Many people also feel faint or light-headed. When blood is not passed through the heart as effectively as it should be, other symptoms may occur. People may feel short of breath, especially when lying down flat, their ankles may become swollen, and they feel unusually tired for a great deal of the time. Those people who have suffered any damage to their heart, from a heart attack for example, or damage to the heart valves, are more likely to be affected by atrial fibrillation. Having diabetes, or an overactive thyroid gland producing too much thyroid hormone may also cause it as may having un-treated high blood pressure.
Excess alcohol is commonly responsible too.
Often, however, no precise cause of atrial fibrillation is determined. Blood tests are used to exclude causes such as an over-active thyroid gland. Other tests such as a chest x-ray and an echocardiogram are also usually performed to help establish the cause of the atrial fibrillation. Having atrial fibrillation also increases the risk of someone suffering a stroke. Atrial fibrillation may be a result of other heart problems such as coronary artery disease, which may in itself need treatment.