Researchers discovered that cardiac amyloid burden is associated with all-cause mortality in patients with transthyretin (ATTR) amyloidosis, according to a study published in the Journal of the American College of Cardiology: Cardiovascular Imaging.

In systemic amyloidosis, misfolded fibrillar proteins are deposited into the tissues of the body. This causes the extracellular space to expand and impairs the proper functioning of these tissues. 

“In particular, ATTR amyloidosis has been found in multiple settings of heart failure,” the authors of the study wrote. “For example, in 13% of patients with heart failure with preserved ejection fraction and in 1 in 7 elderly patients (75 years of age and over) with severe aortic stenosis undergoing transcatheter aortic valve replacement.”

Therapeutic advancements mean that early identification of cardiac amyloidosis is key to improving long-term clinical outcomes. The extracellular expansion caused by myocardial infiltration of amyloid fibrils can be quantified by extracellular volume fraction imaging using computed tomography (ECVCT). ECVCT is well tolerated and takes just over 3 minutes to complete; in addition, it can be done in patients with cardiac pacemakers or defibrillators. 

Read more about hereditary ATTR amyloidosis patient education

The authors of the study sought to investigate any association between ECVCT and mortality in patients with systemic amyloidosis. Patients with systemic amyloidosis (n=77) were recruited for this study and underwent various cardiac assessments, such as electrocardiography, echocardiography, and the 6-minute walk test. The researchers analyzed whole cardiac and septal ECVCT and compared the values obtained across different extents of cardiac infiltration. They then assessed the association between ECVCT and all-cause mortality. 

“ECVCT increased with cardiac amyloid involvement in both [light chain] and [ATTR amyloidosis],” the authors of the study reported. “Septal ECVCT was independently associated with all-cause mortality in [ATTR amyloidosis] after adjustment for age and septal wall thickness.” 

In conclusion, ECVCT correlates with parameters of adverse myocardial remodeling; in the ATTR subtype, it is also independently associated with all-cause mortality.

Reference

Gama F, Rosmini S, Bandula S, et al. Extracellular volume fraction by computed tomography predicts long-term prognosis among patients with cardiac amyloidosisJACC Cardiovasc Imaging. Published online October 19, 2022. doi:10.1016/j.jcmg.2022.08.006