Can Low Potassium of 3.1 to 3.3 Cause Atrial Fibrillation

The body needs the mineral potassium to regulate muscle contraction. The heart, being a muscle, may respond to changes in potassium levels by developing an irregular heartbeat, or arrhythmia. Atrial fibrillation (A-fib) is a particular type of arrhythmia, and low potassium levels can contribute to its development.

Normally, potassium levels in the blood range from 3.5 to 5.2 milliequivalents per liter (mEq/L). Symptoms from low potassium, or hypokalemia, usually don't appear until levels drop to 3 mEq/L, according to StatPearls. A doctor may consider anything below this to be severe hypokalemia. However, any level below normal may cause symptoms such as A-fib in some people.

Atrial fibrillation occurs when the wiring in your heart gets its signals crossed. Electrical signals that originate in the sinus node regulate your heartbeat. The SA node acts as the heart's natural pacemaker, sending signals through the heart that cause different muscles to contract in a coordinated fashion.

This action pumps blood from the atria (the two top chambers of the heart) down to the ventricles (the lower chambers), then out to the rest of your body. If you have atrial fibrillation, the atria get signals that cause them to fire too frequently, so that they quiver rather than forcefully contract.

Hypokalemia may increase the risk of low potassium. For example, in research that involved 281 individuals with A-fib and 260 people with normal sinus rhythm, almost double the number of people with A-fib had potassium levels lower than 3.5 mEq/L than those in the control group.

Another study also found that a person’s risk of A-fib increases with potassium levels lower than 3.5 mEq/L. In the research, low potassium was more likely to be present on days when people experienced longer episodes of A-fib. Also, every drop in mEq/L below the normal value made A-fib 5 times more likely.

A potassium level between 3.1 and 3.3 mEq/L might not cause A-fib, but it can increase the risk, according to this study. Only a medical professional can determine if you have lower than normal potassium levels and whether that's causing A-fib.

Low potassium levels can disrupt how cells in the heart hold and fire electrical charges, which may cause them to fire in an abnormal pattern, causing A-fib. This means that hypokalemia may affect the heart’s ability to reset its electrical charge after each beat.

According to the British Heart Foundation, up to 30 percent of people with A-fib don’t show symptoms. The condition may only show up if they have an electrocardiogram.

However, for many people, symptoms of A-fib may include the following:

• A rapid, fluttering, or pounding heartbeat
• Chest pain
• Fatigue
• Dizziness
• Lightheadedness
• Not being as able to exercise as you had before
• Breathlessness
• Feeling weak

Because the heart doesn't beat forcefully, blood can pool in the atria, increasing the risk of developing blood clots in the chambers, according to the American Heart Association. As the heart beats, these clots may be forced through the heart into the circulation. If they lodge in the arteries to the brain, a stroke can result.

If you have atrial fibrillation from a potassium level in the 3.1 to 3.3 mEq/L range, increasing your potassium level should treat the problem. You can take potassium in pill form or receive it intravenously. Guidelines recommend IV infusion for more severe hypokalemia to restore potassium levels more rapidly.

Generally, symptoms will resolve once you restore potassium levels through treatment.

Avoid taking potassium tablets without your doctor's approval, as diagnosing and treating the underlying cause of low potassium is as important as correcting the imbalance.

Other medications you take, such as insulin or diuretics, and health problems, including chronic kidney disease and adrenal disorders like Cushing’s syndrome, can cause hypokalemia, according to Cleveland Clinic. A doctor may need to alter existing medications or manage these underlying conditions to restore potassium levels.