Cup of coffee a day may not be harmful for some adults with AFib and could lower episodes

Research Highlights:

• During the 6 months after treatment to restore a normal heart rhythm, adults with atrial fibrillation (AFib) who were randomly assigned to drink coffee every day were 39% less likely to have a recurrence of AFib compared to participants assigned to not have any coffee or other caffeinated drinks.
• The results of the 200-person trial may challenge the common belief that caffeine may spur more abnormal heart rhythms such as AFib.
• Researchers say it is reasonable for health care professionals to let their AFib patients try naturally caffeinated drinks like tea and coffee if they enjoy them. However, some people may still find that caffeine, including caffeinated coffee, may trigger or worsen their AFib symptoms.
• Note: This trial is simultaneously published today as a full manuscript in the peer-reviewed scientific journal JAMA.

Embargoed until 8:45 a.m. CT/9:45 a.m. ET, Sunday, Nov. 9, 2025

NEW ORLEANS, Nov. 9, 2025 - Adults treated for atrial fibrillation (AFib) who drank a daily cup of coffee were 39% less likely to have an irregular heart rhythm episode compared to those who avoided all caffeinated products, according to a new study. The preliminary late-breaking science was presented today at the American Heart Association's Scientific Sessions 2025. The meeting, Nov. 7-10, in New Orleans, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

"We conducted this study to assess whether caffeinated coffee increased or decreased the risk of AFib. Participants were randomly assigned to continue drinking at least one cup of caffeinated coffee daily or to avoid any caffeine for 6 months," said study lead author Christopher X. Wong, M.B.B.S., M.Sc., M.P.H., Ph.D., formerly of the University of California, San Francisco, and currently professor of cardiology at the University of Adelaide in Australia.

The Does Eliminating Coffee Avoid Fibrillation (DECAF) trial enrolled 200 adults diagnosed with AFib who experienced an irregular, fast heart rhythm and were about to be treated with cardioversion therapy, using medication or an electrical shock to restore a normal rhythm. Participants reported that they typically drank about one cup of caffeinated coffee per day, and they agreed to follow the researchers' advice on caffeine for 6 months after the cardioversion therapy. Half of the participants were randomly chosen to continue drinking at least one cup of coffee daily, and the other half were instructed to avoid all caffeine.

During the 6-month study:

• The coffee group maintained their pre-enrollment habit of drinking about 1 cup of coffee a day, while the no coffee group reported that they consumed no caffeine each day.
• 47% of the participants in the coffee group had a recurrent AFib or atrial flutter (rapid but regular heartbeat) episode lasting more than 30 seconds, compared with 64% of the no-caffeine group, representing a 39% lower risk among the coffee drinkers.
• Similar reductions in risk were found when only AFib episodes (excluding atrial flutter episodes) were considered.

"Our study results suggest that caffeinated coffee may not be responsible for raising the risk of AFib and may even reduce it," said senior study author Gregory M. Marcus, M.D., M.A.S., a professor of medicine at the University of California, San Francisco.

This study enrolled only people who already drink coffee, so future studies might investigate whether AFib episodes are reduced in people who start drinking coffee or other caffeinated beverages for the first time.

Because the study participants consumed about one cup of coffee per day, the results may not apply to people who drink more coffee or other beverages containing caffeine, such as energy drinks.

"It is reasonable for health care professionals to let their AFib patients consider experimenting with naturally caffeinated substances that they may enjoy, such as caffeinated tea and coffee. However, some people may still find that caffeine or caffeinated coffee triggers or worsens their AFib," Marcus said.

AFib currently affects more than 6 million people in the U.S. and can lead to blood clots, stroke, heart failure and other heart-related conditions, according to the American Heart Association's 2025 Heart Disease and Stroke Statistics.

Study details, background and design:

• The study enrolled 200 adults (average age of 69 years; 71% men; 80% self-identified as white adults) with AFib who usually drank about 1 cup of coffee per day.
• After the heart rhythm was successfully returned to normal using either medication or electric shock, participants were eligible to enroll and were randomly assigned to either continue drinking at least one cup of coffee daily or to avoid all caffeine for the next 6 months.
• Half of the participants were already taking medications to prevent irregular heart rhythm episodes, and they continued to take the prescribed medications throughout the trial.
• All participants were followed for up to 6 months for the recurrence of AFib or atrial flutter that lasted more than 30 seconds. The episodes were verified by their health care professional or on personal health devices with a medical-grade electrocardiogram. The episodes were then entered in the participants' medical records.
• The study was conducted at five health care centers in the United States, Australia and Canada, with participants enrolled between 2021 and 2024.
• Drinking coffee and other caffeinated beverages was self-reported by participants in three detailed phone interviews during the study.

Co-authors, disclosures and funding sources are listed in the abstract.

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Additional Resources:

• Multimedia is available on the right column of the release link.
• View the abstract in the American Heart Association Scientific Sessions 2025 Online Program Planner
• American Heart Association news release: Drinking coffee may help prevent mental decline in people with atrial fibrillation (Dec. 2024)
• American Heart Association news release: Drinking 2 or more cups of coffee daily may double risk of heart death in people with severe hypertension (Dec. 2022)
• American Heart Association health information: Caffeine and Heart Disease
• About Scientific Sessions 2025
• For more news at the American Heart Association's Scientific Sessions 2025, follow us on X @HeartNews,#AHA25

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