MONDAY, April 8, 2024 (HealthDay News) -- Just a little exposure to secondhand smoke may increase your risk for the heart rhythm disorder atrial fibrillation (A-Fib), a new, large study suggests.

People who have A-Fib, the world's most common heart rhythm disorder, are five times more likely to have a stroke than their healthy peers. 

While passive smoking has been linked to heart disease and early death, links between secondhand smoke and A-Fib have been unclear, researchers said in a European Society of Cardiology news release. This large study appears to make a direct connection.

"The dangers of secondhand smoke were significant regardless of whether individuals were at home, outdoors or at work, indicating that exposure universally elevates the risk of atrial fibrillation," said study author Dr. Kyung-Yeon Lee, of Seoul National University Hospital in South Korea.

The study included more than 400,000 people between the ages of 40 and 69 who were part of the UK Biobank, a large biomedical and research database. Current smokers and those who already had A-Fib were excluded.

Participants answered questions about their exposure to other people's smoke at home and elsewhere in the past year. One in five (86,000) said they had been exposed to secondhand smoke, with an average exposure of 2.2 hours. In all, 6% of participants developed A-Fib over a median followup of 12.5 years. (Median means half were followed longer, half for less time.)

After accounting for factors that could affect the results such as age, sex, ethnicity, economic status, weight, exercise levels, alcohol use, as well as diabetes, high blood pressure and high cholesterol, researchers found participants exposed to secondhand smoke had a 6% higher risk for A-Fib.

As exposure increased, so did A-Fib risk -- compared to those with no secondhand smoke exposure, those who were around it for 7.8 hours a week had an 11% higher A-Fib risk.

"Once exposed to secondhand smoke, the likelihood of developing atrial fibrillation begins to increase, with the risk escalating significantly as the exposure time lengthens," Lee said. "The finding that passive smoking is harmful not only in enclosed spaces but also outdoor environments underscores the importance of smoking bans to protect public health."

Meanwhile, Lee urged everyone to avoid spending time in places where people are smoking.

The findings were presented Sunday at a meeting in Berlin of the European Society of Cardiology. Research presented at meetings is considered preliminary until published in a peer-reviewed journal.

More information

There's more about the health problems caused by exposure to secondhand smoke at the U.S. Centers for Disease Control and Prevention.

SOURCE: European Society of Cardiology, news release, April 7, 2024