Complete AV Block From Septal Cardiac Metastases of Anal Squamous Carcinoma Managed With Leadless Pacing

BACKGROUND: Cardiac metastases from anal squamous cell carcinoma (ASCC) are exceedingly rare; complete atrioventricular (AV) block from septal involvement has not previously been reported In Vivo. CASE SUMMARY: A 79-year-old woman with p16-negative ASCC developed complete AV block with asystolic pauses during chemoradiotherapy. Restaging computed tomography showed a 49-mm interventricular septal mass and 2 left ventricular lesions, consistent with cardiac metastases. A Micra AV leadless pacemaker was implanted because of pacemaker dependence, frailty, infection risk, and challenging vascular access. Cemiplimab, an anti-PD-1 immunotherapy, was initiated for progressive metastatic disease. DISCUSSION: Septal metastatic infiltration was the most likely cause of the AV block. New conduction disease in patients with cancer warrants multimodality imaging to assess cardiac involvement. TAKE-HOME MESSAGES: Leadless pacing can be a practical option for complete AV block in frail oncology patients. Cardiac metastases should be considered in new arrhythmias or conduction disturbances, particularly with septal lesions.