READ ME: this page has two parts. Part One is about afib generally. Part Two below is about afib related to a thyroid problem.

PART ONE: info about afib generally

Atrial fibrillation (AFib) is an irregular heartbeat. Often, it means the heart starts beating very rapidly, called tachycardia. Or it can beat too slowly, called bradycardia. Patients often report noticing the faster beat, but not always. i.e. it’s irregular. And it can come and go.

You’ll also hear AFib termed as an arrhythmia. You can see the word “rhythm” within the latter word, and as the whole word, it means the rhythm of the heart is not normal. For example, the two upper chambers of the heart can beat out of coordination with the two lower chambers of the heart. Some call it a faulty “electrical system” in the heart.

And AFib is the most common type of arrhythmia, means millions can have this.

Is AFib dangerous?

Mayo explains that though it usually isn’t life threatening, it has the risk of leading to other complications.1 For one, it could cause blood clots to form in the heart, which in turn can move to other parts of the body, increasing the risk of stroke. It can cause heart failure and other heart-related complications.2 And the irregular heart rate may result in being unable to pump enough blood to the body, which means less oxygen being carried around.

Are there symptoms? How do people figure out they have it?

Sometimes, one may not even know they have it. Other times, people with AFib report noticing that fast heart rate, or the slow heart rate. Some might notice a fluttering feeling in their chest. Then there are reports of having chest pain (a serious symptom that should mean getting this checked out immediately), dizziness or fainting, or shortness of breath–the latter related to the heart pumping ineffectively. Some note overall fatigue.3

Patients also report it was made more obvious via their doctors by doing tests like wearing a halter monitor or doing an EKG.

Outside of a thyroid cause, who gets AFib?

Probably those of great risk are related to the aging of their bodies…then come those who have any kind of heart issue. But it’s not limited to aging. Says cardiologist John Mandrola MD, AFib “increases with age, degree of inflammation and general wear-and-tear, but it can also afflict the athletic and nimble.”4

The Heart Rhythm Society5 lists the following as putting anyone at a higher risk of having AFib:

  • Older than 60 years of age
  • Diabetes
  • High Blood Pressure
  • Coronary artery disease
  • Prior heart attacks
  • Congestive heart failure
  • Structural heart disease (valve problems or congenital defects)
  • Prior open-heart surgery
  • Untreated atrial flutter (another type of abnormal heart rhythm)
  • Thyroid disease
  • Chronic lung disease
  • Sleep apnea
  • Excessive alcohol or stimulant use
  • Serious illness or infection

Other websites also include the risks of

  • being overweight
  • high cholesterol, which also goes with being hypothyroid

How is AFib treated for those whose cause is not related to a thyroid problem?

There are a variety of treatments being done. Most common are strategies to lower the risk factors, ranging from lowering high cholesterol and/or high blood pressure, eating in a healthier way (such as cutting down on sugar/carb consumption), ceasing to smoke, limiting alcohol and stimulants, and practicing stress reduction.

Other treatments include lowering the risk of blood clots with certain medications.

More serious treatments include:

a) electrical cardioversion, which is using paddles or patches to reset the heart’s rhythm
b) drug cardioversion, which is using anti-arrhythmic medications. WebMD lists the latter medications as Amiodarone (Cordarone), Flecainide (Tambocor), Procainamind (Procanbid) or Sotalol (Betapace), as well as either Beta Blockers like (metoprolol or Toprol XL) or Calcium channel blockers (verapamil or Calan).6 You can read more in the footnote link.
c) catheter ablation, a procedure that destroy the areas of the heart that are out of sync.

NOTE: the anti-arrhymic drug Amiodarone is known to cause a raise in reverse T3, and is considered a very toxic drug. Also see Causes of Hypothyroidism.

PART TWO: info about afib related to thyroid issues

Even if your doctor says you don’t have a thyroid problem, you may! And that thyroid problem might be contributing to the AFib in some!

First, it’s important to understand that the worst test to diagnose hypothyroidism is the TSH. The TSH, which represents a pituitary messenger hormone meant to signal the thyroid, can be “normal” for years while we are actually hypothyroid….long before it rises high enough to reveal it. Additionally, going by the T4 test is simply not enough, because it’s “where” it falls in the so-called normal range that counts, not the fact that it falls in the range. Doctors overall do NOT get this.

So, before you assume you do NOT have a thyroid problem causing your AFib, do the following:

1) Get the right tests, which are free T3 and free T4 (if you don’t see the “free”, or see “Total”, it’s the wrong test), plus RT3 (i.e. if you don’t see the free, you have the wrong test).
2) Compare those lab results to this page to see if your doctor’s pronouncement is really correct. So many times, say patients, their doctor is wrong.
3) Check out this list of patient-reported hypothyroid symptoms and see how many might apply to you.

Why might being hypothyroid, underdosed on thyroid meds, or being on a poor treatment with Synthroid or levothyroxine (thus continued hypo for all too many), increase the risk of AFib?

Being hypothyroid…

  1. …can raise cholesterol in some, sooner or later, report many hypothyroid patients who are either undiagnosed, or on Synthroid or levo. And there is some evidence that high cholesterol increases the risk of AFib for some.7
  2. …can raise blood pressure too high in some, sooner or later, report many hypothyroid patients who are either undiagnosed, or on Synthroid or levo. And prolonged high blood pressure has been associated as a risk for AFib.8
  3. …can cause excessive weight gain in some, report many hypothyroid patients who are either undiagnosed, or on Synthroid or levo. And there is an association between excessive weight/obesity and Afib.9
  4. …can cause heart problems in some, as reported by some patients. And this can lead to a diagnosis of AFib for some along with other heart issues.10 See this page about T3 and your heart.
  5. …can get worse as we age or show up for the first time, and may be one reason why there is more Afib for those getting older (besides genetic reasons).
  6. …can cause sleep apnea in some, a risk factor for AFib11 Additionally, being undiagnosed or poorly treated hypothyroid can cause low cortisol, which in turn can give a diagnosis of sleep apnea.

P.S. Hyperthyroidism, asa Graves disease, is also a risk factor for AFib if not treated.

Can our adrenals contribute to AFib?

It appears so. When we have a cortisol problem, whether low cortisol, high cortisol, or mixed high and low, we have problems raising a medication like Natural Desiccated Thyroid or T3. Raising causes heart issues, anxiety, excess adrenaline and more. And having a cortisol problem also keeps us hypothyroid!

Click here to order a cortisol saliva test to see what’s going on with your adrenals. It’s never about blood testing, which doctors don’t understand.


Yes, there can be other causes for AFib as explained above that might have nothing to do with hypothyroidism! Hopefully you are working with a doctor. But since there appears to be strong connections to hypothyroidism, too, as well as having an adrenal problem in some, it might be worth one’s time to see if these are the cause.

(Important note: STTM is an information-only site based on what many patients have reported or learned in their treatment. Please work with your doctor. This is not meant to replace that relationship or guidance, and you agree to that by reading this website. See the Disclaimer.)



Here’s an interesting article making a supposition that having low aldosterone, another steroid in the adrenals (and low cortisol) may be a risk factor for AFib:



Important note: STTM is an information-only site based on what many patients worldwide have reported in their treatment and wisdom over the years. This is not to be taken as personal medical advice, nor to replace a relationship with your doctor. By reading this information-only website, you take full responsibility for what you choose to do with this website's information or outcomes. See the Disclaimer and Terms of Use.