Identifying Electrolyte Abnormalities in the COVID-19 Era: The Role of ECG

New information regarding COVID-19 continues to emerge daily. This content was based on the sources available at the time of writing.

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Although COVID-19 primarily targets the respiratory system, accumulating evidence indicates that cardiac involvement is also common, especially among patients who are hospitalized with the disease. There are a number of electrocardiogram (ECG) findings that may be apparent in assessing patients with COVID-19, including ST-segment elevation, as documented in a case series from the New England Journal of Medicine (NEJM), and varying degrees of ECG changes due to electrolyte abnormalities.

Common Electrolyte Abnormalities on ECG

Symptoms related to electrolyte imbalance are often vague, but ECG findings can provide a means of early detection, according to an educational resource from the Clerkship Directors in Emergency Medicine. ECG can indicate potential electrolyte derangements even before lab results are returned, from the tall, peaked T waves most visible in the precordial leads in early hyperkalemia, to the T-wave inversions that can progress into a prolonged QTc and mild ST depression with progressive degrees of hypokalemia, to the shortening of the QT interval typical of hypercalcemia.

Hypokalemia in Patients with COVID-19

As a StatPearls review article notes, electrolyte imbalance can occur in any critical illness of a systemic nature, including COVID-19, and these abnormalities can be arrhythmogenic. Further, patients with underlying cardiac disease are more vulnerable to the development of such arrhythmias.

Hypokalemia appears to be of particular concern for patients with COVID-19 due to the interaction of SARS-CoV-2 with the renin-angiotensin system. Additionally, in patients who have both diabetes and COVID-19, the presence of hypokalemia can worsen glucose control, as the review article in Diabetes & Metabolic Syndrome reports.

A preliminary report from Wenzhou, China preprinted in medRxiv revealed that 108 (61.7%) of 175 patients admitted with COVID-19 by February 15, 2020 had varying degrees of hypokalemia, with 39 patients (22.3%) categorized as having severe hypokalemia. Abnormal ECG findings were seen in 77% of patients with severe hypokalemia, and severity of hypokalemia was correlated with severity of COVID-19 illness, leading to longer hospital stays, more frequent usage of antiviral medications (such as lopinavir/ritonavir), and longer durations of PCR-positive results.

A systematic review and meta-analysis published in Gastroenterology found that multiple gastrointestinal signs and symptoms have been reported in patients with COVID-19. These include abdominal pain, nausea/vomiting, diarrhea, and liver enzyme abnormalities. Patients with vomiting and/or diarrhea are at particular risk of electrolyte imbalance, which may be apparent on ECG at presentation. Careful consideration should be given to detection and correction of electrolytes in these patients.

Although hypokalemia is currently the only electrolyte deficiency specifically identified as a potential concern in patients with COVID-19, other electrolyte abnormalities may become relevant as more research is published on the systemic implications of the disease.

ECG for COVID-19 Triage

As a review article in the NEJM states, the majority of patients in whom COVID-19 is suspected should have a baseline ECG performed upon presentation. In addition to detecting other cardiac complications with ECG manifestations, this baseline ECG can identify electrolyte deficiencies like hypokalemia, allowing for correction upon presentation. Laboratory testing should include a comprehensive metabolic panel and a complete blood count in all patients who are hospitalized with COVID-19.

The use of diagnostic ECG is a long-established and powerful tool in assessing patients with a wide range of presentations. It can reveal myocardial ischemia and infarction, other forms of myocardial injury such as myocarditis or arrhythmias, and electrolyte abnormalities, among other conditions. Any of these ECG findings may be present in patients admitted with COVID-19. This underscores the importance of obtaining a baseline ECG in patients hospitalized with COVID-19 and highlights the utility of ECG in implementing guideline-directed cardiac triage during the COVID-19 pandemic.