What is an ECG? Resting ECG vs 24-hour ECG, public or private, and how to prepare in Hong Kong

What is an ECG and what does it check?

An ECG records the faint electrical changes produced as the heart muscle beats as a wave pattern, showing heart rate and changes in the heart's electrical potential; it can be used in routine check-ups, to assess the heart before surgery, to check how a pacemaker is working, and to see how a patient is after taking certain medicines; patients with symptoms such as chest pain, breathing difficulty, palpitations, weakness or dizziness may also need one (Hong Kong Adventist Hospital – Stubbs Road, accessed October 2026).

The Primary Healthcare Commission's Hong Kong Reference Framework for Hypertension Care for Adults in Primary Care Settings (2021 revised edition) lists a 12-lead ECG as a recommended routine test for all adults newly diagnosed with hypertension, to detect heart complications that high blood pressure may cause, such as left ventricular hypertrophy and cardiac ischaemia; the framework is written for primary care practitioners, and individual cases are decided by the treating doctor.

Anyone who suspects coronary heart disease should see a doctor at once; the doctor reviews the medical history and arranges tests as needed, which may include an ECG, imaging and cardiac catheterisation (Centre for Health Protection, accessed October 2026).

How do a resting ECG, a 24-hour ECG and longer ambulatory ECGs differ?

The table is arranged from two hospitals' published test descriptions; for an ECG during exercise see exercise ECG, and for the ultrasound test of the heart's structure and function see echocardiogram.

Where can I have an ECG? Public or private?

To book a new case at a public hospital specialist outpatient clinic, a referral letter issued by a locally registered doctor within the last three months is required (Hospital Authority, January 2018); for public cardiology waiting arrangements and fees see public cardiology waiting time vs private.

For private hospital and medical centre ECG fees see heart test fees; the CUHK Medical Centre Cardiology Centre has designated fees for patients holding a valid Hospital Authority referral letter, who must show the original letter (CUHK Medical Centre, accessed October 2026).

How do I prepare for an ECG?

Hong Kong Adventist Hospital – Stubbs Road states that in the hour before the test patients should not exercise strenuously, smoke, or drink stimulating drinks such as coffee or strong tea, and should remove items that affect electrical conduction, such as watches, metal jewellery and stockings (accessed October 2026).

Requirements differ between hospitals; follow the instructions of the hospital where you book. If you take regular medicines, ask when booking how to handle them on the day of the test.

Who decides whether I need an ECG?

Whether to have an ECG, and whether a resting or ambulatory one, is decided by the doctor according to the condition; the report is interpreted by the doctor, and individual cases are decided by the treating doctor. For arrhythmia see arrhythmia symptoms; for choosing a doctor see how to choose a cardiologist.

Signs of a heart attack include severe chest pain that may spread to the neck, arm or jaw, heavy sweating, shortness of breath, chest tightness, nausea, dizziness or even loss of consciousness; the Department of Health Elderly Health Service advises seeing a doctor at once or going to an Accident and Emergency department if these signs appear (accessed October 2026). For emergencies see urgent help.

Frequently asked questions