Individualized Studies of Triggers of Paroxysmal Atrial Fibrillation - I-STOP-AFIB

Contribution To Literature:

Highlighted text has been updated as of December 22, 2023.

The I-STOP-AFIB trial showed that individual trigger testing did not result in improved AF-related quality of life, although these patients did report less AF episodes in the next 4 weeks.


The goal of the trial was to assess the efficacy of trigger-based testing for atrial fibrillation (AF) versus routine tracking alone among patients with AF.

Study Design

Patients were enrolled via a mobile application. They were randomized in a 1:1 fashion to either trigger testing (n = 251) or tracking alone (n = 248). The top three triggers selected for testing were caffeine, alcohol, and reduced sleep.

  • Total number of enrollees: 499
  • Duration of follow-up: 10 weeks
  • Mean patient age: 58 years
  • Percentage female: 42%

Inclusion criteria:

  • Adult symptomatic AF patients
  • Owned a smartphone (either Android or iOS)
  • Interested in testing a presumed AF trigger they could readily introduce or withhold

Exclusion criteria:

  • Those who planned to change their AF management (e.g., with catheter ablation or medication changes) in the subsequent 6 months
  • Did not speak English
  • A history of an atrioventricular (AV) junction ablation

Other salient features/characteristics:

  • White race: 93%
  • Taking Vaughn-Williams class I or III drug at baseline: 25%
  • Baseline Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) for trigger-testing vs. monitoring only: 76.1 vs. 72.4

Principal Findings:

The primary outcome, change in AFEQT at week 10 compared with baseline, for trigger testing vs. monitoring only, was 1.7% vs. 0.5% (p = 0.17).

Secondary outcomes:

Those randomized to N-of-1 testing self-reported 40% fewer AF events in the 4 weeks following receiving the results of their N-of-1 study compared to monitoring-only participants during the same time frame (adjusted relative risk 0.60, 95% confidence interval [CI] 0.43-0.83, p < 0.0001). This was driven by those testing alcohol, dehydration, and exercise.

Preceding night sleep quality and AF: Data were available for 419 patients (15,755 days). Sleep quality was characterized as “Amazing,” “Good,” “Average,” “Bad,” or “Horrible.” Each one-category worst sleep quality on any given night was associated with higher odds of a self-reported AF episode the next day (odds ratio [OR] 1.15, 95% CI 1.10-1.20, p < 0.0001, after adjustment for the day of the week). On the other hand, no statistically significant associations between worsening sleep quality and mobile electrocardiogram (ECG)-confirmed AF events were observed (OR 1.04, 95% CI 0.95-1.13, p = 0.43). Poor sleep was also associated with longer self-reported AF episodes, with each progressive category of worsening sleep associated with 16 (95% CI 12-21, p < 0.001) more minutes of AF the next day.


The results of this trial indicate that individual trigger testing did not result in improved AF-related quality of life, although these patients did report less AF episodes in the next 4 weeks. Alcohol exhibited consistent evidence of a near-term effect on self-reported AF episodes. Poor sleep quality the night before appeared to have an association with self-reported but not mobile ECG-confirmed AF events the next day. There was also an increase in prolonged AF episodes the subsequent day.


Wong CX, Modrow MF, Sigona K, et al. Preceding Night Sleep Quality and Atrial Fibrillation Episodes in the I-STOP-AFIB Randomized Trial. JACC Clin Electrophysiol 2023;Nov 1:[Epublished].

Editorial Comment: Heinzinger CM, Chung MK, Mehra R. Salient Temporalities of Patient-Reported Sleep Disturbance and Burden of Atrial Fibrillation. JACC Clin Electrophysiol 2023;Dec 13:[Epublished].

Presented by Dr. Gregory M. Marcus at the American Heart Association Virtual Annual Scientific Sessions (AHA 2021), November 14, 2021.

Clinical Topics: Arrhythmias and Clinical EP, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Sleep Apnea

Keywords: AHA Annual Scientific Sessions, AHA21, Arrhythmias, Cardiac, Atrial Fibrillation, Mobile Applications, Secondary Prevention, Sleep Deprivation, Smartphone

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