Cardiac amyloidosis diagnosed by endomyocardial biopsy. Clinical, histopathological, immunohistochemical and ultrastructural studies.

Background: The heart is often involved by primary (AL) and familial transthyretin-related (ATTR) amyloidosis. Endomyocardial biopsy is a valuable diagnostic method, useful in detection and recognition of the type of amyloid.

Aim: The aim of the study was to determine the type of amyloid deposits found in endomyocardial biopsies, using histochemical, immunohistochemical and ultrastructural methods. The correlations between morphological and clinical parameters were evaluated.

Methods And Results: During 1999-2004, endomyocardial biopsy was performed in 41 patients hospitalized in our institution due to heart failure of unknown etiology. Amyloid deposits were revealed in 3 patients, in 2 of them the intraoperative specimens were also taken. The deposits were located in myocardial interstitium as well as in the wall of small vessels. One patient showed deposits in the atrial and pericardial walls. Electron microscopy study revealed amyloid fibers adhering to the basement membranes of the myocardial cells and small vessels. Immunohistochemical staining determined two types of amyloid. A woman aged 42 showed transthyretin-related amyloidosis, most probably hereditary. A woman aged 69 exhibited the light chains amyloidosis (AL-lambda). In contrast, diagnosis was not certain (most probably ATTR) in a 35 year old woman. Essential involvement of the pericardium was observed in two younger patients. They underwent pericardiotomy. The survival time (from diagnosis to death) was one year in the patient with amyloidosis ATTR, 17 days in the patient with the AL type, and 2 years in the patient with amyloidosis of undetermined type.

Conclusions: Cardiac amyloidosis is associated with poor prognosis. Better recognition of this disease may allow the early diagnosis and institution of modern therapy.