Why does atrial fibrillation cause dizziness?

Atrial fibrillation changes the coordinated rhythm of the upper chambers of the heart. The heartbeat may feel fast, uneven or both. When the rhythm is poorly tolerated, the amount of blood moved with each beat can vary, leaving the brain briefly less well supplied and causing lightheadedness, unsteadiness or a feeling that you may faint.

Dizziness is a common presentation of Atrial Fibrillation. It can also arise from many non-heart causes, including dehydration, illness, medicines and inner-ear problems. The timing of dizziness in relation to a racing or irregular pulse is useful information for assessment.

Sit or lie down straight away if dizziness begins, particularly if you feel unsteady. Avoid driving, climbing or using machinery until the feeling has passed and you understand the cause. Take heart medicines as prescribed and do not change or stop them without medical advice.

Record when symptoms happen, how long they last, what your pulse feels like and any associated chest discomfort, breathlessness or faintness. Bring this record and a list of medicines to your appointment.

Call emergency services immediately if dizziness comes with chest pain, severe shortness of breath, fainting, new weakness or numbness on one side, facial droop, trouble speaking, severe headache, or confusion. Seek prompt medical assessment for repeated dizziness, a new irregular heartbeat, or symptoms that are becoming more intense.

Ask whether your rhythm or rate could be causing the episodes, whether your medicines could contribute, how you should check your pulse, and which warning symptoms mean you should call for emergency help.