How atrial fibrillation feels varies from person to person. Some patients notice palpitations and irregular heartbeats and are immediately aware when atrial fibrillation starts. Others feel chest discomfort, shortness of breath, lightheadness, dizziness or a general tiredness, without having palpitations. In some individuals symptoms of atrial fibrillation can be present at rest, while in others they appear during exercise.
The onset of an episode of atrial fibrillation is not always clear. In some cases symptoms start abruptly while in others there is a reduction in the ability to exercise. In the latter case one may not suspect atrial fibrillation and it can take a long time before the patient seeks medical attention.
Finally, it is possible that someone with atrial fibrillation has no symptoms at all and the arrhythmia is discovered accidentally, for instance during a routine check-up or using wearables.
The reason why some people with atrial fibrillation experience symptoms, while others do not, is unclear. In many patients the symptoms are related to a faster heartbeat. However some patients have symptoms, even if the heart rate is not fast. In other cases the heart beats too slowly during atrial fibrillation which can also cause symptoms.
Atrial fibrillation episodes may disappear without treatment, nevertheless you should discuss what to do if an episode occurs with your physician. If you experience any unpleasant symptoms which make you feel really unwell (like nausea, chest pain, fainting etc.), you should seek immediate medical attention at a hospital.