AFib Risk: Potassium Less Necessary After Heart Surgery Than Previously Thought

• Researchers say the standard practice of potassium supplementation after coronary artery bypass grafting surgery could be more relaxed.
• A new study suggests potassium supplementation after cardiac surgery is only needed if a patient has low potassium levels.
• This lower threshold could help decrease the risk of side effects and reduce healthcare costs.

Potassium supplementation is not needed as often as previously thought to prevent atrial fibrillation (AFib) after certain types of heart surgery.

That’s the conclusion from researchers in a new study presented this weekend at the ESC 2024 , the European Society of Cardiology annual conference held this year in London. The findings were published in JAMA on August 31.

According to the study authors, the current standard practice of administering potassium supplements to most patients in the first five days after coronary artery bypass grafting (CABG) “can be abandoned.”

They say using potassium supplementation in a smaller percentage of postsurgery patients can reduce healthcare costs and decrease the risk of side effects.

“We were able to show that routinely supplementing potassium for tight control offers no benefits compared with relaxed control but is more expensive,” said Benjamin O’Brien, MD , a chief investigator for the study and the director of the Clinic for Cardioanaesthesiology and Intensive Care Medicine at Berlin Health Excellence in Germany, in a statement .

“Unnecessary intervention can carry risks, such as drug errors, and can negatively impact the patient experience, for example, the unpleasant taste of oral potassium supplements. So, the results from TIGHT-K [study] are good news. We can safely stop the widespread practice of maintaining high-normal potassium levels after isolated CABG, improve the patient experience and also save money,” O’Brien continued.

Potassium after heart surgery

The researchers of the current study noted that roughly 1.5 million cardiac surgical procedures are performed worldwide every year. Of those, CABG, also known as heart bypass surgery , is the most common.

They explained that AFib after cardiac surgery (AFACS) is the most frequent postoperative adverse event. It affects about 30% of people after a CABG procedure.

About 90% of people who develop AFACS do so in the first five days after surgery. AFACS is associated with higher morbidity rates as well as longer hospital stays and higher healthcare costs.

The researchers said serum potassium concentrations in the blood can influence the risk of developing AFib. They noted that the current practice is administering potassium supplements if a postoperative patient’s serum potassium concentration level falls below 4.5 mEQ/L.

The researchers wanted to determine if delivering potassium supplements only after a person’s serum potassium concentration level dropped below 3.6 mEQ/L would make a difference.

Effects of ‘relaxed’ potassium supplementation

The researchers examined 1,690 individuals with an average age of 65 from 23 cardiac surgery units in the United Kingdom and Germany. About 85% of the subjects were male.

The study period lasted from October 2020 to November 2023. The participants were monitored for 120 hours after CABG surgery.

About half of the study subjects, known as the “tight group,” were to be given potassium supplements after their serum levels fell below 4.5 mEQ/L.

The others were to be given potassium supplements after their serum levels dropped below 3.6 mEQ/L. They were classified as the “relaxed group.”

The researchers reported there was no significant difference in the rate of AFACS development between the tight group and the relaxed group.

They concluded the lower threshold for potassium supplementation was non-inferior to the higher threshold. They noted that most patients in the relaxed group did not require any supplementation.

How potassium levels affect heart health

According to experts, potassium levels in the blood are important for heart health , but too much potassium may come with certain risks.

“Potassium is a very important electrolyte for cardiac health. Potassium travels in and out of cardiac cells every time the heart beats,” explained Paul Drury, MD , a cardiologist and associate medical director of electrophysiology at MemorialCare Saddleback Medical Center in California. Drury was not involved in the study.

“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 continued.

Cardiologist Jayne Morgan, MD , executive director of Health and Community Education at the Piedmont Healthcare Corporation in Atlanta, GA, and vice president of medical affairs at Hello Heart, explained why potassium supplements are administered after heart surgery. Morgan was not involved in the study.

“Since potassium is essential for the normal electrical activity of the heart, maintaining levels has been a component of reducing post-op complications of arrhythmias, as the heart is particularly vulnerable and susceptible during this time period,” Morgan told Healthline.

“Further, patients may lose potassium during cardiac surgery or be receiving diuretics post-op that could lower potassium stores.”

Experts said they agreed with the study’s conclusions, although there were some qualifications.

“While this study is provocative, there are certain limitations, and widespread adoption should be used with caution,” Shephal Doshi, MD , a cardiac electrophysiologist and director of cardiac electrophysiology and pacing at Providence Saint John’s Health Center in Santa Monica, CA, told Healthline. Doshi was not involved in the study.

“First, this study only included patients who had no prior history of AFib and therefore should not be applied to those who have a prior history where potassium supplementation may be beneficial. For those who have no prior history of AFib, there appears to be no significant benefit of potassium supplementation in the ‘low normal’ range and intravenous use can certainly increase the cost per case,” Doshi continued.

“However, this could probably be reduced with greater use of oral supplementation. There appears to be minimal risk, however, and no reported adverse events with the strategy of supplementation. Overall, this study is important and shows us how some standards about potassium supplementation in this population of cardiac surgery patients my make the clinicians ‘feel better’ but not have a significant benefit for the patient,” Doshi concluded.

Morgan had some concerns of her own: “Health economics are a serious consideration in medical care and health of a population,” she said.

“However, there are several questions left unanswered in this study, including whether patients could be going in and out of atrial fibrillation, but never trigger an endpoint of the primary outcome definition because such episodes either lasted less than 30 seconds or were not ‘present throughout an entire 12-lead electrocardiogram recording’. Moreover, the route of administration for potassium was not standardized across all study sites,” Morgan noted.

“Nevertheless, this does provide food for thought. Further tightly controlled, standardized RCT trials need
to be done to answer this question,” she added.

Drury said he found the study results convincing. “I agree with the conclusion of the study,” he said. “It appears that maintaining normal potassium levels (> 3.6 mEQ/L) is all that is needed and that there is no benefit for trying to maintain that higher level at 4.5 mEQ/L,” Drury noted.

Takeaway

Potassium supplementation is given to most people after heart bypass surgery as a way to reduce the risk of atrial fibrillation (AFib). However, new research suggests that potassium supplements may not needed as often.

The study authors say potassium supplementation should only be used when postsurgery patients reach low potassium levels .