Doctors have traditionally told patients with atrial fibrillation and other heart arrhythmias to either avoid or significantly restrict their caffeine intake. A growing number of studies, however, indicate that moderate caffeine consumption is safe — and potentially beneficial — for patients with these heart conditions.
A paper published earlier this month in the Journal of the American Medical Association (JAMA) found that one cup of coffee a day was associated with less recurrence of heart arrhythmias in A-fib patients compared to those who abstained from caffeine.
“It was a little surprising to some that not only was it not provoking A-fib, but it seemed to have a little bit of a protective effect,” said Dr. David Pederson, a cardiologist with Methodist Healthcare, who primarily works at Methodist’s cardiology clinic in the South Texas Medical Center.
Atrial fibrillation, characterized by irregular, rapid heartbeats, is the most common type of heart arrhythmia condition, affecting 12 million Americans, according to the U.S. Centers for Disease Control and Prevention.
A-fib risk increases with age and alongside other conditions like hypertension, diabetes and obesity — all of which afflict San Antonio and South Texas at higher rates than the national average. A-fib is a major contributor to ischemic strokes, when a blood clot prevents oxygen from reaching the brain.
“I see A-fib very commonly, every week,” said Dr. James Keeton, a University Health cardiologist, who practices at the county hospital system’s main campus and its downtown Robert B. Green clinic. “It’s becoming more and more prevalent, especially with aging. There’s a lot of overlap with other cardiovascular diseases.”
Here’s what the research and local cardiologists have to say about the connection between caffeine and cardiovascular health, how much caffeine is too much, and limitations to the research on caffeine and heart conditions.
Does caffeine spur cardiac arrhythmias?
The common answer from health care providers to that question has traditionally been “yes.” The conventional wisdom has been that caffeine is pro-arrhythmic, meaning it can spur new arrhythmias or worsen existing ones in patients with A-fib or similar conditions, according to the local cardiologists and research papers.
“That is the prevailing thought amongst not just general practitioners, but also maybe some cardiologists as well,” Keeton said. “In the past 10 years, I think that it wasn’t uncommon for providers to recommend patients to decrease their caffeine intake because of arrhythmias.”
Caffeine — whether in the form of coffee, energy drinks or caffeine pills — can cause brief spikes in blood pressure, mostly in people who don’t consume caffeine regularly. This effect, as well as increased heart rate from caffeine, was thought to pose a danger to people with A-fib.
“It was common advice for a long time, because it kind of seemed to make sense,” Pederson said. “Some people drink coffee and feel kind of jittery, and can feel some palpitations. And we thought caffeine was a mild stimulant, so it made sense that it might cause some arrhythmias.”
Several studies, however, now contradict caffeine’s pro-arrhythmic reputation.
For example, meta-analyses in 2013 and 2024 found no association between cardiac arrhythmias and caffeine consumption, with the 2013 paper suggesting that low doses of caffeine might even have a protective effect. And in 2016, a randomized clinical trial found that even high doses of caffeine — 500 milligrams, which is roughly five cups of coffee, administered over five hours, didn’t spur arrhythmias in people with heart conditions.
“An increasing body of research appears to support the idea that drinking coffee has no negative effects and may even be beneficial,” researchers said in the 2024 paper.
The most recent JAMA paper published earlier this month, nicknamed the DECAF study, tracked 200 adults with A-fib over six months, all of whom had a history of drinking caffeinated coffee.
Half of the participants consumed one cup of caffeinated coffee per day, the rest abstaining from caffeine. The group of caffeine users’ risk of atrial fibrillation recurrence was 39% lower than the abstaining group.
Limitations and ‘moderate’ caffeine intake
There were limitations to the DECAF study, Pederson and Keeton pointed out. It was relatively small, conducted over a short period of time, and relied on participants accurately reporting how much caffeine they consumed on a daily basis.
And more broadly, a challenge with all of the studies that investigate the connections between heart conditions and caffeine is that they’re hard to compare since they rely on varying amounts of caffeine and in different forms — coffee, caffeine pills, caffeinated gum.
Whether moderate intake of coffee and caffeine really has a protective effect for people with heart conditions, the growing body of research signals to Keeton and Pederson that caffeine abstinence is unnecessary.
“This is telling me that it’s safe,” Keeton said, “that probably we should not be instructing patients to avoid caffeine. Whether or not caffeine use decreases the risk of arrhythmias like A-fib, I think it’s too early to tell.”
Both doctors emphasized that caffeine should be consumed in moderation.
For them that means somewhere between one and three cups of coffee a day, or no more than about 300 milligrams. But, Keeton noted, everyone responds to caffeine differently. The U.S. Food and Drug Administration advises consuming no more than 400 milligrams of caffeine daily.
It’s also worth remembering that energy drinks and pre-workout supplements often contain much higher level amounts of caffeine than the average cup of coffee. Soda, tea, dark chocolate, and even decaffeinated coffee also contain varying amounts of caffeine.
If you’re someone who has a history of cardiovascular conditions, paying attention to your intake, and reducing it if you do experience palpitations or discomfort is advisable.
Pederson tells his patients not to worry about coffee as long as it’s not excessive and not causing physical discomfort. “I assure them it’s not going to hurt them and it may be beneficial,” he said. “If you really don’t like coffee or caffeine, it makes you generally feel bad, then don’t start taking it. It’s not a treatment.”
So, what are the treatments for A-fib and similar heart conditions?
Blood thinners and heart-rate-regulation medications, procedures like a cardioversion, which uses an electric shock to bring the heart back into a normal rhythm; and lifestyle factors such as maintaining a healthy weight, controlling blood pressure, treating sleep apnea, regular exercise and limiting alcohol consumption, Pederson said.
That morning cup of coffee, though, can probably stay.
“I wouldn’t want anyone to tell me I couldn’t drink coffee,” Keeton said. “I couldn’t do that.”
