Not everyone will experience symptoms with their atrial fibrillation. These cases are typically discovered during a routine physical exam or EKG test. When symptoms of atrial fibrillation do occur they vary from person to person and can include feeling a racing or irregular heartbeat, pounding in the chest, weakness, shortness of breath, reduced stamina, lack of energy, a sudden increase in the need to urinate, lightheadedness/feeling faint, sweating and chest pain. Sometimes symptoms will start very suddenly, and sometimes the symptoms are more subtle — making it hard to pinpoint the exact date or time that they started. Many other conditions can create symptoms that are similar or identical to those caused by atrial fibrillation, and often it is only after seeing a healthcare professional that the specific cause of symptoms can be found.