Cardiac Diffusion Tensor Imaging May Detect Early Cardiac Amyloidosis in Carpal Tunnel Syndrome

Cardiac amyloidosis (CA) occurs when amyloid fibrils deposit in the myocardium, leading to diastolic dysfunction and subsequent heart failure. An early symptom of systemic amyloidosis is carpal tunnel syndrome (CTS). The prevalence of CTS in patients with transthyretin amyloidosis has been shown to be up to 50%, with CTS preceding clinically overt CA by 5 to 10 years on average.

This study applied cardiac diffusion tensor imaging (cDTI) to patients with CTS who underwent carpal tunnel release surgery and had confirmed amyloid deposition on tenosynovial biopsy in an attempt to screen for early CA.

cDTI was performed on 20 patients with CTS with confirmed tenosynovial amyloid, 20 patients with CA, 20 patients with hypertrophic cardiomyopathy, and 20 healthy controls. The diffusion scheme was an electrocardiogram-gated, free-breathing, second-order, motion-compensated spin echo acquisition obtained in systole. Mean diffusivity (MD), fractional anisotropy (FA), helix angle transmurality, absolute sheetlet angle, T1, and T2 were calculated from respiratory motion-corrected images.

MD was significantly elevated in CA compared to CTS (1.79 ± 0.16 vs 1.63 ± 0.09, P = 0.0016), and in CTS compared to healthy controls (1.63 ± 0.09 vs 1.51 ± 0.10, P = 0.0016). FA was significantly reduced in CA compared to controls (0.25 ± 0.052 vs 0.31 ± 0.057, P = 0.0044) and CTS compared to controls (0.24 ± 0.027 vs 0.31 ± 0.057, P = 0.0004). cDTI outperformed T1 and T2 in distinguishing between healthy myocardium and those of the CA and CTS groups.

MD and FA were significantly different between healthy patients and those with CA or CTS, suggesting that cDTI may detect evidence of myocardial microstructural alterations consistent with possible early CA.