Heart failure is a leading health issue in the United States — about five million people live with heart failure, and about half of the people who develop it will die within five years of diagnosis. Experts have long identified risk factors for heart failure, including high blood pressure, diabetes, and obesity. It’s also been known that hearts change over time, and that aging hearts face different risks than young hearts. But a  new study shows that another factor — gender — may play an important role in how the heart ages, too.

The Aging Heart

Previous studies that have examined the way the heart gets older have shown that the heart’s main chamber, the left ventricle, gets smaller over time. This chamber fills with blood, then forces it out, so having a smaller left ventricle means less blood can enter the heart and get pumped out to the rest of the body.

Researchers found that in men, the muscle surrounding the left ventricle grows and thickens with age, but in women, this muscle retains its size or gets smaller. “Thicker heart muscle and smaller heart chamber volume both portend heightened risk of age-related heart failure, but the gender variations we observed mean men and women may develop the disease for different reasons,” said Dr. John Eng, associate professor of radiological science at the Johns Hopkins University School of Medicine, and lead investigator of the study, in a statement.

A hallmark of heart failure is the weakening of the muscle and gradual loss of pumping ability. In response to this, cardiologists prescribe drugs designed to boost cardiovascular performance by reducing the thickness of the heart muscle. This new research suggests, however, that women may not derive the same benefits from these treatments as men do, since their heart muscles tend to shrink or remain the same size naturally.

Scientists caution that the study does not indicate what exactly causes these differences between the sexes, but say it should fuel further investigation into the “fascinating discrepancy.”

A New Approach

The research involved almost 3,000 adults, who were followed between 2002 and 2012. The participants had no preexisting heart disease and underwent MRI testing at the beginning of the time frame, and again at the end. The new study used MRI to assess heart changes rather than ultrasound, creating a more detailed image of the heart’s structure. The MRI scans provided 3D images of the heart’s exterior and interior, which allowed researchers to determine the volume and size of the heart muscle.

Over 10 years, the weight of the left ventricle increased by an average of 8 grams in men and decreased by 1.6 grams in women, the study found. The heart’s filling capacity — the amount of blood the main chamber can hold between heartbeats — decreased in both sexes, but slightly more so in women (down 13 milliliters, compared to a decrease of 10 milliliters in men).

“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,” said Dr. Joao Lima, a professor of medicine and radiological science at the Johns Hopkins University School of Medicine and senior study author.

Source: Rodriguez K, Kwan A, Lai s, Lima J, Vigneault D, Sandfort V, et al. Coronary Plaque Burden at Coronary CT Angiography in Asymptomatic Men and Women. Radiology. 2015.