Severe Hyperkalemia: Can the Electrocardiogram Risk Stratify for Short-term Adverse Events?

Introduction: The electrocardiogram (ECG) is often used to identify which hyperkalemic patients are atrisk for adverse events. However, there is a paucity of evidence to support this practice. This studyanalyzes the association between specific hyperkalemic ECG abnormalities and the development ofshort-term adverse events in patients with severe hyperkalemia.Methods: We collected records of all adult patients with potassium (K+) ≥6.5 mEq/L in the hospitallaboratory database from August 15, 2010, through January 30, 2015. A chart review identified patientdemographics, concurrent laboratory values, ECG within one hour of K+ measurement, treatments andoccurrence of adverse events within six hours of ECG. We defined adverse events as symptomaticbradycardia, ventricular tachycardia, ventricular fibrillation, cardiopulmonary resuscitation (CPR) and/ordeath. Two emergency physicians blinded to study objective independently examined each ECG forrate, rhythm, peaked T wave, PR interval duration and QRS complex duration. Relative risk wascalculated to determine the association between specific hyperkalemic ECG abnormalities and shorttermadverse events.Results: We included a total of 188 patients with severe hyperkalemia in the final study group. Adverseevents occurred within six hours in 28 patients (15%): symptomatic bradycardia (n=22), death (n=4),ventricular tachycardia (n=2) and CPR (n=2). All adverse events occurred prior to treatment with calciumand all but one occurred prior to K+-lowering intervention. All patients who had a short-term adverse eventhad a preceding ECG that demonstrated at least one hyperkalemic abnormality (100%, 95% confidenceinterval [CI] [85.7-100%]). An increased likelihood of short-term adverse event was found forhyperkalemic patients whose ECG demonstrated QRS prolongation (relative risk [RR] 4.74, 95% CI[2.01-11.15]), bradycardia (HR<50) (RR 12.29, 95%CI [6.69-22.57]), and/or junctional rhythm (RR 7.46,95%CI 5.28-11.13). There was no statistically significant correlation between peaked T waves andshort-term adverse events (RR 0.77, 95% CI [0.35-1.70]).Conclusion: Our findings support the use of the ECG to risk stratify patients with severehyperkalemia for short-term adverse events. [West J Emerg Med. 2017;18(5)963-971.