What is the true cause of afib?

Numerous: There are a number of things that can lead to the electrical short in the upper chambers of your heart that leads to a. Fib. Too many to list here, but this is a nice link summing it up: http://www.Mayoclinic.Com/health/atrial-fibrillation/ds00291/dsection=causes.

Abnormal rhythm: Af is the most common heart rhythm disorder. There are numerous causes- including hyperthyroidism, heart valve disease, alcholol, hypertension, and others. Many times a specific cause is not found but is due to the body itself.

Scar formation: There are several risk factors that contribute to atrial fibrillation (left atrial size, hypertension, obstructive sleep apnea, aging, etc) however, all of these risk factors influence the way atrial cardiac cells interact. They do this by increasing collagen deposition (scarring). Scar formation leads to electrical, structural and contractile changes in the cells which leads to afib.