Around two million people in the UK are living with angina. Many of them waited months — or longer — before getting a proper diagnosis, because their symptoms were dismissed or their resting ECG came back normal. That delay carries real risk. Angina is a warning sign that the heart is not receiving enough blood, and without treatment, it can increase the risk of a heart attack significantly.
One of the most common questions we hear at The Private GP is: “I had an ECG and it was normal — so why do I still have chest pain?” The answer is that a normal ECG does not mean a normal heart. And understanding what an ECG can and cannot show for angina could make a real difference to how quickly you get the right diagnosis.
If you have chest pain or any symptoms you are concerned about, our ECG heart health check-up is available on site in Birmingham with results reviewed by a doctor on the same day.
What Is Angina and Why Is It Easy to Miss?
Angina is chest pain or discomfort caused by reduced blood flow to the heart muscle. It is not a heart attack, but it is a warning sign that the heart is not getting enough oxygen — usually because one or more coronary arteries are narrowed.
The NHS describes angina as a sudden pain or tightness in the chest, neck, shoulders, jaw, or arms. These symptoms are often brought on by exercise, emotional stress, cold temperatures, or a heavy meal — and they typically ease within a few minutes of resting. This pattern is the hallmark of stable angina, the most common type.
Unstable angina is more dangerous. It occurs without warning, often at rest, and does not follow a predictable pattern. It is a medical emergency, as it can signal an impending heart attack.
Research published in Pavilion Health Today confirms that approximately two million people in the UK have been diagnosed with angina, with around 96,000 new cases identified every year. It is more common in men and in those over 55, though it can affect anyone — particularly those with high blood pressure, high cholesterol, diabetes, a family history of heart disease, or a history of smoking.
Angina is easy to miss for several reasons. The pain often comes and goes. It can feel like heartburn or indigestion. In women especially, symptoms are frequently atypical — presenting as fatigue, breathlessness, or jaw discomfort rather than classic chest pressure. As a result, many people live with undiagnosed angina for months or even years before getting the right assessment.
Can an ECG Detect Angina?
An ECG can provide important clues that suggest angina, but it cannot diagnose it with certainty on its own. Whether an ECG picks up angina depends heavily on when it is done — specifically, whether the heart is under stress at the time of the recording.
A resting ECG taken between episodes may appear entirely normal. Research published in PMC confirms that approximately 50% of patients with angina have completely normal findings on a resting ECG. This is because angina, unlike a heart attack, does not usually cause permanent damage to the heart muscle — so when the heart is at rest and receiving adequate blood, the trace may look unremarkable.
The National Heart, Lung, and Blood Institute confirms that certain ECG patterns can be a sign of unstable angina or vasospastic angina. However, even during an episode, your ECG may sometimes be normal. This does not mean your symptoms are not real or not cardiac in origin — it simply means the ECG alone is not sufficient to rule angina out.
An ECG is most useful for angina in three specific situations. First, when it is recorded during an active episode of chest pain — when changes to the heart’s electrical activity are most likely to show up. Expert Cardiologist London advises that if you have chest pain, it is best to have an ECG performed while the discomfort is still present. Second, when it shows signs of a previous heart attack or ongoing ischaemia that point towards underlying coronary artery disease. Third, as part of a broader clinical picture alongside your symptoms, risk factors, and other tests.
A normal resting ECG does not rule out angina. It is the beginning of an investigation, not the end of one.
What Does Angina Look Like on an ECG?
During an angina episode, the ECG may show characteristic changes that indicate the heart muscle is not receiving sufficient blood. The most significant of these is ST segment depression.
PMC research on the ECG profile of angina patients explains that a depression of 1mm or more in the ST segment — the flat line between the main spike of the heartbeat and the recovery wave — is the most characteristic ECG change associated with myocardial ischaemia. In plain terms, this dip in the trace is the heart’s electrical way of signalling that its blood supply is temporarily compromised.
Other changes that may appear during an angina episode include T wave flattening or inversion, where the recovery wave after each heartbeat looks abnormal in shape or direction. In a rare form of angina called vasospastic (or Prinzmetal) angina — caused by coronary artery spasm rather than narrowing — the ECG may instead show ST segment elevation, which can look similar to a heart attack on the trace.
Between episodes, when the heart is at rest and receiving enough blood, the ECG often returns to normal. This is why a resting ECG performed when a patient is symptom-free can appear completely unremarkable even in someone with significant coronary artery disease. The trace is essentially a snapshot — and if the problem only shows itself under stress, a resting snapshot will not capture it.
The ECG may also show signs of a previous heart attack, such as abnormal Q waves, which can indicate past damage to the heart muscle. In this context, the ECG helps build a picture of the underlying coronary artery disease that typically causes angina.
Is an Exercise ECG Better at Detecting Angina?
An exercise ECG — where the heart is monitored while you walk on a treadmill or cycle on a stationary bike — is better at provoking and capturing the changes associated with angina than a resting test. By making the heart work harder, it recreates the conditions under which angina typically occurs.
Research cited in PMC confirms that the exercise ECG is more sensitive and specific than the resting ECG for detecting myocardial ischaemia, and it is described as the test of choice for identifying inducible ischaemia in patients suspected of having stable angina. During an angina episode triggered by exercise, the ST segment changes discussed above are far more likely to appear and be captured.
However, it is important to understand the current UK clinical guidance on this. NICE — the National Institute for Health and Care Excellence — no longer recommends the exercise ECG as the first-line diagnostic test for suspected stable angina. This change to guidelines came in 2010 and was reinforced in 2016 and 2021, based on evidence that the exercise ECG has limited sensitivity and specificity compared to modern imaging techniques. A review published in PMC found that the exercise ECG has a weighted mean sensitivity of 68% and specificity of 77% when compared to coronary angiography — meaning it misses a meaningful proportion of true cases and occasionally flags false positives.
NICE now recommends CT coronary angiography as the first-line investigation for patients with typical or atypical chest pain where stable angina is suspected. This gives a detailed image of the coronary arteries and can directly show narrowing or blockage.
The British Journal of Cardiology confirms that the exercise ECG still has a role in specific situations — for example, assessing exercise tolerance, evaluating exercise-induced arrhythmias, and monitoring patients with known coronary disease. However, it should not be used as the sole test to confirm or rule out a new diagnosis of stable angina.
What Other Tests Are Used Alongside an ECG for Angina?
Because an ECG alone is rarely sufficient to diagnose angina, it is almost always used as part of a broader assessment. A complete picture typically involves several investigations.
CT coronary angiography is now the NICE-recommended first-line test for suspected stable angina. It uses a type of X-ray scanning with injected dye to show whether the coronary arteries are narrowed or blocked. It is non-invasive and provides detailed anatomical information that an ECG cannot.
Blood tests play an important supporting role. Troponin levels in the blood can help clinicians distinguish between unstable angina and a heart attack — troponin is a protein released when heart muscle is damaged, and it rises in a heart attack but typically remains normal in stable angina. Cholesterol levels, blood glucose, and inflammatory markers also help assess cardiovascular risk. At The Private GP, our private blood tests can be arranged on site, including a BNP blood test which measures a hormone released when the heart is under increased strain.
An echocardiogram uses ultrasound to look at the structure and function of the heart. It can identify areas of poor muscle movement that suggest reduced blood supply, and it gives useful information about heart valve function and chamber size.
A Holter monitor — a wearable device that records the heart’s activity continuously over 24 hours or longer — is occasionally used when silent ischaemia is suspected, or when symptoms occur at irregular and unpredictable times.
When Should You Get an ECG for Chest Pain?
If you are experiencing symptoms that could be angina, you should not wait for them to happen again before getting checked. Act on what you are feeling now.
NICE guidance is clear that an ECG should be taken as soon as possible when a clinician suspects angina. This is because the test is most useful during or shortly after an episode, when changes are most likely to be captured. Waiting weeks for an NHS referral means the window in which that recording would be most informative may have passed.
Symptoms that warrant prompt assessment include chest tightness or discomfort that comes on during exercise, exertion, or stress and eases with rest. Pain that spreads to the jaw, left arm, shoulders, or upper back. Unexplained breathlessness, fatigue, or dizziness. Palpitations occurring alongside any of these symptoms.
If your chest pain does not stop after resting for a few minutes, is getting worse, or is accompanied by sweating, nausea, or severe breathlessness, call 999 immediately. This could be a heart attack or unstable angina, both of which are medical emergencies.
If your symptoms are less acute — coming and going, linked to exertion, easing with rest — then a same-day private assessment is the right step. Our home visit service is also available for patients who are unable to come to the clinic.
A normal ECG does not mean your symptoms can be ignored. It means further investigation is needed. Getting that first ECG done promptly is the step that sets everything else in motion.
Frequently Asked Questions
- Can you have angina with a normal ECG?
Yes, and this is very common. Research confirms that approximately half of all patients with angina have a completely normal resting ECG when they are not experiencing an episode. A normal ECG does not rule out angina. If your symptoms are consistent with angina, further investigation is always warranted regardless of what a resting ECG shows.
- What is the best test to diagnose angina in the UK?
NICE currently recommends CT coronary angiography as the first-line investigation for patients with suspected stable angina. This scan gives a detailed image of the coronary arteries and can directly identify narrowing or blockage. It is typically used alongside an ECG, blood tests, and a full clinical assessment of your symptoms and risk factors.
- Does angina always show on an ECG during an episode?
Not always. Most patients with angina show characteristic ECG changes — particularly ST segment depression — during an episode, but this is not universal. Some patients have a normal or near-normal ECG even while experiencing chest pain. This does not mean the pain is not cardiac in origin. It means the ECG alone is not a reliable way to confirm or exclude angina during any given episode.
- Can angina be confused with a heart attack on an ECG?
Occasionally, yes. Both angina and a heart attack can produce similar changes on an ECG, particularly ST segment changes. The key difference is that in a heart attack, ST elevation is typically more marked and sustained, and troponin — a protein released when heart muscle is damaged — rises significantly in the blood. Blood tests alongside the ECG help clinicians distinguish between the two. If there is any doubt, the patient is treated as a cardiac emergency until a heart attack is ruled out.
- How quickly should I get an ECG if I think I have angina?
As soon as possible. NICE guidance states that an ECG should be taken promptly when angina is suspected. An ECG performed during or shortly after an episode is far more likely to show relevant changes than one taken days or weeks later. At The Private GP, same-day appointments are available and results are discussed with you on the day. Do not wait — acting quickly gives you and your doctor the best chance of capturing the information needed to reach the right diagnosis.