A normal electrocardiogram can be reassuring, but it does not explain every episode of chest pain. A systematic review of chest-pain investigation found that ECG findings can be useful for diagnosing a heart attack, while a normal tracing cannot by itself rule out every important cause. Doctors interpret the ECG with symptoms, risk factors, examination, blood tests and other investigations.
An ECG records the heart’s electrical activity during a short period. It does not directly show the inside of the coronary arteries.
Changes may be absent when pain has stopped, when a blockage is not causing an electrical change at that moment, or when the problem requires another test.
The description of the pain matters. Pressure, heaviness or squeezing during physical effort may raise concern. Pain with sweating, nausea, breathlessness or spreading discomfort may require urgent assessment.
People with diabetes, high blood pressure, high cholesterol, kidney disease, tobacco exposure or previous heart disease may need a lower threshold for further investigation.
Women, older adults and people with diabetes may experience less typical symptoms. Severe tiredness, breathlessness, nausea or upper-back discomfort can sometimes be important.
A clinician may repeat the ECG or order troponin blood tests. Troponin can help identify injury to the heart muscle, but the timing of the test matters.
Other possible tests include an echocardiogram, exercise stress test, CT coronary angiography, another imaging test or invasive angiography. The appropriate test depends on the situation.
Chest pain can also come from the lungs, stomach, food pipe, muscles, ribs, nerves or anxiety. These possibilities should not be assumed before urgent causes have been considered.
Do not use a normal ECG as permission to ignore pain that is continuing, worsening or returning.
Home oxygen monitors, smartwatches and blood-pressure machines cannot rule out a heart attack or coronary blockage.
If a person has been assessed and discharged, they should understand which symptoms require a return to emergency care and what follow-up has been arranged.
Madhavbaug’s educational guide explains what an ECG can and cannot show about heart blockage. Information about its broader clinical services is available on the Madhavbaug homepage.
Call emergency services for severe or persistent chest pressure, fainting, sweating, sudden breathlessness or pain spreading to the arm, jaw, shoulder or back.