Electrocardiographic findings of hyperkalemia tend to follow a progression as toxicity progresses. Often, the earliest finding is narrow-based, peaked T waves, and at the extreme end of the hyperkalemia spectrum, a sine wave morphology is a harbinger of pending ventricular fibrillation. The ECG can be used to predict short-term hyperkalemic adverse events. According to one retrospective study of 188 patients with severe hyperkalemia, the following three findings predicted adverse outcomes within six hours:

  1. Bradycardia < 50 bpm
  2. QRS > 110 ms
  3. Junctional rhythm

Notice that peaked T waves were not found to predict acute adverse outcomes.


Expected electrocardiographic changes with given serum potassium levels.



  1. Long B, Warix JR, Koyfman A. Controversies in Management of Hyperkalemia. Journal of Emergency Medicine. 2018;55(2):192-205.
  2. Durfey N, Lehnhof B, Bergeson A, et al. Severe Hyperkalemia: Can the Electrocardiogram Risk Stratify for Short-term Adverse Events? Western Journal of Emergency Medicine. 2017;18(5):963-971.