Doctors' Notes: Researchers examining why heart attacks on rise among Chinese Canadians

Republished from the Toronto Star

Heart disease rates are rising rapidly for Chinese Canadians. Our current guidelines for heart health are largely based on studies in white people of European origins — we shouldn’t assume the same advice applies to people of all ethnicities.

Stroke was always the biggest heart problem affecting Chinese populations, due to uncontrolled blood pressure among people with limited access to doctors and medications. In Canada, cardiologists say it was once very rare to see an East Asian patient who’d had a heart attack.

That is now changing. We’re starting to see more Chinese patients with heart attacks in Canadian hospitals. One possible reason may be that when people immigrate, their traditional habits become disrupted, and adapting to new lifestyles can be difficult. For second-generation Chinese Canadians, Western fast foods may be a major culprit. In traditional Chinese diets, rice, noodles and vegetables are common, with small amounts of meat. Sugary desserts rarely factor into the typical meal.

Also, Chinese immigrants — and possibly their children — may be getting less exercise. While visiting China three decades ago, I was amazed at the lack of cars — everyone rode bicycles or walked and many people practised traditional movements like t'ai chi and chi gong in public areas.

Today, with the adoption of more Westernized lifestyles, heart disease, obesity, diabetes and cholesterol levels aren’t just rising among Chinese migrants — they’re exploding in China too.

Unfortunately, we’re not entirely sure why. Ethnic minorities have been under-represented in medical studies that have helped us to identify the causes of heart disease and cancer. Many immigrants are from countries without the same tradition of medical research, and may underestimate how their participation in studies leads to better medical care for their ethnic communities — or the safeguards taken to protect their privacy. Language barriers are also a problem.

My fellow researchers and I are trying to change that. We’re conducting a large multi-ethnic pan-Canadian cohort study called the Canadian Alliance for Healthy Hearts and Minds (Alliance).

We’re studying people of various ethnic backgrounds including white Caucasians, South Asians, East Asians, and indigenous peoples to determine the specific factors that lead to chronic diseases in each group. For example, South Asians and Chinese may gain weight around their bellies, so the traditional body mass index (BMI) — developed largely from studies in white Caucasians — might not be the best measure of being overweight.

The effects of migration on health haven’t been studied nearly enough, so we’ll be asking detailed questions about the way people’s lifestyles may have changed since moving to Canada and comparing that with people born in Canada. We would like to identify which aspects of Chinese and Western diets decrease or increase the risk of developing heart disease and cancer and how living in different neighbourhood environments influences people’s likelihood of smoking, diet, physical activity levels and access to health care.

In addition to questionnaires, everyone in the study undergoes a MRI scan of their brain, heart, liver and neck. We’re measuring heart chamber size using MRI technology so we can learn what the normal weight, wall thickness and volume of the heart is in different ethnic groups. Measuring liver and abdominal fat will let us examine whether this is a better way than BMI to predict who will later develop diabetes and have heart attacks due to obesity. Brain and neck imaging will help to see if it’s possible to predict strokes.

All participants receive personalized information about their heart disease risk and a 3-D image of their heart and brain. The study data will be combined with other health databases to determine chronic disease outcomes and will be anonymized before any analyses are conducted.

Once we know each group’s particular vulnerabilities, we can create heart-healthy guidelines specific to them.

We’ve recruited most of the people needed for the study but we are still actively looking for more participants aged 35 to 69 of Chinese heritage, whether born overseas or in Canada, to join the study. The MRI study visit takes place at Sunnybrook Health Sciences Centre in Toronto. If you’d like to learn more or to join the study, please email us at alliance@ices.on.ca or visit allianceheartsandminds.ca.

Dr. Jack Tu is a professor of medicine at U of T, a senior scientist at the Institute for Clinical Evaluative Sciences and the Sunnybrook Research Institute and a cardiologist at Sunnybrook’s Schulich Heart Centre. He holds a Canada Research Chair in Health Services Research and an Eaton Scholar award from U of T. Doctors’ Notes is a weekly column by members of the U of T Faculty of Medicine.