There have been several anecdotal examples of atrial fibrillation associated with chronic pain. The REGARDS study followed 30,239 patients over 4 years. The prevalence of AF was higher in opioid users than nonusers (12.5% vs 7.6%). The postulated mechanism is : Endogenous opioid peptides open mitochondrial potassium ATP channels, making mitochondria resistant to oxidative stress….