What is the role of amyloidosis in the etiology of dilated cardiomyopathy?

Updated: Nov 28, 2018
  • Author: Vinh Q Nguyen, MD; Chief Editor: Gyanendra K Sharma, MD, FACC, FASE  more...
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Answer

The most common type of amyloidosis involving the myocardium results from plasma cell dyscrasias. The extracellular deposition of insoluble amyloid fibrils due to protein misfolding causes predominantly diastolic heart failure, followed by systolic heart failure in advanced stages. [45] Conduction block is also present, as is pericardial involvement, manifested by pericardial effusion. [46]  It is diagnosed via EMB or with noninvasive modalities, such as the following:

  • Echocardiography: The echocardiographic appearance of cardiac amyloidosis includes LV and right ventricular (RV) wall thickness with a normal chamber size, pericardial effusion, granular myocardial appearance, atrial enlargement, and thickened papillary muscles and valves, with valvular dysfunction if endocardial involvement is present. [44]  Two-dimensional speckle tracking demonstrates “apical sparing” of longitudinal strain. The disease involves the four chambers; thus, there is also atrial involvement. Atrial strain reveals impaired atrial systole and diastole and thereby acts as a conduit. The combination of low atrial stroke volume and irregular endocardial deposits due to amyloid deposits leads to a thrombogenic atrium. [47]
  • Cardiac MRI: This imaging modality shows diffuse subendocardium late gadolinium enhancement (LGE) in both ventricles. [48]
  • Electrocardiography (ECG): The QRS amplitude is decreased.

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