53-Year-Old Amyloid A (AA) Man With a History of Hypertension
A 53-year-old man with history of hypertension presents with gradually worsening shortness of breath and atypical chest pain for a few months. He is a retired professional football player. Symptoms are associated with orthopnea and paroxysmal nocturnal dyspnea; HIV, antinuclear antibody, creatinine, ceruloplasmin, ferritin, angiotensin-converting enzyme, thyroid stimulating hormone and serum protein electrophoresis were normal. Electrocardiogram demonstrates normal sinus rhythm with low voltage and first degree atrioventricular block. His physical examination is consistent with acute decompensated heart failure. Echocardiogram reveals increased thickening of left ventricular wall (end diastolic inter-ventricular septum diameter of 13 mm), with mildly reduced left ventricular systolic function (estimated left ventricular ejection fraction of 40-45%), and left atrial enlargement (see Figures 1, 2 and 3). Cardiac catheterization demonstrates minimal coronary disease. Cardiac magnetic resonance imaging (MRI) reveals diffuse thickening of left ventricular wall from base to mid cavity. There is global hypokinesis of the left and right ventricles. Both atria are enlarged. There are no perfusion abnormalities, but patchy diffuse heterogeneous late gadolinium enhancement of left ventricular wall, with intramural and subendocardial component from base to apex, and right ventricular inferior wall involvement are present.
Given the above, which of the following describes the most likely diagnosis?