90-day mortality risk related to postoperative potassium levels in patients undergoing coronary bypass surgery

Aims
While electrolyte depletion is known to occur during coronary artery bypass grafting (CABG) with extracorporeal circulation, little is known about the frequency of potassium disturbances following either on- or off-pump CABG and its association with mortality. We examined the frequency of potassium disturbances and the association of plasma potassium with mortality risk in patients following CABG.

Methods and results
From Danish National Registries, we identified 6123 adult patients (≥18 years old) undergoing first-time CABG, and who had a registered potassium measurement within 14 days before and 7 days after their surgery between 1995 and 2018. Using 4.0–4.6 mmol/L as reference, potassium was stratified into five predefined intervals:

Conclusion
Although the cox regression presented a trend of increased mortality only in hyperkalemia, the absolute mortality risk supported a strategy of careful monitoring and evaluation of any potassium disturbance, including in the lower normokalemia interval.