The TIGHT-K trial reported an important finding in the peri-procedural management of coronary artery bypass grafting (CABG) patients: aggressive supplementation of potassium does not provide any clinical benefit, and in fact leads to higher costs. Professor Benjamin O’Brien, of the Deutsches Herzzentrum der Charité, Berlin, presented these results on Saturday at the European Society of Cardiology (ESC) Congress in London. After CABG, 1 in 3 patients experiences atrial fibrillation after cardiac surgery (AFCAS). AFCAS is associated with increased rates of morbidity, mortality, length of hospital stay and care costs. The TIGHT-K trial was an open label, non-inferiority, randomized controlled trial investigating the non-inferiority of administering potassium (K) “tightly,” when serum levels are <4.5 mEq/L, versus “relaxed,” when levels are <3.6 mEq/L, to patients with no history of arrhythmias receiving isolated CABG. A total of 1,690 patients were 1:1 randomized to the “tight” versus “relaxed” strategy at 23 centers in the United Kingdom and Germany. The primary outcome studied was either occurrence of new onset of AFCAS for 30 seconds until 5 days of CABG, or until discharge. Outcomes were validated by the event validation committee. Secondary outcomes included non-AFACS arrhythmias, inpatient and 6-month mortality, length of hospitalization and associated costs. The patients in this study had a mean age of 64.7 years, 15% female gender and an average European System for Cardiac Operative Risk Evaluation (EuroSCORE) II score of 1.5%. In the “tight” versus “relaxed” groups, there was no difference in the primary outcome (26.2% vs 27.8%). Similarly, no difference was reported for “tight” vs “relaxed” group for non-AFACS (21.1% vs 19.1%) and for ventricular tachycardia (12.4% vs 12.2%). The “tight” group received a median of 7 [4-12] potassium administration as compared to the “relaxed” group, which received 0 [0-5], along with four-fold medical costs in the “tight” group. In summary, aggressive supplementation of potassium to CABG patients did not provide any clinical benefit. However, it did lead to higher medical expenses. “We were able to show that routinely supplementing potassium for tight control offers no benefits compared with relaxed control but is more expensive. Unnecessary intervention can carry risks, such as drug errors, and can negatively impact the patient experience, for example, the unpleasant taste of oral potassium supplements. 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,” Professor O'Brien stated in a press release on Saturday. The TIGHT-K trial was funded by the British Heart Foundation and sponsored by Barts Health NHS Trust. Photo Credit: Screenshot by Bailey G. Salimes, CRTonline.org Photo Caption: Professor Benjamin O’Brien presents results from the MATTERHORN Trial on Saturday at ESC 2024.