MRI scans showed significant differences in how men's and women's hearts change over time.
This was the finding of a federally funded study, led by Johns Hopkins University in Baltimore, MD, published in the journal Radiology.
The study is thought to be the first long-term follow-up using magnetic resonance imaging (MRI) to show how the human heart changes as it ages.
After analyzing MRI scans of the aging hearts of nearly 3,000 adults, the researchers found some significant differences in how men's and women's hearts change over time.
They conclude that while they do not know what causes these gender-related heart changes, the results explain some of the differences we see in heart failure between men and women, suggesting treatments for the condition should be sex- specific.
The findings mainly surround changes to the main chamber of the heart - the left ventricle - which fills with blood and then pumps it out. As the heart ages, less blood enters the heart, and so less is pumped out.
The study builds on previous research that uses ultrasound to investigate how the heart changes with age. But this study, because it uses MRI scans, is able to make assessments using more detailed - and more reliable - images.
Left ventricle heart muscle grew in men, shrank slightly in women
Another distinguishing feature of the study is that it compares scans taken about a decade apart in the same patients. Most other studies of heart aging have tended to compare snapshots of young and old patients, which makes it difficult to rule out changes among individuals, such as lifestyle and health history.
John Eng, lead researcher and associate professor of radiological science at Johns Hopkins, notes:
"We had the opportunity to re-examine the same people after 10 years so that we could see what happened to their hearts after a decade. This is a more reliable way to assess left ventricular changes over time."
He and his colleagues found that in men, the heart muscle around the left ventricle grows and thickens with age, while in women it stays the same, or even shrinks slightly.
"Thicker heart muscle and smaller heart chamber volume both portend heightened risk of age-related heart failure," Prof. Eng explains, "but the gender variations we observed mean men and women may develop the disease for different reasons."
Heart filling capacity reduced with age, but more so in women
The participants in the study were aged between 54-94 and did not have any pre-existing heart disease when they enrolled. They underwent two sets of MRI scans, taken about 10 years apart between 2002-2012.
The MRI scans showed the interior and exterior of the heart in 3D, and allowed the researchers to assess size and volume of heart muscle, and from these to calculate its weight.
The results showed that over 10 years, on average, the weight of the left ventricle increased in men by about 8 gms, and decreased by 1.6 gms in women.
The heart's filling capacity - reflected by the amount of blood the left ventricle can hold between heart beats - reduced in both men and women, but more so in women. In men it fell by just 10 mls, and in women by 13 mls.
Around 5 million Americans have heart failure, a condition where the heart muscle becomes "floppy" and weak and less able to pump blood around the body.
To reduce the risk of developing the disease, cardiologists prescribe drugs that boost cardiovascular performance by reducing heart muscle thickness. However, the researchers suggest this strategy may benefit men more than women.
Senior author João Lima, professor of medicine and radiological science at Johns Hopkins, concludes:
"Our results are a striking demonstration of the concept that heart disease may have different pathophysiology in men and women and of the need for tailored treatments that address such important biologic differences."
He and his colleagues also recommend further investigation of what might explain the physiological reason for the differences they discovered.
Following a heart attack, patients are advised to take certain medicines so as to reduce the risk of another one. But Medical News Today has recently learned of a study that finds many heart attack patients are either not prescribed such medications or do not take them. It also identifies a gender gap in use of heart medications, with younger women being the least likely to be prescribed or take them.