What is the treatment for unstable angina?

Treatment of Unstable Angina

Patients with unstable angina should be treated with 75 mg of aspirin daily for 18 months, followed by long-term aspirin therapy according to stable angina recommendations. 1

Initial Pharmacological Management

First-Line Medications

1. Antiplatelet Therapy

   • Aspirin: 75-150 mg daily 1
   • Clopidogrel: 75 mg daily (after 300 mg loading dose) when aspirin is contraindicated 1, 2

2. Beta-Blockers

   • Short-acting beta-selective blockers without intrinsic sympathomimetic activity, initially intravenously in hemodynamically stable patients 1
   • Oral beta-blockers can be substituted later or started promptly without prior IV administration 1
   • Delay beta-blocker initiation if patient has heart failure or shock until stabilization 1

3. Nitrates

   • Sublingual nitroglycerin or nitroglycerin spray for immediate relief of angina 1
   • IV nitroglycerin for initial management in severe cases 1, 3
   • Buccal nitroglycerin every 4 hours is a safe alternative to IV nitroglycerin 3

Second-Line/Additional Medications

1. Calcium Channel Blockers

   • Add long-acting calcium antagonists when beta-blockers alone are unsuccessful 1
   • Consider non-dihydropyridine CCBs (verapamil or diltiazem) if beta-blockers are contraindicated 1
   • Avoid short-acting dihydropyridines as they may increase adverse cardiac events 1

2. ACE Inhibitors

   • Add if hypertension persists, if patient has LV dysfunction/heart failure, anterior MI, or diabetes 1

3. Lipid-Lowering Therapy

   • Statin therapy to reduce LDL cholesterol 1

Risk Stratification and Management Algorithm

High-Risk Features (Requiring Aggressive Management)

• Recurrent ischemia (chest pain or dynamic ST changes)
• Elevated troponin levels
• Hemodynamic instability
• Major arrhythmias
• Early post-infarction unstable angina 1

Management Based on Risk

1. High-Risk Patients:

   • Add GP IIb/IIIa receptor blocker
   • Perform coronary angiography during initial hospitalization
   • Consider revascularization (PCI or CABG) based on coronary anatomy 1

2. Lower-Risk Patients:

   • Continue medical therapy with aspirin, beta-blockers, nitrates
   • Consider non-invasive testing to assess for inducible ischemia

Duration of Therapy

• Aspirin: 75 mg daily for 18 months, then continue long-term at 75 mg daily 1
• Beta-blockers: Continue indefinitely in patients with prior MI or ongoing symptoms 1
• Nitrates: Ensure a daily "nitrate-free" interval of 10-12 hours to prevent tolerance 4
• For isosorbide mononitrate (ISMN), typical dosages are 20 mg twice daily (standard) or 60-240 mg once daily (slow-release) 4

Important Considerations and Pitfalls

Medication Cautions

• Nitrates: Avoid concomitant use with phosphodiesterase inhibitors (sildenafil, tadalafil, vardenafil) due to risk of profound hypotension 4
• Blood Pressure Management: Target BP <130/80 mmHg, but lower DBP slowly and cautiously, especially in older patients with wide pulse pressures 1
• Clopidogrel: Effectiveness may be reduced in patients who are CYP2C19 poor metabolizers; avoid concomitant use with omeprazole or esomeprazole 2

Common Pitfalls

1. Nitrate Tolerance: Failing to implement a nitrate-free interval, which reduces effectiveness 4
2. Underuse of Beta-Blockers: These are cornerstone therapy but are often underutilized 1
3. Inadequate Antiplatelet Therapy: Aspirin significantly reduces risk of subsequent vascular events (NNT of 15) 1
4. Overlooking Comorbidities: Diabetes, hypertension, and heart failure require specific medication considerations 1

The evidence strongly supports that early and aggressive medical therapy significantly reduces the risk of progression to myocardial infarction or death in patients with unstable angina, with aspirin showing particularly strong benefits in reducing subsequent vascular events.