Effects of Toxic Lithium Levels on ECG-Findings from the LiSIE Retrospective Cohort Study
Petra Truedson1, Michael Ott2, Krister Lindmark2,3
1Sunderby Research Unit, Department of Clinical Sciences, Psychiatry, Umeå University, 90187 Umeå, Sweden.
Insights
Lithium intoxication can cause discrete heart rate changes and QT prolongation, with some cases becoming severe. Always obtain an electrocardiogram (ECG) for patients with lithium toxicity.
Area of Science:
- Cardiology
- Clinical Pharmacology
- Toxicology
Background:
- Limited research exists on the cardiac effects of lithium intoxication.
- Lithium is a mood stabilizer with potential cardiotoxic effects.
- Understanding these effects is crucial for patient management.
Purpose of the Study:
- To investigate electrocardiogram (ECG) changes during lithium intoxication.
- To assess the impact of lithium toxicity on heart rate (HR) and QT interval (QTc).
Main Methods:
- Retrospective cohort study (LiSIE).
- Analysis of ECGs from 1136 patients, including before, during, and after 112 lithium intoxication episodes.
- Statistical analysis of heart rate and QTc intervals.
Main Results:
- Lithium intoxication showed a statistically significant decrease in mean heart rate (76 to 73 bpm, p=0.046).
- QTc correlated weakly with lithium concentration (ρ=0.329, p=0.014).
- QT prolongation occurred in 24% of episodes, with QTc exceeding 500 ms in 54% of these, more common in chronic intoxications.
Conclusions:
- Cardiac effects of lithium intoxication on HR and QTc appear mostly discrete and not clinically significant.
- However, severe QT prolongation is a risk.
- ECG monitoring is essential for all patients presenting with lithium intoxication.
Abstract:
(1) Background: Few studies have explored the impact of lithium intoxication on the heart. (2) Methods: We examined electrocardiogram (ECG) changes associated with lithium intoxication in the framework of the LiSIE (Lithium-Study into Effects and Side Effects) retrospective cohort study. We analysed ECGs before, during, and after intoxication. (3) Results: Of the 1136 patients included, 92 patients had experienced 112 episodes of lithium intoxication. For 55 episodes, there was an ECG available at the time; for 48 episodes, there was a reference ECG available before and/or after the lithium intoxication. Lithium intoxication led to a statistically significant decrease in heart rate from a mean 76 beats/min (SD 16.6) before intoxication to 73 beats/min (SD 17.1) during intoxication (p = 0.046). QTc correlated only weakly with lithium concentration (ρ = 0.329, p = 0.014). However, in 24% of lithium intoxication episodes, there were QT prolongations. In 54% of these, QTc exceeded 500 ms; patients with chronic intoxications being more affected. (4) Conclusions: Based on summary statistics, effects of lithium intoxication on HR and QTc seem mostly discrete and not clinically relevant. However, QT prolongation can carry a risk of becoming severe. Therefore, an ECG should always be taken in patients presenting with lithium intoxication.
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