Relaxed control of potassium levels and only giving supplements in the rare event that levels became pathologically low was just as effective in preventing atrial fibrillation (AFib) after cardiac surgery as tightly controlling levels, according to findings from the TIGHT-K study presented at ESC Congress 2024 in London and simultaneously published in JAMA.

Researchers randomized 1,690 patients from the UK and Germany with no history of atrial dysrhythmias and who were scheduled for isolated CABG to either tight control of potassium levels or relaxed control where supplements were only given when serum potassium concentration fell below 4.5 mEq/L or 3.6 mEq/L, respectively. All patients wore any ambulatory heart rhythm monitor.

The primary endpoint of clinically detected and electrocardiographically confirmed new-onset AFib in the first 120 hours after CABG surgery or until hospital discharge (whichever occurred first), occurred in 26.2% of patients (n=219) in the tight control group and 27.8% of patients (n=231) in the relaxed control group. Researchers also observed no differences between the groups in the incidence of at least one AFib after cardiac surgery episode, inpatient mortality, or length of stay. Additionally, researchers noted per-patient costs for purchasing and administering potassium were significantly lower in the relaxed control group.

"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, PhD, the study's lead author. "Unnecessary intervention can carry risks, such as drug errors, and can negatively impact the patient experience … So, the results from TIGHT-K 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."