A woman in her 20s presented to the emergency department with a 1-day history of palpitations and dyspnea. Her medical history was significant for breast cancer, for which she had received total mastectomy of the right breast, followed by 5 cycles of dual anti–human epidermal growth factor receptor 2 (ERBB2 [formerly HER2]) treatments with trastuzumab and pertuzumab before the admission. She had no history of cardiovascular diseases or family history of sudden death and hereditary arrhythmia syndromes. Electrocardiography (ECG) and echocardiography performed before initiating the anti-ERBB2 therapy yielded normal results. On arrival, her heart rate was 209/min, her blood pressure was 90/60 mm Hg, her respiratory rate was 31/min, and her oxygen saturation was 92% on room air. Investigations revealed a troponin I level of 0.017 ng/mL (reference range, <0.034 ng/mL) (conversion of troponin I to μg/L is 1:1), an N-terminal fragment of the prohormone brain natriuretic peptide (NT-proBNP) level of 3600 ng/L (reference range, <125 ng/L), and normal levels of serum electrolytes. A transthoracic echocardiogram revealed a reduced left ventricular ejection fraction (LVEF) of 46%. Her initial ECG is shown in the Figure, A.
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Corresponding Authors: Tong Liu, MD, PhD, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, No. 23, Pingjiang Road, Hexi District, Tianjin 300211, China (email@example.com; firstname.lastname@example.org); and Xuhong Geng, MD, Department of Function, Fourth Hospital of Hebei Medical University, No. 12, Jiankang Road, Shijiazhuang 050011, Hebei, China (email@example.com).
Published Online: June 26, 2023. doi:10.1001/jamainternmed.2023.1563
Conflict of Interest Disclosures: None reported.
Funding/Support: The work was funded by grant 82170327 from the National Natural Science Foundation of China (Prof Liu) and grant TJYXZDXK-029A from the Tianjin Key Medical Discipline (Specialty) Construction Project.
Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
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Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:
It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.
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