What is the next step in management for a 74‑year‑old patient with chest pain radiating to the back, now pain‑free, and electrocardiogram showing ST‑segment depression in leads II, aVL, V3‑V6?

Immediate Coronary Angiography Within 24 Hours

This 74-year-old patient with chest pain radiating to the back, now pain-free, and ST-segment depression in multiple leads (II, aVL, V3-V6) requires urgent coronary angiography within 24 hours along with immediate dual antiplatelet therapy and anticoagulation. 1

Risk Stratification

This patient meets high-risk criteria for non-ST-elevation acute coronary syndrome (NSTE-ACS):

• ST-segment depression in multiple leads (6 leads: II, aVL, V3-V6) indicates significant myocardial ischemia and is associated with 1-year mortality/MI risk of approximately 16% 2
• Chest pain radiating to the back raises concern for aortic dissection as a critical differential diagnosis that must be excluded 1
• Age 74 years is an independent risk factor for adverse outcomes 1
• ST-segment depression ≥0.5 mm in ≥3 leads strongly suggests significant coronary artery disease 2

The European Society of Cardiology classifies this presentation as requiring an early invasive strategy within 24 hours based on dynamic ST-segment changes suggesting ongoing ischemia 1

Immediate Management (First 10 Minutes)

Exclude Life-Threatening Mimics

• Obtain focused history for sudden tearing/ripping back pain, pulse differential, or blood pressure differential between arms to exclude aortic dissection before administering antithrombotic therapy 1
• Perform bedside echocardiography if available to assess for regional wall motion abnormalities, pericardial effusion, or aortic dissection 1

Initial Medical Therapy

Antiplatelet therapy:

• Aspirin 150-300 mg oral loading dose (or 75-250 mg IV if unable to take oral), followed by 75-100 mg daily 1, 3
• Ticagrelor 180 mg loading dose, then 90 mg twice daily (preferred over clopidogrel for moderate-to-high risk patients) 1, 3

Anticoagulation:

• Unfractionated heparin or low-molecular-weight heparin (enoxaparin) should be initiated immediately 1, 3

Anti-ischemic therapy:

• Beta-blocker (e.g., metoprolol 5 mg IV every 2 minutes × 3 doses if hemodynamically stable, then oral metoprolol 50 mg every 6 hours) to reduce myocardial oxygen demand with target heart rate 50-60 bpm 1, 4
• Sublingual or IV nitroglycerin for ongoing chest discomfort; IV route is more effective for symptom relief and regression of ST depression 3
• Morphine for pain relief if nitroglycerin is insufficient 1

Diagnostic Workup

Serial Cardiac Biomarkers

• Measure high-sensitivity cardiac troponin immediately and repeat at 3 hours and 6-12 hours 1, 2
• Elevated troponin identifies patients at high risk for progression to MI or death who benefit most from intensive antiplatelet therapy and early invasive strategy 1, 3

Continuous Monitoring

• Continuous 12-lead ECG monitoring identifies ischemic changes in an additional 16% of patients compared with standard serial ECGs 2
• Monitor for recurrent chest pain, during which an ECG should be recorded immediately 1
• Monitor for hemodynamic instability (hypotension, pulmonary rales) which would upgrade to immediate invasive strategy (<2 hours) 1

Additional Laboratory Tests

• Complete blood count (hemoglobin to detect anemia) 1
• Serum creatinine for renal function assessment 1
• Electrolytes (especially potassium, as hypokalemia can cause ST-T changes) 2
• Lipid profile in the early phase of admission 1

Timing of Invasive Strategy

Coronary angiography within 24 hours is indicated based on: 1

• Dynamic ST-segment changes suggesting ongoing ischemia
• ST-segment depression in multiple leads (6 leads)
• Elderly patient with likely elevated troponin

Upgrade to immediate invasive strategy (<2 hours) if any of the following develop: 1

• Hemodynamic instability or cardiogenic shock
• Recurrent or refractory chest pain despite medical treatment
• Life-threatening arrhythmias
• Heart failure clearly related to NSTE-ACS

Critical Pitfalls to Avoid

• Do not dismiss the back pain component – aortic dissection must be excluded before administering antithrombotic therapy, as this is a life-threatening contraindication 1
• Do not delay dual antiplatelet therapy – both aspirin and a P2Y12 inhibitor should be given immediately unless aortic dissection is suspected 3
• Do not use fibrinolysis – it is contraindicated and harmful in NSTE-ACS 3
• Do not attribute ST depression to age or hypertension alone – this ECG pattern in the setting of chest pain represents acute coronary syndrome until proven otherwise 2
• Do not rely on a single troponin measurement – serial assessments are required to reliably exclude myocardial injury 2

Additional Considerations

• Check for posterior MI – obtain posterior leads (V7-V9) as approximately 4% of acute MIs present with ST elevation only in posterior leads, which may manifest as ST depression in anterior leads 2
• Assess for contraindications to beta-blockers – overt heart failure, hemodynamic instability, or severe bradycardia 1
• Avoid nitrates if phosphodiesterase-5 inhibitor taken within 24 hours (sildenafil/vardenafil) or 48 hours (tadalafil) due to severe hypotension risk 3