Nonamyloidotic Light Chain Cardiomyopathy: The Arrhythmogenic Magnetic Resonance Pattern

Light chain deposition disease (LCDD) is a rare plasma cell dyscrasia consisting of nonamyloidotic deposition of misfolded immunoglobulin light chain (LC) in tissues and organs. Heart involvement is a rare and late event in the course of the disease.1 Therefore, such a nonfibrillar deposition of LC in the myocardium has so far been described only in few endomyocardial biopsies. Potentially lethal ventricular arrhythmias and a nondiagnostic echocardiogram are 2 clinical hallmarks of the disease.1,2 In addition, no other in vivo imaging of the condition is presently available. A 52-year-old man was admitted to the emergency department for syncope at rest. ECG showed a sinus rhythm with negative T waves in inferolateral leads alternating with ventricular bigeminism and episodes of torsades de pointes triggered by R-on-T phenomenon (Figure 1A). The previous history included serum IgGκ + κ monoclonal gammopathies and nephrotic syndrome. The bone marrow biopsy showed 60% clonal plasma cells, and the kidney biopsy examination by immunofluorescence and immunoelectron microscopy was consistent with LCDD. Light microscopic finding of kidney biopsy showed glomeruli with increased mesangial cellularity and nodular expansion of mesangial matrix; mesangial nodules were positive at periodic acid Schiff and trichrome stain (Figure 2A …