RESUMEN
BACKGROUND Cardiac lymphomas can lead to heart block through tumor disruption of the cardiac conduction system. It is reported that with cardiac tumor treatment, conduction abnormalities can resolve. We present a case of cardiac lymphoma resulting in complete heart block requiring a pacemaker, followed by reduction of the pacing burden after chemotherapy. CASE REPORT A 72-year-old woman with a medical history of hypertension, hypothyroidism, and persistent atrial fibrillation presented with dyspnea on exertion and fatigue for 2 weeks. Electrocardiography revealed complete heart block with junctional bradycardia of 48 beats per min. Transthoracic echocardiography demonstrated preserved left ventricular systolic function along with a large mass (3.6×3.7 cm). An endomyocardial biopsy was consistent with diffuse large B cell lymphoma, and the cardiac involvement was thought to be secondary based on positron emission tomography scan findings. Her clinical course was complicated by an episode of syncope deemed to be due to transient asystole, and an urgent single-chamber permanent pacemaker was implanted. Chemotherapy was initiated with R-CHOP, and, following the second cycle of chemotherapy, a positron emission tomography scan revealed no increased radiotracer uptake and thus resolution of all tumors. An echocardiogram 6 weeks after chemotherapy showed complete resolution of the cardiac mass. Subsequent serial pacemaker checks demonstrated improvement of atrioventricular nodal function as manifested by reduced pacing burden. CONCLUSIONS Lymphoma with cardiac involvement can lead to conduction abnormalities, including CHB, and heart block in the setting of these tumors may be reversible with appropriate therapy; however, implantation of a pacemaker remains inevitable is some cases.