Cardiac involvement in familial amyloidosis with polyneuropathy

Abstract: Familial amyloidosis with polyneuropathy (FAP) is a neuropathic form of heredofamilial systemic amyloidosis. Clusters of patients have been reported predominantly from Portugal, Japan and Sweden. The present study examines the involvement of the heart in individuals with the Swedish variety of FAP. During long-term ECG recording in 16 patients, a high frequency of disturbances of sinus node function and atrioventricular conduction were observed. Long-term ECG may help considerably in the evaluation of symptoms attributable to disturbances of heart rhythm in FAP. A retrospective survey of 20 patients with FAP treated with a pacemaker showed that the indication for pacing was advanced atrioventricular block (12 cases), dysfunction of the sinus node (5 cases), and atrial fibrillation with a slow ventricular response (3 cases). All patients experienced the effective relief of symptoms attributable to a slow ventricular rate. The long-term prognosis, however, seemed unaffected by this treatment. Histopathological examination of the sinoatrial (9 cases) and atrioventricular (6 cases) parts of the conduction system showed marked amyloid infiltration in all cases, which may explain the high occurrence of disturbances of cardiac rhythm and conduction. Twelve patients were examined by two-dimensional echocardiography and changes of varying degrees, such as highly refractile myocardial echoes (12 cases) and thickened ventricular walls (8 cases) and valves (7 cases), could be observed. Technetium-99m-pyrophosphate scintigraphy of the same patients revealed abnormal myocardial uptake of the isotope only in four. Echocardiography thus seems to be superior to scintigraphy for non-invasive detection of cardiac involvement in FAP. Myocardial samples from regions producing highly refractile myocardial echoes were obtained at in vitro échocardiographie examination of hearts from FAP autopsy cases. Histological examination showed that the highly refractile echoes corresponded to more or less sharply delineated nodules, containing amyloid and collagen in various amounts.