Long-term effect of tocilizumab on left ventricular hypertrophy and systolic dysfunction in AA amyloidosis with rheumatoid arthritis

Abstract Because cardiac involvement of amyloid A (AA) is not frequent, little is known about the effects of tocilizumab (TCZ; a humanized monoclonal anti-interleukin-6 receptor antibody). We present the case of a 77-year-old man with cardiac AA amyloidosis due to rheumatoid arthritis (RA). He was admitted to our hospital because of gastrointestinal bleeding. Upon admission, chest radiography and electrocardiogram showed progression of cardiomegaly and atrioventricular conduction delay, respectively. Echocardiography showed diffuse left ventricular (LV) hypertrophy with reduced LV contraction. AA amyloid deposits in the myocardium were identified by Congo red staining and immunohistochemical staining with anti-AA antibody, suggesting cardiac AA amyloidosis. After starting treatment with TCZ, his condition improved. Hypertrophic LV mass was significantly reduced, and impaired LV contraction was restored after 10 months of TCZ treatment. The effects of TCZ were sustained for 2 years. Plasma N terminal pro-B-type natriuretic peptide level decreased from 2947 pg/mL (reference level,