Lithium: Cardiac Adverse Effects and When to Get an ECG

BIPOLAR UPDATE

A recent consultation motivated an evaluation of the evidence on when one should monitor electrocardiograms (ECGs) in patients taking lithium. Opinions vary and tend to be vague about when and how often to measure the ECG. Mogens Schou, MD, who was perhaps the world’s foremost expert on lithium and a passionate advocate for its use, observed that lithium occasionally changes the function or electrical activity of the heart, but the presence of heart disease rarely should prevent lithium treatment.¹ If heart disease was present, however, he recommended a consultation with a cardiologist and serial ECGs might be considered. Much more recently, The Maudsley Prescribing Guidelines in Psychiatry from the United Kingdom recommended getting an ECG if there are risk factors for, or preexisting, cardiac disease—but offered no further details.²

In what appears to be the most thorough review of the subject, Mehta and Vannozzi proposed that, though data are limited, routine monitoring of ECGs seems unnecessary. However, if patients are maintained on or develop high lithium levels (eg, 1.2 mEq/L or higher), then the risks of arrhythmias, ST segment changes, and QRS prolongations become significant, and a baseline ECG and periodic repeats are worth doing.³ They also noted that lithium-induced ECG changes are more likely over the age of 60 years. This population has a high prevalence of ischemic heart disease, and the 2 most common lithium-induced changes (T wave inversions and sinus dysfunctions such as bradycardia) are also common manifestations of cardiac ischemia. Thus, it would be important to delineate the cause if such abnormalities were found. Therefore, Mehta and Vannozzi recommended a baseline ECG and follow-up at least every 6 to 12 months for anyone over age 60 years taking lithium and with risk factors like hypertension, hyperlipidemia, diabetes, smoking, and a positive family history.

In reviewing the literature since this “complete” literature search (as the authors described it), we only found case reports. In the most recent one, a 52-year-old woman with a complex medical presentation including fever and sepsis had been taking lithium for 10 years. Her ECG showed a wide range of abnormalities that, after excluding other factors, seemed mostly due to lithium as they were present even when her medical problems had resolved.⁴ There was atrial fibrillation acutely when her lithium level was 2.0 mEq/L (also found in some case reports in the Mehta and Vannozzi review and in another recent case report⁵), but this converted rapidly when the lithium level came down to normal. Six months later, with normal lithium levels, the patient still had ST segment elevation and inverted T waves. The report’s authors concluded that unpredictable genetic and comorbid illness factors could render a patient vulnerable to life-threatening arrhythmias if the right provocations come along, and the presence of abnormalities at therapeutic levels could predict who is vulnerable. Hence, they recommended that all patients receiving lithium should have a baseline ECG and “regular” monitoring. They noted that these vulnerabilities might be more common in patients taking long-term lithium, hence the need for the continued monitoring.³

In summary, it seems that although there are no standardized, officially approved guidelines for serial ECG monitoring with lithium, we probably should be getting more baseline ECGs and repeating them more frequently in patients on long-term lithium and in those who develop cardiac risk factors. Consultation with our cardiology colleagues on any abnormal findings would be prudent.

Dr Osser is an associate professor of psychiatry at Harvard Medical School in Boston, Massachusetts, and codirector of the US Department of Veterans Affairs National Bipolar Disorder Telehealth Program in Brockton, Massachusetts. The author reports no conflicts of interest concerning the subject matter of this article.

References

1. Schou M. Lithium Treatment of Manic-Depressive Illness: A Practical Guide. 3rd ed. Karger; 1986:33.

2. Taylor DM, Barnes TRE, Young AH. The Maudsley Prescribing Guidelines in Psychiatry. 14th ed. Wiley Blackwell; 2021:251.

3. Mehta N, Vannozzi R. Lithium-induced electrocardiographic changes: a complete review. Clin Cardiol. 2017;40(12):1363-1367.

4. Diserens L, Porretta AP, Trana C, Meier D. Lithium-induced ECG modifications: navigating from acute coronary syndrome to Brugada syndrome. BMJ Case Rep. 2021;14(6):e241555.

5. Maddala RNM, Ashwal AJ, Rao MS, Padmakumar R. Chronic lithium intoxication: varying electrocardiogram manifestations. Indian J Pharmacol. 2017;49(1):127-129.