What is the management of unstable angina?

Management of Unstable Angina

The management of unstable angina requires immediate antiplatelet therapy with aspirin and clopidogrel, anticoagulation with heparin, anti-ischemic therapy with nitrates and beta-blockers, and risk stratification to determine the timing of invasive management. 1

Initial Assessment and Risk Stratification

Initial management should focus on rapid diagnosis and risk stratification:

1. Risk Assessment Tools:

   • Use validated scoring systems such as TIMI Risk Score or GRACE Risk Score 1
   • High-risk features include:
     • Age ≥65 years
     • ≥3 coronary artery disease risk factors
     • Known coronary stenosis ≥50%
     • ST-segment deviation on ECG
     • ≥2 anginal episodes in past 24 hours
     • Elevated cardiac markers (troponins)
     • Prior aspirin use 1

2. Immediate Measures:

   • Continuous cardiac monitoring
   • Oxygen if SaO₂ <90% or respiratory distress
   • Establish IV access
   • Obtain 12-lead ECG within 10 minutes of arrival 1

Pharmacological Management

Antiplatelet Therapy

1. Aspirin:

   • Administer 162-325 mg (chewed, non-enteric coated) immediately
   • Continue with maintenance dose of 75-100 mg/day long-term 1
   • Aspirin reduces risk of death and MI in unstable angina 2

2. P2Y12 Inhibitor:

   • Clopidogrel: Loading dose of 300 mg followed by 75 mg daily 3
   • Should be administered in conjunction with aspirin 3
   • Continue for 12 months 1
   • Consider genetic testing for CYP2C19 poor metabolizers, as clopidogrel may have diminished effect in these patients 3

Anticoagulation

• Options include:
  • Unfractionated heparin (UFH): 60-70 U/kg IV bolus, followed by 12-15 U/kg/hr infusion
  • Enoxaparin: 1 mg/kg subcutaneously every 12 hours
  • Fondaparinux: 2.5 mg subcutaneously daily 2, 1
• Continue for at least 48 hours or until revascularization 2

Anti-Ischemic Therapy

1. Nitrates:

   • Sublingual nitroglycerin 0.4 mg for acute symptoms
   • IV nitroglycerin (10 μg/min initial dose) for persistent pain 1

2. Beta-Blockers:

   • Initiate within 24 hours if no contraindications 1
   • Metoprolol: Effective for reducing heart rate, blood pressure, and cardiac output 4
   • Caution: May precipitate heart failure in susceptible patients; monitor closely 4
   • Do not abruptly discontinue in patients with coronary artery disease 4

3. Statins:

   • High-intensity statin therapy should be initiated early 1

4. Morphine Sulfate:

   • Reserved for uncontrolled ischemic chest pain despite nitroglycerin 1

Invasive vs. Conservative Strategy

Early Invasive Strategy (within 24-48 hours)

• Recommended for high-risk patients:
  • Recurrent angina/ischemia at rest or with low-level activities
  • Elevated cardiac biomarkers (troponin)
  • New or presumably new ST-segment depression
  • Signs or symptoms of heart failure
  • High-risk findings on non-invasive testing
  • Reduced left ventricular function (LVEF <40%)
  • Hemodynamic instability 2, 1

Conservative Strategy

• Suitable for low-risk patients:
  • No recurrent chest pain
  • No signs of heart failure
  • Normal ECG or ECG with unchanged from baseline
  • Normal troponin levels 2, 1
• Measure LVEF; if ≤0.40, consider diagnostic angiography 2
• If LVEF >0.40, perform stress testing 2

Revascularization

• PCI (Percutaneous Coronary Intervention):

  • Continue aspirin and administer loading dose of clopidogrel if not given previously
  • Consider GP IIb/IIIa inhibitor for troponin-positive and high-risk patients
  • Discontinue anticoagulant therapy after uncomplicated PCI 2

• CABG (Coronary Artery Bypass Grafting):

  • If selected, discontinue clopidogrel 5-7 days before surgery
  • Discontinue enoxaparin 12-24 hours before surgery
  • Discontinue fondaparinux 24 hours before surgery
  • Discontinue bivalirudin 3 hours before surgery 2

Long-Term Management

• Secondary Prevention:
  • Continued antiplatelet therapy
  • Beta-blockers
  • ACE inhibitors/ARBs (especially with LV dysfunction)
  • High-intensity statins
  • Lifestyle modifications (smoking cessation, exercise, diet)
  • Cardiac rehabilitation 1

Common Pitfalls and Caveats

1. Avoid fibrinolytic therapy in unstable angina without ST-segment elevation, as it is contraindicated and potentially harmful 2

2. Monitor for bleeding complications with dual antiplatelet therapy and anticoagulation 3

3. Consider proton pump inhibitors for patients at high risk of gastrointestinal bleeding who are receiving antiplatelet therapy 1

4. Do not abruptly discontinue beta-blockers in patients with coronary artery disease, as this can exacerbate angina and precipitate MI 4

5. Be aware of CYP2C19 poor metabolizers who may have reduced response to clopidogrel; consider alternative P2Y12 inhibitors in these patients 3