Old people may be missing out on vital treatment because they have an unrecognised form of heart disease.

Doctors in the United States say a newly identified type of heart failure may go undiagnosed.

Our research indicates that this newly recognised disorder is a true second form of heart failure

Dalane Kitzman, cardiologist

Unlike classical heart failure, there is no single test for it.

It is common among the elderly but it may be confused with other diseases, obesity or ageing.

"There has been a debate among doctors about whether patients with this newly recognised disorder truly have heart failure," said cardiologist Dalane Kitzman of the Wake Forest University Baptist Medical Center.

"That is because there is no simple means to diagnose it and its symptoms could have other causes.

"This confusion has kept some patients from getting treatment and prevented researchers from finding the most effective way to treat the disorder."

Pumping problems

Heart failure is the term used to describe the symptoms and signs which occur if the heart becomes less efficient at pumping blood around the body.

In most cases of heart failure - systolic heart failure - the heart does not contract strongly enough.

In the second type - diastolic heart failure - the heart's main chamber is too stiff and does not fill with enough blood.

According to a study of 147 patients, both types of heart failure have a similar impact on the ability to exercise, quality of life and the levels of certain hormones.

"Our research indicates that this newly recognised disorder is a true second form of heart failure," said Dr Kitzman.

"We have recently shown that it is associated with a substantial burden of excess disability and death in older Americans. This disorder should be the focus of intensive research."

Funding call

Dr Lip-bun Tan of Leeds General Infirmary says diastolic heart failure has been known about for some years but diagnosis is difficult.

Unlike classical heart failure, it can not be detected by a simple scan so may be overlooked by junior doctors.

He told BBC News Online: "More money needs to be poured into properly conducted studies to find out a simple way of diagnosing diastolic heart failure that can be applied to large numbers of the population, especially the elderly."