Sudden cardiac death in athletes: causes, warning signs and screening

The UK National Screening Committee defines sudden cardiac death (SCD) as the sudden and unexpected death of a person caused by a problem with their heart. The British Heart Foundation explains that cardiac arrest is when the heart stops beating and blood is no longer pumped around the body, and that it happens when the heart's electrical system does not work properly, so the heart beats too quickly, too slowly or irregularly. Without immediate treatment, the person will die.

The UK NSC acknowledges that SCD in young people is an important health problem and that the effect on families, friends and communities is devastating. Most athletes will never be affected, and the conditions behind it are individually uncommon, which is a key part of why policy on screening is debated.

The UK NSC says that in people under 39 the causes are often a thickening of the heart muscle or an electrical problem with the heart. The NHS describes the main heart muscle diseases (cardiomyopathies) in more detail.

Many people with these conditions have no symptoms, which is part of the problem. The NHS says that the heart changes in hypertrophic cardiomyopathy can cause dizziness, chest pain, shortness of breath and temporary loss of consciousness, and that some people have no symptoms at all and do not need treatment. For dilated cardiomyopathy it lists shortness of breath, extreme tiredness and ankle swelling as typical signs of heart failure.

Symptoms such as these deserve to be assessed by a doctor rather than put down to fitness or tiredness, and a GP can arrange initial tests and referral to a cardiologist if appropriate. The UK NSC also points to testing of family members when a relative is at risk of sudden cardiac death.

The UK NSC says, based on its review of December 2019, that it does not currently recommend systematic population screening of people under the age of 39 for cardiac conditions associated with SCD. It gave several reasons. Most research on the tests was in professional athletes, whose hearts have different characteristics from the general population; the research did not report good accuracy, and a high percentage of people with positive tests will not have a condition that causes SCD; it found no research on treatments or interventions to prevent SCD in people found by screening; and it was concerned that people might stop participating in sport after an incorrect positive result.

The Committee noted that previous reviews found screening programme examples mainly in professional athletes, and that it is not known whether population screening would reduce deaths. The next review was estimated for 2026 to 2027, so the position may change. Screening offered by charities or sports bodies is voluntary and separate from this NHS policy, so if you are considering it, ask what tests are done, who reviews the results and what follow-up is arranged if something is found.

The UK NSC says there is guidance on testing family members of people at risk of SCD and that effective implementation through a targeted screening programme may help prevent SCD in some groups at high risk. The NHS explains that hypertrophic cardiomyopathy is mostly inherited from parents and arrhythmogenic cardiomyopathy is an inherited condition. If a relative has been diagnosed with a cardiomyopathy or has died suddenly and unexpectedly from a heart cause, tell your GP, who can discuss whether referral for specialist assessment is appropriate.

The BHF says to call 999 and start CPR immediately if someone is having a cardiac arrest, and to ask someone to fetch a defibrillator. The defibrillator gives a controlled electric shock to try to get the heart beating normally, and you do not need training to use one because the machine talks you through the steps. Starting CPR immediately keeps blood and oxygen moving to the brain and around the body.

Knowing where the nearest defibrillator is and how to start CPR is worthwhile for coaches, teammates and sports clubs.

The NHS says that if you have severe hypertrophic cardiomyopathy you will need to see your doctor regularly so your condition can be monitored, and that your doctor will advise about the level and amount of exercise you can do. For arrhythmogenic cardiomyopathy it notes increasing evidence that prolonged, strenuous exercise makes symptoms worse. A cardiologist who sees athletes can advise on what is safe in your situation, and it is worth asking for clear written guidance for you and your coach.

On the NHS, your GP can arrange an ECG and refer you to a cardiologist if symptoms or family history suggest a heart condition. Inherited conditions are usually followed up by specialist cardiology teams and, where relevant, family testing.

Some athletes also choose private cardiology assessments or take part in charity-run screening. As the UK NSC points out, tests in people without symptoms have limits, including false positives and missed conditions, so a normal result is not a guarantee, and any new symptoms should still be reported.