Hot Line: No need to routinely supplement potassium after CABG
01 Sep 2024
As Professor Benjamin O'Brien (Deutsches Herzzentrum der Charité - Berlin, Germany) explained yesterday, many centres supplement potassium after coronary artery bypass graft (CABG) surgery to maintain serum levels in the high-normal range to prevent new-onset atrial fibrillation (AF); however, there is no robust evidence to support this practice.
The open-label, non-inferiority TIGHT-K trial compared the strategy of ‘tight’ potassium control to high-normal levels (potassium supplementation if <4.5 mEq/L) with more ‘relaxed’ potassium supplementation only when levels were pathologically low (if <3.6 mEq/L) in participants with no history of atrial dysrhythmias scheduled for isolated CABG surgery.
The primary endpoint was the presence of new-onset AF after cardiac surgery (AFACS; episode of AF, flutter or tachyarrhythmia, of at least 30 seconds duration) in the 120 hours after the operation, or up until discharge from hospital, whichever was sooner.
In total, 1,690 participants were randomised, with a mean age of 64.7 years and 15% were women. The mean EuroSCORE II score was 1.5%.
There was no significant difference in the primary endpoint, which occurred in 27.8% of patients in the relaxed control group and 26.2% in the tight control group.
The rate of AFACS detected by any means (clinically and/or ambulatory heart rhythm monitoring) was 33% in both groups. Furthermore, there was no significant difference in non-AFACS dysrhythmias, including ventricular tachycardia, with relaxed control (19.1% and 12.2%, respectively) vs. tight control (21.1% and 14.8%, respectively). The median number of potassium administrations in the relaxed control group was 0 compared with 7 in the tight control group, and costs were four-fold higher with tight control.
“In the first trial of its kind, we showed that supplementing potassium only when serum levels dropped below the normal range was non-inferior to tight control for new-onset AF. It was safe to intervene less and there was the added benefit of reduced healthcare resource utilisation with relaxed potassium control. Unnecessary intervention carries risks and can negatively impact the patient experience. 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,” concluded Prof. O'Brien.
