How Dangerous Is Fainting?

The Short Answer from a cardiologist

Q: I’ve passed out a few times; should I be concerned?

A: Occasional fainting is usually harmless. But if you are older and have certain risk factors, recurrent fainting could signal a dangerous problem with your heart.

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People over age 60 are more likely to faint for heart-related reasons than those who are younger. For example, it’s not unusual to take too much blood pressure medicine, which makes your pressure drop too low. Once the dose is adjusted, you should stop passing out.

Of much greater concern is fainting caused by episodes of a slow or fast rate. The most dangerous is a heart rhythm disturbance called ventricular tachycardia, or ventricular fibrillation (VFib).

In VFib, your heart fibrillates (races away in a disorganized way). After four to five seconds, you lose consciousness, stop breathing and have no pulse. When this happens, it’s called sudden cardiac arrest.

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It’s possible to lose consciousness only temporarily and then wake up. When this happens, you think you’ve simply fainted. But with VFib or sudden cardiac arrest, you won’t wake up — and unless someone restores normal heart rhythm with an automated external defibrillator (AED), you’ll die within 10 minutes.

Sudden cardiac arrest is fatal 95% of the time. It’s the most common single cause of death in our country. So it’s vital to know whether you have any of these risk factors for it:

If you do have any of these risk factors, tell your cardiologist promptly about these fainting spells. He will test your heart’s electrical system with an electrocardiogram in the office.

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If you are found to be at risk of VFib, or of having a sudden cardiac arrest episode, an implantable cardioverter-defibrillator (ICD) can save your life. Whenever an episode occurs, the ICD will automatically restore normal heart rhythm — within seconds.

—Heart rhythm disorder specialist Bruce Wilkoff, MD

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