Cardiac Amyloidosis Without Increased Left Ventricular Wall Thickness

Objectives: To determine how often left ventricular wall thickness (LVWT) is normal and to assess the effect of LVWT on clinical outcomes of patients with immunoglobulin light chain (AL) cardiac amyloidosis. Patients and Methods: A total of 117 patients with systemic AL amyloidosis were retrospectively categorized from April 1, 1995, to September 15, 2012; group A included cardiac amyloidosis patients with an LVWT greater than 12 mm (45 patients); group B, cardiac amyloidosis patients with an LVWT of 12 mm or less (25 patients); and group C, no evidence of cardiac amyloidosis (47 patients). We compared echocardiographic parameters and survival rates among the 3 groups. Results: No differences were found between groups A and B in the following parameters: left ventricular ejection fraction (median, 56% [interquartile range (IQR), 46%-63%] vs 56% [IQR, 49%-63%], P=.76), left arterial volume index (median, 44.5 [IQR, 38.5-59.7] vs 43.9 [IQR, 33.8-57.1] mL/m(2), P=.79), e' (median, 0.04 [IQR, 0.03-0.05] vs 0.05 [IQR, 0.04-0.06] m/s, P=.10), and E/e' (early diastolic mitral inflow velocity (E)/e') (median, 18.4 [IQR, 12.0-23.3] vs 18.0 [IQR, 13.6-25.0], P=.98). Patients in group C exhibited significantly different values for these parameters (median, 65% [IQR, 61%-69%], 23.4 [IQR, 18.0-29.0] mL/m(2), 0.08 [IQR, 0.06-0.09] m/s, and 8.8 [IQR, 7.2-10.5], respectively; all P<.001). The survival rates were statistically different, with median survival times of 422, 729, and 2080 days in groups A, B, and C, respectively (P=.002). Using multivariate Cox proportional hazards regression analysis, we found that age, an N-terminal pro-B-type natriuretic peptide level of 1800 pg/mL or greater, E/e', and complete hematologic remission were significant predictors of survival. Conclusions: A third of patients with AL cardiac amyloidosis were diagnosed as having an LVWT of 12 mm or less. Because appropriate therapy can improve the survival of patients with AL cardiac amyloidosis, early detection by sensitive diagnostic methods should be pursued even when LVWT is not increased. (C) 2014 Mayo Foundation for Medical Education and Research