Excessive alcohol consumption is an established risk factor for atrial fibrillation. In a new study, researchers showed that regular moderate alcohol consumption results in more electrical evidence of scarring and impairments in electrical signaling compared with non-drinkers and light drinkers. 
Patients consuming two to seven drinks per week were considered mild drinkers, while those consuming eight to 21 drinks per week (average 14 drinks per week) were defined as moderate drinkers.
An average of 14 glasses per week results in more electrical evidence of scarring and impairments in electrical signaling compared with non-drinkers and light drinkers. Alcohol consumption is therefore an important modifiable risk factor for AF.
Investigators performed detailed invasive testing on the atria of 75 patients with AF, 25 in each of three categories: lifelong non-drinkers, mild drinkers, and moderate drinkers. Patients self-reported their average alcohol consumption in standard drinks per week (one standard glass is around 12 grams of alcohol) over the preceding 12 months,

(Note: Many non drinkers have had atrial fibrillation for various reasons.)