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Only alcohol – not caffeine, diet or lack of sleep – might trigger atrial fibrillation

Only alcohol use was found to be consistently associated with more episodes of heart arrhythmia in research by the University of California, San Francisco that tested a range of possible triggers of a common heart condition.

The study has just been published in the journal JAMA Cardiology and was presented on 14 November 2021 at the annual Scientific Sessions of the American Heart Association.

The authors conclude that people might be able to reduce their risk of atrial fibrillation (AF) by avoiding certain triggers, according to this material from the University of California, San Francisco (UCSF), written by Elizabeth Fernandez and released on 23 November,

Researchers were surprised to find that although most of the things that participants thought would be related to their AF were not, those in the intervention group still experienced less arrhythmia than the people in a comparison group that was not self-monitoring.

“This suggests that those personalised assessments revealed actionable results,” said lead author Professor Gregory Marcus, professor of medicine in the Division of Cardiology at UCSF.

“Although caffeine was the most commonly selected trigger for testing, we found no evidence of a near-term relationship between caffeine consumption and atrial fibrillation. In contrast, alcohol consumption most consistently exhibited heightened risks of atrial fibrillation.”

Atrial fibrillation contributes to more than 150,000 deaths in the United States each year, reports the Centers for Disease Control and Prevention, with the death rate on the rise for more than 20 years.

To learn more about what patients felt was especially important to study about the disease, researchers held a brainstorming session in 2014. Patients said researching individual triggers for AF was their top priority, giving rise to the I-STOP-AFib study, which enabled individuals to test any presumed AF trigger.

About 450 people participated, more than half of whom (58%) were men, and the overwhelming majority of whom were white (92%).

Participants in the randomised clinical trial utilised a mobile electrocardiogram recording device along with a phone app to log potential triggers like drinking alcohol and caffeine, sleeping on the left side or not getting enough sleep, eating a large meal, a cold drink, or sticking to a particular diet, engaging in exercise, or anything else they thought was relevant to their AF.

Although participants were most likely to select caffeine as a trigger, there was no association with AF. Recent research from UCSF has similarly failed to demonstrate a relationship between caffeine and arrhythmias – on the contrary, investigators found it may have a protective effect.

The new study demonstrated that consumption of alcohol was the only trigger that consistently resulted in significantly more self-reported AF episodes.

The individualised testing method, known as n-of-1, did not validate participant-selected triggers for AF. But trial participants did report fewer AF episodes than those in the control group, and the data suggest that behaviours like avoiding alcohol could lessen the chances of having an AF episode.

“This completely remote, siteless, mobile-app based study will hopefully pave the way for many investigators and patients to conduct similar personalised ‘n-of-1’ experiments that can provide clinically relevant information specific to the individual,” said Marcus.

Funding and disclosures: The study was funded by a Patient Powered Research Network Demonstration Project Award from the Patient-Centered Outcomes Research Institute and the National Institutes of Health/National Institute of Biomedical Imaging and Bioengineering Disclosures can be found in the paper.


Study details

Individualised Studies of Triggers of Paroxysmal Atrial Fibrillation: The I-STOP-AFib Randomized Clinical Trial

Gregory M Marcus, Madelaine Faulkner Modow, Christopher H Schmid, Kathi Sigona, Gregory Nah, Jiabei Yang, Tzu-Chun Chu, Sean Joyce, Shiffen Gettabecha, Kelsey Ogomori, Vivian Yang, Xochitl Butcher, Mellanie True Hills, Debbie McCall, Kathleen Sciarappa, Ida Sim, Mark J Pletcher and Jeffrey E Olgin.

Author affiliations: University of California, San Francisco; Brown university; and the American Foundation for Women’s Health.

Published online in JAMA Cardioogy on 14 November 2021.



Atrial fibrillation (AF) is the most common arrhythmia. Although patients have reported that various exposures determine when and if an AF event will occur, a prospective evaluation of patient-selected triggers has not been conducted, and the utility of characterising presumed AF-related triggers for individual patients remains unknown.


To test the hypothesis that n-of-1 trials of self-selected AF triggers would enhance AF-related quality of life.

Design, setting and participants

A randomised clinical trial lasting a minimum of 10 weeks tested a smartphone mobile application used by symptomatic patients with paroxysmal AF who owned a smartphone and were interested in testing a presumed AF trigger. Participants were screened between 22 December 2018 and 29 March 2020.


n-of-1 Participants received instructions to expose or avoid self-selected triggers in random 1-week blocks for 6 weeks, and the probability their trigger influenced AF risk was then communicated. Controls monitored their AF over the same time period.

Main outcomes and measures

AF was assessed daily by self-report and using a smartphone-based electrocardiogram recording device. The primary outcome comparing n-of-1 and control groups was the Atrial Fibrillation Effect on Quality-of-Life (AFEQT) score at 10 weeks. All participants could subsequently opt for additional trigger testing.


Of 446 participants who initiated (mean [SD] age, 58 [14] years; 289 men [58%]; 461 White [92%]), 320 (72%) completed all study activities. Self-selected triggers included caffeine (n = 53), alcohol (n = 43), reduced sleep (n = 31), exercise (n = 30), lying on left side (n = 17), dehydration (n = 10), large meals (n = 7), cold food or drink (n = 5), specific diets (n = 6), and other customised triggers (n = 4).

No significant differences in AFEQT scores were observed between the n-of-1 vs AF monitoring-only groups. In the 4-week postintervention follow-up period, significantly fewer daily AF episodes were reported after trigger testing compared with controls over the same time period (adjusted relative risk, 0.60; 95% CI, 0.43- 0.83; P < .001).

In a meta-analysis of the individualised trials, only exposure to alcohol was associated with significantly heightened risks of AF events.

Conclusions and relevance

n-of-1 Testing of AF triggers did not improve AF-associated quality of life but was associated with a reduction in AF events. Acute exposure to alcohol increased AF risk, with no evidence that other exposures, including caffeine, more commonly triggered AF.


University of California, San Francisco, material – Only alcohol – Not caffeine, diet or lack of sleep – might trigger heart rhythm condition (Open access)


JAMA Cardiology journal article – Individualised studies of triggers of paroxysmal atrial fibrillation: The I-STOP-AFib Randomised clinical trial (Open access)


See also from the MedicalBrief archives


Just a drink a month may put those with atrial fibrillation at risk


Alcohol may have immediate effect on atrial fibrillation risk, events


Frequent drinking greater risk factor for atrial fibrillation than binge drinking


Troubled sleep link to increased risk of AD and bradyarrhythmia — UK Biobank data


Coffee consumption’s complex effects on arrhythmias — CRAVE trial


Omega-3 supplementation linked with atrial fibrillation risk — Meta-analysis



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