Atrial fibrillation, or AFib, is a fast and irregular heart rhythm that, left untreated, can lead to blood clots, stroke and heart failure. It's the most common type of arrhythmia, a potentially ...

There are three common heart rhythm disorders that cause an irregularly irregular rhythm: Atrial fibrillation Atrial flutter with variable conduction Multifocal atrial tachycardia (MAT).