A study by the University of Notre Dame Australia (UNDA) and the National Echo Database Australia (NEDA) has warned aortic stenosis is deadlier than previously understood.

The condition involves a hardening and narrowing of the aortic valve which makes it difficult for the heart to pump blood around the body.

About 100,000 Australians are believed to be living with the severe form of the disease.

Researchers overlaid NEDA's database of echocardiogram test results, including data from almost a million Australian patients, with national death figures.

They discovered that patients with only moderate aortic stenosis (AS) were at a far greater risk of death than previously understood.

Around two-thirds were likely to die within five years if left untreated, a death rate only slightly lower than for those with a severe case.

UNDA professor Geoff Strange said the research suggested aortic stenosis was deadlier than colon, breast and prostate cancer.

"That should be ringing alarm bells within the medical community," Prof Strange said on Tuesday.

"As the tragic deaths of several high-profile sports stars have shown us this year, heart disease does not discriminate.

"We strongly recommend that if you have symptoms such as unexplained breathlessness, or are over the age of 65, you should talk to your doctor about getting an echocardiogram performed."

Patients diagnosed with moderate AS should ensure they receive regular echocardiograms to monitor the severity of their condition, he said.

AS is referred to as a silent killer because as many as a third of sufferers are asymptomatic.

Because it mostly affects older Australians, symptoms such as breathlessness were often dismissed as merely signs of old age, Prof Strange said.

Regular screening of over-65s would help identify more cases, he said, allowing patients to undergo potentially life-saving aortic valve replacement surgery.

UNDA professor David Playford said echocardiograms - ultrasound tests that can identify structural problems within the heart - were covered by Medicare and cost only a few hundred dollars.

While patients once had to undergo open heart surgery, they could now have replacement valves implanted through catheters.

"But due to the high levels of under-diagnosis in Australia, many people are simply missing out on that opportunity," he said.

"Widespread screening, particularly for older Australians, would help to overcome that problem, saving as many 11,000 lives in Australia each year alone."

Australian Associated Press