Key result
Postoperative hyperkalemia is not significantly associated with higher 90-day mortality after CABG.
Why the study?
Little is known about the frequency of potassium disturbances following on- or off-pump CABG and its association with mortality.
Does postoperative plasma potassium disturbance increase 90-day all-cause mortality risk compared with normokalemia (4.0-4.6 mmol/L) in adult patients undergoing first-time CABG?
Cohort (n=6,123)
Yes
Does postoperative plasma potassium disturbance increase 90-day all-cause mortality risk compared with normokalemia (4.0-4.6 mmol/L) in adult patients undergoing first-time CABG?
Although adjusted Cox proportional hazards regression showed only a non-significant trend toward increased 90-day mortality in postoperative hyperkalemia, standardized absolute mortality risks were elevated in hypokalemia, low-normokalemia (3.5-3.9 mmol/L), and hyperkalemia (≥5.1 mmol/L), supporting careful potassium monitoring after CABG.
Answers are grounded in this paper and cite their sources.
Does not support changing potassium targets after CABG; leaves open independent mortality risk from postoperative hyperkalemia.
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: <3.5, 3.5-3.9, 4.0-4.6, 4.7-5.0, and ≥5.1 mmol/L. We examined the absolute mortality risk and assessed the Cox proportional hazard model to analyze the 90-day all-cause mortality risk in relation to the first available post-operative potassium sample. Pre- and postoperative potassium disturbances were rare, while more common in patients with chronic kidney disease. The adjusted cox regression presented a trend of increased mortality only in hyperkalemia. The absolute mortality risk increased in hyperkalemia, hypokalemia and low-normokalemia, while high normokalemia presented a lesser relative risk of mortality, compared to the reference of 4.0-4.6 mmol/L. 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.
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Kjeldgaard et al. (2023) conducted a cohort in First-time coronary artery bypass grafting (CABG) (n=6,123). Postoperative hyperkalemia (plasma potassium ≥5.1 mmol/L) and potassium disturbances (<3.5 or 3.5-3.9 mmol/L) vs. Reference postoperative plasma potassium 4.0-4.6 mmol/L was evaluated on 90-day all-cause mortality (HR 1.4, 95% CI 0.97-2.00). Postoperative hyperkalemia (≥5.1 mmol/L) showed a non-significant trend toward higher 90-day mortality (adjusted HR 1.4, 95% CI 0.97-2.00) with higher absolute mortality risk vs reference.
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