The UK’s longest waiting patient for a heart transplant has appealed for potential donors to “be a hero”, as organ donation week begins.

Gareth Evans, 45, from Stockport, has been waiting for a new heart for more than nine years. His condition has deteriorated recently and he has spent the last three months in Wythenshawe hospital, south Manchester.

He needed his first heart transplant when he was just 17 due to cardiomyopathy, a disease of the heart muscle. Against the odds, the organ has lasted for 28 years, but returned to the waiting list on 23 February 2009.

Evans said: “The only way I can describe it is that for nearly a decade of my life I have been existing and not living.

“When I took retirement I thought three years would be the worst-case scenario before I got a new heart. Nine and a half years later and I’m still waiting … If somebody saves a life while they’re living they are classed as a hero – the final thing you could do is be a hero, save people’s lives. There is nothing more marvellous than that.”

Gareth Evans has waited almost a decade for a new heart transplant. Photograph: Danny Lawson/PA

He encouraged donors to inform their families of their wishes – the theme of organ donation week. NHS Blood and Transplant (NHSBT) said that last year 1,148 families (34%) declined to support organ donation, preventing an estimated 3,000 extra transplants.

Evans first became ill when he was doing his GCSEs but put it down to exam stress. He eventually went for tests and found out his heart was twice the size it should have been.

He said: “I was 17 and I was told: ‘You will maybe live five or 10 years.’ And I just thought ‘I’ll earn my money, I’ll spend my money’ and that’s what I did.

“But as time went on I thought ‘well, I’m still here’ and then I met my wife Danielle, and we had the two boys [William, 13, and Callum, 10] and I thought ‘I need to start planning for my future’.”

In a career spanning 19 years, he became a senior purchasing executive before being forced to take early retirement due to ill-health. “All of a sudden I went back to square one, back on the list,” said Evans.

At one stage he was removed from the transplant list and was forced to tell his wife and children to expect the worst – “the lowest point in my life”, he recalls.

He was put back on the list after adjustments to his medication made him able to cope with surgery again.

There are 6,133 people on the transplant waiting list. NHSBT says family refusals are the biggest obstacle to organ donation.

Anthony Clarkson, interim director for organ donation and transplantation at NHSBT, said: “People like Gareth are living moment to moment, in desperate need of someone saying ‘yes’ to donation – their lives depend upon a selfless organ donor and their brave family agreeing to donate their organs for transplant.”

The government plans to plans to change from the current opt-in system in England to an opt-out system, which presumes consent, from 2020 but family members will retain a right of veto. Wales introduced an opt-out system in December 2015.