Usefulness of the nerve ultrasound for the transthyretin amyloid cardiomyopathy

<p>Symptoms of transthyretin amyloid cardiomyopathy (ATTR-CM) has been known to develop peripheral neuropathy, such as carpal tunnel syndrome (CTS), earlier than cardiac. In this study, we investigated whether nerve ultrasound is useful in the diagnosis of ATTR-CM. Among 18 cases suspected of ATTR-CM at our institution, we used nerve ultrasound to compare the median nerve cross-sectional area (CSA) at the wrist and forearm, the wrist-to-forearm median nerve CSA ratio (WFR), and transthoracic echocardiographic (TTE) findings indicative of cardiac amyloidosis (CA), between 11 patients in the ATTR-CM group and 7 patients in the non-ATTR-CM group. ATTR-CM group had a significantly larger CSA at the wrist (18.0 mm² (IQR: 16.0–20.8) vs 10.0 mm² (10.0–11.0); p < 0.001) and a higher WFR (2.24 (IQR: 2.00–2.42) vs 1.16 (1.03–1.26) ; p < 0.001) compared to non ATTR-CM group, but the difference was not significant at the forearm (p = 0.457). The frequency of TTE findings for CA suspicious in the ATTR-CM group was 27% in pericardial effusion, 64% in the right ventricular wall thickness, 64% in the atrial septal thickness, 36% in the E/A ≥ 2.0, and 73% in the apical sparing, whereas WFR using nerve ultrasound was shown in all patients in the ATTR-CM group. In conclusion, our study suggests that nerve ultrasound may be a useful tool for the diagnosis of ATTR-CM.</p>