The diagnosis and management of atrial fibrillation in athletes present unique challenges. Atrial fibrillation (AF) is an irregular and often rapid heart rhythm. It happens when the upper chambers of the heart (the atria) beat out of sync with the lower chambers (the ventricles). This can cause a fast, fluttering or pounding heartbeat, and sometimes it leads to symptoms like shortness of breath, fatigue or chest pain. If left untreated, AF can increase the risk of stroke and heart ...