Blackouts: is it my heart?

Most simple faints are called vasovagal syncope. You are likely to get a trio of symptoms known as the three P’s:

• Prodrome – symptoms prior to the fainting, such as feeling hot or cold and sweaty.
• Posture – you may have been standing for an extended period or changed quickly from crouching or lying to standing.
• Provoking factors – such as a medical procedure or severe pain.

You may have none of these with a cardiac cause. You may get palpitations beforehand or no warning sign, and you suddenly collapse. It may happen suddenly during exercise, even if you are young and fit.

If you have a close family member diagnosed with a heart problem before the age of 40 or sudden unexplained death before 40, this may point to an inherited heart problem. New or unexplained breathlessness needs further investigation, and you will be at risk of cardiac collapse with known heart problems such as heart failure.

You should see your doctor if you have more than one unexplained faint in close succession without an obvious cause, if you collapsed during exercise, or if you have a family history of early unexplained death or a heart arrhythmia. Your doctor will listen to your symptoms, take your vital signs and listen to your heart and lungs. They will likely order urgent investigations, depending on their findings, such as an electrocardiogram (ECG), which measures the electrical activity of your heart, and/or an echo, which assesses the structure of your heart. They may also request blood tests to rule out other causes, such as thyroid disease. They may consider referring you urgently to a cardiologist or a heart specialist.

If you have unexplained blackouts or collapses and are awaiting investigations or a specialist's opinion, you should not drive. Your specialist will advise you further once the cause has been established.