Reversible osimertinib-associated heart failure mimicking cancer recurrence in EGFR-mutated non-small cell lung cancer after pneumonectomy: A case report.

Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor widely used in patients with EGFR mutation-positive non-small cell lung cancer (NSCLC). Although generally well tolerated, clinically notable cardiovascular toxicities, including heart failure, have been recognized. The present study describes the case of a 77-year-old man who developed symptomatic heart failure 5 months after initiating osimertinib treatment for postoperative recurrence of NSCLC. The patient presented with dyspnea and right-sided pleural effusion, which was initially suspected to represent tumor progression. However, the pleural effusion was transudative and echocardiography revealed a marked reduction in left ventricular ejection fraction from 69 to 27%. Discontinuation of osimertinib and treatment for heart failure resulted in resolution of the pleural effusion and recovery of cardiac function. The present case highlights the importance of differentiating heart failure-related pleural effusion from tumor recurrence and indicates the need for careful monitoring of cardiac function during osimertinib therapy, particularly in patients with conditions that may compromise cardiopulmonary reserve, such as prior pneumonectomy or aortic stenosis.