Clinical Practice and Cases in Emergency Medicine

Introduction: 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.

Case Report: 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.

Conclusion: 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.