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A tale of two hearts: How they’re different for men and women

The structure of women's hearts is significantly different to those of men.

The structure of women's hearts is significantly different to those of men. Photo: Getty

A recent study from Deakin University investigated the risks for cardiovascular disease (CVD) that come from the foods we choose to eat.

Drawing on data from a global disease burden study from 1990 to 2019, the researchers estimated how much death and disability could be attributed to hearts sickened and damaged by different foods.

The interesting thing: The dietary choices that drove the risk of heart disease were different between men and women.

A diet high in red meat for women and a diet low in wholegrains for men “were the two leading individual dietary risk factors for diet-related CVD burden in Australia”.

On the upside, the study found, over time, a decline in heart disease deaths and disability related to dietary choices.

Looking closer at this decline, the researchers found that a diet high in sodium for women and a diet high in processed meat for men had the lowest decrease in CVD burden.

This suggests that women have been slower to give up salty foods and men have been slower to give up bacon and salamis than other foods that were hurting them.

Bottom line, the study findings serve as one more reminder that men and women do it differently when it comes to heart health.

Their hearts are markedly different

Up until puberty, the hearts of males and females are about the same size. This changes significantly with adulthood.

According to a comprehensive comparison of female and male hearts, a woman’s heart is 26 per cent smaller than a man’s.

A woman’s heart is 26 per cent smaller than a man’s. And shaped differently.

Gray’s Anatomy advises that the mean weight of the heart is 280 to 340 grams in males and 230 to 280 grams in females.

Still, it’s widely thought that the female heart is the same as the male’s, only smaller.

In 2020, researchers at Queen Mary University of London, used new technology to look at the heart structure of 667 healthy people – 309 men and 358 women – from the UK Biobank imaging study.

When researchers compared numerous measures of heart texture and shape, they found that in men, the heart muscle was dominated by more coarse textures. Whereas women’s hearts had finer grained textures.

They also found significant differences in the overall shape of male and female hearts.

Men had a larger surface area of heart muscle compared to women, even after accounting for body size.

But wait there’s more

A 2020 paper from Stanford’s Department of Mechanical Engineering, found that “the sex differences in cardiac form and function are too complex to be ignored”.

The female heart, they say, “is not just a small version of the male heart”.

What has been long been ignored, they say, is that the female heart “also has a different microstructural architecture”.

Compared to the male heart, the researchers observe, “the female heart has a larger ejection fraction and beats at a faster rate but generates a smaller cardiac output”.

Your ejection fraction is the amount of blood that your heart pumps out of your left ventricle each time it beats. It is measured as a percentage of the total amount of blood in your heart that is pumped out with each heartbeat.

Women have a higher resting heart rate than men, but their hearts take a long time from contraction to relaxation.

The average adult male heart rate is between 70 and 72 beats per minute. The average for adult women is between 78 and 82 beats.

The smaller female heart, pumping less blood with each beat, needs to beat at a faster rate to match the larger male heart’s output.

The female heart needs new diagnostic criteria

The female heart’s differences to the male heart are so marked, the Stanford researchers say, it needs to be seen anew in clinical settings.

The authors conclude that there “is an urgent need to better understand the female heart”.

What’s needed is “sex-specific diagnostic criteria that will allow us to diagnose cardiac disease in women equally as early, robustly and reliably as in men”.

In 2020, a study from the University of Bergen, made a similar conclusion.

The argument went like this:

More women than men die of heart failure. The reason is that only 50 per cent of the heart failure cases among women are caused by having a heart attack, which can be treated with modern methods.

For the other 50 per cent of women experiencing heart failure the cause is generally related to having untreated high blood pressure levels. Over time these lead to progressive stiffening of the heart.

Women are more likely to have heart attacks that are not caused by coronary artery disease.

There is no effective treatment for this kind of heart failure yet.

“Men and women have different biologies and this results in different types of the same heart diseases. It is about time to recognise these differences,” said Professor Eva Gerdts, who led the research.

An advantage over men?

Cardiovascular disease develops seven to 10 years later in women than in men. And it’s still the major cause of death in women.

Why does it develop later? Because of the ‘female’ hormone oestrogen, which has a protective effect on your heart.

It helps to control your cholesterol levels. This reduces the risk of fat building up in your arteries. It also helps keep your blood vessels healthy.

When menopause kicks in, and your oestrogen levels begin fall. This leads to fat building up in your arteries causing them to become narrow.

And so, the perceived advantage turns around and bites women.

The net effect of this delayed onset is that the risk of heart disease in women is often underestimated. This might be due to the misperception that females are protected against CVD.

According to a 2010 review from the Netherlands: “The under-recognition of heart disease and differences in clinical presentation in women lead to less-aggressive treatment strategies and a lower representation of women in clinical trials”.

Furthermore, “self-awareness in women and identification of their cardiovascular risk factors needs more attention. This should result in a better prevention of cardiovascular events”.

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