First-of-its-kind study of more than 200 UK Biobank participants’ scans could help doctors to spot early heart failure in type 2 diabetes patients.
Summary
The hearts of healthy South Asian people are lighter, thinner-walled and beat more vigorously than those of white Europeans, scans from 242 UK Biobank participants have revealed. The results have played a part in redefining someone’s risk of early-stage heart failure, taking into account factors such as age, sex and, importantly, ethnicity.
A healthy heart looks and functions differently depending on whether you’re of South Asian heritage or white, a pioneering analysis of UK Biobank participants’ cardiac scans has revealed. The results are now being incorporated into a method that could help clinicians to predict whether someone with type 2 diabetes will develop heart failure.
People from South Asian ethnic groups – meaning those with ancestry from Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka – make up about a quarter of the world’s population, yet account for up to 60% of all heart disease cases. They are twice as likely to develop coronary heart disease than white Europeans and are more likely to die from a heart attack than people from other backgrounds.
A dogma-breaking study
In the first study of its kind, researchers looked at magnetic resonance imaging (MRI) scans to compare the hearts of people from different backgrounds. Out of the available scans from nearly 40,000 UK Biobank participants, the researchers carefully selected those of 242 healthy South Asian and white men and women.
Some of their findings mirror earlier research done on ultrasound images, which are less detailed than MRI scans: South Asians have lighter hearts and smaller heart chambers than white Europeans. But South Asians’ heart walls are strikingly thinner than those of white people – not thicker, as previous ultrasound studies had indicated.
Relatively thicker heart walls, which increase the risk of heart failure, “have been purported to be the harbinger of excess cardiovascular risk in South Asians”, explains study team member Gaurav Gulsin from the University of Leicester, UK. Thickened heart walls often develop as the organ has to pump against the higher resistance of, for example, chronic high blood pressure.
“I think [our study] challenges the dogma,” says Gulsin. “I don’t think there’s anything in [our findings] that explains in healthy people why the heart health risk is higher in South Asians.”
Functional heart differences
We suspect that once a South Asian individual develops a cardiovascular risk factor, such as high blood pressure, diabetes or obesity, the deleterious impact that has on the heart is heightened.
Dr Gaurav Gulsin, University of Leicester, UK
“We suspect that once a South Asian individual develops a cardiovascular risk factor, such as high blood pressure, diabetes or obesity, the deleterious impact that has on the heart is heightened,” Gulsin suggests. The fact that the hearts of people from South Asian groups contract and relax more vigorously may be contributing to this.
Although the number of people studied was small, “it is still the biggest resource that is available”, comments heart imaging specialist Zahra Raisi-Estabragh from Queen Mary University of London, UK. “I think it’s really valuable.”
Clinics currently don’t take ethnicity into account when they assess someone’s heart health or their risk of developing heart conditions. “[The study] demonstrates clearly the need for personalisation,” she says. “The measurements that we take from imaging directly inform our clinical decisions about diagnosis or even treatments.”
Spotting heart failure
The Leicester team has now created a method that could help GPs to spot early-stage heart failure in anyone with type 2 diabetes. The method redefines who is at highest risk of early-stage heart failure, taking into account factors such as age, sex and, importantly, ethnic background.
“Currently there’s nothing; people with type 2 diabetes are not screened [for heart failure] at all,” says Gulsin’s colleague Emer Brady. This is despite the fact that people with type 2 diabetes are at high risk of heart failure.
People with early, ‘stage B’ heart failure don’t have any symptoms yet, so their condition often remains undiscovered until it gets much worse. Yet intervening early, with medications or changes to diet and exercise for example, can slow down the disease’s progression. “We would be looking to test [our method] in the next 12 months,” Brady says.
The shape of healthy hearts
These reference ranges are now being implemented into clinical centres worldwide. I’m just very glad that this work has made a real difference to clinical care.
Dr Zahra Raisi-Estabragh, Queen Mary University of London, UK
Raisi-Estabragh and her colleagues are working to include ethnicity as one of the factors that clinicians consider when analysing heart scans. She is part of a research group that has collated the largest and most diverse databank of heart MRI scans, containing more than 9,000 healthy adults, including around 7,600 UK Biobank participants.
From the databank, the team developed reference values for what constitutes a healthy heart. Doctors can use these values to assess their patients’ cardiac health. “These reference ranges are now being implemented into clinical centres worldwide,” Raisi-Estabragh says, and are already used across Scandinavia. “I’m just very glad that this work has made a real difference to clinical care,” she adds.
Gulsin says that without UK Biobank participants, none of this would have been possible. He also urges South Asian participants, who are a small minority of participants, to consider attending an imaging appointment: “We’re down to less than 1% of South Asians coming in the first place. We really want as many of them to come back for the repeat [imaging visit].”