Supplementing potassium only when levels fall below 3.6 mEq/L following cardiac surgery may be just as effective in preventing atrial fibrillation as the more common practice of maintaining levels above 4.5 mEq/L, while reducing costs, according to a new clinical trial.
In the randomized TIGHT K clinical trial, published in JAMA Network, investigators evaluated the effectiveness of lower potassium supplementation thresholds in preventing atrial fibrillation after cardiac surgery (AFACS). Conducted at 23 centers in the United Kingdom and Germany, they compared supplementation at serum potassium concentrations below 3.6 mEq/L vs the current practice of maintaining concentrations above 4.5 mEq/L. The trial included 1,690 patients undergoing isolated coronary artery bypass grafting (CABG) surgery, with an average age of 65 years, and 15% (n = 256) of the patients were female.
The primary endpoint—clinically detected, electrocardiographically confirmed AFACS—was observed in 26.2% of the patients in the tight potassium control group (supplementation below 4.5 mEq/L) and 27.8% of those in the relaxed control group (supplementation below 3.6 mEq/L). The risk difference between groups was 1.7% (95% confidence interval [CI] = −2.6% to 5.9%), demonstrating the noninferiority of the relaxed strategy.
Secondary outcomes, including non-AFACS dysrhythmias, mortality, and length of stay, showed no statistically significant differences between both groups. Notably, the cost of potassium supplementation was significantly lower in the relaxed group, with a mean per-patient savings of $111.89 (95% CI = $103.60−$120.19). Potassium supplementation was given a median of 7 times in the tight control group during the study (interquartile range [IQR] = 4−12), while the relaxed control group received potassium a median of 0 times (IQR = 0−1).
The findings indicated that maintaining high-normal serum potassium concentrations was noninferior for AFACS prophylaxis and resulted in cost savings.
Full disclosures can be found in the published study.
