Electrocardiogram (ECG)
An ECG records the heart's electrical rhythm in about five minutes; it is a standard part of the checks before weight-loss surgery or some medicines because obesity strains the heart and can mask problems.
Plain English
Patient-Friendly Explanation
An electrocardiogram is a recording of the electrical signals that make your heart beat. Sticky pads go on your chest, wrists and ankles, wires connect them to a machine, and a tracing prints out within a couple of minutes. It does not hurt, nothing is injected, and it needs no preparation. From the tracing we can check your heart rate and rhythm, whether the rhythm is regular or in an abnormal pattern such as atrial fibrillation, whether there is evidence of a previous heart attack, whether the heart muscle looks thickened, and how long the electrical reset time (the QT interval) lasts. All of those matter when you are carrying excess weight, because obesity raises the risk of high blood pressure, atrial fibrillation and a stiff, thickened heart, and because some weight-loss medicines can affect the same electrical signals. Extra body tissue also changes the tracing: voltages look larger and the pattern can be harder to interpret, which is one reason an ECG is reported by someone who knows what obesity does to the print-out. Not everyone needs one. We arrange it when there are symptoms such as palpitations or breathlessness, when several risk factors stack up, or before surgery and general anaesthesia.
Medical
Clinical Definition
The 12-lead resting electrocardiogram measures atrial and ventricular depolarisation and repolarisation, giving rate, rhythm, PR and QRS duration, QT interval with corrected QTc (Bazett or Fridericia), QRS axis and voltage criteria for left ventricular hypertrophy. Obesity alters the tracing: increased chest-wall adiposity raises QRS voltage and shifts the axis leftwards, QT dispersion is increased with more frequent non-specific ST-T changes, and QTc may be mildly prolonged, so voltage-based criteria such as Sokolow-Lyon must be interpreted with caution. Epidemiologically obesity is a strong risk factor for atrial fibrillation and for heart failure with preserved ejection fraction, both of which may be first suspected on an ECG. Within weight-management pathways the ECG is used for pre-operative assessment before bariatric surgery alongside anaesthetic review, as a baseline before medication that can prolong the QT interval, and in the evaluation of palpitations, exertional breathlessness, dizziness or syncope. A normal resting ECG does not exclude structural heart disease - echocardiography, ambulatory Holter monitoring or cardiopulmonary exercise testing are used when the clinical picture requires it.
Key Insight
Why It Matters
An ECG is the cheapest way we have to look at your heart's wiring, and it takes longer to put the pads on than to record the trace. If you are planning weight-loss surgery, starting a medicine that can affect heart rhythm, or you have noticed palpitations, breathlessness on mild exertion, or dizziness, this test should be part of your work-up. It also gives us a baseline, so that any change later on has something to be compared with.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: September 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
