Scientists warn that sexual orientation may be a previously unknown risk of cardiovascular problems.
They believe marginalization may have something to do with the finding but accept it is unusual. Heightened risks were not recorded in gay women or homosexual or bi men.
LGBT groups have long been known to face a higher risk of multiple health problems, including depression.
In the latest study, scientists at the Columbia School of Nursing, New York, analyzed data from 12,180 men and women with an average age of around 40.
It included 5,600 heterosexual women, as well as 270 bisexual women, 82 lesbian women and 52 who said their sexuality was ‘something else’.
Each was given a cardiovascular health score from 0 to 100 based on their diets and physical exams.
Those who got 80 to 100 were considered to have ‘good’ heart health, while those with 50 to 79 had a ‘moderate’ and those below 50 were considered ‘poor’.
Bisexual female individuals had lower scores compared with heterosexual female individuals, which was primarily attributed to nicotine exposure and higher body mass index.
Higher levels of stress because of ‘exposure to discrimination and/or rejection from both their gay/lesbian and heterosexual peers’ was also thought to drive up the risk.
But no differences in cardiovascular disease were found between other groups of sexual minority adults and their heterosexual peers.
Bisexual men were, however, twice as likely as heterosexual men to report a diagnosis of high blood pressure. It was not clear why there was this difference.
The study also found that gay men generally had better scores than their heterosexual counterparts.
Scientists at Columbia School of Nursing, New York, suggested that this was because gay men were more likely to have better diets and were less likely to be overweight.
They said they were also more likely to seek out healthcare compared to heterosexual men.
Scientists urged doctors to take into account patients’ sexuality when considering treatment and risk factors for disease.
Heart disease is the biggest killer in America, claiming the lives of about 695,000 citizens annually according to estimates.
People who are overweight, smoke, have high blood pressure, lower physical activity and have an unhealthy diet are more at risk of the condition.
This paper is thought to be the first to link bisexual women to a higher risk of heart disease. Previous research has also suggested the group may be at higher risk of breast cancer.
For the paper — published in JAMA Cardiology — scientists extracted survey data from the National Health and Nutrition Examination Survey, a US-agency-backed study assessing health in adults.