Christchurch researchers are working to more accurately predict New Zealanders’ risk of having a heart attack.
Sharon Duthie’s job is to help save lives. But on a hot Mid-Canterbury evening, as the St John intensive care paramedic neared the end of a 12-hour shift, it was her life on the line.
The slim, fit 52-year-old had no warning signs of a heart attack. She was suddenly nauseous, sweating profusely, and her face had turned what her colleagues later described as a worrying ‘cardiac’ shade of grey.
Duthie’s colleagues rushed her to Ashburton Hospital. She went into cardiac arrest, lost consciousness, and had her heart shocked back into rhythm twice by a defibrillator. Duthie was airlifted to Christchurch Hospital and had lifesaving surgery to insert a stent into an artery that was 90 per cent blocked.
The traumatic experience left her grateful to her colleagues, but also puzzled. “I’d done a risk assessment during my paramedic training, and was classified as low risk,” Duthie says. “But to my surprise, there I was, collapsed on a stretcher in the back of my ambulance, clearly having a heart attack.”
In the days before her collapse she had vaccinated and weaned almost 600 lambs on her rural property, and had a healthy lifestyle. But in fact, Duthie is one of many New Zealanders who have heart attacks despite not fitting the classic risk profile.
After her release from hospital, Duthie signed up to a major new study examining the complex interplay between genes and lifestyle factors in determining a person’s risk of heart disease. The Multi-Ethnic New Zealand Study of Acute Coronary Syndromes (MENZACS) is aimed at better understanding New Zealanders’ real risk of heart disease. To put it simply, the study investigates why thin, fit and seemingly healthy people such as Duthie suffer heart attacks, when other more overweight, stressed-out and unfit people do not.
The study is a collaboration between the University of Auckland and the University of Otago’s Christchurch Heart Institute (CHI). More than 3000 people who have had a heart attack, or a case of angina, are being recruited through hospitals nationwide.
Geneticist Professor Vicky Cameron is leading the study in Christchurch and will oversee the analysis of information on the genetics and lifestyles of the New Zealanders involved. International studies have identified key genetic variations that might put people of European descent at greater risk of having a heart attack. Cameron and her MENZACS colleagues will see if those variations are reflected in the New Zealand population, including Māori and Pacific Island people.
Cameron says understanding genetic variations is important because they are probably the reason seemingly fit and healthy people have heart attacks. They can also affect the way people respond to medication, which is why drugs to thin the blood or lower cholesterol, for example, don’t work as well for everyone. If doctors understand the genetic profile of a high-risk person, they can prescribe the best medications, surgery or lifestyle changes for that patient. To try to predict who will have a heart attack, CHI researchers are studying healthy people like Duthie before her heart attack, and her two healthy adult sons. By studying detailed information from thousands of participants, the researchers hope to build up a picture of the characteristics of heart attack patients.
“The research won’t help me, but it could help my boys and prevent them or other people going through a frightening and life-threatening heart attack.”
To understand the reasons for higher rates of heart disease among Māori and Pacific peoples, the CHI have set up the Hauora Manawa/ Community Heart Study and the Pasifika Heart Study. These studies document levels of cardiovascular disease and diabetes, and look at risk factors particular to these ethnic groups.
Cameron says thanks to tens of thousands of participants in CHI research, the group has developed promising new blood tests for doctors to use to help predict the risk of an imminent heart attack. They have also developed better strategies for prioritising which patients to monitor more closely, and heart disease and diabetes risk factor management for those individuals most at risk.
Duthie is proud to be a research participant in one of CHI’s research studies to better define risk. “The research won’t help me, but it could help my boys and prevent them or other people going through a frightening and life-threatening heart attack.”
“I’m very proud to be playing a small part in research to make lives better.”