Silent heart attack: how it goes unnoticed, how it is found and what follows

The NHS explains that a heart attack happens when blood flow to your heart is blocked, and that it is usually caused by a blood clot stopping enough blood reaching the heart. Heart muscle that is starved of blood can be damaged whether or not the person feels it. In a silent heart attack the event passes without the severe chest pain or collapse most people associate with the diagnosis.

The British Heart Foundation, writing for the public, defines it simply as a heart attack that has no symptoms. Some people cannot remember any symptoms at all, while others recall only a vague spell of feeling unwell that they did not link to the heart. The damage is real in either case, and the underlying disease of the coronary arteries is the same.

There is no single explanation. The BHF suggests that older people may be less likely to recognise symptoms because they are already living with discomfort that may or may not be related to the heart, and that in people with diabetes nerve damage can dull the perception of chest pain. Symptoms can also be mild or look like something else: the NHS lists indigestion-like burning, feeling sick, sweating and breathlessness among possible heart attack symptoms, any of which can be mistaken for a stomach upset or a chest cold.

The BHF gives examples of people who see a doctor for toothache, back pain or generally feeling unwell and, after an ECG and blood tests, are found to have had a silent heart attack. The practical message is that vague, unexplained, new symptoms in someone with heart risk factors deserve a proper assessment rather than reassurance.

A silent heart attack can happen to anyone. The NHS lists smoking, high blood pressure, high cholesterol, a close relative who has had a heart attack, diabetes and living with overweight or obesity as factors that make a heart attack more likely. The NHS also describes coronary heart disease as the build-up of fatty deposits in the coronary arteries, which can be influenced by smoking and heavy drinking and is more likely with high cholesterol, high blood pressure or diabetes.

The BHF adds that the key to prevention is a healthy lifestyle, and that people at higher risk because of high cholesterol, high blood pressure or diabetes should talk to their doctor about treatment.

Silent heart attacks are usually found by chance or while investigating other symptoms. The NHS describes an electrocardiogram (ECG) as a test that records the electrical activity of the heart and is usually quick and painless, done in a hospital, clinic or GP surgery. The BHF notes that ECGs and blood tests are the investigations that reveal a past heart attack.

If an ECG or other result raises suspicion, the NHS says further tests may include an echocardiogram, which can find out whether the heart has been damaged, and a coronary angiogram, which shows exactly where the blood flow is blocked, sometimes allowing the blockage to be treated at the same time. A doctor will discuss what the results may mean for you.

The NHS says you may get ECG results the same day, though some types take a few weeks. If you have heard nothing after a few weeks you should contact the doctor who referred you, and you can ask for results to be explained.

Being told you have already had a heart attack is unsettling, but the BHF is clear that the key is starting treatment. The NHS says that after a heart attack you will be given medicines to take long-term that treat the causes and help reduce the risk of having another one. These may include antiplatelets to help stop arteries getting blocked, statins to lower cholesterol and medicines to lower blood pressure, such as ACE inhibitors and beta-blockers.

Cardiac rehabilitation is usually offered, either in person or remotely using video calls or apps. The NHS describes recovery as varying: for some it takes several weeks with little impact on life, for others months or years. It also says to talk to your GP if you are anxious or have low mood afterwards.

Lifestyle changes support the medicines. The NHS recommends stopping smoking, keeping cholesterol and blood pressure at a healthy level, a balanced diet with less salt and saturated fat, a healthy weight, regular exercise and cutting down on alcohol.

The NHS says to call 999 if you have chest pain that feels tight or like squeezing, pain spreading to your arms, neck or jaw, severe difficulty breathing, pale, blue or grey lips or skin, or if someone has passed out and is not responding normally. Do not drive yourself to A&E. While waiting, the NHS advises sitting and resting and, if you have aspirin available and no allergy, taking a 300mg aspirin if you have one and are not allergic to it.

Call NHS 111 if you are suddenly more short of breath than usual, or have chest pain with feeling sick, or with a racing, slow, skipping or fluttering heartbeat. A heart attack is different from cardiac arrest, which is when the heart suddenly stops and the person loses consciousness.