A device which works like a pacemaker to help people with heart failure could potentially aid 18,000 across the UK.
The device has been hailed as a breakthrough
"Cardiac Resynchronisation Therapy" has been billed as the next big thing in heart care, and a major breakthrough for the treatment of heart failure patients.
Results presented at a US conference suggested it could prolong the lives of many patients for years.
The cost of each unit is unclear, but could be as much as £20,000.
It is estimated that 18,000 UK patients could benefit and it could present the NHS with a large bill.
But some experts say that the NHS could actually end up saving money if it prevents patients being hospitalised - the main NHS expense linked to heart failure.
So far, only a few hundred people in this country have been fitted with them.
The heart has four chambers, which, in a healthy patient, beat in an organised pattern to push blood out and around the body.
If you have heart failure, the weakening heart cannot maintain this healthy rhythm, and is unable to pump blood efficiently.
The pacing device is implanted just under the skin, with wires that go into the two pumping chambers of the heart.
The pacing device has wires that go into the two pumping chambers of the heart.
Impulses are sent down these to get the two ventricles beating in the correct rhythm.
It is a step up from a conventional pacemaker because it actively synchronises the beating of two individual chambers of the heart, rather than simply accelerating the speed of the heart as a whole.
A study of 1,600 patients with the devices, presented at the American College of Cardiology Conference in Chicago, found that "all-cause" mortality fell by 43% in heart failure patients implanted with the device.
There was almost a 40% increase in the average time before patients either died, or had to be hospitalised because of their condition.
The trial has provided such convincing evidence of benefits that it has been stopped early, say researchers.
The body which decides which treatments the NHS should fund has just been asked to look at "dual chamber pacing" - a slightly different type of resynchronisation.
So it is likely that it will be asked to examine the case for "bi-ventricular pacing" within the next year.
A spokesman for the British Heart Foundation said: "Resynchronisation therapy has been suggested as a significantly beneficial approach to help improve the symptoms and outlook of patients with chronic heart failure.
"The full results of the Companion Study have been awaited with interest and we hope they will confirm that cardiac resynchronisation therapy will have an important place in the management of patients with this limiting condition.
"However, it is also important to stress that coronary heart disease and hypertension are major causes of heart failure and these conditions are largely preventable with lifestyle changes."