Scientists have developed heart patches that could benefit hundreds of thousands of people who have a heart attack.

The British Heart Foundation (BHF) said the patches, which are grown in a lab and help repair damaged hearts, could one day provide an off-the-shelf treatment. They have shown promise in animals, and clinical trials in humans will begin in the next two years.

The thumb-sized (3cm x 2cm) patches of heart tissue contain up to 50m human stem cells programmed to turn into working heart muscle cells.

Experts say one or more patches could be implanted on to a patient’s heart to prevent or reverse damage to the organ.

During a heart attack, the heart is starved of vital nutrients and oxygen, killing off parts of the heart muscle. This weakens the heart and can eventually lead to heart failure, which affects an estimated 920,000 people in the UK.

The patches are intended to physically support the damaged heart muscle and help it pump more efficiently. Chemicals are also released that stimulate the heart cells to repair and regenerate.

Lab tests show that the patches start to beat after three days and start to mimic mature heart tissue within one month.

In animals, the patches led to an improvement in the function of the heart after a heart attack, and blood vessels from the heart were able to grow into the patches.

The ultimate goal is to have a stock of pre-made patches that are compatible with all patients, so that a person having a heart attack could quickly have one implanted.

Dr Richard Jabbour, from the London BHF Centre of Regenerative Medicine, said: “One day we hope to add heart patches to the treatments that doctors can routinely offer people after a heart attack. We could prescribe one of these patches alongside medicines for someone with heart failure, which you could take from a shelf and implant straight into a person.”

Prof Metin Avkiran, an associate medical director at the BHF, which is funding the research, said: “This is a prime example of world-leading research that has the potential to mend broken hearts and transform lives around the globe. If clinical trials can show the benefits of these heart patches in people after a heart attack, it would be a great leap forward for regenerative medicine.

“Heart failure is a debilitating and life-changing condition with no cure, making everyday tasks incredibly difficult. If we can patch the heart up and help it heal, we could transform the outlook for these people.”