In this article, the authors report prespecified six-month follow-up outcomes from the TIGHT K randomized trial comparing relaxed potassium supplementation after isolated coronary artery bypass grafting (CABG) surgery, triggered below 3.6 mEq/L, with tight supplementation, triggered below 4.5 mEq/L. Among 1,667 analyzed patients, six-month mortality was similarly low in both groups, occurring in 1.2 percent vs 1.1 percent, with no significant difference in hazard. Quality of life measured by the EQ-5D-5L was also comparable. Self-reported post–discharge atrial tachyarrhythmias, anticoagulation for atrial fibrillation, flutter, or tachyarrhythmia after cardiac surgery (AFACS), stroke, pacemaker implantation, and adverse events were infrequent and similar between groups. These exploratory findings support the in-hospital TIGHT K results, suggesting that relaxed potassium replacement is not associated with worse medium-term outcomes after CABG.
