Dr. Murat Yiğitbaşı

Name of the Study: Potassium Supplementation and Prevention of Atrial Fibrillation After Cardiac Surgery (TIGHT-K)

Published in Congress: ESC Congress 2024

Link: Full Text

https://jamanetwork.com/journals/jama/fullarticle/2823246

Background

Potassium supplementation to maintain high-normal serum concentrations is a common strategy for preventing atrial fibrillation following cardiac surgery (AFACS). However, this approach lacks a solid evidence base, carries potential risks, and incurs significant costs.

Objective

This study aimed to evaluate whether a lower threshold for serum potassium supplementation is noninferior to a high-normal threshold in preventing AFACS.

Methods

This open-label, noninferiority, randomized clinical trial was conducted across 23 cardiac surgical centers in the United Kingdom and Germany. Patients with no prior history of atrial dysrhythmias, scheduled for isolated coronary artery bypass grafting (CABG) surgery were enrolled between October 20, 2020, and November 16, 2023. The final participant was discharged from the hospital on December 11, 2023. Participants were randomized to either a tight potassium control group (supplementation if serum potassium concentration fell below 4.5 mEq/L) or a relaxed potassium control group (supplementation only if serum potassium concentration fell below 3.6 mEq/L). Ambulatory heart rhythm monitoring was used, with the data analyzed by a core laboratory blinded to treatment allocation.

The primary endpoint was the incidence of clinically detected and electrocardiographically confirmed new-onset AFACS within the first 120 hours after CABG surgery or until hospital discharge, whichever occurred first. All primary outcome events were adjudicated by an event validation committee blinded to treatment allocation. Noninferiority of the relaxed potassium control strategy was defined as a risk difference for new-onset AFACS with the upper bound of a one-sided 97.5% confidence interval (CI) of less than 10%. Secondary outcomes included other heart rhythm-related events, clinical outcomes, and costs associated with the intervention.

Results

 A total of 1,690 patients (mean age, 65 years; 15% female) were randomized. The primary endpoint 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, resulting in a risk difference of 1.7% (95% CI, -2.6% to 5.9%). There was no significant difference between the groups in the incidence of at least one AFACS episode detected by any method or by ambulatory heart rhythm monitoring, in the occurrence of non-AFACS dysrhythmias, in-hospital mortality, or length of stay. The per-patient cost of potassium supplementation was significantly lower in the relaxed control group (mean difference, $111.89 [95% CI, $103.60 to $120.19]; P < .001).

Conclusion

 In the context of AFACS prophylaxis, potassium supplementation triggered at a serum concentration below 3.6 mEq/L was found to be non-inferior to the conventional practice of maintaining serum potassium levels at or above 4.5 mEq/L. The lower supplementation threshold was not associated with an increased incidence of dysrhythmias or adverse clinical outcomes.

Interpretation

This study provides important insights into the management of potassium supplementation for the prevention of atrial fibrillation after cardiac surgery (AFACS). The findings suggest that maintaining a lower threshold for potassium supplementation (triggered at serum levels below 3.6 mEq/L) is not inferior to the current practice of supplementing at higher serum levels (?4.5 mEq/L). The absence of significant differences in the incidence of AFACS, other dysrhythmias, or adverse clinical outcomes between the two groups indicates that a relaxed potassium control strategy is both safe and effective. Additionally, the relaxed supplementation approach substantially reduces costs, making it a more economical option for cardiac surgery centers. These results challenge the need for aggressive potassium supplementation and support a more conservative approach, potentially influencing future clinical guidelines and practices in AFACS management.