Department of Cardiovascular Medicine, Shinshu Univerisity
Cardiac amyloidosis is a cardiomyopathy characterized by increased left ventricular（LV）wall thickness and normal or decreased LV cavity size. Congestive heart failure in cardiac amyloidosis is generally considered a predominantly diastolic phenomenon, with systolic dysfunction only occurring late in the disease. Echocardiography is a noninvasive, reproducible method to assess cardiac features and function in cardiac amyloidosis, and some echocardiographic indices are prognostic in systemic amyloidosis, with M-mode and two-dimensional echocardiography able to detect increased LV wall thickness. Moreover, Doppler flow measurements can incrementally assess diastolic LV dysfunction, which is characteristic of cardiac amyloidosis, and provide important prognostic information. Additionally, tissue Doppler imaging can detect subtle changes in both systolic and diastolic LV functions, which cannot be detected by Doppler flow measurements, and LV longitudinal strain assessed by color tissue Doppler and speckle tracking echocardiography can provide more accurate LV functional and prognostic information than tissue Doppler imaging especially in light-chain amyloidosis. Many studies have focused on light-chain associated cardiac amyloidosis, but recently several studies concerning about transthyretin associated cardiac amyloidosis（ATTR）had been reported. Mutated ATTR cardiac amyloidosis is characterized by progressive impairment in longitudinal and basal radial function when global circumferential shortening and torsion remain unchanged. When we compare the cardiac function in ATTR（wt, wild type）and ATTR（m, mutated type）patients who were selected from an echocardiographic database and matched by age and LV wall thickness, patients with ATTRwt are characterized by lower ejection fraction, LV basal, and LV mid-radial strains compared with patients with ATTRm. As determined by ROC curve analysis, LVEF＜50.5％could discriminate 2 types of cardiac amyloidosis with sensitivity 76.2％and specificity 85％，and LV basal mean radial strain＜19.9％with sensitivity 76.2％and specificity 90％． A multi-layer approach of measuring myocardial strain demonstrated that complete endomyocardial radial systolic dysfunction and longitudinal transmural systolic dysfunction exist in basal and mid-LV wall in both patients with light-chain and ATTRm amyloidosis. Thus, echocardiography is useful in assessing cardiac function, prognosis especially in light-chain amyloidosis, and in differentiation between ATTRwt and ATTRm.