Our pioneering researchers: detecting heart failure with a blood test

In the 1990s Professor Allan Struthers and his team at the University of Dundee pioneered a blood test called the BNP (B-type natriuretic peptide) test, which can show if people have heart failure.

Professor Struthers talked to us about the historic research that enabled him to make his BHF-funded breakthroughs, and the exciting new uses for the substance, B-type natriuretic peptide.

Early science that paved the way

“It goes back to work that started in the mid-20th century by a scientist called Adolfo J de Bold. In those days research was very crude.

Adolfo J de Bold (Credit: University of Ottawa Heart Institute)

In his lab, he removed the hearts from rats, mashed up the heart tissue and injected it into some other rats, and was surprised to discover that this made the other animals pass lots of urine.

Now this may sound rather gruesome but this was also the way, even long before that, that scientists discovered insulin. There they took the pancreas out of some dogs, mashed it up and injected it into other dogs and discovered that in these animals the blood sugar went down. This was a crude version of science way back in the early 20th century.”

The heart as a gland

“The fact that injecting this heart muscle into other animals made them urinate more suggested there is a substance within the heart that causes urine to be excreted. It was only in 1984 that this substance was identified as atrial natriuretic peptide, or ANP.

This was fascinating because people thought of the heart as a pump, no one thought of the heart as a gland that secretes substances into the bloodstream. This finding made the heart sound like it was not only a pump, but it made substances, stored them and released them into the bloodstream to affect other areas in the body.”

Why would the heart secrete a substance that would increase urine production?

“The thinking was that if the heart was being stretched then it could release, as a compensatory mechanism, a substance that would reduce the blood volume in the body and hence reduce the stretch in the heart. This substance might exist to protect the heart when other things were causing it to stretch. And the obvious disease where the heart might stretch is heart failure. So at this time it was logical to see if the substance was elevated in heart failure, and lo and behold it was.

How heart failure can affect the heart (Credit: Harvard Medical School)

B-type natriuretic peptide, or brain natriuretic peptide, was discovered in 1988. It was found in the brain, hence its name. It turns out to be a better blood test.

It’s all very well to say levels of BNP in the blood are increased in heart failure patients but what we then wanted to show was whether it was an accurate enough test to discriminate between patients with normal hearts and patients with heart failure.”

Proving the BNP test identifies people with heart failure

Our paper in The Lancet back in 1993 was one of the first to show that BNP levels could indeed accurately identify heart failure. The study was done in patients who had just had heart attacks.

We did a later study in collaboration with the Royal Brompton Hospital in London, studying people in the community — identifying those with stretched hearts and the beginnings of heart failure. The results of this were published in The Lancet in 1997.

The test is important because it can be hard to diagnose mild heart failure just by looking at a patient with breathlessness. Their breathlessness could be due to a whole host of other things. The only other way to diagnose heart failure is with an echocardiogram or scan, but a simple blood test is much simpler and cheaper.”

Heart failure report

A recent All-Party Parliamentary Group report has reiterated the existing NICE guidelines to say this test should be rolled out nationwide, as the test is still not used widely by the NHS.

“It’s been in the guidelines a long time. As usual the problem is money. If you say to a hospital manager you’d like to use the test, they know they will then be flooded with blood tests which will cost money. So the manager then, knowing it should reduce the number of echos, goes to the cardiac department and say they need some of their money to go the labs instead, to fund the test. But the cardiac department will say they need the money to treat patients on their cardiac waiting lists.

This report isn’t necessarily saying anything new, but it’s trying to make people do what’s been in guidelines for a long time. Often what’s in the guidelines needs money to be allocated to it and that’s the problem.”

More than just a heart failure test

Professor Allan Struthers, University of Dundee

Professor Struthers and his team are now looking at other uses of BNP blood tests.

“Over the years it’s been discovered that in almost in every type of heart disease there is an increase in BNP.

BNP in certain levels could show, for example, aortic valve disease. We are still working on this but it could help identify patients who need operations. It could also play an important role in identifying people with ‘silent coronary heart disease’. People with overt coronary heart disease will have chest pains, but there’s lots of people out there who have coronary disease who do not appear to have chest pain, and some just die suddenly — this is silent coronary disease. Our current research is looking at how useful BNP is to screen for this type of coronary heart disease.”

Professor Struthers has so far received 38 research grants from the BHF and it’s with the continued support of the BHF’s donors that he is able to work on these new heart disease tests.

“I’m not sure if I received more grants than other scientists but I’m delighted to have so many grants. The BHF has funded a huge number of studies into BNP.”

From lab bench to hospital bedside with BHF funding

With the BHF’s support Professor Struthers has taken early laboratory discoveries made in animals through to a test, which could dramatically improve the prospects for people with heart failure in the UK and around the world.

The BHF is keen to work with the Government and the NHS to ensure they implement the recommendations in the report so people with heart failure benefit from the medical advances driven by decades of research by Professor Struthers and others.

Find out more about the heart failure report and its recommendations.