"Back in the 1990s I was in the United States playing on a tennis scholarship and they had a mandatory cardiac screening programme for all of their athletes," he explains.
Dr Cox discovered he had a heart condition, and back in the UK his story came to public attention.
At the time he was told that only one in five million people were affected by the same problem. Today, with better research and more accurate post-mortems, we know it is one in a few thousand.
He has been involved with CRY since his own experience with screening, spurred on by the many people who have contacted the charity since its foundation in 1995 with their own stories of tragedy and loss of young life.
CRY's efforts in raising awareness of cardiac risk among young people has had some strong support.
The Lawn Tennis Association was an early adopter in the UK. In 1993 the first cardiac screening of elite players, among them Tim Henman and Jo Durie, was conducted by Professor McKenna and CRY founder Alison Cox.
The LTA became the first sporting body in the UK to offer comprehensive cardiac testing to all its elite junior athletes.
CRY has kept up its awareness campaigns over the years, advocating the need for expert cardiac screening for all young people engaged in organised sport.
Today the charity provides screening services for professional sporting bodies including the English Institute of Sport, the RFU, RFL, LTA and a number of FA teams."
However, nothing has done more to raise awareness than the dramatic collapse of Bolton Wanderers footballer Fabrice Muamba during a Premier League match against Tottenham on Saturday 17 March.
The 24-year-old midfielder had suffered a cardiac arrest and was clinically dead for 78 minutes.
He has made a remarkable recovery and is expected to return to top flight football in the near future.
"Had that occurred 15 years ago it could have been very different." says Dr Cox.
"There is a greater level of awareness (of sudden cardiac incidents) now."
Fabrice Muamba's ordeal has made headlines across the world. It has also led to a huge public response for CRY's advice and services, with Dr Cox's statements on the risks to young, healthy people from undetected heart problems prominently featured in The Sun and the Daily Mail.
"Sport increases the risk by three fold if you have an underlying condition," he explains.
"Last year CRY carried out 8,500 screenings for young people aged between 18 and 35 who choose it. They undergo an ECG and a questionnaire with a specialist doctor. 10 to 20% will have a follow-up ultrasound test on the day."
Dr Cox stresses that young people must have an informed choice and be offered the option of screening.
There are a range of underlying conditions that can be detected, some of which can be cured. The screening can also detect structural or electrical problems in the heart, some of them genetic.
Dr Cox says Muamba's collapse has led to "the greatest level of awareness since I became involved with CRY".
"All of our public screening events are fully booked and we are trying to open up more events."
The case for screening is compelling.
"Every week in the UK, 12 apparently fit and healthy young people, under the age of 35, die from undiagnosed cardiac conditions," Dr Cox explains.
"80% of these deaths will occur with no prior symptoms.
"One in every 300 of the young people that CRY tests will be identified with a potentially life threatening condition.
"Although screening will not identify all young people at risk, in Italy, where screening is mandatory for all young people engaged in organised sport, they have reduced the incidence of young sudden cardiac death by 90%."
Dr Cox says that while mandatory testing is not the way forward in the UK – "we have a different legal and medical environment" – the NHS's advice on screening must be changed.
Currently, the policy states that "screening should not be offered".
CRY says that discourages young people who may be at risk from having a simple non-invasive test.
The charity has launched a national campaign and a petition on the Government website to get the NHS to review its policy.
They are backed by Shadow Health Secretary Andy Burnham MP.
"The loss of these young people in their prime causes absolute devastation for their families and yet I believe there is more we could do to prevent most of these deaths," he says.
"I believe the current screening policy is out-of-date and based on a number of flawed assumptions."
Dr Cox stresses that testing must always be carried out by a expert cardiologist.
"When you have that level of expertise at the front line and provide that specialism you dramatically reduce false positives and false negatives."
The Olympics will begin in London in July, and since 2007 CRY has been screening the UK's potential elite athletes.
"Everyone who forms part of Team GB will have been offered screening," reveals Dr Cox.
CRY will continue to promote their message throughout 2012, including at the prestigious Royal Academy Summer Science Programme.
The case of Fabrice Muamba had brought the issue of undetected cardiac conditions into sharp public focus.
Dr Cox says all young people to be aware that cardiac screening of fit and healthy young people saves lives.
"We want young people to have the opportunity to be tested.
"This e-petition is to show the government that something must be done to reduce the terrible death toll of over 600 fit and healthy young people each year."