Primary Cardiac Lymphoma Treated With R-CHOP Resulting in Rhythm Recovery and Avoidance of Permanent Pacing: A Case Report

Abstract Background Primary cardiac lymphoma (PCL) is a rare, aggressive extranodal lymphoma involving the heart and pericardium. It often presents with non-specific symptoms and conduction disturbance, resulting in diagnostic delay. Multimodal cardiac imaging can characterise PCL tumours and guide biopsy, while histology is required for definitive diagnosis and treatment. Case Summary A man in his 60s with well controlled HIV presented with recurrent syncope preceded by fever, chest pain and fatigue. He was found to have profound first degree atrioventricular block (PR interval 414ms). Transthoracic echocardiography revealed a large interatrial septal mass protruding into both atria with close association to the aortic root. Cardiac CT, MRI and FDG PET-CT confirmed a metabolically active mass extending around the peri-aortic structures. Transoesopheal guided biopsy confirmed PCL of B – cell origin. R-CHOP chemotherapy was commenced with continuous cardiac monitoring. Despite paroxysmal atrial flutter and intermittent higher-grade AV conduction disturbance, permanent pacing was deferred. After two cycles of R-CHOP, imaging showed substantial tumour regression, reduced FDG avidity, improved AV conduction (PR 250 ms) and resolution of syncope. Discussion PCL can present with cardiogenic syncope due to tumour-related involvement of the conduction system and mass effect. This case highlights the value of early multimodal imaging to rapidly characterise cardiac masses and monitor treatment response, while emphasising the necessity of tissue diagnosis. In selected stable patients, early chemotherapy may reverse tumour-related conduction disease, allowing for deferral of permanent pacemaker implantation.