Introduction
An electrocardiogram (ECG or EKG) is a simple, painless test that measures the electrical activity of your heart. It helps doctors detect heart conditions such as arrhythmias, heart attacks, and other cardiac abnormalities. However, understanding your ECG test results can be confusing if you don’t know what to look for.
In this comprehensive guide, we’ll break down:
- What a normal ECG looks like
- How to interpret ECG results
- Common ECG abnormalities and their meanings
- What causes abnormal ECG readings
- When to seek medical advice
Whether you’re a patient reviewing your ECG report or a beginner learning ECG interpretation, this guide will help you make sense of your results.
What Is an ECG Test?
An ECG records the electrical signals produced by your heart with each beat. Electrodes placed on your skin detect these signals, which are then displayed as waves on a graph. Doctors analyze these waves to assess:
- Heart rate (fast or slow)
- Heart rhythm (regular or irregular)
- Signs of heart damage (like a past heart attack)
- Structural heart abnormalities
Why Would an ECG Test Be Abnormal?
Abnormal ECG test results can indicate:
- Arrhythmias (irregular heartbeat)
- Ischemia (reduced blood flow to the heart)
- Heart attack (myocardial infarction)
- Cardiomyopathy (thickened heart muscle)
- Electrolyte imbalances (low potassium, high calcium)
How to Understand Your ECG Report
An ECG consists of several key components:
1. Heart Rate (Beats Per Minute – BPM)
- Normal: 60–100 BPM
- Bradycardia: <60 BPM (could be normal in athletes)
- Tachycardia: >100 BPM (may indicate stress, fever, or heart disease)
2. Heart Rhythm
- Normal (Sinus Rhythm): Regular, evenly spaced beats
- Abnormal Rhythms:
- Atrial Fibrillation (AFib): Irregular, rapid heartbeat
- Ventricular Tachycardia (VTach): Life-threatening fast rhythm
- Heart Block: Delayed or blocked electrical signals
3. ECG Waves and Intervals
Each heartbeat produces a series of waves (P, QRS, T):
| Wave | What It Represents | Normal Duration |
| P wave | Atrial depolarization (contraction) | <0.12 sec |
| PR interval | Time from atrial to ventricular activation | 0.12–0.20 sec |
| QRS complex | Ventricular depolarization | <0.12 sec |
| ST segment | Ventricular repolarization | Flat or slightly elevated |
| T wave | Ventricular repolarization | Follows QRS |
4. Common ECG Abnormalities
| Abnormality | Possible Meaning |
| ST Elevation | Heart attack (STEMI) |
| ST Depression | Ischemia (reduced blood flow) |
| Prolonged QT Interval | Risk of dangerous arrhythmias |
| Left Bundle Branch Block (LBBB) | Heart disease or past heart attack |
| Premature Ventricular Contractions (PVCs) | Extra beats, may be benign or serious |
Normal vs. Abnormal ECG Results Explained
What Does a Normal ECG Look Like?
A normal ECG shows:
- Regular rhythm (sinus rhythm)
- Heart rate between 60–100 BPM
- Correct P, QRS, and T wave morphology
- No ST-segment elevation or depression
What Do Abnormal ECG Test Results Mean?
- Atrial Fibrillation (AFib): Increased stroke risk, needs treatment.
- ST Elevation Myocardial Infarction (STEMI): Immediate medical intervention required.
- Bradycardia/Tachycardia: Could indicate underlying heart disease.
- Bundle Branch Block: May require further cardiac testing.
When Should You Worry About ECG Results?
Seek medical attention if your ECG test results show:
- Severe arrhythmias (e.g., ventricular fibrillation)
- Signs of a heart attack (ST elevation, abnormal Q waves)
- Extremely fast or slow heart rates with symptoms (dizziness, chest pain)
How Accurate Are ECG Tests?
ECGs are highly useful but not perfect. Some limitations include:
- False positives/negatives (may miss intermittent arrhythmias)
- Non-specific changes (some abnormalities don’t always indicate disease)
- Need for further tests (Echocardiogram, stress test, Holter monitor)
Final Thoughts: Understanding Your ECG for Better Heart Health
Interpreting ECG test results can be complex, but knowing the basics helps you engage in informed discussions with your doctor. If your report shows abnormalities, don’t panic—many findings are benign. However, always follow up with a cardiologist for a thorough evaluation.
