What Your Racing Heart Might Mean: Symptoms of Atrial Fibrillation (A-fib)

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Worried that you or your loved one may be suffering from symptoms of atrial fibrillation? It's a reasonable concern: An estimated 3 million Americans have this common heart condition. If you have no previous diagnosis of atrial fibrillation (also known as A-fib), here's what to watch for and what to do:

Racing heartbeat

A fast resting pulse can be a sign of atrial fibrillation; doctors usually investigate resting pulses that are higher than 100 beats per minute. A heart rate that gets above 100 with mild exertion (such as walking across the room) should also be checked into.

What to do: Report a high resting heartbeat to a doctor promptly. If you have a home blood pressure cuff, be sure to report the blood pressure, along with the heart rate. Many other acute health problems, such as low red blood cell count and infection, can cause a high heart rate, so your doctor's response will depend on what other symptoms are present. Be sure to mention all symptoms.

What Your Irregular Heartbeat Might Mean

Irregular heartbeat

When the pulse is felt at the wrist or neck, beats may feel irregular, meaning that within 30 seconds or so, the time between beats is sometimes very short and other times longer. (Note: It's normal for the pulse to occasionally skip a beat or give a double beat, but most beats should be coming regularly.)

What to do: Report this irregular heartbeat to a doctor promptly. An ECG can determine if the irregular heartbeat is A-fib. If other symptoms such as shortness of breath, dizziness, or racing heartbeat are present, you should seek same-day medical care.

What Shortness of Breath Might Mean

Shortness of breath

A-fib can sometimes cause shortness of breath, especially if the A-fib causes the person to have a racing heartbeat. The shortness of breath is usually worse with exertion, such as when climbing stairs, and sometimes it's worse when the person lies flat in bed.

What to do: New shortness of breath should always be promptly reported to a doctor and usually requires same-day evaluation. Shortness of breath is a symptoms of many potentially serious illnesses, including pneumonia, COPD exacerbation, heart failure exacerbation, and coronary artery disease.

What Lightheadedness Might Mean

Light-headedness and/or fatigue

This symptom is usually a result of a racing heartbeat. The person may complain of feeling light-headed or tired, especially after walking or other physical exertion.

What to do: Check the person's pulse if you can, then report any new light-headedness or fatigue with exertion to a doctor promptly. If you have a home blood pressure cuff, it can be very helpful to report the person's blood pressure along with the pulse. Light-headedness can be caused by a variety of medical problems, so the doctor's response will depend on what other symptoms are present.

What Swelling of the Shins Might Mean

Swelling of the shins

A more unusual symptom, lower leg swelling can be caused by A-fib if the A-fib happens to provoke symptoms of heart failure in a susceptible person. In this case, the person also usually experiences some shortness of breath with exertion.

What to do: Check the person's pulse if you can, then report any new lower leg swelling to a doctor promptly.

For more on how A-fib is diagnosed, see FAQ How Is Atrial Fibrillation Diagnosed?

For more on how A-fib is managed, see Atrial Fibrillation (A-fib): Rhythm Control or Rate Control? and Atrial Fibrillation (A-fib) and Blood Thinners.

Dr. Leslie Kernisan

Leslie Kernisan is a clinical instructor in the University of California, San Francisco, Division of Geriatrics, and maintains a popular blog and podcast at BetterHealthWhileAging. See full bio

about 1 month, said...

I had taken 1 Tylenol PM about 5 minutes before going to bed last night. As soon as I layed down, my heart started racing. I called the local Emergency room and got no help (she didn't ask one question) I think it was still racing when I went to sleep but is fine this morning. I do have Prolapsed Mitral valve, and I am 87 years old, but very active.

almost 2 years, said...

i had a very short episode of AF while at work. Went to emerg and this was stabalized on IV within 10 minutes. I have been taking estrogen/testosterone for the past 6 years and my doctor wants me to decrease my daily dosage and eventually not take anymore. He took me off of testosterone and i have been decreasing the estrogen by taking every other day. Could this imbalance cause the short episode of AF?

over 3 years, said...

My dear Dr. Kernisan -- Have you ever suggested magnesium for AF? As I said in my last 2 comments on your other 'warnings' - one may not need drugs to manage it. I find it ever so difficult to hear about the darkest result of this condition. And am disappointed in our medical society who are so keen to jump into prescription drugs as the only cure. I suspect that many times, experts are paid by the pharmaceuticals to suggest, firmly, the need for drugs. At 83 I've seen too many folks get hooked on something that needs something else to take care of the side effects. And when I know folks near and dear to me who take on board the 'warnings' and who are taking up to 20 drugs a day??? What is that saying about medical care

over 3 years, said...

I have A-Fib and cannot find a doctor that cares. It appears you are a brother.

over 3 years, said...

I am now afraid to even walk to the car because of shortness of breath so how do I get exercise

over 4 years, said...

I have COPD and have had this problem along with a lot of others that were previously mentioned, but to add to the problem I might even have a case of mold poison that has been lingering for years and building up adding to the very same of this. Your article has been most enlightening and a very educating one, as to add to it my problem includes a mold problem with a dullness of thinking or say awareness being sluggish and highly fatigued, can fall asleep at any point. So another good article for you to look into. Thank you for all the great knowledge.

over 4 years, said...

It was straight and to the point. Easy to understand.

over 4 years, said...

I forgot to tell you that the tests were for an event in January where i had chest pressure and breathing issues, and due to family history.

over 4 years, said...

I'm a 42 yr old female and had a spell a few weeks ago as I was walking out the door heading to work. My heart was racing and I was dizzy. I stopped at CVS to check blood pressure 116/69 and pulse 110. It lasted from 830am to 3pm. I've had an EKG, heart cath test, brain scan, and MRI a few months ago to try and figure out why i had chest tightness and shortness of breath. Everything seems clear. And they don't know why I get random vertigo. Ive mentioned the heart racing to a few nurses and everyone seems stumped. Any thoughts?

over 4 years, said...

Tremendously helpful as I have COPD and my feet swell at times, on Lasix and really do not like taking, I thought due to hot weather, my pulmonary doctor informed me was lack of oxygen in the lower legs, I thought maybe lack of walking and shortness of breath. Thank you!

over 4 years, said...

Sometimes fast heart rates are common for me especially if I over-exercise. If I walk for too long I am prune to faster heart beats. I watch for common symptoms and stop if necessary.

over 4 years, said...

My father developed A-fib at 82 with no symptoms except what could be heard with a stethoscope. His doctor shrugged it off and my Dad had a stroke 1 month later. A $4 prescription of blood thinner could have prevented a quarter million dollars of needless healthcare spending.

almost 5 years, said...

Difficult really to say, now at the age of 82, one can expect a few signs here and there, now and again. Must admit, I do feel sort of "under the skin", something around the heart area where there is a bit of a pitter-patter which I counter by taking several consecutive deep breaths: the positive is not always "instantaneous" yet there is a sort of relief though there can remain a sort of unsettled feeling underneath and on the left side of the breast. I'm not sure that this personal response is actually covered by the various aspects presented among your various symptoms. I do feel these symptoms have quite a wide range of variation, possibly person to person, which does not make it easy to go further (diagnose). Maintaining a wise diet, consistently, can be doing no harm, keeping Cayenne Pepper intake will also do no harm. Overall am not particularly worried, but there is a level of perplexity. It might be a bit unfair to expect the doctor to automatically unravel it all for you if your description is a bit vague! But your offerings certainly provide food for thought, thank you!

over 5 years, said...

The whole article was most informative

over 5 years, said...

Believe it or not when I started my menopause, the shifting hormones all over my body gave me the oddest heart rhythms... for a time. I wouldn't be doing ANYTHING and suddenly, the old ticker would start tap dance on me...and I headed to my Doctor. They checked and found I had what is determined to be 'normal sinus rhythm" - and that the estrogen levels in various parts of my body were re configuring. I am overweight but not by more than twenty pounds, so I keep active, try not to do too much sugar and caffeine, eat healthy and pace myself. The heart rhythm is fine, now menopause has settled in with my body (it began when I was in my mid 50's - I'm now 64) And a common sense diet and attitude have made a big difference - not just in my heart health. But when in doubt - check it out. I come from a family where heart disease is common, so I took no chances!

over 5 years, said...

This can be quite a risk, but fortunately I miss out on these symptoms: Every so often I pause and spend a little while taking deep breaths, really deep, & exhale slowly, repeating this for the little while. Whatever it may do, there is that better feeling afterward. Once a day is a good time scale, might help keep out other symptoms which are not so amenable!

over 5 years, said...

In explaining symptoms of a-fib, it assisted me in determining whether I was someone who may have it or not, and in this case, I do not.

over 5 years, said...

I have atrial Fib that is controlled. So anything I can know about it is beneficial