Commentary

Atrial fibrillation: Sex differences and modifiable risk factors


 

This transcript has been edited for clarity.

Hello. This is Dr. JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women’s Hospital. I’d like to talk with you about a recent report in JAMA Cardiology on atrial fibrillation (AF), sex differences, and modifiable risk factors.

We looked at these questions in our vitamin D and omega-3 trial VITAL in an ancillary study called VITAL Rhythm, led by Dr. Christine Albert at Cedars-Sinai. And this particular project was led by Dr. Hasan Siddiqi at Vanderbilt.

As you know, AF is the most common arrhythmia in the world, and it’s burgeoning in numbers, primarily because of the aging of the population. It’s also a major cause of stroke, heart failure, and cardiovascular mortality. Although women are known to have lower rates of AF than men, they’re also known to have a higher risk for cardiovascular complications and sequelae, such as higher risk for stroke and CVD mortality. Therefore, we thought that understanding sex differences in risk and modifiable risk factors for AF that could reduce the burden of disease would be important.

It’s known that greater height is a risk factor for AF, but the extent to which it explains the differences in AF risk between men and women isn’t really known. So we looked at these questions in the VITAL cohort. VITAL has more than 25,000 participants. It’s a large, diverse, nationwide cohort. About 51% are women, and all are aged 50 years or older, with a mean age of 67. All were free of known clinical cardiovascular disease at the start of the study.

AF reports were confirmed by medical records and also supplemented by Medicare CMS linkage for fuller ascertainment of outcomes. We had 900 incident cases of AF in the study, and we did see that women were less likely to be diagnosed with AF. They had a 32% lower risk – strongly statistically significant compared with men, with a P < .001. Women were also more likely to be symptomatic: About 77% of women vs. 63% of men had symptoms prior to or at diagnosis.

It was very interesting that adjustment for height eliminated the lower risk for AF in women compared with men. After accounting for height, there was not only no reduction in risk for AF among the women, there was actually a reversal of the association so that there was a slightly higher risk for AF in the women. Other risk factors for AF in the cohort included older age, higher body mass index, hypertension, and higher consumption of alcohol. We did not see an association between diabetes and higher risk for AF. We also saw no clear association with physical activity, although very strenuous physical activity has been linked to AF in some other studies.

We looked at the interventions of vitamin D (2,000 IU/day) and omega-3 fatty acids (460 mg/day of EPA and 380 mg/day of DHA) and found no association with AF, although some other studies have seen increased risk for AF with higher doses of the marine omega-3s > 1 g/day and certainly at doses of 4 g/day. So overall, the findings highlight the fact that many of the risk factors for AF do seem to be modifiable, and it is really important to identify and try to reduce these risk factors in order to reduce the burden of AF. This may be particularly important in women because women are more likely to have stroke and cardiovascular mortality in these adverse cardiovascular outcomes.

A version of this article first appeared on Medscape.com.

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