Electrocardiographic Manifestations and Targeted Management of Cardiac Complications in Cardiac-involved DLBCL: A Retrospective Case Series

Background: Cardiac involvement in diffuse large B-cell lymphoma (DLBCL) is rare but often complicated by life-threatening arrhythmias, conduction disturbances, and heart failure. Electrocardiography (ECG) is essential for early recognition and guiding intervention. Objectives: To characterize ECG manifestations of cardiac-involved DLBCL and evaluate strategies for managing associated cardiac complications. Methods: We retrospectively reviewed five patients with histologically confirmed primary or secondary cardiac DLBCL treated at MacKay Memorial Hospital from 2010 to 2025. Data on tumor location, ECG and echocardiographic findings, cardioprotective and anti-arrhythmic therapy, chemotherapy regimens, and outcomes were analyzed to correlate electrical abnormalities with anatomical involvement and therapeutic response. Results: ECG patterns varied according to tumor distribution. Right atrial involvement was often associated with atrial tachycardia or atrial fibrillation. Pericardial infiltration produced low-voltage QRS complexes and electrical alternans in cases of massive effusion, whereas minimal effusion preserved normal sinus rhythm. Myocardial infiltration increased the risk of ventricular tachycardia and high-grade atrioventricular block, likely attributable to reentry circuits at tumor–myocardium interfaces. As chemotherapy remains the mainstay of treatment for cardiac DLBCL, patients need the use of effective anti-arrhythmic agents and cardioprotective therapy to facilitate tolerance of systemic chemotherapy. Successful arrhythmia control frequently correlated with improved clinical outcomes. However, the use of standard first-line anthracycline-based chemotherapy in this population remains controversial and warrants further investigation. Conclusions: Prompt recognition of cardiac involvement and multidisciplinary, individualized treatment planning are essential for improving outcomes in cardiac DLBCL. Cardioprotective strategies, anti-arrhythmic management, and careful chemotherapy selection are crucial to balance oncologic efficacy with cardiovascular safety.