What is the management approach for chest pain in non-ST-elevation myocardial infarction (NSTEMI)?

Management of Chest Pain in NSTEMI

For patients with NSTEMI presenting with chest pain, immediately administer aspirin 162-325 mg (non-enteric formulation, chewed or oral), sublingual nitroglycerin 0.4 mg every 5 minutes for up to 3 doses, supplemental oxygen if saturation <90%, and morphine sulfate IV for uncontrolled pain, while simultaneously initiating continuous ECG monitoring and risk stratification to determine invasive versus conservative management strategy. 1, 2

Immediate Anti-Ischemic Management

First-Line Interventions (Within Minutes of Presentation)

• Aspirin: Administer 162-325 mg immediately as a non-enteric formulation (chewed or oral) for rapid buccal absorption, followed by 75-162 mg daily indefinitely 1, 2
• Nitroglycerin: Give sublingual NTG 0.4 mg every 5 minutes for total of 3 doses for ongoing ischemic discomfort 1, 2
  • If chest pain persists after 3 doses, initiate intravenous NTG for the first 48 hours to treat persistent ischemia, heart failure, or hypertension 1
• Oxygen therapy: Administer supplemental oxygen only if arterial saturation is <90%, respiratory distress present, or other high-risk features for hypoxemia exist 1, 3, 2
• Analgesia: Give morphine sulfate intravenously for uncontrolled ischemic chest discomfort despite nitroglycerin 1, 3, 2

Critical Nitroglycerin Contraindications to Avoid

Do not administer nitrates if: systolic blood pressure <90 mmHg or ≥30 mmHg below baseline, severe bradycardia (<50 bpm), tachycardia (>100 bpm) without symptomatic heart failure, right ventricular infarction, or phosphodiesterase inhibitor use within 24 hours (sildenafil) or 48 hours (tadalafil) 1

Monitoring and Environment

• Admit to monitored unit with continuous ECG monitoring and bed/chair rest for at least 24 hours 1, 3, 2
• Ensure immediate availability of defibrillation equipment 3

Anti-Ischemic Medications (Within First 24 Hours)

Beta-Blockers

Initiate oral beta-blocker therapy within the first 24 hours unless the patient has: (1) signs of heart failure, (2) evidence of low-output state, (3) increased risk for cardiogenic shock, or (4) contraindications including PR interval >0.24 seconds, second or third degree heart block, active asthma, or reactive airway disease 1, 3, 2

• Critical warning: Intravenous beta blockers may be harmful in patients with contraindications, signs of heart failure, low-output state, or risk factors for cardiogenic shock 1

ACE Inhibitors

Administer ACE inhibitor orally within the first 24 hours if pulmonary congestion present or LVEF ≤0.40, provided systolic blood pressure ≥100 mmHg 1, 3, 2

• Never give intravenous ACE inhibitors within the first 24 hours due to increased risk of hypotension (exception: refractory hypertension) 1

Calcium Channel Blockers

For patients with continuing or frequently recurring ischemia in whom beta blockers are contraindicated, administer a non-dihydropyridine calcium channel blocker (verapamil 240-480 mg/day or diltiazem 120-360 mg/day) in the absence of clinically significant LV dysfunction 1

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

Antiplatelet and Anticoagulant Therapy

Dual Antiplatelet Therapy

• Continue aspirin indefinitely 1, 2
• P2Y12 inhibitor timing depends on management strategy: 1, 2, 4
  • For early invasive strategy (angiography within 24-48 hours): Delay P2Y12 inhibitor loading dose until after coronary anatomy is determined to avoid excess bleeding if urgent CABG needed 1, 4
  • For conservative strategy or delayed angiography: Administer clopidogrel 300-600 mg loading dose immediately, then 75 mg daily for up to 12 months 1, 2
  • Prasugrel contraindication: Never use in patients with prior TIA or stroke 4

Anticoagulation

Administer parenteral anticoagulation to all NSTEMI patients in addition to antiplatelet therapy 2

Preferred agents and duration:

• Unfractionated heparin: Continue for at least 48 hours or until discharge 1, 2
• Enoxaparin (preferred over UFH): Continue for duration of hospitalization, up to 8 days 1, 2
• Fondaparinux: Continue for duration of hospitalization, up to 8 days 1, 2

Risk Stratification and Management Strategy Selection

High-Risk Features Requiring Early Invasive Strategy (Angiography Within 24-48 Hours)

Proceed with early invasive approach if patient has: refractory angina despite medical therapy, hemodynamic instability, electrical instability, elevated cardiac biomarkers, or high GRACE/TIMI risk score 2, 5

Conservative Strategy

For lower-risk patients without ongoing ischemia or those with significant comorbidities where invasive risks outweigh benefits, pursue conservative management with medical therapy and stress testing 2

Critical Medications to Avoid

NSAIDs (except aspirin) are contraindicated during hospitalization due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 1, 2

Special Consideration: Type 2 NSTEMI

If Type 2 NSTEMI suspected (supply-demand mismatch from non-coronary cause), identify and treat the underlying precipitant (severe anemia requiring transfusion, tachyarrhythmias requiring rate/rhythm control, hypotension/shock requiring volume resuscitation or vasopressors, hypoxemia requiring oxygen/ventilatory support) rather than pursuing early invasive strategy unless concurrent Type 1 MI suspected or patient becomes unstable with refractory ischemia 3