Abstract 11919: Cardiac Conundrum: A Novel Case of Isolated Cardiac Scleromyxedema

Abstract

Case Presentation: A 41-year-old woman with history of diabetes, inferior STEMI with RCA PCI, and HFmrEF was transferred to our hospital with worsening cardiogenic shock on ionotropic support. She was admitted to an outside facility one month prior with worsening dyspnea on exertion, peripheral edema, paroxysmal nocturnal dyspnea, pre-syncope, and weakness. TTE demonstrated LVEF of 30-35% (40-45% previously) with severe inferior and posterior wall hypokinesis. Cardiac MRI revealed LVEF of 23%, prior RCA infarct, full-thickness late gadolinium enhancement in the left ventricular basilar wall, global abnormal parametric mapping parameters of both native T1, T2 and ECV, and severe biventricular dysfunction concerning for infiltrative cardiomyopathy. Left heart catheterization revealed nonobstructive CAD. Right heart catheterization showed severely elevated right sided filling pressures and endomyocardial biopsy revealed frequent deposits of interstitial mucin (Figure 1), later confirmed by electron microscopy; a Congo red stain was negative for amyloid deposition. Additional work up included serum protein electrophoresis, which was negative for monoclonal proteins. She had no dermatologic disease. A diagnosis of isolated cardiac scleromyxedema was made. Discussion: Scleromyxedema is a rare mucinous disorder typically characterized by cutaneous mucin deposits and fibroblastic proliferation. It is commonly associated with monoclonal gammopathies, specifically IgG lambda; however, there are rare cases without paraproteinemia. Systemic mucinous infiltration has been reported and cardiac involvement specifically has been described in up to 20% of patients, although it has never been reported without cutaneous manifestations or monoclonal gammopathy as demonstrated with our patient. The patient received IVIg treatment, however required two additional hospitalizations over the next four months for decompensated heart failure.