What is the treatment for unstable angina?

Treatment of Unstable Angina

Patients with unstable angina require immediate hospitalization with aggressive antiplatelet, anticoagulation, and anti-ischemic therapy, followed by early invasive coronary angiography within 24-48 hours for intermediate to high-risk patients. 1

Immediate Management Upon Presentation

Hospitalization and Monitoring

• Admit all patients immediately to a coronary care unit for continuous ECG monitoring to detect ischemia and arrhythmias 1, 2
• Patients should sit down when taking medications to prevent falls from lightheadedness or dizziness 3

Antiplatelet Therapy (Start Immediately)

• Administer aspirin 75-325 mg immediately (can use 75-150 mg daily for maintenance), which significantly reduces risk of myocardial infarction, stroke, or death 1, 2
• Add clopidogrel with a loading dose if not already given, and continue 75 mg daily for at least 12 months 4, 1
• For high-risk patients (elevated troponin, ST-segment changes), administer intravenous GP IIb/IIIa inhibitors (abciximab, eptifibatide, or tirofiban) 4

Anticoagulation (Start Immediately)

• Enoxaparin (low molecular weight heparin) is preferable to unfractionated heparin unless CABG is planned within 24 hours 4, 1
• Continue anticoagulation for at least 48 hours or until discharge if managed conservatively 4
• If enoxaparin was started before angiography, continue for duration of hospitalization up to 8 days 4

Anti-Ischemic Therapy

Beta-blockers:

• Administer intravenously in hemodynamically stable patients, followed by oral maintenance therapy 1
• This reduces myocardial oxygen consumption and may redirect coronary flow to ischemic areas 5

Nitrates:

• Provide sublingual nitroglycerin (0.3-0.6 mg) for immediate symptom relief 1, 3
• One tablet dissolved under the tongue at first sign of chest pain; may repeat every 5 minutes up to 3 doses 3
• If pain persists after 3 tablets over 15 minutes, this constitutes a medical emergency requiring immediate evaluation 3
• Transition to intravenous nitroglycerin for acute management, then long-acting nitrates for maintenance 1
• Critical contraindication: Do not give nitrates to patients taking phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil) or guanylate cyclase stimulators (riociguat) due to risk of severe hypotension 3

Calcium channel blockers:

• Can be added as part of triple anti-ischemic therapy (nitrates, beta-blockers, calcium antagonists) 6

Risk Stratification (Perform Within Hours of Admission)

High-Risk Features Requiring Early Invasive Strategy

Identify patients with any of the following 4, 1:

• Recurrent angina/ischemia at rest or with minimal activity despite intensive medical therapy
• Elevated troponin T or troponin I (troponin T >0.01 ng/mL or troponin I >0.1 ng/mL)
• New or presumably new ST-segment depression
• Hemodynamic instability
• Heart failure symptoms (S3 gallop, pulmonary edema, new/worsening mitral regurgitation)
• Sustained ventricular tachycardia
• Depressed left ventricular function (ejection fraction <0.40)
• Prior PCI within 6 months or prior CABG

TIMI Risk Score

• TIMI risk score ≥3 identifies patients who benefit most from early invasive strategy 4

Invasive vs Conservative Strategy

Early Invasive Strategy (Preferred for High/Intermediate-Risk)

• Perform coronary angiography within 24-48 hours followed by revascularization if anatomy is suitable 4, 1, 2
• The TACTICS-TIMI 18 trial demonstrated that early invasive strategy reduced death, MI, or rehospitalization at 6 months (15.9% vs 19.4%, p=0.025) compared to conservative strategy 4, 1
• This benefit is particularly evident in patients with elevated troponin, ST-segment deviation, or TIMI risk score ≥3 4
• The routine use of GP IIb/IIIa antagonists before angiography eliminates the excess risk of early MI seen with invasive strategies 4

Conservative Strategy (For Lower-Risk Patients Only)

• Reserved for patients without elevated troponin, ST-segment deviation, or rest pain within 12 hours 4
• Perform noninvasive stress testing 4
• If stress test shows high-risk features, proceed to coronary angiography 4
• If stress test is negative, consider alternative diagnoses including variant angina 4

Revascularization Decisions

Percutaneous Coronary Intervention (PCI)

• Continue aspirin and administer clopidogrel loading dose if not already given 4
• Administer GP IIb/IIIa inhibitor for troponin-positive and high-risk patients 4
• PCI with stenting is effective, especially when combined with dual antiplatelet therapy 2
• For diabetic patients with single-vessel disease and inducible ischemia, PCI is reasonable 4
• Abciximab is recommended for diabetic patients treated with coronary stenting 4

Coronary Artery Bypass Grafting (CABG)

• Preferred for patients with:
  • Significant left main disease 1
  • Three-vessel disease, particularly with depressed left ventricular function 1
  • Diabetic patients with multivessel disease (using internal mammary arteries) 4, 2
• Discontinue GP IIb/IIIa inhibitors 4 hours before CABG (for eptifibatide or tirofiban) 4
• Anticoagulation management before CABG 4:
  • Continue unfractionated heparin
  • Discontinue enoxaparin 12-24 hours before and dose with UFH
  • Discontinue fondaparinux 24 hours before and dose with UFH
  • Discontinue bivalirudin 3 hours before and dose with UFH

Lipid Management (Initiate Before Hospital Discharge)

High-intensity statin therapy should be initiated for all patients with unstable angina before hospital discharge. 1

• The MIRACL trial showed that atorvastatin 80 mg daily started 24-96 hours after acute coronary syndrome reduced the composite endpoint from 17.4% to 14.8% at 16 weeks (p=0.048) 4
• Observational data from the Swedish Registry showed 25% lower adjusted mortality risk when statins were initiated before discharge 4
• Patients who start statins in-hospital are much more likely to continue therapy long-term (91% vs 10% at 1 year) 4
• Target LDL cholesterol <100 mg/dL 4
• Add fibrate or niacin if HDL cholesterol is <40 mg/dL 4

Long-Term Management and Secondary Prevention

Medications to Continue Indefinitely

• Aspirin 75-150 mg daily 1, 2
• Clopidogrel 75 mg daily for at least 12 months 1
• Beta-blockers, particularly in post-MI patients 1, 2
• High-intensity statin therapy for all patients with coronary disease 1, 2
• ACE inhibitors for patients with:
  • Left ventricular dysfunction (EF <0.40) 4, 1
  • Hypertension 4, 1
  • Diabetes 4, 1
  • Heart failure 4

Lifestyle Modifications (Aggressive Implementation Required)

• Smoking cessation (consider referral to cessation program) 4, 2
• Achievement/maintenance of optimal weight 4, 2
• Daily exercise program 4, 2
• Dietary modifications 4, 2
• Tight glucose control in diabetic patients 4
• Control of hypertension 4
• Consider referral to outpatient cardiac rehabilitation 4

Follow-Up Schedule

• High-risk patients: return in 1-2 weeks 4, 2
• Lower-risk and revascularized patients: return in 2-6 weeks 4, 2
• Regular outpatient follow-up to assess symptom control and optimize medical therapy 2

Common Pitfalls to Avoid

• Failure to recognize unstable angina as a medical emergency requiring immediate hospitalization 2
• Delaying antiplatelet therapy in unstable angina patients 2
• Giving nitrates to patients on phosphodiesterase-5 inhibitors or guanylate cyclase stimulators 3
• Inadequate risk stratification leading to inappropriate conservative management of high-risk patients 2
• Withholding early invasive strategy from women at high/intermediate risk with suitable coronary anatomy 4
• Overlooking secondary prevention measures including statin initiation before discharge 2
• Failing to address extracardiac precipitating factors (fever, anemia, arrhythmias, severe hypertension, pulmonary embolism, thyrotoxicosis) 4
• Not recognizing that persistence of pain after admission is the most significant indicator of adverse prognosis 7