Role of ambulatory blood pressure monitoring as a non-invasive autonomic screening tool in hereditary transthyretin amyloidosis.

Abstract

Hereditary transthyretin amyloidosis (ATTRv) is a life-threatening disease with frequent autonomic manifestations. Autonomic testing is not widely accessible, which might cause underdiagnosis of autonomic dysfunction and delay in treatment. This retrospective study evaluates ambulatory 24-hour blood pressure measurement (ABPM) as a screening tool for neurogenic orthostatic hypotension (nOH), postprandial hypotension and worsening of orthostatic tolerance postexercise by comparison with gold standard testing. Furthermore, it investigates circadian BP rhythm in ATTRv over time. 93 patients and 12 asymptomatic <i>TTR</i> variant carriers had ABPM including autonomic diary and quantitative autonomic function testing (AFT; 30% females, mean age 57.6 years). A subset of individuals underwent a modified exercise and liquid meal test. 47 individuals had follow-up ABPM. Sensitivity/specificity of ABPM in detecting nOH and postprandial hypotension were 73%/98% and 86%/81%, respectively. ABPM captured worsening of orthostatic tolerance postexercise (p=0.007). 71/105 (68%) individuals showed an abnormal dipping profile (51 reduced dippers, 20 non- or reverse dippers), and 4/71 were carriers (all reduced dippers). All non- or reverse dippers presented with pathologic AFT. 7/8 (88%) carriers and 20/26 (77%) patients with normal ABPM had abnormal AFT. At follow-up, 21% showed progressive circadian rhythm abnormalities. ABPM with an autonomic diary is a widely accessible screening tool to detect nOH, postprandial hypotension, and impaired circadian rhythm. However, it does not allow for a quantitative parasympathetic/sympathetic assessment confirming subtle autonomic dysfunction, which is why a formal AFT is still required. Pathologic BP profiles are common in ATTRv, including in certain carriers, and can show progression over time.