Day after day, healthy, fit young men in their 20s and 30s are mysteriously dropping dead. Experts may have finally discovered the 'ticking timebomb' that is to blame

The end of the race was in sight – yet 26-year-old Mike Harper, an experienced runner, collapsed just 200 metres short of the half-marathon finishing line.

Despite receiving CPR, he was later pronounced dead in hospital.

‘After we were told Mike had died, my first question was, “how can my fit boy just drop dead?”’ asks his grieving mother, Tracy, 59.

The doctor explained that they thought the electrical signals in Mike’s heart had stopped working, stopping it from pumping blood properly – known as a cardiac arrest.

‘But I just didn’t believe that it could happen to someone so young and fit,’ says Tracy, two years to the day since Mike died. ‘We had no inkling anything was wrong with him.’

Mike, a quantity surveyor living in London, had previously completed several half-marathons and was excited to take part in the Great Bristol Run in May 2024 – a city he’d previously lived in.

His partner, Ailsa, was in the crowd cheering him on. The first sign that all was not well that Sunday came in a call from her mother.

Mike’s father, Roy, was mowing the lawn at the family home in Lincoln.

‘I got a call at about noon to say something had happened to Mike at the race – and that we needed to get to Bristol,’ says Roy, 63, who runs a business skills company with Tracy. ‘We had the most dreadful journey to Bristol, not knowing what was going on during the three-and-a-half hours’ drive.’

There was little information from the hospital – the couple later learned this was because doctors wanted to break the news of Mike’s death in person.

At Bristol Royal Infirmary, the couple were told that a police officer who happened to be running alongside Mike, as well as a nurse in the crowd and another bystander, had immediately administered CPR on their son when he collapsed.

The race’s medical team was also rapidly on the scene.

‘Mike had the best chance, but we still lost him,’ says Roy. Their disbelief was even greater as Mike seemed his normal self when celebrating Tracy’s birthday only two days earlier.

It’s still not clear what triggered Mike’s episode or whether the exertion of the race played a role – a postmortem concluded only that the cause of death was a cardiac arrest.

‘No abnormalities were found with his heart,’ says Tracy.

Every year in the UK there are more than 600 sudden cardiac deaths in teenagers and younger adults aged 14 to 35, according to the charity Cardiac Risk in the Young (CRY). And, as with Mike, 80 per cent of those teenagers and young people exhibit no symptoms of heart problems leading up to their death.

The charity has long campaigned for all those in this age group to be tested for underlying heart conditions.

CRY delivers free heart screenings at community venues such as schools and sports clubs – funded through donations.

Screening involves an electrocardiogram (ECG), which captures the rhythm and electrical activity of the heart through electrodes placed on to the chest.

If necessary, it can also include an echocardiogram, which uses sound waves to show the structure and functioning of the heart in real time.

An ECG is an effective detection tool in people under 35, because most cardiac deaths are due to conditions that affect the heart muscle, its blood supply or electrical activity – which can all impact the natural rhythm of the heart, explains Professor Sanjay Sharma, a consultant cardiologist at St George’s University Hospitals NHS Foundation Trust in London.

Heart disease in older adults is more likely to stem from ‘furred-up’ arteries (where the artery walls narrow due to a build-up of fatty deposits such as cholesterol) than from electrical signals. The effectiveness of screening in identifying hidden heart conditions and saving young lives was recently highlighted by a major study. Researchers followed more than 104,000 young people (their average age was 23) screened by CRY over a ten-year period from 2008. Some 5,700 participants were referred for secondary evaluation based on their ECG results and medical history.

Echocardiography then ‘cleared’ 3,801 of these, and the remaining 2,619 underwent further checks. Of these, 280 were diagnosed with high-risk cardiac conditions – in other words, these were young people with previously undiagnosed and potentially fatal heart conditions.

Around half underwent interventions – including possibly life-saving treatments to reduce their risk, says Professor Sharma, who was involved in the research, published in the Journal of the American College of Cardiology.

These treatments included cardiac ablation (when heat or cold is used to make tiny scars in the heart that block faulty electrical signals and restore a regular rhythm). It’s used to treat Wolff-Parkinson-White syndrome, the most common condition found by screening, which causes the heart to beat abnormally fast.

‘Other patients have had implantable defibrillators and pacemakers fitted while two patients had heart transplants,’ says Professor Sharma.

Importantly, the study also found no significant difference in risk between athletes and non-athletes – and so CRY, which funded the research, is calling for screening among the general population and not just those who are sporty, like Mike.

‘Around 40 per cent of all deaths in young people occurred during sleep – not when they were exercising,’ says Professor Sharma.

And as a small number of young people – one in 3,000 – were later diagnosed with a cardiac abnormality (and some even died) within six years of a normal ECG, CRY is also pushing for repeated screenings. ‘Some people, for instance, are born with cardiomyopathy [a heart muscle fault] that may not show itself until later in life, when you’re about 26,’ explains Professor Sharma. ‘So if they’re screened at 16 and nothing was wrong, something could still develop in the future.’

After Mike’s death, Roy and Tracy, as well as Mike’s siblings Phill, 31, and Fiona, 25, underwent heart screenings. Their results were normal, while genetic tests to check whether Mike had inherited heart disease did not flag up any concerns.

Sadly, around 50 to 60 per cent of families who have lost a young member due to sudden cardiac death will never find out exactly why, says Professor Sharma – ‘so it can be hard to move on’.

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Mike’s death is being looked at as part of research by City St George’s University of London – and Tracy is hopeful the cause will one day be found.

Mike’s family is convinced that a screening could have saved him – ‘there’s absolutely every chance he’d be alive and with us today’, says Tracy. But not all experts agree that screenings will provide the answers campaigners hope for.

Professor David Hildick-Smith, a consultant cardiologist at the Royal Sussex County Hospital in Brighton, believes that the benefits of spotting undiagnosed heart conditions with screenings must be weighed up against the possibility of false-positive results.

He says: ‘If a young person has died, it’s easy to say “if only they’d undergone an ECG – this could have been avoided”.

‘But that doesn’t account for a false-positive outcome, when someone is told they have a heart issue when they do not.

‘False-positives can cause lots of undue anxiety and this stress isn’t trivial – so this risk [2.1 per cent in CRY’s latest research] has to be weighed against who gets a genuine positive result where something can be done to reduce a fatal outcome.’

In 2019, the UK National Screening Committee, which advises the Government, said a screening programme should not be offered as ECGs are not reliable enough and that it was not clear if screening would reduce deaths.

But CRY says a three-month public consultation is due to open imminently and the charity will be submitting details of this new research.

Since Mike’s death, the family has been calling on the Government to fund cardiac screening for every young person.

‘When we’re feeling low, we think of the positives,’ says Tracy. ‘We were so lucky that we had Mike for 26 years – we now know he could have passed away at any time.’

testmyheart.org.uk