A 70-year-old man affected by a metastatic lung adenocarcinoma developed an atrioventricular block. Due to an extensive thrombosis of the superior vena cava with invasion of the right atrium, a traditional transvenous pacemaker system (TTPS) implantation was not feasible. Despite the extensive development of the thrombosis in the right atrium, the patient successfully underwent Micra transcatheter pacing system (MTPS) implantation. This case report describes a quite rare condition in which a leadless pacemaker (LP) is the best option to treat an atrioventricular block and where the recent introduction of the groundbreaking AV MTPS would be the optimal therapy.