Surprising heart study finds daily coffee may cut AFib risk by 39%

For years, doctors have advised people with AFib and other heart issues to stay away from caffeine, fearing it could worsen symptoms. But a new study from UC San Francisco and the University of Adelaide has found the opposite: participants who drank one cup of caffeinated coffee a day had a 39% lower risk of developing AFib.

Why Coffee May Help the Heart

"Coffee increases physical activity which is known to reduce atrial fibrillation," explained Gregory M. Marcus, MD, MAS, an electrophysiologist at UCSF Health and the senior author of the study, published November 9 in JAMA. Marcus added that "caffeine is also a diuretic, which could potentially reduce blood pressure and in turn lessen AFib risk. Several other ingredients in coffee also have anti-inflammatory properties that could have positive effects."

Rates of AFib have been climbing in recent years, largely due to aging populations and increasing obesity. More than 10 million adults in the United States have been diagnosed, and experts estimate that as many as one in three people may experience the condition at some point in their lives.

Testing Coffee's Effect on Heart Rhythm

To explore whether coffee helps or harms, researchers designed the DECAF study (Does Eliminating Coffee Avoid Fibrillation?), the first randomized clinical trial to test the relationship between caffeinated coffee and AFib. The project was funded by the National Institutes of Health.

The trial involved 200 patients who were regular coffee drinkers and had persistent AFib or a related condition known as atrial flutter, along with a history of AFib. All were scheduled to undergo electrical cardioversion, a procedure that uses a controlled electrical shock to restore normal heart rhythm. Participants were randomly assigned to either drink at least one cup of caffeinated coffee or an espresso shot each day, or to completely avoid coffee and other caffeinated beverages for six months.

Coffee Drinkers Had Lower Risk

At the end of the study, the group that drank coffee experienced a 39% lower risk of recurring AFib episodes. In addition to coffee's potential anti-inflammatory effects, the researchers proposed that those who drank coffee may have naturally replaced less healthy drinks, such as sugary sodas, with coffee instead.

"The results were astounding," said first author Christopher X. Wong, PhD, of UCSF, the University of Adelaide, and the Royal Adelaide Hospital. "Doctors have always recommended that patients with problematic AFib minimize their coffee intake, but this trial suggests that coffee is not only safe but likely to be protective."

Authors from UCSF include Gabrielle Montenegro; Hannah H. Oo; Isabella J. Pena; Janet J. Tang, PhD; Grace Wall; Thomas A. Dewland, MD; Joshua D. Moss, MD; Edward P. Gerstenfeld, MD; Zian H. Tseng, MD; Henry H. Hsia, MD; Randall J. Lee, MD, PhD; Jeffrey E. Olgin, MD; Vasanth Vedantham, MD; Melvin M. Scheinman, MD; and Catherine Lee, PhD.

Marcus is supported by R01 HL158825-01, R01 HL167975-01, R01 DA058069-01, and R01 HL159069-01A1 grants from the National Heart, Lung and Blood Institute, as well as R01 AA022222 from the National Institute on Alcohol Abuse and Alcoholism.