- A new study has shown that a lower threshold for potassium supplementation after cardiac surgery saves patient costs and does not create any further risks of atrial fibrillation or other dysrhythmias.
- Atrial fibrillation is the most common clinical arrhythmia worldwide, and nearly one-third of people who undergo cardiac surgery experience it.
- Potassium, along with other electrolytes, plays an important role in cardiac health.
It’s common practice for patients to receive intravenous potassium supplementation after any form of heart surgery if their potassium levels drop below 4.5 mEq/L (Milliequivalents per liter). However, a new study, published in JAMA Network, suggests that potassium supplementation only at levels below 3.6 mEq/L is non-inferior to standard practice as a way to lower the risk of atrial fibrillation (AFib) after surgery.
Nearly one-third of people who undergo the estimated 1.5 million cardiac surgeries a year worldwide experience atrial fibrillation, which is the most common clinical arrhythmia worldwide. Estimates suggest that it affects up to 3% of the Western population ages 20 years or older.
The risk of AFib increases with age, but it can sometimes occur among young people. People with AFib may have a much faster heart rate than usual, and the heart does not pump blood around the body efficiently. Blood may collect or pool in the heart, increasing the likelihood of clots.
There are four chambers in the heart — two atria and two ventricles — and atrial fibrillation occurs when those chambers don’t function properly due to abnormal electrical activity, which causes the atria and ventricles to contract at different speeds.
Advanced age, high blood pressure, hyperthyroidism, diabetes, binge drinking, and a history of underlying heart disease are all factors that can contribute to the development of atrial fibrillation. However, it is the most frequent postoperative adverse event, and according to the authors of the new study, it can lead to expensive hospital bills, longer hospital stays, and a higher risk of death.
Researchers conducted a randomized clinical trial at 23 cardiac surgical centers in the United Kingdom and Germany between October 2020 and November 2023, utilizing 1,690 patients with no history of atrial dysrhythmias who were scheduled for isolated coronary artery bypass grafting surgery.
Of those, 843 were in the group with the “relaxed” standard for supplementation. The lowered threshold for potassium supplementation did not result in any further adverse developments or increased heart dysrhythmias, and the cost savings per patient in the “relaxed” group had a mean difference of $111.89.
Paul Drury, MD, board certified cardiologist and associate medical director of electrophysiology at MemorialCare Saddleback Medical Center in Laguna Hills, CA, who was not involved in the study, told Medical News Today that potassium plays an extremely important role as an electrolyte for cardiovascular health.
“Potassium travels in and out of cardiac cells every time the heart beats. When potassium levels are very low, people are at much higher risk of arrhythmias including life-threatening ventricular fibrillation and even AFib. Severely elevated potassium levels are also unsafe and can lead to very slow heart rates and a condition called heart block. Severely elevated potassium levels can be fatal,” Drury said.
Maintaining a potassium level between 3.6 mEq/L and 5.5 mEq/L is optimum for cardiovascular health in general, he added.
“Allowing potassium levels to get too low, which is normally due to medications, can increase the risk of AFib or increase the burden of AFib. There is a risk of taking too much potassium which can lead to serious heart conditions or even death.”
— Paul Drury, MD
Dr. Shephal Doshi, MD, board certified cardiac electrophysiologist and director of cardiac electrophysiology and pacing at Providence Saint John’s Health Center in Santa Monica, CA, who also was not involved in the study, told Medical News Today that the potassium-level range considered “normal” for most people is quite broad.
“Potassium (along with other electrolytes such as calcium and sodium and magnesium) are involved in the electrical functions of cardiac cells and the ‘normal range’ between 3.5 and 4.5 mEq/L is the concentration in the blood plasma thought to generally reflect a stable environment within the cardiac cells,” Doshi said.
“This is a somewhat broad range and, on either extremes, can lead to electrical instability, especially on the low end. This instability on the low end is thought to lower the resistance of the cardiac atrial cell in developing fibrillation,” he added.
Changes in the electrical signals in the heart cause AFib. It can happen to anyone at any age, but it is more common among older people.
Other AFib risk factors include:
- Hypertension: Long-term high blood pressure can place strain on the heart.
- Pulmonary embolism: This is the medical term for a blood clot in the artery that delivers blood to the lung.
- Heart disease: People with underlying heart conditions have a higher risk of AFib. These conditions include heart valve disease, heart failure, coronary artery disease, and heart attack.
- Alcohol consumption: Although regularly consuming large amounts of alcohol puts people at the highest risk, even modest amounts can be a trigger for some individuals. Other toxic drugs, such as methamphetamine, can also cause AFib.
- Family members with AFib: People with a family history of AFib may be more likely to experience the condition themselves.
- Sleep apnea: This can increase a person’s risk of AFib, particularly when it is severe.
- Other chronic conditions: Some long-term medical conditions — including thyroid problems, asthma, diabetes, and obesity — may add to the risk.
Doshi added that anyone who has already had AFib is at the highest risk.
“Other risk factors such as a history of congestive heart failure and a weak heart muscle (cardiomyopathy) have been shown to place people at higher risk. Generally speaking, the cardiology field also tries to keep the electrolytes, especially potassium, in the ‘high-normal’ range as low levels have been traditionally thought to increase the risk of AFib,” he said.
