Cardiac Structural and Functional Consequences of Amyloid Deposition by Cardiac Magnetic Resonance and Echocardiography and Their Prognostic Roles.

OBJECTIVES: This cross-sectional study aimed to describe the functional and structural cardiac abnormalities that occur across a spectrum of cardiac amyloidosis burden and to identify the strongest cardiac functional and structural prognostic predictors in amyloidosis using cardiac magnetic resonance (CMR) and echocardiography. BACKGROUND: Cardiac involvement in light chain and transthyretin amyloidosis is the main driver of prognosis and influences treatment strategies. Numerous measures of cardiac structure and function are assessed by multiple imaging modalities in amyloidosis. METHODS: A total f 322 subjects (311 systemic amyloidosis and 11 transthyretin gene mutation carriers) underwent comprehensive CMR and transthoracic echocardiography. The probabilities of 11 commonly measured structural and functional cardiac parameters being abnormal with increasing cardiac amyloidosis burden were evaluated. Cardiac amyloidosis burden was quantified using CMR-derived extracellular volume. The prognostic capacities of these parameters to predict death in amyloidosis were assessed using Cox proportional hazards models. RESULTS: Left ventricular mass and mitral annular plane systolic excursion by CMR along with strain and E/e' by echocardiography have high probabilities of being abnormal at low cardiac amyloid burden. Reductions in biventricular ejection fractions and elevations in biatrial areas occur at high burdens of infiltration. The probabilities of indexed stroke volume, myocardial contraction fraction, and tricuspid annular plane systolic excursion (TAPSE) being abnormal occur more gradually with increasing extracellular volume. Ninety patients (28%) died during a median follow-up of 22 months (interquartile range: 10 to 38 months). Univariable analysis showed that all imaging markers studied significantly predicted outcome. Multivariable analysis showed that TAPSE (hazard ratio: 1.46; 95% confidence interval: 1.16 to 1.85; p < 0.01) and indexed stroke volume (hazard ratio: 1.24; 95% confidence interval: 1.04 to 1.48; p < 0.05) by CMR were the only independent predictors of mortality. CONCLUSIONS: Specific functional and structural abnormalities characterize different burdens of cardiac amyloid deposition. In a multimodality imaging assessment of a large cohort of amyloidosis patients, CMR-derived TAPSE and indexed stroke volume are the strongest prognostic cardiac functional markers.

Myocardial Edema and Prognosis in Amyloidosis.

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.

Magnetic Resonance in Transthyretin Cardiac Amyloidosis.

BACKGROUND: Cardiac transthyretin amyloidosis (ATTR) is an increasingly recognized cause of heart failure. Cardiac magnetic resonance (CMR), with late gadolinium enhancement (LGE) and T1 mapping, is emerging as a reference standard for diagnosis and characterization of cardiac amyloidosis. OBJECTIVES: The authors used CMR with extracellular volume fraction (ECV) measurement to characterize cardiac involvement in relation to outcome in ATTR. METHODS: Subjects comprised 263 patients with cardiac ATTR corroborated by grade 2 to 3 99mTc-DPD (99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid) cardiac uptake, 17 with suspected cardiac ATTR (grade 1 99mTc-DPD), and 12 asymptomatic individuals with amyloidogenic transthyretin (TTR) mutations. Fifty patients with cardiac light-chain (AL) amyloidosis acted as disease comparators. RESULTS: Unlike cardiac AL amyloidosis, asymmetrical septal left ventricular hypertrophy (LVH) was present in 79% of patients with ATTR (70% sigmoid septum and 30% reverse septal contour), whereas symmetrical LVH was present in 18%, and 3% had no LVH. In patients with cardiac amyloidosis, the pattern of LGE was always typical for amyloidosis (29% subendocardial, 71% transmural), including right ventricular LGE (96%). During follow-up (19 ± 14 months), 65 patients died. ECV independently correlated with mortality and remained independent after adjustment for age, N-terminal pro-B-type natriuretic peptide, ejection fraction, E/E', and left ventricular mass (hazard ratio: 1.164; 95% confidence interval: 1.066 to 1.271; p < 0.01). CONCLUSIONS: Asymmetrical hypertrophy, traditionally associated with hypertrophic cardiomyopathy, was the commonest pattern of ventricular remodeling in ATTR. LGE imaging was typical in all patients with cardiac ATTR. ECV correlated with amyloid burden and was an independent prognostic factor for survival in this cohort of patients.