Why does atrial fibrillation cause shortness of breath?

In atrial fibrillation, the upper chambers of the heart quiver instead of squeezing in a coordinated way. The lower chambers can then fill less effectively and may beat rapidly. Less efficient pumping can leave you aware of breathlessness during activity, while lying flat, or at rest when symptoms are more marked.

Shortness of Breath is a common presentation of Atrial Fibrillation. Breathlessness can also have other heart, lung, blood, or anxiety-related causes, so the symptom needs assessment in its own right.

Sit upright, pause activity, and note when the breathlessness started, whether it comes with palpitations, and what you were doing. Arrange medical review promptly if this is new, worsening, or interfering with usual activities. Take heart medicines exactly as prescribed and do not alter a dose without advice.

A clinician may check your pulse, heart rhythm, oxygen level, and signs of fluid retention, then decide whether changes to rhythm or rate treatment are needed.

Call emergency services now for severe or suddenly worsening breathlessness, chest pressure or pain, fainting, blue or grey lips, confusion, or new weakness, facial droop, or trouble speaking. Seek same-day medical advice for breathlessness with a persistently racing or irregular pulse, new ankle swelling, or inability to lie flat comfortably.

Ask what may be triggering your episodes, how to monitor your pulse and symptoms, whether your current medicines could contribute to breathlessness, and which changes should prompt urgent review. Bring a record of episode timing, activity, and associated symptoms.