Familial amyloid polyneuropathy (FAP) is a rare and severe hereditary form of
amyloidosis, due to nervous deposits of a genetic variant
transthyretin produced by the liver and characterized by both sensorimotor and autonomic neuropathy.
Left ventricular systolic dysfunction is rare, but conduction disturbances and sudden deaths can occur. The neurological status of the heart has not been elucidated, and an alteration of the sympathetic nerves may be involved. We studied 17 patients (42+/-12 years) before
liver transplantation by
iodine-123 metaiodobenzylguanidine (
MIBG) scintigraphy, heart rate variability analysis, coronary angiography,
radionuclide ventriculography, rest
thallium single-photon emission tomography (SPET) and echocardiography. Coronary arteries, left ventricular systolic function and rest
thallium SPET were normal in all patients. Only mild evidence of
amyloid infiltration was found at echocardiographic examination. Cardiac
MIBG uptake was dramatically decreased in patients compared with age-matched control subjects (heart-to-mediastinum activity ratio at 4 h: 1.36+/-0.26 versus 1.98+/-0.35, P<0.001), while there was no difference in
MIBG washout rate. Heart rate variability analysis showed a considerable scatter of values, with high values in four patients despite cardiac
sympathetic denervation as assessed by
MIBG imaging. The clinical severity of the
polyneuropathy correlated with
MIBG uptake at 4 h but not with the heart rate variability indices. Cardiac
MIBG uptake and the heart rate variability indices did not differ according to the presence or absence of conduction disturbances. Patients with FAP have sympathetic cardiac
denervation as assessed by
MIBG imaging despite a preserved left ventricular systolic function and cardiac perfusion, without correlation with conduction disturbances. Results of the heart rate variability analysis were more variable and this technique does not seem to be the best way to evaluate the extent of cardiac
sympathetic denervation in FAP patients.