AFib Photo (IMAGE) Intermountain Medical Center Caption Researchers have identified a microRNA biomarker that demonstrates a strong association with the incidence of atrial fibrillation, the most common abnormal heart rhythm. Credit Intermountain Medical Center Heart Institute Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.