What is the management of unstable angina?

Management of Unstable Angina

The management of unstable angina requires immediate antiplatelet therapy with aspirin, addition of a P2Y12 inhibitor (preferably clopidogrel), anticoagulation with either unfractionated heparin or low molecular weight heparin, and risk stratification to determine the need for an early invasive strategy. 1

Initial Assessment and Risk Stratification

Risk assessment is crucial for determining the appropriate management strategy:

High-Risk Features:

• Recurrent ischemia despite treatment
• Elevated cardiac troponins
• Dynamic ST-segment changes
• Heart failure signs
• Hemodynamic instability
• Major arrhythmias
• Diabetes mellitus
• High GRACE or TIMI risk scores
• LVEF ≤ 0.40

Risk Assessment Tools:

• TIMI Risk Score: Age ≥65 years, ≥3 coronary risk factors, prior coronary stenosis, ST-segment deviation, ≥2 angina events within 24 hours, aspirin use within 7 days, and elevated cardiac markers 2
• GRACE Risk Score: Considers age, heart rate, systolic blood pressure, ST-segment depression, signs of heart failure, and cardiac biomarkers 2

Immediate Management

Antiplatelet Therapy:

1. Aspirin:

   • Loading dose: 162-325 mg (non-enteric coated, chewed or crushed)
   • Maintenance dose: 81 mg daily indefinitely 1

2. P2Y12 Inhibitor:

   • Clopidogrel: 300-600 mg loading dose (600 mg preferred for planned invasive strategy), followed by 75 mg daily 3
   • Continue for at least 1 month and ideally up to 12 months 2, 1
   • Withhold 5-7 days before elective CABG 2

Anticoagulation:

• Unfractionated heparin (UFH): IV bolus and infusion for at least 48 hours or until PCI 1
• Enoxaparin: 1 mg/kg SC every 12 hours for duration of hospitalization up to 8 days 1

Anti-ischemic Therapy:

1. Nitroglycerin:

   • Sublingual or IV for ongoing chest pain
   • Contraindicated if systolic BP <90 mmHg, severe bradycardia, tachycardia without heart failure, or right ventricular infarction 1

2. Beta-Blockers:

   • Start early in absence of contraindications
   • IV administration followed by oral therapy in high-risk patients
   • Example regimen: IV metoprolol 5 mg increments (up to 15 mg total), followed by oral metoprolol 25-50 mg every 6 hours for 48 hours, then 100 mg twice daily maintenance 2, 4
   • Monitor heart rate, blood pressure, and for signs of heart failure

3. Calcium Channel Blockers:

   • Use when beta-blockers are contraindicated or for refractory symptoms
   • Avoid rapid-release dihydropyridines (e.g., nifediparin) without adequate beta-blockade
   • Prefer heart rate-slowing agents (verapamil, diltiazem) when beta-blockers cannot be used 2

Management Strategy Based on Risk

High-Risk Patients:

• Early invasive strategy (coronary angiography within 24 hours)
• For severe ongoing ischemia, major arrhythmias, or hemodynamic instability: immediate invasive strategy (<2 hours) 1
• Consider GP IIb/IIIa inhibitor (abciximab, eptifibatide, or tirofiban) for troponin-positive patients undergoing PCI 2

Intermediate/Low-Risk Patients:

• Initial conservative strategy
• Measure LVEF
• If LVEF ≤0.40: consider diagnostic angiography
• If LVEF >0.40: perform stress testing 2

Post-Angiography Management

For Patients Undergoing PCI:

• Continue aspirin
• Continue P2Y12 inhibitor (clopidogrel) for at least 1 month and up to 9 months 2
• Consider GP IIb/IIIa inhibitor for troponin-positive patients 2
• Discontinue anticoagulant therapy after uncomplicated PCI 2

For Patients Managed Medically:

• Continue aspirin indefinitely
• Continue clopidogrel for at least 1 month and up to 9 months 2
• Continue anticoagulation for at least 48 hours or until discharge 2

Secondary Prevention

• High-intensity statin therapy
• ACE inhibitors for hypertension not controlled with beta-blockers and nitrates, or for patients with LV dysfunction 2
• Lifestyle modifications (smoking cessation, diet, exercise)
• Risk factor management (diabetes, hypertension, hyperlipidemia)

Important Considerations and Pitfalls

• Bleeding Risk: P2Y12 inhibitors increase bleeding risk; monitor hemoglobin and platelet counts daily during GP IIb/IIIa inhibitor administration 1
• CYP2C19 Poor Metabolizers: Consider alternative P2Y12 inhibitor in these patients 3
• NSAID Avoidance: All NSAIDs except aspirin should be discontinued due to increased risks of mortality and reinfarction 1
• Beta-Blocker Caution: Do not administer IV beta-blockers in patients with signs of heart failure or cardiogenic shock 1
• Abrupt Discontinuation: Never abruptly discontinue beta-blockers in patients with coronary artery disease due to risk of exacerbating angina 4