A large, multicenter randomized controlled trial has demonstrated that a relaxed approach to potassium supplementation after coronary artery bypass graft (CABG) surgery is non-inferior to the current standard practice of tight potassium control for the prevention of new-onset atrial fibrillation (AF). The study, presented at the ESC Congress 2024 and published in JAMA, challenges the widespread practice of maintaining high-normal serum potassium levels post-CABG, suggesting a potential for reduced healthcare costs and improved patient experience.
The TIGHT-K trial, conducted across 23 centers in the UK and Germany, enrolled 1,690 patients with no history of atrial dysrhythmias undergoing isolated CABG surgery. Participants were randomized to either a tight potassium control group (supplementation if serum levels fell below 4.5 mEq/L) or a relaxed potassium control group (supplementation only if serum levels fell below 3.6 mEq/L).
The primary endpoint, new-onset AF after cardiac surgery (AFACS) within 120 hours or until hospital discharge, occurred in 27.8% of patients in the relaxed control group and 26.2% in the tight control group. This non-significant difference confirmed the non-inferiority of the relaxed control strategy. Furthermore, the rate of AFACS detected by any means was 33% in both groups.
Cost Savings and Patient Benefits
The study also revealed significant cost savings associated with relaxed potassium control. The median number of potassium administrations was substantially lower in the relaxed control group (0) compared to the tight control group (7), resulting in a four-fold reduction in costs. According to Professor Benjamin O'Brien from the Deutsches Herzzentrum der Charité, Berlin, the lead investigator, "routinely supplementing potassium for tight control offers no benefits compared with relaxed control but is more expensive... 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."
Impact on Clinical Practice
These findings challenge the long-held belief that maintaining high-normal potassium levels is crucial for preventing AFACS. Atrial fibrillation is a common complication after CABG, affecting approximately one in three patients and is associated with increased morbidity, mortality, and healthcare costs. The TIGHT-K trial provides robust evidence that a more conservative approach to potassium supplementation is safe and effective.
Secondary Outcomes
Secondary outcomes, including non-AFACS dysrhythmias, in-hospital and 6-month mortality, and length of intensive care unit/hospital stay, showed no significant differences between the two groups. This further supports the safety and efficacy of relaxed potassium control.
The trial's design included rigorous monitoring with ambulatory heart rhythm monitors and validation of all primary outcome events by an independent, blinded committee. This strengthens the reliability of the results and their applicability to clinical practice.
The TIGHT-K trial suggests that healthcare providers can safely reduce potassium supplementation after CABG surgery, leading to cost savings and improved patient comfort, without compromising the prevention of atrial fibrillation.
