Abstract
Background: Right ventricular (RV) function is inadequately investigated and routinely overlooked in transthyretin amyloid cardiomyopathy (ATTR-CM). Novel imaging distinguishers between intrinsic RV myocardial disease in ATTR-CM and primary RV overload disorder phenotypes may enhance mechanistic and pathophysiological understanding of RV dysfunction. We aimed to investigate RV performance in ATTR-CM employing comprehensive 2D and 3D echocardiography, and to compare these indices with primary RV afterload disease. Methods: We investigated conventional and novel indices of RV contractile function, myocardial work and ventricular-vascular coupling in 21 well-characterized ATTR-CM patients, 10 PAH patients and 12 healthy controls. RV long axis function and pulmonary artery (PA) systolic pressure were evaluated using 2D Doppler echocardiography. RV ejection fraction (RVEF), volumes, global longitudinal strain (GLS) and novel myocardial work indices were analyzed by 3D echocardiography. RV elastance (E(es)), afterload (E(a)) and RV-PA coupling (E(es)/E(a)) were estimated using the single-beat volume method. Results: ATTR-CM showed lower RVEF, GLS and E(es), and a higher RV global myocardial work index (GWI), constructive work (GCW), E(a) and reduced RV-PA coupling compared with controls. RV EF, stroke volume, GLS and circumferential strain did not differ between ATTR-CM and PAH. However, GWI, GCW, E(es) and E(a) were lower in ATTR-CM. RV-pulmonary coupling displayed strong association with RV 3D strain (r = 0.84, p < 0.001), whereas RV E(es) (contractility) was related to RV GWI (r = 0.54, p < 0.001). Conclusions: ATTR-CM displayed lower RV performance, higher GMW and reduced RV-PA coupling. Myocardial work indices E(es) and E(a) are novel distinguishers of RV dysfunction phenotypes. The clinical and prognostic value of these novel variables warrant further investigation.