What is the initial management of a patient with unstable angina presenting to the Emergency Room?

Presentation of Unstable Angina in the Emergency Room

Patients with unstable angina typically present with chest pain or discomfort lasting more than 20 minutes that is unresponsive to sublingual nitroglycerin, often accompanied by hemodynamic instability, ECG changes, or other high-risk features.

Clinical Presentation

Chest Pain Characteristics

• Duration: Pain lasting >20 minutes at rest 1
• Quality: Substernal chest discomfort of characteristic anginal quality 1
• Pattern: May present as:
  • Rest angina (pain occurring at rest)
  • New-onset severe angina (within past 2 months)
  • Increasing angina (previously stable pattern that becomes more frequent, longer, or occurs at lower threshold) 1

Associated Symptoms

• Shortness of breath
• Diaphoresis (cold sweat)
• Nausea
• Lightheadedness 1
• Elderly patients and women may present with atypical symptoms such as dyspnea, nausea, or fatigue rather than classic chest pain 2

High-Risk Features

Patients with unstable angina may present with:

• Hemodynamic instability (hypotension, tachycardia)
• Pulmonary edema
• New or worsening mitral regurgitation murmur
• S3 heart sound or new/worsening rales 1
• Sustained ventricular arrhythmias 1

Diagnostic Findings

ECG Changes

• Transient ST-segment depression >0.5 mm
• T-wave inversions >1 mm
• Transient ST-segment elevation
• Normal ECG does not exclude the diagnosis 1, 2

Cardiac Biomarkers

• In unstable angina, cardiac troponins are typically negative or only slightly elevated
• Serial measurements are required (8-12 hours after symptom onset) 1, 2
• High-sensitivity troponin assays are now preferred with shorter repeat measurement intervals 2

Risk Stratification

High-Risk Indicators (TIMI Risk Score components)

• Age ≥65 years
• ≥3 coronary artery disease risk factors
• Known coronary stenosis ≥50%
• ST-segment deviation
• ≥2 anginal episodes in past 24 hours
• Aspirin use in past 7 days
• Elevated cardiac markers 1, 2

Additional High-Risk Features

• Prolonged ongoing chest pain
• Pulmonary edema
• New or worsening mitral regurgitation
• Hypotension, bradycardia, or tachycardia
• Age >75 years 1

Initial Management in the Emergency Room

1. Immediate Measures:

   • Continuous cardiac monitoring
   • Oxygen if SaO₂ <90% or respiratory distress
   • IV access establishment
   • 12-lead ECG within 10 minutes of arrival 1, 2

2. Anti-ischemic Therapy:

   • Sublingual nitroglycerin (0.4 mg) every 5 minutes for a total of 3 doses
   • IV nitroglycerin for persistent pain (starting at 10 μg/min, titrating up to 200 μg/min)
   • Morphine sulfate IV for uncontrolled ischemic chest pain despite nitroglycerin 1, 2

3. Antiplatelet Therapy:

   • Aspirin 162-325 mg (chewed, non-enteric coated) immediately
   • P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel) 2

4. Anticoagulation:

   • Parenteral anticoagulation with options including:
     • Unfractionated heparin
     • Enoxaparin
     • Fondaparinux 2

5. Other Medications:

   • Beta-blockers within 24 hours if no contraindications
   • High-intensity statin therapy 1, 2

Common Pitfalls to Avoid

1. Delayed Recognition: Do not wait for troponin elevation to initiate treatment, as unstable angina may not show troponin elevation initially 2

2. Inadequate Monitoring: Continuous ECG monitoring is necessary as ventricular fibrillation is a major preventable cause of death 2

3. NSAID Administration: Avoid all NSAIDs (except aspirin) due to increased risk of mortality, reinfarction, and heart failure 1

4. Overlooking Atypical Presentations: Especially in elderly patients, women, and diabetics who may present without classic chest pain 2

5. Premature Discharge: Patients with negative initial troponin should have serial measurements before ruling out ACS 1, 2

By recognizing the presentation patterns of unstable angina and implementing prompt, guideline-directed management, clinicians can significantly improve outcomes for these high-risk patients.