Case report: isolated cardiac amyloidosis: an enigma unravelled

Amyloidosis is a rare, multisystem disease characterized by deposition of fibrils in extracellular tissue involving kidney, liver, heart, autonomic nervous system, and several other organs. This report discusses a 75-year-old male who presented with worsening dyspnea on exertion, orthopnea, and lower-extremity edema. On physical exam, he had elevated jugular venous pressure and lower-extremity edema. Electrocardiogram depicted low voltage in limb leads and a prolonged PR interval. Echocardiogram revealed left ventricular hypertrophy, severe biatrial dilatation, and restrictive filling physiology. Coronary angiography showed absence of significant epicardial coronary artery disease. On right heart catheterization, a "dip-and-plateau sign" was noted on right ventricular pressure tracings. A diagnosis of cardiac amyloidosis was considered, but a complete hematology work-up for systemic amyloidosis was negative. Cardiac magnetic resonance imaging was pursued, showing delayed gadolinium enhancement, and this ultimately led to the myocardial biopsy confirming the diagnosis of isolated cardiac amyloidosis. Further genetic analyses confirmed isolated cardiac amyloid caused by mutant transthyretin protein (Val-122-Ile). Isolated cardiac amyloidosis is an extremely rare entity, and diagnosis may be difficult despite the use of multimodality imaging. If the index of suspicion is high, then myocardial biopsy should be considered.