Prevalence and prognostic value of small fiber neuropathy assessed by Sudoscan ® in transthyretin wild-type cardiac amyloidosis

Abstract

The prevalence of small-fiber neuropathy (SFN) is high in patients with hereditary transthyretin amyloidosis (ATTRv) but remains unknown in transthyretin wild-type cardiac amyloidosis (ATTRwt-CA). To determine the prevalence of SFN in patients with ATTRwt-CA using Sudoscan®, a non-invasive method used to provide evidence of SFN in clinical practice and based on measurement of electrochemical skin conductance at the hands (hESC) and feet (fESC). A series of 62 non-diabetic patients with ATTRwt-CA was prospectively included over 2 years and compared to healthy elderly subjects, matched on age, gender and body mass index. The presence of SFN was defined as hESC < 60 μS and/or fESC < 70 μS and conductances were analyzed according to clinical, biological, and echocardiographic data. Mean hESC and fESC were significantly lower in patients with ATTRwt-CA than in elderly controls: 61.5 vs. 70.0 μS ( P = 0.006) and 68.3 vs. 76.9 μS respectively ( P < 0.0001). Prevalence of hESC < 60 μS and fESC < 70 μS was higher in patients with ATTRwt-CA than in controls: 33.9% versus 16.7% and 48.4% versus 19.9%, P < 0.05. Univariate analysis showed that fESC, NT-proBNP, creatinine plasma levels, and echocardiographic global longitudinal strain were associated with decompensated cardiac failure and death. Multivariate analysis revealed that fESC was an independent prognostic factor and Kaplan-Meier estimator evidenced a larger occurrence of cardiac decompensation and death in patients with fESC < 70 μS, P = 0.046. A reduced fESC was observed in almost 50% of patients with ATTRwt-CA and was associated with a worse prognosis. Sudoscan® could be used easily to screen ATTRwt-CA patients for the presence of SFN and identify patients at higher risk of outcome.