A cardiologist has issued a cautionary note about an underlying heart condition that could manifest unexpectedly. Fainting from shock, often depicted in films and TV as a response to emotional distress, is known as vasovagal syncope.
This type of fainting is common, harmless, and typically not indicative of a serious underlying issue. However, there’s another form of fainting that raises alarm among health professionals.
Cardiac syncope refers to losing consciousness due to an underlying heart disease, such as a heart rhythm disorder, explains Elijah Behr, M.D., a cardiologist at Mayo Clinic Healthcare in London.

What it means when you faint
Fainting, or syncope, is a temporary loss of consciousness caused by inadequate blood flow to the brain.
Dr Behr said: “In some people, if they have a drop in blood pressure from emotional distress, pain, illness or dehydration, for example, or just generally have a low blood pressure, any provocation causes a reflex in the heart.
“Rather than the heart speeding up and pumping more forcefully to maintain the blood pressure, it starts to slow down. The blood pressure drops, the heart rate slows further, and the heart can pause for many seconds; sometimes close to a minute for some people who have more severe fainting episodes.”
Typically, when someone experiences this kind of fainting spell, they collapse, which allows blood pressure to normalise and consciousness to return.
Dr Behr has warned that fainting can be perilous if it occurs in a risky location or position, posing danger not just to the individual but potentially to others as well.

A warning sign of a heart condition
Medical professionals consider cardiac syncope a serious type of fainting given that it is caused by underlying heart conditions such as heart rhythm abnormality (arrhythmia).
“This is usually a more abrupt loss and return of consciousness than in simple fainting,” Dr Behr explained.
“If you’re older, you’re more likely to have underlying heart disease that you may or may not be aware of. That’s one of the reasons to be more concerned about loss of consciousness in older individuals.
“Young people can also have heart diseases that can cause cardiac syncope that may be a warning sign of something more serious to come, so it is important to investigate it.”
Dr Behr further noted that blackouts could signal severe heart issues in certain groups, including those with a family history of inherited heart conditions, unexplained deaths, or premature sudden deaths; individuals who faint during physical activity; and those whose fainting episodes are accompanied by palpitations or sensations of a rapidly beating heart.
What to do if you or someone else faints
- Check that the person is breathing and has a pulse. If not, call for emergency help, and if you know how to provide cardiopulmonary resuscitation, initiate it.
- If the person is still breathing and has a pulse, ensure they are lying flat, and their airway is open using the recovery position and call for help.
- If you feel like a faint may be coming on, position your head lower than your heart: for example, between the knees.
- Rest after coming out of the faint.
- Drink water after the faint, adding electrolytes if you have them.