Women who experience menopause before the age of 40 may face an increased risk of heart failure and atrial fibrillation, a large new study has found.

According to the findings, the younger the age at menopause, the higher the risk of new-onset of these heart conditions.

Premature menopause – under the age of 40 - affects 1% of women. Previous research has found a link between premature (before age 40) and early (before age 45) menopause and cardiovascular disease overall. However, the evidence relating specifically to heart failure and atrial fibrillation is limited.

This study examined the associations between premature menopause, age at menopause, and incident heart failure and atrial fibrillation. Researchers in Korea used data from the Korean National Health Insurance System, which provides health screening at least every two years and includes 97% of the population.

Over 1.4 million postmenopausal women were followed up between 2009 and 2018 to see if they had developed new-onset heart failure and/or atrial fibrillation. Information was collected on a range of factors, such as reproductive health and use of hormone replacement therapy (HRT).

Premature menopause was defined as having the final menstrual period before the age of 40 years. Over 28,000 women – 2% of the participants – had experienced this.

The study found that those who experienced premature menopause had a 33% increased risk of developing new-onset heart failure and a 9% increased risk of atrial fibrillation compared to those who went into menopause later.

The researchers had taken into account factors that may have influenced the findings, such as age, smoking, physical activity, body mass index, hypertension, type 2 diabetes, coronary heart disease and use of HRT.

The researchers then analysed the associations between age at menopause and incidence of heart failure and atrial fibrillation after adjusting for the same factors as in the previous analyses.

They found that the risk of incident heart failure increased as the age at the time of menopause decreased. Compared with women aged 50 years and over, those aged 45-49, 40-44, and below 40 years at menopause had an 11%, 23%, and 39% increased risk of incident heart failure respectively.

Similarly, the risk of incident atrial fibrillation increased as the age at menopause decreased, with 4%, 10%, and 11% higher risks for those aged 45-49, 40-44 and under 40 years at menopause respectively, when compared with women aged 50 years and over.

The researcher said there may be a number of reasons for this, including the drop in oestrogen levels after menopause and changes in body fat distribution.

“Women with premature menopause should be aware that they may be more likely to develop heart failure or atrial fibrillation than their peers. This may be good motivation to improve lifestyle habits known to be linked with heart disease, such as quitting smoking and exercising,” commented the study’s author Dr Ga Eun Nam of Korea University College of Medicine in Seoul.

She noted that the “misconception” that heart disease primarily affects men “has meant that sex-specific risk factors have been largely ignored”.

“Evidence is accumulating that undergoing menopause before the age of 40 may increase the likelihood of heart disease later in life. Our study indicates that reproductive history should be routinely considered in addition to traditional risk factors, such as smoking, when evaluating the future likelihood of heart failure and atrial fibrillation,” she added.

The study is published in the European Heart Journal.