Abstract 17644: Noninvasive Assessment of Diastolic Myocardial Stiffness by Echocardiography in Patients With Cardiac Amyloidosis

Abstract

Background: Cardiac amyloidosis (CA) results from extracellular deposition of insoluble amyloid fibrils in the myocardium, leading to myocardial stiffening, restrictive cardiomyopathy and poor prognosis. Thus, measurements of myocardial stiffness might help with identification of patients with cardiac amyloid deposition. The speed of wave transmission of myocardial stretch (Vm) is a novel measure of myocardial elasticity. Our aim was to investigate the behavior of Vm in the left ventricular (LV) myocardium of patients with CA. We hypothesized this wave speed will be increased in these patients and will partly explain the reduction in systolic myocardial function. Methods: We prospectively studied 23 consecutive patients with systemic amyloidosis, of whom 17 (age 59±13 years) had confirmed cardiac involvement (15 AL, 2 TTR), and compared to 18 control subjects (age 47±13 years) with normal LV function. Comprehensive transthoracic echocardiography was performed. Tissue Doppler cineloops (350-450 frames/s) were acquired from 6 LV walls from 3 standard apical views. Regional and global Vm were measured as the wave speed of the onset of myocardial stretch from LV base to apex (late diastole). Results: Subjects with CA (n=17) had higher Vm compared to normal subjects (2.5±0.8 vs 1.5±0.2 m/s; P<0.001, respectively). They also had lower LV ejection fraction (56±11 vs 65±4%; P=0.02), global longitudinal strain (GLS -14±5 vs -20±2%, P<0.001), and myocardial relaxation (mitral annulus septal e’ velocity 4.7±1.9 vs 9.2±2.4 cm/s; P<0.001) and higher LV mass (150±54 vs 87±18 g/m2; P<0.001), left atrial volume (44±7 vs 27±6 mL/m2; P<0.001), and estimated LV filling pressure (E/e’ 20±9 vs 8±3; P<0.001). There was a strong positive association between Vm and LV wall thickness (R=0.62; P<0.001), GLS (R=0.45; P=0.01) and septal E/e’ (R=0.42; P=0.02) and an inverse correlation between Vm and septal e’ (R=-0.39; P=0.03), but not with ejection fraction (P=0.37). Conclusion: This pilot study indicates that Vm is elevated in patients with CA compared to normal subjects, commensurate with the effects of amyloid deposition on LV structure and function. This novel measurement shows promise for noninvasive assessment of diastolic myocardial stiffness in patients with CA.