For the first time, more Canadian women than men are dying of cardiovascular disease. While the difference is slim - 50.5 per cent of heart attack, stroke and heart failure deaths are in women and 49.5 per cent are in men - it still represents a seismic shift, according to one of the country's leading researchers.
"Historically, we've thought of heart disease as a disease of middle-aged men. But the burden has shifted to women and older women in particular," Jack Tu, senior scientist at the Institute for Clinical Evaluative Sciences in Toronto, said in an interview.
In fact, in 2004 (the most recent year for which detailed data are available), 41.7 per cent of all heart-related deaths occurred in women over the age of 75, followed by 29.9 per cent in men over the age of 75. All other age groups combined accounted for 28.4 per cent of deaths, according to research published in today's edition of the Canadian Medical Association Journal.
Researchers said it is not entirely clear why more women than men are now dying of cardiovascular disease, but believe there are three principal reasons: Smoking rates are now similar among women and men; research has documented disparities in care between men and women, many of them the result of the mistaken belief that women are not at high risk of heart disease; and there may be gender-based biological differences in how heart disease plays out. The Heart and Stroke Foundation, for example, has an education campaign aimed at patients and health professionals alike that underscores that the symptoms of a heart attack are very different in women than men.
The new study, led by Dr. Tu, also showed the number of Canadians dying from cardiovascular disease plunged 30 per cent between 1994 and 2004. The rate of hospitalization fell by a similar degree.
The mortality data show that fatal acute myocardial infarctions (the formal name for heart attacks) fell 38.1 per cent over that decade, while deadly strokes dropped 28.2 per cent and deaths from heart failure diminished 23.5 per cent.
The remarkable improvements in survival of patients who suffered from heart attacks, stroke and heart failure are likely the result of a combination of factors, according to the researchers.
These include prevention measures such as decreased smoking, more widespread treatment of high blood pressure and improved outcomes for interventions such as angioplasty and bypass surgery. About two-thirds of the improvement is due to preventative measures and one-third to enhanced treatments.
But experts in the field, including Marco Di Buono, director of research at the Heart and Stroke Foundation of Ontario, cautioned that the sharp declines in death, while welcome, likely represent the calm before the storm.
He said two factors could easily send the numbers soaring again: the "explosion of ethno-cultural diversity in Canada," coupled with the fact that some ethnic groups - Chinese, South Asian and aboriginal in particular - have much higher rates of cardiovascular disease; and rising rates of childhood obesity that may translate into more people suffering from cardiovascular disease at a younger age.
"There is a rocky road ahead," Dr. Di Buono said.
In a commentary also published in the CMAJ, Simon Capewell of the University of Liverpool in Britain said many developing countries have seen big declines in cardiovascular deaths in the past generation but, in those other jurisdictions, the numbers are beginning to creep back up.
He cautioned too that the patients who survive heart attacks, stroke and heart failure are increasingly older, and more difficult and more expensive to treat.
This is particularly true of older women, a group about which there is very little research.
"Most of the heart research was done on middle-aged men because it was believed that is who would benefit," Dr. Tu said. "But we really have to invest in research about women, and older women in particular."
In 2005, there were 51,574 deaths due to heart disease and 14,054 due to strokes, according to Statistics Canada.
The mortality rate for cardiovascular disease - heart and stroke combined - is second only to cancer, which accounted for 67,343 deaths in 2005.