Characteristic echocardiographic appearance of cardiac amyloid includes increased thickness of both LV and right ventricular walls, normal or small LV cavity size, and a nonspecific granular appearance of the myocardium. Atrial enlargement, thickened papillary muscles, and valve leaflets and small to moderate pericardial effusion are also commonly present. LV compliance gradually decreases as myocardial deposition of amyloid fibrils progresses. The hallmark of Doppler Echocardiography is the feaature of a restrictive cardiomyopathy with low myocardial velocities on tissue Doppler with classical pulsed wave patterns of mitral and pulmonary vein flow. Progressive diastolic dysfunction is a universal finding. Systolic dysfunction is typically evident only in the advanced stage. Recently an interesting finding has been noted on evaluation of longitudinal strain of the left ventricle with demonstration of a a pattern of relative sparing of the apex from the decreased strain noted in basal segments. This appears to be highly specific for amyloidosis (ref. 4).
Doppler echocardiography is used to establish and serially monitor the magnitude of diastolic and systolic dysfunction. CMR will show diffuse LGE (late Gadolinium enhancement) throughout both ventricles, particularly the subendocardium .
Despite increased ventricular wall thickness, 30% to 50% of patients with demonstrable amyloid disease will have normal-voltage QRS complexes, and the remainder show low-voltage complexes. A pseudoinfarction pattern, particularly in the inferoseptal wall, may be observed in the precordial leads. A decrease in QRS complex amplitude occurs because of myocyte atrophy along with decreased conduction velocity and dyssynchronous activation resulting from amyloid deposition.
Cardiac amyloidosis is diagnosed either directly by endomyocardial biopsy or indirectly using noninvasive diagnostic tools (2-dimensional echocardiography, magnetic resonance imaging, and ECG) and histologic confirmation of amyloid on a noncardiac tissue specimen. Upon unequivocal establishment of the diagnosis and tissue confirmation of amyloid type, prompt therapy is warranted for primary amyloidosis to arrest or reverse cardiac dysfunction .
Poor cardiac reserve severely narrows the management strategies in the late stages. Untreated patients have a median survival of 6 months after the onset of heart failure. Melphalan, steroids, immune-modulating agents, and stem cell transplantation after chemotherapy yield promising results.
1. James B. Seward, MD, Grace Casaclang-Verzosa, MD J Am Coll Cardiol 2010;55:1769–79 A review on infiltrative cardiomyopathies
2. Eui-Young Choi et al. ,J Am Soc Echocardiogr 2007;20:738-743 Tissue Doppler in restrictive myopathy versus contrictive pericardiitis
3. Jun Koyama, and Rodney H. Falk J. Am. Coll. Cardiol. Img. 2010;3;333-342. Prognostic Significance of Strain Doppler Imaging in Light-Chain Amyloidosis
4. Phelan et al. Heart 2012; 98:1442e1448. Relative apical sparing of longitudinal strain