Conference Coverage

Alcoholic drinks stand out in novel trial exploring AFib triggers


People with paroxysmal atrial fibrillation who explored potential triggers of their arrhythmia, and used them to make lifestyle changes, went on to show a 40% decline in subjectively experienced bouts of AFib in a randomized trial with an unusual design.

Dr. Gregory Marcus professor of medicine at the University of California, San Francisco American Heart Association

Dr. Gregory M. Marcus

But the study didn’t provide evidence that the drop in self-reported AFib necessarily improved their quality of life, its primary endpoint. Nor was there any apparent relationship between potential triggers and AFib episodes detected less subjectively using a handheld electrocardiography monitor.

Although the study – called I-STOP-AFib – has limitations, its results jibe with alcohol intake’s increasingly appreciated status as a potential AFib trigger. It was alone among many possible triggers tested in showing a consistent association with self-reported AFib.

As a result, the study offers no support for such a link between the arrhythmia and caffeine intake, sleep deprivation, dehydration, exercise, or other conditions sometimes perceived as triggers, observed principal investigator Gregory M. Marcus, MD, MAS, University of California, San Francisco, when presenting results at the American Heart Association scientific sessions. He is also lead author on the study’s simultaneous publication in JAMA Cardiology.

The I-STOP-AFib trial was unusual in part for its virtual design, in which participants followed instructions and tracked AFib episodes – both perceived and detected by the handheld ECG device – through a smartphone application. It also featured an N-of-1 randomized comparisons of different weeks in which individuals were or were not exposed to their self-selected trigger.

Such patients following their own weekly personalized randomization were compared to an entirely separate randomized control arm of the trial, in which patients simply tracked any ECG-monitored and self-perceived AFib episodes.

Current use in patients

Although wearable and smartphone-based ECG recorders are increasingly popular for AFib screening, Dr. Marcus said the devices may be especially helpful for validating whether a person’s symptoms are actually caused by AFib.

“I have actually suggested to some of my patients that they run some of these experiments,” he said at a media briefing on I-STOP-AFib before his main presentation of the trial. The demonstration might help patients recognize that some perceived triggers actually do not induce AFib.

Allowing patients to determine on their own whether a substance indeed triggers their AFib “is an efficient use of these devices,” Dr. Marcus said. Such N-of-1 exploration of possible triggers “might help free patients up to enjoy substances – caffeine or coffee is one example – that they otherwise might not, and may help actually reassure them that certain exposures –like certain exercises, which can also be beneficial – might actually not be harmful.”

Dr. Marcus and the other authors on the report noted – as he did at the AHA sessions – that the study has several limitations, such as the subjectivity of self-reported AFib, dropouts from the trial that shrank the randomization arms, and a population that may not be very representative.

There is also the potential for detection bias in the group assigned to track their selected triggers, as Dr. Marcus and some observers have noted.

Dr. David Conen, cardiologist, McMaster University, Hamilton, Canada

Dr. David Conen

It follows that conscious avoidance of a potential AFib trigger might well lead to a reduction in AFib subjectively identified by symptoms, proposed David Conen, MD, MPH, Population Health Research Institute, McMaster University, Hamilton, Ont. But perhaps there would have been no reduction in AFib had it been objectively documented with the handheld ECG device, he said in an interview.

“If I were to redesign the study,” he said, “I think the primary endpoint should be confirmed atrial fibrillation, because we would have to show first that the specific trigger actually reduced objective AFib events before we then try to address the question whether reducing that trigger improves quality of life.”


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