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

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

News - Nov. 15, 2021

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 StopAfib.org 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

  • There was no difference in the primary outcome, AF-related quality of life, between the two arms.
  • There was a 40% reduction in self-reported AF events in those in the N-of-1 trials in the 4 weeks after receiving the study results compared to monitoring-only patients during the same time period (adjusted RR 0.60, 95%CI:0.43-0.83, P<0.0001).
  • This 40% reduction was driven by those testing alcohol, dehydration, and exercise.
  • In a meta-analysis of all treatment periods per-protocol, alcohol was the only trigger that was associated with AF episodes (OR 2.15, 95%CI:1.27-3.61). This association was not found in ITT analysis.


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.

  • Our reporting is based on the information provided at the American Heart Association’s Scientific Sessions 2021 -

Watch a video on the I-STOP-AFib study

Facebook Comments


We’re glad to see you’re enjoying PACE-CME…
but how about a more personalized experience?

Register for free