ECG and echocardiography are different tests that may both be used to assess heart symptoms or known heart conditions. They measure different aspects of the heart, and the appropriate route depends on symptoms, clinical findings and the question a clinician is trying to answer. The clinic confirms appointment route, any referral requirements and availability at booking.
An ECG — electrocardiogram — records the electrical signals that make your heart beat. An echocardiogram uses ultrasound to create a moving image of your heart's structure and mechanical function. Think of the ECG as listening to the orchestra's timing, and the echocardiogram as watching the musicians themselves. Both perspectives are valuable; neither replaces the other.
What an ECG Measures
Every heartbeat begins with an electrical impulse generated in the sinoatrial node — the heart's natural pacemaker — which then travels through a precisely coordinated pathway to trigger each chamber to contract in sequence. An ECG captures this electrical journey in real time, producing the familiar waveform trace that cardiologists read to assess rhythm, rate, and conduction.
A standard 12-lead ECG places electrodes on the chest, arms and legs to record electrical activity from different directions. The recording is interpreted alongside symptoms, history and other clinical information; it does not by itself establish every cause of a symptom.
The conditions a 12-lead ECG can identify include atrial fibrillation and other arrhythmias, heart block and conduction delays (bundle branch blocks), evidence of a previous or ongoing heart attack (ST-segment changes), left or right ventricular hypertrophy, and the effects of certain medications and electrolyte imbalances. What an ECG cannot do is show you the physical structure of the heart — the size of the chambers, the condition of the valves, or how powerfully the muscle is pumping.
What a 12-Lead ECG Can Detect
What an Echocardiogram Shows
An echocardiogram is an ultrasound scan of the heart. It uses sound waves to create images of the heart's chambers, valves and surrounding structures. A clinician selects the test type for the clinical question; the clinic confirms practical appointment arrangements at booking.
Echocardiography can contribute information about how the heart is working, including ejection fraction, which describes the proportion of blood pumped from the left ventricle with each beat.[3] A clinician interprets this alongside symptoms, examination findings and other relevant tests.
Echocardiography can provide detailed information about valve appearance and function. It is selected and interpreted in the context of the clinical question, and may be combined with other tests where appropriate.[NHS]
Critically, an echocardiogram cannot tell you about the heart's electrical activity. A patient can have a perfectly normal echocardiogram — healthy valves, good ejection fraction, normal chamber sizes — and still have atrial fibrillation or a dangerous conduction abnormality that only an ECG would detect.
What an Echocardiogram Can Show
Key Differences at a Glance
The table below summarises the principal differences between the two tests. Understanding these distinctions helps explain why your cardiologist may recommend one, the other, or both during a single consultation.
| Feature | ECG | Echocardiogram |
|---|---|---|
| What it measures | Electrical activity | Structure and mechanical function |
| Technology | Electrode sensors on skin | Ultrasound (sound waves) |
| Appointment length | Confirmed at booking | Confirmed at booking |
| What it shows | Rhythm, rate, conduction, ischaemia | Chambers, valves, ejection fraction, wall motion |
| Best for | Arrhythmia, AF, heart attack, conduction blocks | Heart failure, valve disease, cardiomyopathy |
| Cannot detect | Structural abnormalities, valve disease | Electrical abnormalities, arrhythmias |
| Radiation | None | None |
| Preparation | None required | None required (gel applied to chest) |
When You Need an ECG
An ECG may be considered when symptoms or clinical findings suggest a rhythm or electrical question. It can provide useful information when a rhythm change is captured, but the result needs to be interpreted alongside symptoms, clinical history and, where appropriate, further assessment.
An ECG is also the primary investigation for chest pain, particularly when there is concern about acute coronary syndrome or a previous myocardial infarction. ST-segment elevation on an ECG is the hallmark of a heart attack in progress; Q waves indicate prior infarction. Importantly, the ACC/AHA guidelines recommend echocardiography as a complement to ECG when clinical history is unavailable or unreliable during a chest pain episode[6].
Other situations where an ECG is the appropriate first-line test include: unexplained syncope (fainting), pre-operative cardiac screening, monitoring of patients on medications that affect heart rhythm (such as certain antidepressants or antiarrhythmics), and annual cardiac review for patients with known hypertension or diabetes.
Request an ECG if you have:
A private ECG test at Victoria Medical is available by appointment, with reporting and follow-up arrangements confirmed at booking.
When You Need an Echocardiogram
An echocardiogram may be considered when the clinical question is structural rather than electrical. For progressive breathlessness or ankle swelling, it can form part of the assessment where the clinical history and examination indicate that heart structure or function needs investigation. It can provide information about ejection fraction, diastolic function and cardiac output; the appropriate investigation, urgency and next steps depend on the individual clinical context[3].
For patients with a heart murmur — an abnormal sound heard through a stethoscope — an echocardiogram is essential to characterise the underlying valve abnormality. Echocardiography has demonstrated sensitivity of 72–97% for detecting valve disease across multiple studies, making it far superior to clinical examination alone[5]. An ECG in the same patient may be entirely normal, or may show only non-specific changes that do not guide management.
I also recommend an echocardiogram for patients with a strong family history of cardiomyopathy or sudden cardiac death, for those with hypertension who need assessment of left ventricular hypertrophy and diastolic function, and for athletes undergoing cardiac screening. The echocardiogram answers questions that no other non-invasive test can address as comprehensively.
Request an Echocardiogram if you have:
A private echocardiogram at Victoria Medical is performed by a consultant cardiologist with reporting and follow-up arrangements.
When You Need Both Tests
In clinical practice, the ECG and echocardiogram are frequently complementary rather than mutually exclusive. The ACC/AHA guidelines have long recognised that a complete cardiac assessment for chest pain, heart failure, or complex arrhythmia often requires both an electrical and a structural perspective[6]. Furthermore, research has shown that an abnormal ECG has lower sensitivity for diagnosing heart failure with preserved ejection fraction (HFpEF) — echocardiography was present in 71% of HFpEF patients, confirming that ECG alone is insufficient for this diagnosis[2].
At Victoria Medical, a clinician may consider both tests as part of a comprehensive cardiac assessment when the clinical question requires electrical and structural information. The clinic confirms whether one or both tests are appropriate, alongside the expected appointment length, at booking. Together, the tests can help inform the next clinical step without assuming that every patient needs the same pathway.
Situations Where Both Tests Are Recommended
What to Expect at Victoria Medical
Both tests may be arranged through the appropriate clinical route. The clinic confirms suitability, any referral requirements, availability, preparation, reporting and follow-up arrangements at booking.
Book your appointment
Call 020 3146 9508 or book online. Tell us your symptoms and we will advise whether an ECG, echocardiogram, or both are appropriate — or leave it to the cardiologist to decide at the consultation.
Arrive at the clinic
No fasting or special preparation is usually required for either test. Wear comfortable clothing. The clinic confirms the planned tests and expected appointment length at booking.
ECG recording
Ten electrodes are placed on your chest, arms and legs. You lie still briefly while the trace is recorded. The clinician can explain each step and you can raise any comfort concern.
Echocardiogram
Ultrasound gel is applied to your chest and a probe is moved across the skin to capture images of your heart from multiple angles. You may be asked to change position or hold your breath briefly.
Results and consultation
The clinic explains the reporting process and appropriate follow-up route for your examination at booking.
Follow-up if needed
If further investigation or treatment is required, we can arrange a referral to a specialist or coordinate with your NHS team. Our private GP service is available for ongoing management.
Seek Emergency Care Immediately If You Have:
Call 999 or go to your nearest A&E. Do not wait for a private appointment.
Frequently Asked Questions
Can an ECG detect a heart attack?
An ECG can contribute to the urgent assessment of suspected acute coronary syndrome. Certain ECG changes may be seen, but diagnosis and urgent next steps are based on symptoms, clinical assessment, ECG findings and cardiac blood tests such as troponin. A normal ECG does not rule out all cardiac causes of chest pain.
Is an echocardiogram better than an ECG?
The tests answer different questions. An ECG records electrical activity, including rate and rhythm. An echocardiogram uses ultrasound to create images of the heart. A clinician considers which test, if any, is suitable for your symptoms and clinical context.
How long will an ECG or echocardiogram appointment take?
The clinic confirms the planned tests and expected appointment length at booking. The route, preparation, reporting and follow-up depend on the clinical question and the tests selected.
Do I need a GP referral for a private ECG or echocardiogram?
The appropriate care route and any referral requirements depend on your symptoms and clinical circumstances. The clinic confirms suitability, appointment route, availability and referral requirements at booking.
Will my private echocardiogram results be shared with my NHS GP?
Reporting and follow-up arrangements are confirmed at booking. If sharing information with another clinician may be appropriate, the clinic will explain the relevant consent and reporting route.
Can an echocardiogram detect atrial fibrillation?
An echocardiogram can provide information about structural changes associated with atrial fibrillation, such as left atrial enlargement. It does not diagnose AF by itself. If AF is suspected, the clinician decides whether an ECG or other rhythm monitoring is appropriate according to symptoms, timing and the clinical assessment; echocardiography may contribute structural information where relevant.
References
- [1] Ribeiro AH, Ribeiro MH, Paixão GMM, et al. Automatic diagnosis of the 12-lead ECG using a deep neural network. Nat Commun. 2020;11:1760. https://doi.org/10.1038/s41467-020-15432-4
- [2] Tromp J, Ferreira JP, Janwanishstaporn S, et al. Diagnostic accuracy of the electrocardiogram for heart failure with preserved ejection fraction. J Card Fail. 2023;29(6):906–914. https://doi.org/10.1016/j.cardfail.2023.03.011
- [3] Marwick TH. The role of echocardiography in heart failure. J Nucl Med. 2015;56(Suppl 4):31S–38S. https://doi.org/10.2967/jnumed.114.150433
- [4] Huang CH, Chang WT, Hsu SH, Tsai MS, Chen WJ. Tissue Doppler echocardiography in the diagnosis of acute heart failure. Resuscitation. 2006;70(2):204–210. https://pmc.ncbi.nlm.nih.gov/articles/PMC1861290/
- [5] Davidsen AS, Søndergaard J, Halling A, et al. Diagnostic accuracy of heart auscultation for detecting valve disease: a systematic review and meta-analysis. BMJ Open. 2023;13(3):e068121. https://doi.org/10.1136/bmjopen-2022-068121
- [6] Cheitlin MD, Alpert JS, Armstrong WF, et al. ACC/AHA Guidelines for the Clinical Application of Echocardiography. Circulation. 1997;95(6):1686–1744. https://doi.org/10.1161/01.cir.95.6.1686