Physicians' Academy for Cardiovascular Education

Testing individual triggers for AF in n-of-1 trials

News - Nov. 15, 2021

I-STOP AF: Testing Individualized Triggers of Atrial Fibrillation: A Randomized Controlled Trial

Presented at the American Heart Association’s Scientific Sessions 2021 by: Prof. Gregory Marcus, MD - San Francisco, CA, USA.

Introduction and methods

Study design

Paroxysmal AF patients who were interested in testing individual triggers for AF episodes were recruited from the worldwide Health eHeart Study, at and from patients with connections in social media. Patients were involved in the design and recruitment of the study. If patients met the eligibility criteria in a survey and consented, they were enrolled in the trial. If patients did not own a KardioMobile device, a handheld device to record single lead ECGs that can be connected to a smartphone, it was donated.

Individuals were randomly assigned to only track AF events or to n-of-1 trials to test triggers and receive results. Patients in the n-of-1 trials could select their trigger in a menu or add their own trigger and they were assigned in one-week blocks of exposure to the trigger or avoidance of the trigger for six weeks. All patients were asked every day whether they had an AF episode and to provide their ECG recordings.

After six weeks, patients in the n-of-1 trials received their own results and they were asked to respond to these results with regard to their lifestyle for four weeks.

Primary outcome

At week 10, quality of life was assessed using a validated instrument AFEQT, which captures severity and frequency of AF episodes.

Main results


In this randomized trial of monitoring only vs. n-of-1 trials of individual triggers, there was no difference in AF-related quality of life. There was however a reduction in self-reported AF episodes after 4 weeks in individuals in the n-of-1 trials who received their results compared to individuals who only tracked AF events. In a meta-analysis, alcohol was the only trigger associated with AF episodes.


Prof. Biykem Bozkurt, MD, PhD** (Baylor College of Medicine, Houston, TX, USA) said that it may not be surprising that in the meta-analysis the factors other than coffee were not associated were AF episodes. On an individual level, it may be a trigger and changes in behavior of an individual reduce the exposure to this trigger resulting in reduction of AF episodes. She also found this study fascinating because the questions and methodology of the study were developed with the involvement of patients . With regard to the lack of changes in quality of life, she said that this is not surprising, because it is difficult to measure changes in quality of life. This requires follow-up with other methodologies.

Watch a video on the I-STOP-AFib study

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