A new study from researchers at University of Illinois at Chicago reveals that some antiarrhythmic medications used to treat atrial fibrillation (AFib) are less effective in obese patients. Based on an observational study of more than 300 patients in the UIC AFib Registry, the research team recently published the study results in JAMA Cardiology.

The Problem

AFib is the most common type of irregular heartbeat and is associated with increased mortality (e.g. death). Researchers have identified causal links between obesity and AFib however they do not yet understand in detail the underlying mechanism for how obesity contributes to the heart arrhythmia.

Current Antiarrhythmic Drug Therapy for AFib Variable & Unpredictable

Dr. Dawood Darbar of UIC, senior author of the study, declared that presently responses to antiarrhythmic Drug Therapy for AFib variable & unpredictable and medication selection depends on the treating physician. With no guidelines to suggest whether Class I drugs (affect sodium channels in the heart to regulate heartbeat); or Class II drugs (target potassium channels) work best in which patients, in the past it was assumed that both classes of antiarrhythmic drugs were equally as effective in preventing reoccurrences of AFib reported UIC in a press release.

The Study

In this study, funded by the University of Illinois at Chicago and in part by the Department of Veterans Affairs, Darbar and teams revealed that Class I drugs treatment evidenced increased rates of AFib reoccurrences in obese patients compared with nonobese patients. Their study revealed that about 30% of obese patients had AFib reoccurrence as compared with only 6% of nonobese patients. This effect was not observed among the patients treated with Class III drugs. 

The researchers replicated the study of obese and nonobese mice as well.

A First

According to Darbar this study revealed for the first time that there were differential responses to antiarrhythmic drugs for AFib. As it turns out 50% of the AFib Registry were obese and hence the Chicago-based research team were afforded an opportunity to better understand the impact of obesity and AFib drug response.

The Obesity Epidemic and Social Determinants of Health

Obviously obesity is a growing concern in American society (and beyond) and TrialSite News has declared it to be a public health crisis level impacting economy and society in ways we don’t fully understand as of yet. It absolutely contributes indirectly, via health spend, to accumulating American debt. Minority groups such as African Americans, Latinos and others may be disproportionately impacted but socio-economics plays a role.  In the study 50% of the obese patients in the study were part of an ethnic minority group. UIL noted in the press release that the prevalence of AFib is lower in ethnic minority populations the outcomes may be graver based on the findings.

Next Steps

Darbar commented that “with the obesity epidemic increasing, it leaves these populations at risk” referring about obese and minority populations on these drugs. He continued, “Having treatment options to better manage AFib would greatly improve quality of life and could prevent the risk of serious complications, like stroke, which can cause early death.”

The Chicago-based team will continue this research in the quest to uncover the underlying mechanism of how obesity hinders Class I antiarrhythmic drugs and discover new targeted AFib treatment options.

Lead Research/Investigator

Dr. Dawood Darbar, Professor of Medicine and Pharmacology, Chief, Division of Cardiology

Note that Dr. Darbar was supported in this study by a number of others who are listed in the source press release.

Call to Action: This is a growing area of importance. If you have been diagnosed as obese and are on Class I antiarrhythmic medications, then see your physician in regard to this study.

Source: EurekAlert!

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