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Atrial fibrillation (Afib) patients testing their perceived triggers in n-of-1 experiments were unable to improve their quality of life, but did have fewer episodes in the I-STOP-AFib trial.

Patients scored similarly on the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire whether they had been randomized to data tracking alone on a personal ECG (n=248) or to trigger testing plus lifestyle changes (n=251). There was no difference between groups even after adjusting for age, race, and education, reported Gregory Marcus, MD, of University of California San Francisco, at the American Heart Association (AHA) virtual meeting.

However, trigger testers reported 40% fewer Afib events in the 4 weeks after getting their results compared with peers undergoing ECG monitoring only (adjusted RR 0.60, 95% CI 0.43-0.83) when investigators accounted for people in the data tracking group who opted into trigger testing in the latter part of the study.

It may be that the AFEQT tool is not sensitive enough, or that avoidance of certain triggers (such as alcohol and exercise) might have affected quality of life in a way that counterbalanced any improvements in Afib, suggested AHA session discussant Mina Chung, MD, of Cleveland Clinic.

In I-STOP-AFib, patients were allowed to select and customize the Afib triggers they wanted to test on themselves. All participants underwent personal ECG monitoring using the KardiaMobile device paired with a mobile app.

Caffeine was the most popular trigger tested, but only alcohol appeared to have a consistent association with Afib episodes in a network meta-analysis across study participants.

This is validation of the "holiday heart" phenomenon wherein alcohol increases Afib risk, commented AHA press conference discussant Biykem Bozkurt, MD, PhD, of Baylor College of Medicine in Houston. As for the other presumed triggers that did not turn out to be associated with Afib, they may still be triggering for people on an individual level, she said.

Although the data are consistent on alcohol as a trigger, Marcus said he has suggested that his patients run their own n-of-1 experiments using their smartphone-based ECG recorders to find their own Afib triggers. Not only can they identify triggers so they can reduce their Afib recurrence, but they may also find themselves able to enjoy substances that they otherwise would have been advised against.

"We can reassure them that certain exposures, certain exercises, might be beneficial or might not be harmful," he said.

For the trial, Marcus and colleagues recruited adult symptomatic Afib patients who owned a smartphone and were interested in testing a presumed Afib trigger. The trial cohort had a mean age of 58, and about 60% were men. White patients constituted over 90% of the group.

Participants took a baseline AFEQT, then were randomized to two groups: one undergoing 10 weeks of data tracking alone and another conducting a trigger test over 6 weeks followed by 4 weeks of lifestyle change including trigger avoidance. Both study arms regularly got text-based notes on the presence or absence of Afib the previous day. Outcomes of the follow-up AFEQT were the basis of the study's main analysis.

Trigger tests were conducted over 1-week blocks in which patients received daily text-based instructions to either expose themselves to a given trigger at some point during that week or to avoid that trigger for the entire week. Trigger compliance was assessed with daily questionnaires.

The data tracking group could opt into trigger testing after their initial period of withholding it.

Study authors acknowledged the high dropout rate in I-STOP-AFib, as only 184 and 136 of the tracking and trigger testing arms completed the follow-up AFEQT. This likely introduced bias, Marcus said.

Other study limitations included a lack of continuous ECG monitoring and the questionable generalizability of the results to the wider Afib population.

Bozkurt said a future trial on trigger testing that characterizes patients by type and rate of Afib, as well as whether episodes are accompanied by symptoms, is merited.

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