Whenever fainting is caused by a heart problem, you need immediate medical attention.

In fact, passing out from any cause warrants prompt medical attention, since the next episode may occur while you’re driving.

But fainting due to a heart problem is especially concerning and means a visit to the doctor asap.

If you’re having blackouts or feeling faint, the first thing you should do is have your heart checked out.

What Heart Problems Can Cause Fainting?

“There are a number of cardiac causes of syncope or passing out,” says Donna P. Denier, MD, of The Cardiology Center with the Appalachian Regional Healthcare System.

“Cardiac arrhythmias are one of the more common cardiac causes of syncope. Atrial fibrillation [a rhythm disorder] is not a usual cause of syncope — unless the heart rate becomes extremely fast.

“But other arrhythmias can be, such as supraventricular tachycardia, ventricular tachycardia, heart block or severe bradycardia [abnormally slow pulse].

“This diagnosis is best made by continuous cardiac monitoring, ambulatory monitoring or electrophysiology testing. Probably, the most common cardiac cause of syncope is neuro-cardiogenic in origin.

“This is a typical fainting episode that is caused by an abnormal response to a prolonged upright position resulting in a sudden drop in arterial blood pressure, then followed by a slowing of heart rate.

“It is best diagnosed by a tilt table test which simulates the situation that typically triggers the event.”

Aortic Disease As a Cause

“Aortic stenosis, when the aortic valve becomes critically restricted, can result in syncope,” says Dr. Denier.

“Besides history and physical exam, echo can confirm this diagnosis. Echo is also helpful in diagnosing any structural heart disease such as congenital abnormality, aortic dissection, cardiomyopathy or the acute right heart strain seen in pulmonary embolism.”

Aortic dissection and pulmonary embolism are immediately life-threatening and require immediate medical attention.

They typically cause chest pain, but fainting or a faint feeling can also result.

“The majority of cases of syncope are diagnosed by history and physical exam, understanding the situational factors involved and the patient’s individual risk factors,” says Dr. Denier.

“Echo is helpful in some cases but most often does not reveal the cardiac cause of syncope.”

Fainting absolutely is NOT normal. Causes range from pregnancy, low blood sugar and lack of nourishment/dehydration (especially paired with physical exertion), to potentially fatal heart rhythm disorders.

donna denier, md

Dr. Denier has been practicing medicine for over 15 years and is board certified by the American Board of Internal Medicine – Cardiovascular Disease.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  



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