue aspirin (Level of Evidence: A) 3
• Discontinue clopidogrel 5-7 days before elective CABG (Level of Evidence: B) 3

If Medical Management Selected:

• Continue aspirin (Level of Evidence: A) 3
• Administer P2Y12 inhibitor loading dose if not given before angiography (Level of Evidence: A/B) 3

Long-Term Management and Secondary Prevention

Cardiac Function Assessment

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

ACE Inhibitors/ARBs

• Initiate ACE inhibitor within first 24 hours for patients with pulmonary congestion, LVEF ≤0.40, hypertension, or diabetes 4, 1, 2, 3
• ARBs for ACE inhibitor-intolerant patients 1, 3
• Avoid intravenous ACE inhibitors within first 24 hours due to hypotension risk (exception: refractory hypertension) 4, 2

Beta-Blockers

• Continue indefinitely in all NSTEMI patients without contraindications 2

Statins

• Initiate high-intensity statin therapy regardless of baseline LDL levels 2, 3

Calcium Channel Blockers

• Non-dihydropyridine CCB (verapamil or diltiazem) for continuing/recurring ischemia when beta-blockers are contraindicated, in absence of significant LV dysfunction 4

Patient Education and Discharge Planning

• Provide sublingual or spray NTG and instruct in its use 4
• Educate on symptoms of worsening ischemia and when to seek emergency care 4
• Anginal discomfort >2-3 minutes: discontinue activity, take 1 dose NTG; if pain unimproved or worsening after 5 minutes, call 9-1-1 immediately; may take additional NTG at 5-minute intervals twice while awaiting EMS 4
• Enroll in cardiac rehabilitation program after discharge to enhance education and compliance 4
• Follow-up within 72 hours with primary care physician for low-risk patients 4

Critical Contraindications and Pitfalls

Absolute Contraindications

• NSAIDs (except aspirin) are harmful during hospitalization due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 4, 1, 2, 3
• Immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade should not be given 1, 2, 3
• Fibrinolytic therapy is contraindicated in NSTEMI patients without ST-segment elevation 2

High-Risk Situations Requiring Caution

• Cardiogenic shock risk factors: age >70 years, systolic BP <120 mmHg, sinus tachycardia >110 bpm or heart rate <60 bpm, increased time since symptom onset 4
• Intravenous beta-blockers should not be administered to patients with contraindications, signs of heart failure, low-output state, or cardiogenic shock risk factors 4, 2