Deep vein thrombosis in a patient with wild-type transthyretin cardiac amyloidosis

Wild-type transthyretin cardiac amyloidosis (ATTRwt-CA) is a progressive myocardial disease characterized by an increased ventricular wall thickness. ATTRwt-CA is often accompanied by monoclonal gammopathy of undetermined significance (MGUS), as indicated by an abnormal serum-free light chain ratio or detection of monoclonal protein (M-protein) on serum immunofixation electrophoresis. Increasing evidence has emerged regarding the risk of venous thromboembolic disease in patients with MGUS. Herein, we report a case of ATTRwt-CA with M-protein, where the patient developed deep vein thrombosis (DVT). A 72-year-old man presented with gradual progressive swelling of the right lower extremity. He had undergone surgical treatment for bilateral carpal syndrome and lumbar spinal canal stenosis. He was diagnosed with DVT and severe left ventricular (LV) hypertrophy, and was treated with a direct factor Xa inhibitor. Given severe LV hypertrophy, the patient underwent further cardiac examinations. 99mTc-labelled pyrophosphate scintigraphy revealed grade 3 myocardial uptake. Serum immunofixation electrophoresis detected IgA-κ M-protein. An endomyocardial biopsy revealed amyloid deposits. Based on immunohistochemical staining and genetic testing, the patient was diagnosed as having ATTRwt-CA with IgA-κ M-protein. Therefore, clinicians should be aware that ATTRwt-CA is often associated with M-protein. Under these conditions, attention should be paid to both pathological issues.