Health Corner

What is an ECG test? Can it detect hidden heart disease risks?

Heart disease is one of the three leading causes of death in Hong Kong. Regular check-ups are one of the most effective ways to prevent it.
An electrocardiogram (ECG) is a quick, painless test commonly used to assess heart health. It records electrical changes in the heart muscle as waveforms, essentially creating a visual record of the heart’s electrical activity. Through analysis of these patterns, healthcare professionals can understand basic heart information such as heart rate and electrical potential changes.
ECG testing can be used both as part of a routine health check and as a preoperative heart assessment.

The results help doctors diagnose various cardiac problems, including arrhythmia (irregular heartbeat), abnormal blood flow to the heart muscle, cardiac hypertrophy, congenital heart defects, and valvular diseases.
ECG tests are broadly categorized into three main types: resting ECG, exercise ECG (treadmill test), and 24-hour Holter monitoring.

Which type of ECG should I choose?

1. Resting ECG (ECG)

The resting ECG is the most common method. It is quick, painless, and safe, taking only about 10 seconds to complete. The procedure is simple: metal electrodes are attached to specific points on the body to record electrical waves generated during heart muscle contractions.
This test detects abnormalities in the heart while at rest, such as irregular rhythms or enlargement of heart chambers.

2. Exercise ECG (Treadmill Test)

The exercise ECG evaluates heart function under physical stress. The test is performed while walking or running on a treadmill, during which medical staff record heart rate and ECG changes from rest to exertion and recovery.
It takes approximately 10 minutes and can more accurately reveal issues such as myocardial ischemia (reduced blood flow), coronary artery disease, or other cardiovascular problems like blockage or infarction.

3. 24-hour Holter Monitoring (Continuous ECG)

Because both resting and treadmill ECGs only capture heart activity at the time of the exam, they may miss irregular heart rhythms or transient symptoms. The Holter monitor addresses this by continuously recording heart activity for 24 to 48 hours (or longer) as the person goes about daily activities.
This provides a more complete record for identifying intermittent heart conditions.

What should I be aware of during an ECG test?

• The resting ECG is painless and safe. You may feel slight discomfort when the electrode stickers are removed.

• The Holter monitor also involves no pain or risk. Electrodes attached to the chest with adhesive patches may cause mild skin irritation.
  Inform medical staff if you are allergic to any tape or adhesive materials.

• Avoid strenuous exercise, smoking, or consuming coffee, strong tea, and other stimulants within one hour before testing.

• Remove all items that may interfere with electrical signals—such as watches, metal jewelry, or nylon stockings—to ensure accurate results.