BACKGROUND - Cardiac amyloidosis is an infiltrative cardiomyopathy that is challenging to diagnose. We hypothesized that the novel biomarkers hepatocyte growth factor (HGF), galectin-3 (GAL-3), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF) would be elevated in cardiac amyloidosis and may be able to discriminate from non-cardiac systemic amyloidosis or other cardiomyopathies with similar clinical or morphologic characteristics.
METHODS - Patients were selected from the Vanderbilt Main Heart Registry according to the following groups: (1) amyloid light-chain (AL) cardiac amyloidosis (n = 26); (2) transthyretin (ATTR) cardiac amyloidosis (n = 7); (3) left ventricular hypertrophy (LVH) (n = 45); (4) systolic heart failure (n = 42); and (5) non-cardiac systemic amyloidosis (n = 7). Biomarkers were measured in stored plasma samples. Biomarkers' discrimination performance in predicting AL cardiac amyloidosis (i.e., Concordance index) was reported. A survival analysis was used to explore the relationship between HGF levels and mortality among AL cardiac amyloidosis patients.
RESULTS - HGF levels were markedly elevated in patients with AL cardiac amyloidosis (median = 622, interquartile range (IQR): 299-1228 pg/mL) compared with the other groups, including those with non-cardiac systemic amyloidosis (median = 134, IQR: 94-163 pg/mL, p < 0.001). HGF was not a specific marker for ATTR amyloidosis. Gal-3 was elevated in all groups with amyloidosis but could not differentiate between those with and without cardiac involvement. There was no difference in IL-6 or VEGF between those with AL cardiac amyloidosis compared to other groups (p = 0.13 and 0.057, respectively).
CONCLUSIONS - HGF may be a specific marker that distinguishes AL cardiac amyloidosis from other cardiomyopathies with similar clinical or morphologic characteristics. Further studies are necessary to determine whether HGF levels predict the likelihood of survival.