Two distinguished surgeons have written to ministers urging them not to close congenital heart disease services at a leading London hospital.
The Royal Brompton Hospital said the proposed closure of the unit - and world-leading adult congenital heart disease research centre - would "not be in the best interest of our patients".
Last July, NHS England announced that the number of hospitals in England allowed to perform children's heart surgery was to be cut in a controversial move.
Under the plans, 13 "level 1" centres that perform surgery will be cut to 10, and nine "level 2" specialist cardiac centres will be cut to four - with the Royal Brompton threatened with closure.
The Mail on Sunday reported NHS England would be making its decision this Thursday and carried a letter signed by cancer surgeon Lord Darzi and heart transplant pioneer Sir Magdi Yacoub against the closure.
The letter, also signed by former Speaker and hospital patient Baroness Boothroyd, said: "As two London surgeons and a grateful long-term cardiac and respiratory patient at the Brompton, we ask: why would anyone want to dismantle the highest quality heart service in the country?"
The group added the review states congenital heart surgery should only take place in hospitals where other specialist surgeries are offered - but this ignored partnerships with other hospitals in the area.
It said: "Only one conclusion seems possible - that the standards on co-location have been defined in such a way as to deliberately result in the dismantling of the services at the Brompton.
"This would be an act of unforgivable folly. We urge Ministers to intervene and save the most important heart disease hospital in Britain."
Speaking when a consultation on the plans was launched in February, Professor Huon Gray, National Clinical Director for Heart Disease, NHS England, said: "It's our job to organise services so that every adult and child with congenital heart disease in this country gets not just safe or good care, but excellent care."
NHS England added that to make sure critically ill children receive the full range of support, the new standards specify that specialist children's cardiac services must only be delivered where there are also a wider range of other paediatric specialities present on the same hospital site.
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