for people ages 18 years and up (full criteria)
at San Francisco, California
study started
estimated completion
Principal Investigator
by Gregory M Marcus, MD
Photo of Gregory M Marcus
Gregory M Marcus



The I-STOP-Afib study will test the comparative effectiveness of using N-of-1 trials vs. symptom surveillance alone to reduce Atrial Fibrillation (AF) episode frequency and severity and improve quality of life for AF patients. The study will involve randomizing almost 500 paroxysmal AF patients to either AF episode tracking versus engaging in testing the relationship between participant-selected triggers and AF episodes utilizing a mobile-app based N-of-1 study design. Both groups will complete a validated survey to assess AF severity, essentially a measure of quality of life while living with AF, before and after a 3 month testing period.

Official Title

Using N-of-1 Experiments to Answer Patient Generated Research Questions


N-of-1 Trial arm: Participants will use the Eureka mobile application and AliveCor device to execute at least one N-of-1 trial with the goal of identifying and better controlling their AF triggers. Each N-of-1 trial will last a total of 6 weeks and will include up to 3 periods of trigger exposure and 3 periods of trigger elimination with each exposure/elimination period lasting 1 week. Participants will be randomly assigned to start their trial with a period of either trigger exposure or elimination. During each N-of-1 trial, participants will track daily AF duration and severity, daily mood and sleep quality, daily AliveCor tracings and daily trigger exposure. At the end of each trial, participants will be able to review their trial results which will include visualizations of their daily AF symptom and trigger tracking over time. After completing a trial, participants will be instructed to implement any lifestyle changes they deem appropriate based on what they learned from the results of their trial. Participants will implement these changes for a period of 4 weeks during which they will continue to track AF episode duration and severity via the app. At the end of the 4-week lifestyle change period, participants will complete the Atrial Fibrillation Effect on QualiTy of Life survey (AFEQT) and will then have the option of testing another trigger or ending their study participation. Symptom Surveillance arm: Participants will use the Eureka app and AliveCor device to record daily AF duration and severity, daily AliveCor readings and daily mood and sleep quality for a period of 10 weeks. Participants will be able to visualize their AF, sleep and mood data in real time and will receive a weekly summary of their data via the Eureka app.At the end of the 10-week data tracking period, participants will complete the AFEQT survey and will then have the option of either ending their study participation or crossing over to the N-of-1 trial arm to test their triggers.


Atrial Fibrillation Paroxysmal Atrial Fibrillation Data Tracking


You can join if…

Open to people ages 18 years and up

  • symptomatic paroxysmal AF
  • a smartphone

You CAN'T join if...

  • Non-English speakers
  • Children (age < 18 years)
  • Patients with plans to substantially change AF management (such as with ablation or change in antiarrhythmic drugs) over the ensuing 6 months
  • Unwillingness to test AF triggers.
  • Patients who have had an AV node or AV Junction ablation


  • University of California, San Francisco
    San Francisco California 94143 United States

Lead Scientist at UCSF

  • Gregory M Marcus, MD
    CLINICAL Dr. Gregory Marcus is a specialist in the treatment of arrhythmias, including mapping and catheter ablation for atrial fibrillation, supraventricular tachycardias and ventricular arrhythmias. He is also an expert in pacemaker, biventricular device and defibrillator implantation. RESEARCH Dr. Marcus is Associate Chief of Cardiology for Research at UCSF Health.


in progress, not accepting new patients
Start Date
Completion Date
University of California, San Francisco
Study Type
Last Updated