Young people who survived a heart attack before they hit 40 continue to remain vulnerable to dying earlier than their peers.
The damage stays with them, increasing their risk of death by 10 per cent over a decade.
And their elevated risk of dying could continue to worsen by 1 per cent each year if the trend persists, according to Associate Professor Mark Chan from the National University of Singapore's (NUS) Yong Loo Lin School of Medicine.
The finding was both "unexpected and worrisome", said Prof Chan, who was part of a team of researchers who did a retrospective study of over 15,000 heart attack patients in Singapore.
The data, which spanned 12 years, showed that about 4 per cent, or 601 people, had a heart attack at 40 years old and younger.
"Our initial hypothesis was that younger persons who had a heart attack had a good potential for recovery," he told reporters at a media briefing yesterday.
"Because of their higher resilience and higher potential for repair, we were hoping to see that younger patients over time will match the level of the general population in terms of their long-term survival."
However, this was not the case.
While younger patients were more likely to survive a heart attack, they continued to suffer the effects over the years.
The study was published in The American Journal of Cardiology in August, and is the first that compares the long-term mortality of young heart attack survivors against their peers who did not suffer a heart attack.
Professor Terrance Chua, medical director of the National Heart Centre Singapore, stressed that the risk of heart attacks can be reduced through prevention and control of risk factors such as smoking, diabetes, hypertension, high cholesterol and obesity.
This includes taking medication regularly, exercising and quitting smoking, added Prof Chua, who is also an author of the study.
One in three of the study's younger patients had a family history of premature coronary artery disease.
But what stands out is that most of them, or about 78.4 per cent, are smokers.
Despite the risks, young patients continue to puff.
"You cannot change your genes, but smoking is clearly something that is modifiable," said Prof Chan.
"I think it (smoking) is a major contributor as to why young people get a second heart attack and eventually die from it."
John (not his real name) was just 22 when he had a heart attack.
After that, he stopped smoking, but lasted only four months before lighting up again, smoking one pack of cigarettes daily.
It was only when he got engaged in 2011 that he stubbed out for good.
Looking back, the clerk said he was naive, thinking he was invincible because of his young age.
Today, the father of one often encourages his smoker friends to quit the habit.
"Don't think it cannot happen to you," he said.
The Cardiovascular Research Institute at NUS will also be leading a two-year study on heart attack patients to find out how lifestyle changes and habits affect their health and risks.
It is expected to be completed in 2019.