Baseline Potassium Levels and Their Association With Electrocardiograph Abnormalities in Hyperkalaemia.

Background: Hyperkalaemia poses a life-threatening risk due to cardiac arrhythmias. Hyperkalaemic serum potassium (HK) levels are associated with the development of electrocardiograph (ECG) abnormalities, while the potential relationship between baseline serum potassium (BK) levels and these changes remains unclear.

Methods: This retrospective cohort study involved outpatients identified with severe hyperkalaemia (serum potassium level ≥ 6.5 mEq/L). BK levels were defined as the average of the three most recent values prior to the severe hyperkalaemia episode. Hyperkalaemia-associated ECG changes were determined by comparison with the recordings taken during normokalaemia.

Results: Among 283 patients, the median age was 74 (63-82) years, with 90 patients (31.8%) being female. The median BK and HK levels were 5.0 (4.5-5.3) and 6.8 (6.6-7.1) mEq/L, respectively. The most frequent ECG changes in hyperkalaemia were peaked T waves (35.7%), followed by prolonged PR interval (12.1%), bradycardia (12.0%), widened QRS duration (7.8%), escape rhythm (7.1%), second- or third-degree atrioventricular block (3.5%), and ventricular arrhythmias (0.7%). Logistic regression analyses adjusted for potential confounders demonstrated that both the below-median BK and above-median HK levels were associated with an increased likelihood of developing ECG changes (odds ratio [OR], 4.61; 95% confidence interval [CI], 2.44-8.72 and OR, 2.28; 95% CI, 1.34-3.89, respectively), as was a greater BK-HK level difference (OR, 6.85; 95% CI, 3.68-12.77).

Conclusion: BK levels as well as HK levels were significant predictors of ECG abnormalities. Healthcare professionals should place emphasis on the magnitude of potassium increase when managing hyperkalaemia.