What is the best management approach for a patient presenting with unstable angina?

Management of Unstable Angina

Patients presenting with unstable angina require immediate hospitalization with continuous ECG monitoring, aspirin 162-325 mg immediately, anticoagulation (unfractionated heparin or enoxaparin), clopidogrel loading (300 mg), sublingual nitroglycerin for symptom relief, and beta-blockers in the absence of contraindications, followed by risk stratification to determine whether an early invasive strategy (angiography within 24-48 hours) or initial conservative approach is appropriate. 1, 2

Immediate Management Upon Presentation

Initial Stabilization and Monitoring

• Admit to hospital with continuous ECG monitoring for ischemia and arrhythmia detection in all patients with ongoing or recent rest pain 1
• Administer supplemental oxygen if arterial saturation is <90% or respiratory distress is present 3
• Establish intravenous access and obtain baseline cardiac biomarkers (troponin), 12-lead ECG, and complete blood count 1, 2

Immediate Pharmacological Therapy

Antiplatelet Therapy:

• Aspirin 162-325 mg immediately (chewed for faster absorption), then continue 75-162 mg daily indefinitely 1, 2
• Clopidogrel 300 mg loading dose followed by 75 mg daily 1, 2
• This dual antiplatelet therapy significantly reduces cardiovascular events and should be initiated before knowing angiography results 2

Anticoagulation (choose one):

• Unfractionated heparin: bolus followed by continuous infusion to maintain aPTT 1.5-2.5 times control 1, 2
• Enoxaparin: 1 mg/kg subcutaneously every 12 hours 1
• Fondaparinux: 2.5 mg subcutaneously daily 1
• Bivalirudin: 0.1 mg/kg bolus, then 0.25 mg/kg/hour infusion 1

Anti-Ischemic Therapy:

• Nitroglycerin sublingual 0.4 mg every 5 minutes for up to 3 doses for acute symptom relief 1, 4
• If pain persists after 3 sublingual doses over 15 minutes, initiate intravenous nitroglycerin 5-10 mcg/min, titrating upward by 10 mcg/min every 3-5 minutes until symptoms resolve or blood pressure limits are reached 1
• Beta-blockers should be initiated within 24 hours unless contraindicated (e.g., metoprolol 25-50 mg orally every 6-12 hours, titrating to heart rate 50-60 bpm) 1, 5
• Calcium channel blockers (diltiazem or verapamil) may be used when beta-blockers are contraindicated or for symptom control despite adequate nitrates and beta-blockade 1

Critical Pitfall: Do NOT administer thrombolytic therapy to patients with unstable angina without ST-segment elevation, as this increases bleeding risk without benefit 2, 3, 6

Risk Stratification

High-Risk Features Requiring Early Invasive Strategy (angiography within 24-48 hours):

• Recurrent angina/ischemia at rest or with low-level activity despite intensive medical therapy 1, 2
• Elevated cardiac troponin levels 2
• New or presumably new ST-segment depression ≥0.5 mm 2
• Hemodynamic instability or heart failure 1, 2
• Sustained ventricular tachycardia 2
• Diabetes mellitus 2
• Reduced left ventricular ejection fraction (<40%) 2
• Post-myocardial infarction angina 1
• Prior PCI within 6 months or prior CABG 2

Low-Risk Features Allowing Conservative Strategy:

• No recurrence of chest pain 1
• Normal or unchanged ECG 1
• Normal cardiac biomarkers (especially troponin) at presentation and 6-8 hours later 1
• No hemodynamic instability 1

For high-risk patients, administer GP IIb/IIIa inhibitor (eptifibatide, tirofiban, or abciximab) before or at time of PCI 1, 2

Post-Angiography Management Pathways

If PCI is Performed:

• Continue aspirin indefinitely 1, 7
• Continue clopidogrel 75 mg daily for at least 12 months 1, 7
• Discontinue anticoagulation after uncomplicated PCI 1
• GP IIb/IIIa inhibitors may be omitted if clopidogrel 300 mg was given ≥6 hours before PCI and bivalirudin is used 1

If CABG is Planned:

• Continue aspirin 1, 7
• Discontinue clopidogrel 5-7 days before elective CABG to reduce bleeding risk (more urgent surgery may proceed if bleeding risk is acceptable) 1, 7
• Discontinue GP IIb/IIIa inhibitors 4 hours before surgery 1
• Continue unfractionated heparin; discontinue enoxaparin 12-24 hours before CABG, fondaparinux 24 hours before, and bivalirudin 3 hours before, substituting UFH per institutional protocol 1
• For patients with multivessel disease and diabetes, CABG with internal mammary artery grafts is preferred over PCI 2

If Medical Management is Selected:

• Continue aspirin and clopidogrel 1, 7
• Continue anticoagulation (UFH for at least 48 hours or enoxaparin/fondaparinux for duration of hospitalization) 1
• Discontinue GP IIb/IIIa inhibitors 1
• Measure left ventricular ejection fraction to guide further management 7

Long-Term Secondary Prevention

All patients with unstable angina require aggressive secondary prevention:

• High-dose statin therapy (atorvastatin 80 mg daily) initiated within 24-96 hours, targeting LDL <100 mg/dL (consider <70 mg/dL in very high-risk patients) 7, 2
• Beta-blockers continued indefinitely, particularly in patients with prior MI or heart failure 7, 5
• ACE inhibitors for patients with hypertension, heart failure, LV dysfunction, prior MI with LV dysfunction, or diabetes 7
• Blood pressure control to <130/80 mmHg 7
• Diabetes management with HbA1c target <7% 7
• Smoking cessation counseling and support 7
• Regular physical activity (30 minutes most days) and weight management (BMI 18.5-24.9 kg/m²) 7

Critical Warnings and Pitfalls

Do NOT abruptly discontinue beta-blockers in patients with coronary artery disease, as this can precipitate severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias; taper over 1-2 weeks when discontinuation is necessary 5

Avoid NSAIDs (except aspirin) due to increased cardiovascular event risk 7

Do NOT discharge patients prematurely—those with possible acute coronary syndrome require at least 6-12 hours of observation with serial ECGs and cardiac biomarkers 1, 3

Beta-blockers should NOT be used alone in cocaine-induced chest pain, as unopposed alpha-adrenergic stimulation can worsen coronary vasospasm; use benzodiazepines and nitroglycerin first 1

Monitor for bradycardia with beta-blocker therapy, especially in patients with first-degree AV block or conduction disorders; reduce or stop if severe bradycardia develops 5

Follow-Up and Monitoring

• Patients discharged from chest pain units should have outpatient follow-up within 72 hours 1
• Regular assessment for recurrent angina symptoms 7
• Periodic evaluation of medication adherence and risk factor control 7
• Consider stress testing at 1-2 year intervals in high-risk patients or with changing symptoms 7
• Promptly reassess if symptoms worsen or become unstable, as this may require urgent angiography 7