Irregular menstrual cycles increase the risk of atrial fibrillation

A prospective study from the UK Biobank concludes that irregular menstrual cycles throughout reproductive life are associated with cardiovascular disease (CVD). Researchers have found that both long (>35 days) and short (less than 21 days) menstrual cycles are associated with atrial fibrillation, while short menstrual cycles are associated with increased risk of coronary heart disease and myocardial infarction..

However, the length of the menstrual cycle was not associated with an increased risk of stroke or heart failure.

All are data obtained by a research group from the Department of Endocrinology and Metabolism of the Nanfang Hospital / Guangdong South Medical University (China), led by Professor Huijie Zhang, which are published today in the Journal of the American Heart Association.

New evidence suggests that alterations in the menstrual cycle could have negative health consequences and that it would be important to monitor these women throughout their reproductive lives to prevent CVD and atrial fibrillation.

The authors of the study start from the idea that regular menstrual cycles throughout reproductive life reflect the normal functioning of the hypothalamic-pituitary-ovarian axis and are a vital sign of general health in women, and that menstrual cycles Irregular and prolonged are common endocrine disorders that occur in 20% of those of childbearing age, precisely because of the functional alteration of the aforementioned axis.

In this sense, they explain that cardiovascular disease (CVD), the leading cause of morbidity and mortality among women in the world, affects 45% of women in the West and accounts for a third of all deaths from this cause..

In addition, they state that some risk factors for CVD and cardiovascular mortality related to the female sex were already known, such as polycystic ovarian syndrome and early menopause, but they believe it is important to explore new risk factors, precisely because of the growing prevalence of CVD in women.

What causes menstrual irregularities?

Irregular and prolonged menstrual cycles have previously been reported to be strongly associated with insulin resistance, metabolic disorders, hyperandrogenism, and chronic inflammation, which are associated with increased risk of coronary heart disease and mortality, obesity, and type 2 diabetes.. Or that short menstrual cycles would double the risk of myocardial infarction in women under 55 years of age..

Other studies point to the association of irregular menstrual cycles with multiple risk factors for heart disease, such as insulin resistance, high cholesterol, high blood pressure, chronic inflammation, and polycystic ovary syndrome; or they also point out that women are at greater risk of arrhythmias or irregular heartbeats, precisely due to the hormonal fluctuations of the menstrual cycle.

“However, the evidence linking the characteristics of the menstrual cycle throughout the reproductive life with CVD and cardiovascular mortality remains limited and large prospective studies are needed,” according to these researchers, who have developed a large-scale survey. with a mean follow-up of 11.8 years of 58,056 women from the UK Biobank records, aged 40-69.

“Our data indicated that menstrual cycle length of 21 days or 35 days was significantly associated with increased risk of CVD episodes,” they emphasize, noting that the relationship between menstrual cycle regularity/length and specific CVD subtypes (atrial fibrillation, coronary heart disease and myocardial infarction) is relatively limited.

The article collects the statistics of more than 1,600 cardiovascular episodes reflected in the epidemiological data of the women participating in the study.. Always compared with women who had a regular cycle, a 40% increased risk of atrial fibrillation and a 19% increased risk of heart disease have been seen in women with menstrual cycles of less than 21 days or more than 35; both shorter and longer cycles were associated with increased CVD risk (29% and 11% respectively); regarding atrial fibrillation, the shortest menstrual cycles were associated with a 38% higher risk and the longest with a 30% higher. Finally, the length of the menstrual cycle was not associated with an increased risk of stroke or heart failure.

“To our knowledge, this is the first study to examine the relationships between menstrual cycle characteristics and the risk of atrial fibrillation,” say the authors of the article.. Ultimately, the researchers believe that their findings could be transferred to clinical practice to open avenues for the prevention of atrial fibrillation, myocardial infarction, and coronary disease in women..

“Furthermore, we have seen that the association between menstrual cycle characteristics and cardiovascular disease episodes were modified by smoking, and that the association between short menstrual cycle and cardiovascular disease occurrence was significantly stronger in women with baseline high-density lipoprotein cholesterol (HDL-C) <1.3 mmol/L".

With these data, they reinforce the importance of monitoring the menstrual cycle of these women during their reproductive lives, insisting that “those who have irregular menstrual cycle patterns may be more likely to develop heart disease,” according to Zhang.

Why is there this relationship between periods and heart disease?

Several potential mechanisms could explain the relationships between menstrual cycle regularity and CVD incidence.. On the one hand, irregular menstrual cycles are closely related to the multiple CVD risk factors already mentioned; and on the other, the abnormal duration of the cycle can have consequences for reproductive health.

Monthly cycle length is believed to be an indicator of cumulative ovarian steroid exposure and reflects underlying hormonal patterns.. For this reason, long and irregular cycles are associated with less exposure to estrogens, which may have a vasodilatory function by increasing -adrenergic receptors and reducing oxidative stress.. That would explain its association with CVD risk.

And even more. Irregular or long menstrual cycles are associated with higher testosterone levels and lower sex hormone-binding globulin (SHBG) levels, a relationship that has already been strongly demonstrated in CVD.

“In this study we found that women with long or irregular menstrual cycles had higher incidence rates of diabetes and hypertension, and had higher BMI, higher total cholesterol levels, and lower HDL-C levels, which are strong predictors of CVD events, and that together they could contribute to increased risk,” the researchers argue..

On the other hand, they add that oral contraceptives could also be a potential modifier of the relationship between menstrual cycle characteristics and CVD risk, since they have been widely used for the treatment of irregular menstrual cycles or polycystic ovarian syndrome in women. But none of that was seen in the current study.