A Case Report of Pericardial Constriction and Left Ventricular Dysfunction in a Breast Cancer Survivor: Late Cardiotoxicity From Radiotherapy or 5-Fluorouracil.

Cardiotoxicity from oncologic treatments, including radiotherapy and fluoropyrimidine-based chemotherapy, can manifest years later, leading to pericardial constriction and left ventricular dysfunction in cancer survivors. We report the case of a 53-year-old breast cancer survivor, treated with surgery, radiotherapy (>25 Gy), and 5-fluorouracil (5-FU) chemotherapy in 2015, who remained cancer-free until a pleural recurrence in 2024, managed with pleurodesis and capecitabine. Six months later, she developed cardiac tamponade requiring pericardial drainage. Transthoracic echocardiography showed a preserved left ventricular ejection fraction (LVEF) (60%), and concurrent subclavian vein thrombosis led to anticoagulation. By early 2025, she developed left ventricular dysfunction (LVEF 45%) with exertional dyspnea classified as New York Heart Association (NYHA) class III. NT-proBNP levels were elevated. Coronary disease was excluded. Cardiac magnetic resonance imaging (MRI) revealed evolving constrictive pericarditis, moderate dysfunction (global longitudinal strain (GLS)-13.5%), biatrial enlargement, and bilateral pleural effusion. Right heart catheterization confirmed adiastole with a deep plateau pattern. This case highlights a rare late-onset pericardial constriction and ventricular dysfunction in a breast cancer survivor, potentially linked to prior oncologic treatments. These findings underscore the importance of long-term cardiovascular monitoring in cancer survivors.