Lithium-Induced Bradycardia and Cardiomyopathy in a Patient With Bipolar Disorder and Paranoid Schizophrenia

Lithium is primarily known to cause neurological and gastrointestinal side effects, however, cardiac effects have been rarely reported. We present a unique case of lithium cardiotoxicity causing bradyarrhythmia and cardiomyopathy. A 68-year-old man with a history of paranoid schizophrenia and bipolar disorder presented with altered mental status. On examination, the patient was lethargic, afebrile, with dry oral mucosa, and a regular pulse of 42 bpm. Labs revealed acute kidney injury and elevated lithium levels. Electrocardiogram (ECG) revealed a junctional escape rhythm with a right bundle morphology. Lithium toxicity was strongly suspected in the setting of raised serum lithium levels, decreased oral intake and acute kidney injury. The patient was found to have lithium-induced junctional bradycardia. Transvenous pacing was not indicated as the patient responded to fluids and atropine and had no severe hemodynamic compromise. As his serum lithium levels decreased, the bradycardia gradually improved. His echocardiogram revealed moderate left ventricular systolic dysfunction. Workup of cardiomyopathies was negative: no obstructive coronary artery disease; viral panel, and autoimmune markers were unremarkable. Thus, his cardiomyopathy was attributed to lithium toxicity. Lithium cardiotoxicity may manifest as arrhythmias and/or cardiomyopathy. Clinicians should have a high index of suspicion for lithium cardiotoxicity due to the narrow therapeutic range of lithium.

Into the Unknown: A Case of New-Onset Cardiomyopathy in a Patient Treated With Recently Approved Tyrosine Kinase Inhibitor, Pralsetinib

With the rapid development and adoption of novel anti-cancer therapeutics, physicians commonly encounter cancer patients on regimens with recently approved drugs for which information about rare or long-term side effects may not be available. In this case, we present a young woman with cholangiocarcinoma who was treated with the rearranged during transfection (RET)-selective tyrosine kinase inhibitor (TKI), pralsetinib, and presented to the hospital with shortness of breath. We review her diagnosis of new-onset systolic dysfunction as a possible sequela of her TKI therapy to encourage ongoing efforts to enhance provider familiarity with the side effects of this important and increasingly prescribed drug class.