A low-cost drug at 1.30 pounds per day could save thousands of people suffering from heart failure.
A study of the pill, involving 6,500 patients in 37 countries, including Britain, showed it cuts deaths and hospital admissions by 25 per cent.
The drug, ivabradine, is already licenced for angina, so it is known to be safe. Doctors are allowed to prescribe it for heart failure patients while the new licence is being approved, according to the journal Lancet.
Patients were found to benefit from the new drug despite already receiving a range of other medicines.
Ivabradine, also known with the brand name Procoralan, reduces the heart rate of patients which gives the heart more time to fill with blood before the next beat, making it more efficient.
Beta-blockers, which have a similar effect, are unsuitable for up to half of patients who could, therefore, gain extra benefit from ivabradine.
Professor Martin Cowie, the consultant cardiologist at the Royal Brompton Hospital, London, who led the British arm of the study, said: “The evidence represents a significant clinical breakthrough in the management of heart failure and is incredibly important information for patients with this condition.”