Dual cardiac amyloidosis with AL cardiomyopathy and ATTR cardiomyopathy in systemic AL amyloidosis: Recommendation for a myocardial histology-based diagnosis

Accurate amyloid typing in cardiac amyloidosis is clinically important for determining treatment strategies. A 73-year-old man underwent a renal biopsy due to renal dysfunction and was diagnosed with systemic λ-type light chain (AL) amyloidosis. Echocardiography and cardiac magnetic resonance revealed cardiac involvement, leading to a clinical diagnosis of λ-type AL-cardiomyopathy (CM). However, the clinical course and findings were inconsistent with AL-CM. Technetium-99m-pyrophosphate scintigraphy showed intense myocardial uptake corresponding to Grade 3 on visual assessment. Further examination through an endomyocardial biopsy and protein mass spectrometry revealed the patient had both AL-CM and transthyretin amyloid (ATTR)-CM. In addition to chemotherapy for systemic AL amyloidosis, transthyretin stabilizing therapy was initiated for wild-type ATTR-CM. Initially, this patient was diagnosed with AL-CM complicated by systemic AL amyloidosis; however, it was subsequently determined that the cardiac involvement was a coexistence of both AL-CM and ATTR-CM. Learning objective Even though multimodality imaging approaches have been established with recent advances in imaging technology, it is still challenging to noninvasively and accurately determine specific amyloid subtypes or to predict the presence of multiple types of amyloids. Accurate amyloidosis typing is critically important for determining treatment strategies. When clinical course and imaging findings conflict with the diagnosis, diagnosis based on myocardial tissue should not be deferred. Furthermore, proteomic analysis is highly useful for accurate amyloid typing.