Dr Simon Kennon MB ChB, FRCP, MD Consultant Cardiologist


Blackouts (also called fainting or syncope), are due to temporary loss of consciousness. These are often simple faints but can be due to problems with the heart (causing a reduced blood supply to the brain) or due to a problem with the brain itself.

Common heart problems

causing blackouts include heart rhythm disturbance (either slow or fast heart rhythms) and heart valve malfunction (eg aortic stenosis).


often required after a blackout are: ECG, echocardiogram (ultrasound scan of the heart) and 24 hour heart rhythm monitoring (achieved by wearing a small monitor for a day).

If your GP thinks the blackouts are due to a problem with the brain, you will be referred to a neurologist. Sometimes it is unclear what the likely cause is and you may be referred to both a neurologist and cardiologist.