Abstract
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: This study is a retrospective institutional case series conducted at MacKay Memorial Hospital from 2010 to 2025. We reviewed five patients with histologically confirmed primary or secondary cardiac DLBCL. 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 appeared to increase the risk of ventricular tachycardia and high-grade atrioventricular block, which is supported by the previous research about the reentry circuits at tumor-myocardium interfaces. Chemotherapy remains the principal therapeutic approach for cardiac DLBCL; however, our limited observations suggest that integrating anti-arrhythmic and cardioprotective therapy may improve chemotherapy tolerance. Successful arrhythmia control frequently correlated with improved clinical outcomes. However, the optimal use of anthracycline-based regimens in cardiac DLBCL remains uncertain and warrants further investigation. CONCLUSIONS: Our findings highlight the importance of early recognition and multidisciplinary management for cardiac complications in the patients with cardiac-involved DLBCL. Cardioprotective strategies, anti-arrhythmic management, and careful chemotherapy selection are crucial to balance oncologic efficacy with cardiovascular safety.