This study examined whether potassium supplementation at a lower threshold (below 3.6 mEq/L) is as effective as the standard practice (below 4.5 mEq/L) in preventing atrial fibrillation after coronary artery bypass graft (CABG) surgery. A trial involving 1,690 patients at 23 cardiac surgical centers showed no significant difference in new-onset atrial fibrillation or other clinical outcomes between the two groups. The findings suggest that the current practice of maintaining high-normal potassium levels postoperatively can be reconsidered, potentially lowering healthcare costs and minimizing unnecessary interventions.