Symptoms of atrial fibrillation, also called A-fib, can vary. The most common ones are:
Racing and/or irregular heartbeat
Shortness of breath
Dizziness, fatigue, and/or weakness
Some people also
experience chest pain, cough, and/or leg swelling (which can be caused by related heart failure), or nausea.
A-fib symptoms are usually due to the heart being less able to pump effectively, because it's beating too fast or not as powerfully. In many people, however, the atrial fibrillation doesn't immediately cause a noticeable decrease in heart function. These people may not experience any symptoms at all from atrial fibrillation, especially if the A-fib doesn't cause them to have a particularly fast heartbeat.