How high-tech scans could predict heart disease
Advances in imaging technology are helping BHF-funded researchers fight heart disease. Sarah Kidner finds out how
Getting a clear view of what’s happening in the heart and blood vessels is vital in the fight against heart disease. Technological improvements mean that BHF-funded researchers are advancing their understanding of what causes cardiovascular disease, and how we can better prevent and treat it.
Your donations help to buy this specialist equipment and to fund facilities such as the newly created Centre for Translational Cardiovascular Imaging at the University of Leeds. The BHF has contributed £1,893,264 to help create the facility, which forms part of the Leeds Multidisciplinary Cardiovascular Research Centre.
BHF Senior Research Fellow Professor Sven Plein, who leads the new imaging centre, explains how it works.
“The idea is to link the work of different groups at different stages of the research journey and to get research out of the lab quickly, so it can benefit patients,” he says. “The imaging equipment helps us to bridge those translational gaps.” Specifically, that means bringing together researchers working in genetics, or with heart cells and blood vessels, and those who undertake research with patients.
Here, we look at the different types of imaging techniques. It’s important to note that they are complementary and the best approach for a patient might be a combination of them.
Magnetic resonance imaging
Professor Plein’s speciality is magnetic resonance imaging (MRI), which has advanced significantly over the past decade. In 2012, Professor Plein and his team published the results of a BHF-funded study in the medical journal The Lancet demonstrating that MRI is an accurate and reliable method for detecting coronary heart disease.
“MRI is now recommended for testing people with heart disease, in part thanks to our studies,” he says.
The UK is leading the way in the use of MRI of the heart, which has the advantage of not exposing patients to potentially harmful X-rays.
“In the UK, there are more than 60 centres that offer MRIs of the heart, and more heart MRI scans are done here than in most other countries,” says Professor Plein. He attributes that uptake, in part, to support from the BHF.
Professor Plein will specifically use MRI in clinical trials exploring how to diagnose heart disease in high-risk patients, including those with diabetes – a project the BHF is also funding.
“We’re looking at the different stages of diabetes and trying to identify patients who are also at risk of cardiovascular disease, so we can intervene early and treat them with the right medications,” he says.
Meanwhile, in Edinburgh, BHF Clinical Lecturer Dr Marc Dweck has developed a test that may identify patients at high risk of heart attack using an imaging technology called PET-CT. “Heart attacks are usually caused when fatty plaques within arteries rupture. On top of the site of that rupture, a blood clot forms that can obstruct the artery, stopping the blood flow and causing a heart attack,” explains Dr Dweck. “We’re trying to pick out the plaques that are most likely to rupture before they cause a heart attack, something that’s been described as the Holy Grail of cardiology.”
This involves looking for specific characteristics of the plaques, including inflammation and the presence of microcalcification, which, Dr Dweck explains, is “the body’s very early attempts to heal high-risk areas of the heart arteries”.
PET-CT involves injecting a radioactive tracer, which is designed to pick up microcalcification, into patients before performing the scan, a technique that Dr Dweck’s team first discovered when examining patients with aortic stenosis.
The next big question is if we can prevent a heart attack from occurring
“We first noticed something interesting was happening in a patient who happened to have had a heart attack the week before,” he says. “His PET scan was lighting up at the exact site where the plaque had ruptured and caused the heart attack. We’ve now confirmed this in a further 40 heart attack patients and also showed that you can pick up these high-risk lesions in patients who haven’t yet had a heart attack.”
The next step is to conduct widescale tests involving hundreds of patients to confirm whether PET-CT can be used to pick out those patients most likely to have a heart attack in the near future. For now, though, it remains a research test only.
“The next big question is, if we find one of these ‘hot’ plaques, can we change it and prevent the heart attack from occurring?” says Dr Dweck. “Plenty of new drugs are being developed with anti-inflammatory properties, but they’re very expensive, so we’ll want to target them at those at the highest risk of having a heart attack.”
BHF Professor Martin Bennett also has a keen interest in atherosclerosis. He and his colleagues have pioneered an imaging technique called virtual histology intravascular ultrasound (VH-IVUS), which looks at the specific components of plaques. “It tells us the percentage of the plaque that contains calcium, necrotic [cells that have died prematurely] or fibrous tissue,” says Professor Bennett.
He has already completed a clinical trial looking at 170 patients who had stents fitted, and following them up three years on.
Using VH-IVUS, Professor Bennett and his team have been able to examine the original plaque that caused an event three years on, which has helped to identify the types of plaques that are at high risk of rupture. “A plaque that is soft with a big necrotic core and a thin cap over the top is more likely to produce a heart attack than one that has a lot more fibrous tissue and a less necrotic core,” says Professor Bennett.
The technique is currently only being used in research, but there is a possibility that VH-IVUS could be used to identify not just the presence of disease but specific plaques at higher risk of rupture. In treating these patients with medications, it might be possible to prevent heart attacks.
Surviving a heart attack
As well as helping to predict a heart attack, imaging could improve our understanding of what happens after someone suffers one, thanks to work by Dr Gillian Gray from the BHF Centre for Cardiovascular Science at the University of Edinburgh. “Increasingly, people are surviving the initial heart attack, but it leaves them with an injury to the heart muscle,” she explains. “We’re trying to look at how the body responds to that injury and manipulate it in order to reduce further damage.”
Increasingly, people are surviving the initial heart attack
In particular, Dr Gray is looking at the scarring that occurs following a heart attack, as additional healthy heart cells are lost around the damaged area during the process of scar formation, increasing the chance of heart failure.
“Our research looks at how we can manipulate the processes involved in scar formation to enhance the growth of new blood vessels and therefore reduce the stimulus for the development of heart failure,” she says. She uses MRI, ultrasound and optical imaging to look at injuries within the hearts of small animals.
“We have pioneered the use of optical projection tomography to achieve a very accurate measure of the injury to the heart after a heart attack in three dimensions, and now we are developing that to better assess the blood supply to the injured heart muscle,” she says. “That’s helping us to see that the interventions we’re using are working.”
Tests and treatments
While CT and MRI are becoming increasingly popular in terms of imaging, tests such as ultrasound and angiogram are still the most commonly used in diagnosing heart conditions. Watch our videos of some common heart tests and treatments, or download our free booklet Tests for heart conditions. You can also read our article on imaging techniques.