Association of hyperkalaemia with electrocardiographic changes at a tertiary centre in South Africa

Hyperkalaemia is a common electrolyte disorder in hospitalised patients and is associated with fatal cardiac arrhythmias. In sub-Saharan Africa, there is a paucity of data regarding the prevalence and type of electrocardiographic (ECG) changes in patients who have hyperkalaemia.

A retrospective descriptive study was conducted at Tygerberg Hospital over a one-year period in 2019. Adult patients with hyperkalaemia of ≥ 5.5 mmol/L and associated ECG changes 3 h before or after documented laboratory hyperkalaemia were included. Spearman correlation coefficients and multilinear regression were used to identify correlations and associations, respectively, between serum potassium concentrations ([K⁺]) and various ECG changes.

Of 344 patients who had hyperkalaemia and an associated ECG, 55% had ECG changes. These patients were older (60 years vs. 53 years, p = 0.01), male (57% vs. 43%, p < 0.01) and had more frequent kidney disease (88% vs. 78%, p = 0.02). Statistically significant differences in all ECG measurements were present, except for T wave amplitude. The most frequent ECG alterations were p-wave abnormalities (52%) and peaked T waves (45%). A weak-to-moderate correlation was present for the number of ECG changes and the [K⁺]. The QRS duration (β: 0.0076, p < 0.001), PR interval (β: 0.0039, p < 0.001) and p wave duration (β: -0.0056, p < 0.01) were associated with the [K⁺].

The overall prevalence of ECG changes due to hyperkalaemia was only 55%.

It is essential for clinicians to recognise that the ECG changes during hyperkalaemia may have limited screening value.