Previous work has demonstrated that familial amyloid polyneuropathy (FAP) and light-chain amyloidosis with similar degrees of cardiac involvement cannot be distinguished by standard echocardiographic parameters, yet the severity of congestive heart failure and cardiac mortality is much less in FAP. It was therefore hypothesized that strain and strain-rate imaging, sensitive markers of longitudinal systolic dysfunction, might detect a difference in left ventricular function between FAP and light-chain amyloidosis that could account for the clinical differences.