Atrial fibrillation, also known as AFib, is the most common type of irregular heartbeat, and it is associated with increased mortality.
Previous research has identified a causal link between obesity and AFib, but the underlying mechanism of how obesity contributes to heart arrhythmia is still unknown.
In a new study, researchers found that some antiarrhythmic medications used to treat AFib are less effective in patients who are obese.
The research was done by a team at the University of Illinois at Chicago.
According to the team, response to current antiarrhythmic drug treatment for AFib is highly variable and unpredictable, and medication selection depends on the treating physician.
There are no guidelines to suggest whether Class I drugs — which work on sodium channels in the heart to regulate heartbeat — or Class III drugs –those that target potassium channels — work best in which patients.
Previously, it was assumed that both antiarrhythmic drugs were equally effective in preventing reoccurrences of AFib.
In the study, the team followed more than 300 patients in the UIC AFib Registry.
They found that Class I drug treatment showed increased rates of AFib reoccurrences in obese patients compared with non-obese patients — approximately 30% of obese patients had AFib reoccurrence, compared with only 6% of nonobese patients.
This effect was not seen among patients treated with Class III drugs.
Similar results were replicated in a study of obese and non-obese mice.
This is the first time anyone has shown that there is a differential response to antiarrhythmic drugs for AFib.
As 50% of the patients in the AFib Registry are obese, this provided researchers with a unique opportunity to determine whether obesity affected response to drug treatment for AFib.
The study provides new information that physicians can use to guide their decisions for obese patients with AFib.
One author of the study is UIC’s Dr. Dawood Darbar.
The study is published in JAMA Cardiology.
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