The assessment of autonomic function in patients with systemic amyloidosis: methodological considerations

Autonomic neuropathy is a well-known and prognostically important feature of systemic amyloidosis. In other conditions, autonomic function is commonly assessed by cardiovascular reflex tests, described by Ewing, but the feasibility of these tests has not been investigated in patients with systemic amyloidosis. We studied autonomic function in amyloidotic patients using cardiovascular tests and assessed their feasibility. Patients with AA, AL and ATTR amyloidosis participated. In all patients, cardiovascular reflex testing (mental arithmetic stress test and head-up tilting, besides the Ewing-tests) was performed. Of the 46 patients included, only 28 patients could perform all 4 Ewing-tests. In particular, patients with AA amyloidosis secondary to rheumatoid arthritis could not perform standing up and the isometric handgrip test. However, when the mental stress test replaced the handgrip test and head-up tilting replaced standing up, in 45 of the 46 patients, autonomic function could be assessed with cardiovascular reflex tests. Half of the patients with AA amyloidosis had signs of autonomic neuropathy--which was more than expected. We propose to replace the isometric handgrip test with the mental arithmetic stress test and standing up with head-up tilting if a patient is not able to perform these tests.