Myocardial Edema and Prognosis in Amyloidosis

Abstract

Background: Prognosis in light-chain (AL) and transthyretin (ATTR) amyloidosis is influenced by cardiac involvement. ATTR amyloidosis has better prognosis than AL amyloidosis despite more amyloid infiltration, suggesting additional mechanisms of damage in AL amyloidosis.

Objectives: The aim of the study was to assess the presence and prognostic significance of myocardial edema in patients with amyloidosis.

Methods: The study recruited 286 patients: 100 with systemic AL amyloidosis, 163 with cardiac ATTR amyloidosis, 12 with suspected cardiac ATTR amyloidosis (grade 1 on ^99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid), 11 asymptomatic individuals with amyloidogenic TTR gene mutations, and 30 healthy volunteers. All subjects underwent cardiovascular magnetic resonance with T1 and T2 mapping and 16 underwent endomyocardial biopsy.

Results: Myocardial T2 was increased in amyloidosis with the degree of elevation being highest in untreated AL patients (untreated AL amyloidosis 56.6 ± 5.1 ms; treated AL amyloidosis 53.6 ± 3.9 ms; ATTR amyloidosis 54.2 ± 4.1 ms; each p < 0.01 compared with control subjects: 48.9 ± 2.0 ms). Left ventricular (LV) mass and extracellular volume fraction were higher in ATTR amyloidosis compared with AL amyloidosis while LV ejection fraction was lower (p < 0.001). Histological evidence of edema was present in 87.5% of biopsy samples ranging from 5% to 40% myocardial involvement. Using Cox regression models, myocardial T2 predicted death in AL amyloidosis (hazard ratio: 1.48; 95% confidence interval: 1.20 to 1.82) and remained significant after adjusting for extracellular volume fraction and N-terminal pro-B-type natriuretic peptide (hazard ratio: 1.32; 95% confidence interval: 1.05 to 1.67).

Conclusions: Myocardial edema is present in cardiac amyloidosis by histology and cardiovascular magnetic resonance T2 mapping. T2 is higher in untreated AL amyloidosis compared with treated AL and ATTR amyloidosis, and is a predictor of prognosis in AL amyloidosis. This suggests mechanisms additional to amyloid infiltration contributing to mortality in amyloidosis.

Keywords: CMR; T2 mapping; amyloidosis.