Entrectinib-related Myocarditis Causing a Triangular QRS-ST-T Waveform Electrocardiographic Pattern: A Case Report

Entrectinib is a kinase inhibitor used in ROS1-positive non-small cell lung carcinoma. Cardiovascular toxicity is rare, with only one prior report of myocarditis related to entrectinib use. The triangular QRS-ST-T waveform electrocardiographic pattern is a ST-elevated myocardial infarction equivalent and is rarely associated with myocarditis.

A 42-year-old male with metastatic non-small cell lung carcinoma presented with presyncope, palpitations, and dyspnea three days after initiating entrectinib. Electrocardiograph (ECG) revealed a "shark-fin" T-wave morphology with diffuse ST elevation, QTc prolongation, and elevated troponin. ST-elevated myocardial infarction protocol was initiated with tenecteplase, heparin, clopidogrel, and aspirin. Left heart catheterization was normal. The ECG showed an ejection fraction of 20-25% with global hypokinesis. Myocarditis with heart failure associated with entrectinib use was suspected. Cardiac magnetic resonance imaging confirmed myopericarditis with subsequent recovery of ejection fraction to 57%. The patient was discharged after five days with complete recovery.

This is the second reported case of myocarditis associated with entrectinib use and the second documented case of myocarditis presenting with a T-wave ECG pattern. Clinicians should be aware that entrectinib is associated with early-onset myocarditis and that the T-wave pattern, while strongly correlated to occlusive myocardial infarction, may rarely occur in myocarditis. Prompt recognition is critical to avoid mismanagement.