Alcohol and the Electric Atrium: How Drinking Promotes AF?

January 18, 2019

Regular alcohol intake at moderate levels was associated with electrical and structural changes in atrial myocardium in patients who underwent electrophysiologic mapping studies prior to catheter ablation for atrial fibrillation (AF) in a small cross-sectional study.

Moderate alcohol consumption, defined as eight to 21 drinks per week, was an independent predictor of the atrial remodeling, characterized by significantly reduced atrial voltage and conduction velocities and increased atrial dimensions, reported a group January 9 in Heart Rhythm.

The same was not found for mild alcohol intake levels, defined as two to seven drinks per week.

The findings suggest that moderate alcohol intake has "direct effects on atrial substrate" that are consistent with myocardial fibrosis, although the association can't prove it causes AF, observed senior author Peter M. Kistler, MBBS, PhD, Alfred Hospital, Melbourne, Australia.

However, "this study adds to the growing evidence base that excessive alcohol consumption is implicated in AF pathogenesis and as such is a potentially modifiable risk factor," Kistler told theheart.org | Medscape Cardiology by email.

The study enrolled 75 otherwise mostly healthy patients with paroxysmal or persistent AF who were scheduled for catheter ablation at two hospitals from 2016 to 2018.

They included 25 self-reported lifelong nondrinkers, 25 who reported consuming two to seevn drinks per week (mean, 4.5), and 25 reporting intake of eight to 21 drinks per week (mean, 14.1) in the most recent 12 months. As defined, one drink contained 12 g of alcohol.

Excluded were patients with permanent AF or significant structural heart disease, and those meeting the study definition of occasional drinker or binge drinker.

Mean left atrial size was larger in moderate drinkers than in nondrinkers (28.0 vs 22.7 cm²; P = .008).

Before ablation, off antiarrhythmic drugs, and in sinus rhythm (after external cardioversion, if necessary), the patients underwent high-density left-atrial mapping studies using the CARTO (Biosense Webster) three-dimensional electroanatomic mapping system.

Moderate drinkers, compared with nondrinkers, had significantly lower mean global bipolar voltages, slower conduction velocities (CV), and a higher proportion of complex atrial potentials

Results of CARTO Electroanatomic Mapping Studies by Alcohol Intake Level
Parameter Moderate Drinkers Nondrinkers P Value
Global bipolar voltages (mV) 1.53 1.89 .02
Conduction velocities (cm/s) 33.5 41.7 .04
Proportion of complex atrial potentials (%) 7.8 4.5 .004

Mild drinkers, compared with nondrinkers, showed a larger proportion of complex atrial potentials, a difference that reached marginal significance (6.6% vs 4.5%; P = .047), but no corresponding significant difference in mean global voltage or CV.

AF was seen to recur in 37% of patients at 12-lead electrocardiography and Holter monitoring, performed at prespecified intervals or on development of symptoms, during the postablation follow-up, which averaged 18.7 months.

The 37% included nine moderate drinkers, 11 mild drinkers, and eight nondrinkers, for rates of 40% for moderate and mild drinkers and 32% for nondrinkers (P = .62), Kistler told theheart.org | Medscape Cardiology. Those numbers are not in the report; Kistler said the study is underpowered to detect differences in AF recurrence rate.

However, significant independent substrate-related predictors of recurrent AF included reduced mean global voltage, greater proportion of low-voltage electrograms, and greater prevalence of complex potentials.

"Our study was primarily focused on alcohol's effects on the atrium's electrophysiological properties, but numerous recently published studies have identified excessive alcohol consumption as a significant predictor of postablation recurrence," Kistler said. "This emphasizes the importance of lifestyle modification in improving AF outcomes postablation."

Kistler and the other coauthors had no relevant disclosures.

Heart Rhythm. Published online January 9, 2019. Abstract

Follow Steve Stiles on Twitter: @SteveStiles2. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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