Nivolumab-induced Third Degree Atrioventricular Block in a Patient with Stage IV Squamous Cell Lung Carcinoma

In the era of immune checkpoint inhibitors, pulmonary and critical care physicians frequently encounter patients taking these medications, usually after being admitted to the intensive care unit with life-threatening complications. These complications are rare, present with nonspecific and vague symptoms, which may delay the treatment and have high mortality. We report a very rare complication, with only two previously reported cases of a severe and potentially fatal side effect associated with anti-programmed cell death protein 1 (PD-1) immunotherapy with nivolumab. We provide a literature review to increase physicians’ awareness about this rare side effect and suggest some recommendations derived from our experience.