The number of patients with heart failure is set to increase steadily throughout the next two decades, say researchers.

The UK has an ageing population, and heart failure is a key disease of the elderly.

It happens when the muscles of the heart simply are not able to pump enough blood around the body.

This may be the result of the overall decline of the heart muscle as the body ages, or be hastened by a heart-damaging event such as a heart attack.

Often, it can mean that blood trying to return to the heart from the lungs is not pumped away fast enough, leading to fluid seeping into the lung instead.

As well as proving a disabling condition for many thousands of patients, it accounts for a high number of GP and hospital visits.

However, the projected increase is partly due to advances in science which mean that many more people can survive heart attacks.

Extra thousands

Statisticians from the University of Glasgow looked at current rates of heart failure, then looked ahead, taking into account short term increases - and expected rates of population increase.

There are currently thought to be 40,000 men and 45,000 women with heart failure in Scotland.

Just on the basis of a rising number of older people living in Scotland, almost 20,000 extra would be added to that figure, according to their estimates.

When the likelihood of more heart attack survivors is added, they say, the probability is a much greater burden on the NHS from heart failure in years to come.

The greatest rise will be in men because improvements in medical science mean that men are living much longer.

Survival

And with modern treatments enabling people with heart failure to survive longer, the burden on the NHS is even higher.

The authors of the study say that the health service needs to get ready for the increase.

In the journal Heart, they wrote: "Though surrounded by inevitable uncertainty, our projections, based on the best available data, do suggest the burden of heart failure will continue to increase substantially over the next two decades.

"Future health service planning must take this into account."

Research funded by the British Heart Foundation (BHF) suggests heart disease costs the UK �7bn a year.

A spokesman said: "As more people live with the consequences of heart disease and as the population ages, more people are likely to develop this debilitating and chronic condition."