san francisco California — Regular coffee consumption is not associated with an increased risk of heart arrhythmias, according to a large study published in the JAMA Internal Medicine. 
In fact, the analysis of Dr Eun-jeong Kim et al. (Department of Cardiology, University of California San Francisco, United States) on more than 300,000 subjects, shows that “each additional cup of coffee is associated with an incidence of the risk of arrhythmias 3% times lower”.
Each additional cup of coffee is associated with a 3% times lower incidence of arrhythmia risk.
In addition, the researchers observed that the genetic differences that affect the metabolism of caffeine do not significantly change the likelihood of arrhythmias occurring.
However, these results should not necessarily encourage non-consumers to drink coffee or to indulge in overconsumption, they specify.
“We certainly don’t want to get the message across drink coffee and it will lower your risk of arrhythmias », Says Dr Gregory M. Marcus (associate director of cardiology research at UCSF Health) who participated in the study.
“The important thing is that banning coffee or caffeine in order to reduce the risk of arrhythmias in patients with arrhythmias is probably inappropriate. Considering that according to some recent data, the consumption of coffee would have virtues on diabetes, on well-being and perhaps on overall mortality, it could be problematic to force patients to stop coffee or caffeine when it is not really necessary. “
Prohibiting the consumption of coffee or caffeine in order to reduce the risk of arrhythmias in patients with arrhythmias is probably inappropriate.
Pro-arrhythmogenic coffee: a low level of evidence
The recommendations of learned societies suggest that caffeine-based products should be avoided in order to reduce the risk of arrhythmias, but this opinion “is based on alleged mechanisms and a small observational study, carried out in 1980”, write the authors. Other studies [2,3] suggest that the reputation of coffee held responsible for the increased risk of arrhythmias would be unwarranted. The current view that caffeine increases the risk of arrhythmias has not been properly evaluated.
To further examine whether coffee consumption is related to a risk of arrhythmias and whether certain genetic variants have an impact on the association, Dr Kim and colleagues analyzed data from the UK Biobank. They were interested in longitudinal data collected between 2006 and 2018 from 386,258 subjects who had no known history of arrhythmia.
Participants were on average 56 years old and about 52% were women. Participants reported their coffee consumption, then researchers grouped subjects into 8 categories based on their daily coffee consumption: 0, less than 1, 1, 2, 3, 4, 5, and 6 or more cups per day. .
During a mean follow-up of 4.5 years, 16,979 participants reported the occurrence of arrhythmia. After adjustment for demographic criteria, comorbidities and lifestyle, an identical decrease in risk was observed for each cup of coffee, whether for atrial fibrillation, flutter (Risk ratio: 0.97) and supraventricular tachycardias (HR 0.96).
Also, taking into account genetic variations affecting caffeine metabolism did not modify the results.
The Mendelian randomization using a polygenic score of models of hereditary caffeine metabolism “has not made it possible to demonstrate that the consumption of caffeine is associated with a greater risk of occurrence of arrhythmias”, conclude the researchers.
“The researchers are to be greatly commended for carrying out a high-quality observational survey that allows us to go further in understanding the relationship between coffee consumption and arrhythmias, unless one does not exist.” not ”, commented Dr Zachary D. Goldberger (Department of Cardiovascular Medicine, University of Wisconsin – Madison), who did not participate in the study.
Regarding the limits of the study, in an editorial accompanying the publication  , Zachary D. Goldberger et Rodney A. Hayward (professor of public health and internal medicine at the University of Michigan and researcher at the Ann Arbor Veterans Affairs Center for Clinical Management Research) point out that the magnitude of the effect is small and that only about 4% of participants had a arrhythmia.
They add that the coffee consumption was only given by the participants at one time, which introduces a bias. “Subsequent and substantial changes in coffee consumption are possible, including reductions linked to the onset of symptoms,” they point out.
“This is not a controlled or randomized trial and it is the participants who self-reported their coffee consumption, but despite this and other limitations, the methods employed are rigorous. However, we must be very careful about how to interpret these results and not use them as a prescription to drink more coffee. It is important to recognize that this study does not tell us that we should drink more coffee or start drinking coffee to protect ourselves from the occurrence of arrhythmias. However, it indicates that moderate coffee consumption is not necessarily harmful and will not necessarily lead to the occurrence of arrhythmias. This is important given the commonly accepted idea that coffee is pro-arrhythmogenic, ”they say.
This study does not tell us that we need to drink more coffee or start drinking coffee to protect ourselves from the occurrence of arrhythmias.
Give personalized advice
“As the researchers note, there are certainly plausible biological reasons why caffeine may not cause arrhythmias and may be beneficial in some, despite its stimulating effect,” says Dr. Goldberger.
“However, if our patient reports palpitations or symptoms suggestive of arrhythmia and thinks there is a relationship to coffee or caffeine intake, we should not use this study to tell him that coffee is not. is not guilty. We must listen to our patients and the decision to reduce coffee consumption to reduce the occurrence of these symptoms must be personalized ”.
Neither pro-arrhythmogenic nor antiarrhythmic
Overall the results “support that caffeine is not pro-arrhythmogenic, however they should not be taken as evidence that coffee is an anti-arrhythmic – this distinction is critically important,” write the editorial writers.
“Healthcare professionals can reassure their patients that there is no evidence that coffee increases the risk of arrhythmias. This is especially important in the many patients who have mild palpitations and are devastated at the idea of stopping coffee either because they think it is necessary or because they have been told. In the state of knowledge, it must be a decision of the patient and not a medical verdict ”.
Rhythmologist Dr Marcus reports that his patients are globally “convinced that caffeine should be removed when they have arrhythmia,” he says. “Often it was their GP or cardiologist who told them to avoid caffeine because they have an arrhythmia.”
“What I suggest to my patients is to feel free, to dare and try to have a coffee,” he explains.
According to him, caffeine can be a trigger for arrhythmias in some individuals. But obviously these cases are rare and removing caffeine should not apply to the general population “given the potential health benefits of coffee and frankly the pleasure of drinking a good cup of coffee” .
This study was conducted using the UK Biobank resource, which was established by the Wellcome Trust, the Medical Research Council, the UK Department of Health and the Scottish Government. UK Biobank has also received funding from other agencies and foundations. Dr Marcus reported funding from Baylis, Medtronic and Eight Sleep. In addition, he said he was a consultant for Johnson & Johnson and InCarda, and owns shares in InCarda. A co-author received salary support from the National Institutes of Health during the study. Dr Goldberger and Hayward have not disclosed any links of interest.
Article originally published on MDedge.com, member of the Medscape network.
Translated from the American by Doctor Jean-Pierre Usdin