Coffee Not Linked to Increased Arrhythmia Risk in New Study

Jake Remaly

July 19, 2021

Habitual coffee drinking was not associated with a heightened risk of cardiac arrhythmias in a study of more than 300,000 people.

In fact, an adjusted analysis found that "each additional cup of coffee intake was associated with a 3% lower risk of incident arrhythmia," Eun-jeong Kim, MD, of the division of cardiology at the University of California, San Francisco, and colleagues reported in JAMA Internal Medicine.

In addition, genetic differences that affect caffeine metabolism did not significantly influence the odds of arrhythmias, the researchers found.

Still, these findings should not necessarily encourage people to start drinking coffee if they don't already, or to guzzle additional cups with abandon, they said.

"We certainly don't want to say drink coffee and it will reduce your risk of arrhythmias," study author Gregory M. Marcus, MD, MAS, associate chief of cardiology for research at UCSF Health, said in an interview. "But rather, we think the main point is that a blanket prohibition against coffee or caffeine to reduce the risk of arrhythmias among patients who have a diagnosis of arrhythmias is likely unwarranted. And given some evidence that coffee consumption may actually have other benefits regarding diabetes, mood, and perhaps overall mortality, it may be problematic to admonish patients to avoid coffee or caffeine when it is not really warranted."

Methods and Results

The conventional wisdom that caffeine increases arrhythmic risk has not been well substantiated. To further examine whether moderate, habitual coffee drinking relates to arrhythmia risk, and whether certain genetic variants influence the association, Kim and colleagues analyzed data from the UK Biobank. They focused on longitudinal data collected between 2006 and 2018 from 386,258 people who did not have a prior diagnosis of arrhythmia.

Participants had an average age of 56 years, and about 52% were female. They provided information about their coffee consumption, and the researchers grouped the participants into eight categories based on their daily coffee intake: 0, less than 1, 1, 2, 3, 4, 5, and 6 or more cups per day.

Over an average follow-up of 4.5 years, 16,979 participants developed an incident arrhythmia. After adjusting for demographic characteristics, comorbid conditions, and lifestyle habits, the decreased risk with each cup of coffee was similar for atrial fibrillation or flutter (hazard ratio, 0.97) and supraventricular tachycardia (HR, 0.96).

Taking into account genetic variations that relate to caffeine metabolism did not modify the findings. Mendelian randomization analyses that used a polygenic score of inherited caffeine metabolism patterns "failed to provide evidence that caffeine consumption leads to a greater risk of arrhythmias," the researchers said.

Professional society guidelines have suggested staying away from caffeinated products to reduce the risk of arrhythmia, but this guidance has "relied on assumed mechanisms and a small observational study from 1980," the authors wrote. Subsequent research has indicated that coffee's reputation of increasing the risk of arrhythmia may be undeserved.

"The investigators should be commended on performing a high-quality observational study to try to further understand the association between coffee consumption and arrhythmias, or the lack of one," commented Zachary D. Goldberger, MD, MS, with the division of cardiovascular medicine at the University of Wisconsin–Madison, who was not involved in the study. "This is not a randomized, controlled trial, and coffee consumption was self-reported, but the methods employed are rigorous, despite these and other important limitations. However, we need to be extremely cautious in how we interpret these findings, and not use these data as a prescription for more coffee. It's important to recognize that this study is not telling us to drink more coffee, or start drinking coffee, to protect against developing arrhythmias. However, it should offer more reassurance that moderate coffee consumption is not necessarily harmful, and will not always lead to arrhythmias. This is important, given the widespread notion that coffee is universally proarrhythmic."

A Call for Personalized Guidance

"As the investigators note, there are definitely biologically plausible reasons how coffee and caffeine may not cause arrhythmias, and may be possibly protective in some, despite being a stimulant," Goldberger said. "However, if your patient is reporting palpitations or symptoms of an arrhythmia, and feels they be related to coffee or caffeine, we should not use this study to tell them that coffee may not be the culprit. We need to listen to our patients, and the decision to reduce coffee consumption to reduce these symptoms needs to be personalized."

The effect size was small, and only about 4% of the participants developed an arrhythmia, Goldberger and Rodney A. Hayward, MD, wrote in an invited commentary on the study in JAMA Internal Medicine. Hayward is a professor of public health and internal medicine at the University of Michigan, Ann Arbor, and a senior investigator at the Ann Arbor Veterans Affairs Center for Clinical Management Research.

"Unfortunately, coffee consumption was self-reported at a single time point. Not only can this lead to recall bias, but subsequent and substantial changes in coffee consumption are also possible, including reductions due to new signs or symptoms," they said.

No Evidence That Coffee Ups Risk for Developing Arrhythmias

Another recent study suggests that people may alter their coffee consumption depending on their baseline cardiovascular health, according to the commentary.

Overall, the results "strengthen the evidence that caffeine is not proarrhythmic, but they should not be taken as proving that coffee is an antiarrhythmic—this distinction is of paramount importance," Goldberger and Hayward wrote. "Health care professionals can reassure patients that there is no evidence that drinking coffee increases the risk for developing arrhythmias. This is particularly important for the many patients with benign palpitations who are devastated when they think, or are told, that they have to stop drinking coffee. Given current evidence, this is entirely a patient-preference decision, not a medical one."

Marcus, a cardiac electrophysiologist, sees patients with arrhythmias all the time. They tend to "come in fairly convinced that caffeine is to be avoided when they have arrhythmias," he said. "Often, they been told by their primary care physician or their general cardiologist to avoid caffeine because they have an arrhythmia.

"What I suggest to my patients is that they feel free to go ahead and experiment and try coffee," Marcus said.

Still, Marcus suspects that there are some individuals in whom caffeine is a trigger for the arrhythmia. But evidence indicates these cases likely are rare, and avoiding caffeine need not apply to the general population, particularly "given the potential health benefits of benefits of coffee and also, frankly, just the enhanced quality of life that people can enjoy drinking a good cup of coffee."

The research was conducted using the UK Biobank resource, which was established by the Wellcome Trust, the Medical Research Council, the U.K. Department of Health, and the Scottish government. The UK Biobank has received funding from other agencies and foundations as well. Marcus disclosed grants from Baylis, Medtronic, and Eight Sleep outside the submitted work. In addition, he reported consulting for Johnson & Johnson and InCarda, and holding equity in InCarda. A coauthor received salary support from the National Institutes of Health during the study. Goldberger and Hayward disclosed no conflicts of interest.

This article originally appeared on, part of the Medscape Professional Network.


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