Abstract 12887: Lightning Strikes Twice - A Case of Light Chain and Attr Amyloidosis

Abstract

The most common subsets of amyloidosis that affect the heart include light chain (AL) and transthyretin (ATTR). While both types cause diffuse amyloid fibril deposition within the interstitial space of the myocardium, they arise from two different precursors. AL amyloidosis results from misfolded monoclonal light chains, whereas ATTR amyloidosis results from misfolded transthyretin monomers. This distinction is essential as it suggests that a diagnosis of one disease does not exclude the existence of the other. We present a unique case of a patient with evidence of both systemic ATTR and AL amyloidosis occurring concurrently. An 80-year-old male with a past medical history of severe mitral regurgitation S/p mechanical mitral valve replacement, rotator cuff tear, bilateral carpal tunnel syndrome, and multiple hospitalizations for decompensated systolic heart failure was referred to cardiomyopathy clinic. He presented with class III New York Heart Association (NYHA) symptoms, including significant limitations in activity due to dyspnea. An echocardiogram demonstrated severe left ventricular hypertrophy with a low global longitudinal strain, an apical sparing pattern suspicious of amyloidosis. Monoclonal gammopathy workup showed an elevated lambda free light chain. Subsequent bone marrow biopsy demonstrated plasma cell dyscrasia and amyloid deposition in hypocellular bone marrow. Mass spectrometry showed both lambda light chain and transthyretin amyloid protein. He had elevated cardiac biomarkers, speaking for advanced cardiac involvement, together with nephrotic range proteinuria. He was started on chemotherapy/immunotherapy, with daratumumab, bortezomib and dexamethasone. He was in end stage heart failure requiring inotropic support. Few weeks after chemotherapy, he transitioned toward hospice care. In conclusion, we present a rare case of ATTR and AL amyloidosis coinciding simultaneously that demonstrates the importance of having high index of suspicion for this disease, a stepwise and thorough diagnostic approach highlighting the importance of mass spectroscopy after amyloid protein detection.