Electrocardiogram (EKG/ECG) interpretation is one of the most tested NCLEX topics. For a registered nurse (RN nurse), recognizing ST elevation vs ST depression can mean the difference between saving a life and missing a critical diagnosis. This guide breaks down the basics for nursing students, new graduates, and any nurse preparing for the NCLEX or clinical practice.
🔹 What Is the ST Segment?
The ST segment is the flat line between the end of the QRS complex and the beginning of the T wave. It represents the time between ventricular depolarization and repolarization.
- Normal ST Segment: Flat, at the baseline (isoelectric line).
- Abnormal ST Segment: Either elevated or depressed compared to the baseline.
🔹 ST Elevation – What It Means for Nurses
ST Elevation occurs when the ST segment rises above the baseline.
Common Causes:
- Myocardial Infarction (STEMI): Classic finding in heart attack.
- Pericarditis: Diffuse ST elevation across many leads.
- Early Repolarization: Benign, often seen in young adults.
Nursing Implications:
- Immediate priority: If suspected STEMI, activate emergency response → “Time is muscle.”
- Monitor vital signs, administer oxygen, and prepare for interventions like cardiac catheterization.
- Document and notify provider immediately.
👉 NCLEX Tip: If you see ST elevation + chest pain, treat as a STEMI until proven otherwise.
🔹 ST Depression – What It Means for Nurses
ST Depression is when the ST segment falls below the baseline.
Common Causes:
- Myocardial Ischemia: Not enough oxygen supply to the heart.
- Hypokalemia: Low potassium levels.
- Digoxin Effect: “Scooped” ST depression on digoxin therapy.
Nursing Implications:
- Assess for chest pain, shortness of breath, or dizziness.
- Monitor electrolytes, especially potassium.
- If ischemia is suspected, administer oxygen and prepare for further testing (stress test, labs).
👉 NCLEX Tip: ST depression often signals ischemia or electrolyte imbalance rather than a full STEMI, but still requires immediate nursing action.
🔹 Quick Comparison Chart
| Feature | ST Elevation | ST Depression |
|---|---|---|
| Key Cause | STEMI, pericarditis | Ischemia, hypokalemia, digoxin |
| Appearance | ST rises above baseline | ST falls below baseline |
| NCLEX Priority | Treat as heart attack until ruled out | Assess oxygenation, potassium, meds |
| Nursing Action | Call provider, prepare for cath lab | Monitor, labs, correct imbalance |
🔹 Why This Matters for Nurses and NCLEX
- NCLEX-style questions often ask: “Which patient should the nurse see first?” → A client with ST elevation and chest pain is always the priority.
- As a nursing student or RN nurse, recognizing ST changes helps in both critical care practice and exam success.
- Adding this knowledge to your nursing bundle of study guides ensures you’re confident in cardiac EKG interpretation.
✅ Final Nursing Notes
- Always assess the patient, not just the monitor.
- ST elevation = treat as STEMI until proven otherwise.
- ST depression = ischemia, electrolyte issue, or digoxin effect.
- Registered nurses (RNs) must act quickly and communicate clearly with providers to prevent cardiac complications.
🔹 FAQs
ST elevation usually signals a STEMI (heart attack) and requires immediate action by the nurse to prevent cardiac damage.
ST depression often indicates ischemia, hypokalemia, or digoxin effect and must be addressed quickly by the nurse.
Think Elevation = Emergency (STEMI) and Depression = Down oxygen/electrolyte problem.
ST elevation with chest pain is always the top priority for nurses and NCLEX questions.
Because timely recognition of ST elevation or depression allows the RN nurse to activate interventions that save heart muscle and lives.