Cardiology Tests for Breathlessness and What Normal Results Mean
Heart tests help establish whether a problem with your heart could explain shortness of breath. An ECG, echocardiogram and NT-proBNP blood test assess different aspects of heart function. Reassuring results make some cardiac causes less likely, but their meaning depends on which tests you had, when they were performed and the symptoms being investigated.
If walking, stairs or exercise still leave you breathless, review what remains unexplained. The next step may be a targeted cardiac investigation or assessment of the lungs, blood, breathing pattern and response to exercise.
When breathlessness needs urgent help
Call 999 for severe breathing difficulty, inability to get words out, a tight or heavy chest, pain spreading to the arms, back, neck or jaw, sudden confusion, or skin or lips becoming blue, grey or very pale. Do not drive yourself.
Contact NHS 111 urgently for new or increased breathing difficulty, coughing up blood, pain or swelling in one leg, or palpitations. Emergency features take priority. Follow the NHS advice on shortness of breath, even if previous heart tests were normal.
Why the heart is checked when you are breathless
Problems with the heart’s pumping, filling, valves, rhythm or blood supply can make activity harder and cause breathlessness.
Tell your clinician about chest discomfort, palpitations, swollen ankles, fainting, waking breathless or needing more pillows at night. These clues, examination findings and your medical history help determine which tests are useful.
Cardiology tests used to investigate breathlessness
ECG
An electrocardiogram (ECG) records the heart’s electrical activity through adhesive electrodes on the skin. It can identify an abnormal rhythm present during the recording and electrical changes needing further investigation.
An occasional irregular heartbeat may be absent during this short recording. An ECG also cannot replace ultrasound assessment of heart structure and valves.
A normal ECG needs to be interpreted alongside your symptoms and cannot exclude every cardiac cause of breathlessness.
Echocardiogram
An echocardiogram, or echo, uses ultrasound to examine the heart’s chambers, valves and movement, usually with a probe on the chest.
It assesses pumping function and can identify important valve or structural abnormalities.
However, the full report matters more than one number. Ejection fraction describes the proportion of blood pumped out of the main pumping chamber with each beat. A preserved ejection fraction alone does not exclude heart failure, because the heart can have difficulty relaxing and filling. Some concerns require specialist interpretation or assessment during stress.
NT-proBNP blood test
NT-proBNP is a marker that can rise when the heart is under strain. It helps guide investigation when chronic heart failure is suspected.
Under NICE guidance on diagnosing heart failure, a result below 400 ng/L in an untreated person makes heart failure less likely. Results from 400 to 2,000 ng/L prompt referral for specialist assessment and an echocardiogram within six weeks; above 2,000 ng/L, the recommended timeframe is two weeks.
These are referral thresholds for suspected chronic heart failure, not a way to judge an acute emergency. Obesity and some heart medicines can lower the result, while kidney disease and other illnesses can raise it. The blood test cannot identify the type of heart failure on its own.
If the result is low but clinical concern remains, further discussion with a heart failure specialist may still be appropriate.
Longer heart rhythm monitoring
An ambulatory ECG records heart rhythm during everyday activities using a Holter monitor, patch or another device. The recording period is chosen to match how often symptoms occur.
It can help with episodic breathlessness, particularly alongside palpitations, dizziness or feeling faint. Recording symptom times helps the team compare them with your heart rhythm.
A reassuring recording is most informative when it captures a typical episode. If none occurred, further monitoring may sometimes be needed.
Exercise ECG and stress echocardiography
An exercise ECG records the heart’s electrical activity while you walk on a treadmill or cycle. It can show how symptoms, heart rhythm and exercise tolerance change as demand increases.
A stress echocardiogram adds ultrasound images during or around exercise, or uses a medicine to place the heart under stress when appropriate. It answers a different question from a resting echo.
In people without known coronary artery disease, NICE does not recommend exercise ECG to diagnose or exclude stable angina. The NICE guidance on suspected cardiac chest pain describes when coronary imaging or other functional tests are appropriate.
CT coronary angiography and other cardiac imaging
If the history suggests reduced blood supply to the heart, a cardiologist may recommend CT coronary angiography or another investigation. CT coronary angiography examines the arteries supplying the heart. It differs from an ordinary chest CT used to assess lung tissue.
Other selected tests can assess whether blood supply becomes inadequate under stress or investigate a specific concern about heart muscle. These are chosen according to symptoms, previous results and individual suitability. They are not a routine package for everyone with breathlessness.
What normal heart tests do and do not tell you
The value of a normal result depends on the question the test was intended to answer.
| Reassuring result | What may still need clarification |
|---|---|
| Normal resting ECG | Whether an intermittent rhythm problem occurs during symptoms. |
| Reassuring resting echocardiogram | Whether the full findings explain symptoms that occur only during exertion. |
| Low NT-proBNP | Whether clinical concern remains despite a lower likelihood of heart failure. |
| Normal stress test | What type of test was performed and which conditions it assessed. |
Resting tests may not reproduce symptoms caused by stairs or hills. Breathlessness during exercise does not prove a heart problem, because the lungs, blood and muscles also need to meet the increased demand.
Ask for the actual reports. A normal ECG and a detailed assessment using several complementary tests provide different levels of information.
When further assessment is useful
Arrange a review if breathlessness persists, is worsening, limits activities you previously managed or wakes you at night. New symptoms deserve fresh assessment rather than reassurance based only on an older result.
Your clinician may consider further cardiac investigation if the pattern still suggests a heart problem. If the cardiac assessment is reassuring, respiratory tests, blood tests or assessment of your breathing pattern may be more useful. Heart and lung conditions can also coexist, so investigation does not always follow a strict sequence.
How CPET differs from a cardiac stress test
During cardiopulmonary exercise testing (CPET), you cycle or walk wearing a mask that measures oxygen uptake, carbon dioxide production and ventilation. The team also monitors cardiovascular responses.
Results can help distinguish limitations involving circulation, breathing, gas exchange or conditioning, and identify an unusual breathing pattern during activity.
CPET can help when resting investigations have not explained exertional symptoms. It provides more physiological detail than an exercise ECG, but does not replace every investigation or always identify a single cause. Royal Brompton and Harefield describe these measurements in their information on cardiopulmonary exercise testing.
Preparing for your appointment
Bring your test reports, a medicine list and a brief account of how your activity has changed. Useful details include:
- Whether symptoms start suddenly or build gradually, and how long they last.
- The distance, number of stairs or pace you can manage before stopping.
- Any chest discomfort, palpitations, dizziness, cough or wheeze.
- Whether symptoms occur when lying down, during sleep or after exertion.
- Whether you had your usual symptoms during any previous monitoring or exercise test.
Follow the testing service’s preparation instructions. Do not stop prescribed medicines before a test unless the clinical team specifically asks you to do so.
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Frequently asked questions
Can I still have a heart problem with a normal ECG?
Yes. A resting ECG is one part of assessment. It may miss a rhythm disturbance that was not happening during the recording, and it does not replace tests of heart structure or blood supply. Further testing depends on the clinical picture.
Does a normal echocardiogram rule out heart failure?
A reassuring full echocardiogram makes several important abnormalities less likely. However, a normal ejection fraction alone is insufficient to exclude heart failure. Symptoms, examination, blood tests and the rest of the scan need to be interpreted together.
Should everyone with breathlessness have a stress test?
No. The next investigation should answer a specific question. A stress test may be appropriate for selected cardiac concerns, while lung function tests, blood tests or another assessment may better explain a different symptom pattern.
Is CPET the same as a treadmill heart test?
No. CPET includes measurements of breathing and gas exchange as exercise becomes harder. A standard exercise ECG mainly records electrical heart activity during exertion. Their purposes overlap, but they are not interchangeable.
Should I see a cardiologist or a respiratory consultant?
A GP can help decide based on your symptoms and previous findings. Ongoing cardiac concerns may need a cardiologist. If heart investigations are reassuring but breathlessness remains unexplained, a respiratory consultant can assess possible lung and breathing contributors and advise on further referral.
Consultant Respiratory Physician practising in London and Surrey, and Senior Physician in Respiratory Medicine at Kingston and Richmond NHS Foundation Trust.
He graduated from Cambridge and completed his doctorate at Columbia University, New York. He is a Fellow of the Royal College of Physicians and President of the Cambridge Medical Graduates’ Society.
MA MB BChir MD (Cantab) FRCP · GMC 4117379 · Book an appointment