Israel Medical Association Journal

Eosinophilic myocarditis (EM) is a rare form of myocardial inflammation defined by eosinophilic infiltration with associated myocyte injury. Its clinical expression is heterogeneous, ranging from subtle symptoms of heart failure to fulminant cardiogenic shock. Because these features often overlap with other types of myocarditis and systemic conditions, establishing the diagnosis can be difficult. In such cases, endomyocardial biopsy (EMB) remains the reference standard.

Amyloid transthyretin (ATTR) cardiac amyloidosis is an infiltrative cardiomyopathy marked by amyloid fibril deposition in the heart's extracellular space. It usually presents with signs of heart failure, and echocardiography often shows concentric left ventricular hypertrophy (LVH), restrictive physiology, and a distinctive pattern of apical strain sparing. In recent years, the development of non-invasive diagnostic methods, as well as the availability of disease-modifying treatments, has significantly improved diagnosis and management.

To the best of our knowledge, the coexistence of ATTR cardiac amyloidosis and EM has not been previously reported. Such overlap presents distinct diagnostic and therapeutic challenges. These conditions may have synergistic effects on the structure and function of the myocardium. We describe a case of concurrent ATTR cardiac amyloidosis and EM, highlighting the role of multimodality imaging and multidisciplinary management of these overlapping pathologies.

Cardiac amyloidosis is a form of restrictive cardiomyopathy resulting from the accumulation of misfolded protein aggregates in the myocardial extracellular space. Cardiac amyloidosis stems primarily from the misfolding of monoclonal immunoglobulin light chains (AL) originating from abnormal clonal plasma cell proliferation or transthyretin amyloidosis (ATTR).

Diagnosis of amyloidosis demands a high index of suspicion and requires histological confirmation of pathognomonic green birefringence under polarized light when an infiltrated tissue specimen is stained with Congo-red staining [1,2].

Pleural involvement of systemic amyloidosis has rarely been reported and is considered a serious complication [3]. Pleural amyloidosis is diagnosed with the identification of amyloid deposits in pleural biopsy specimens. However, pleural biopsies are rarely performed for this indication.

We describe the case of a patient with AL cardiac amyloidosis presenting as intractable pleural effusion and diagnosed via pleural biopsy.

Background: Cardiac amyloidosis (CA) is characterized by the extracellular deposition of misfolded protein in the heart. Precise identification of the amyloid type is often challenging, but critical, since the treatment and prognosis depend on the disease form and the type of deposited amyloid. Coexistence of clinical conditions such as old age, monoclonal gammopathy, chronic inflammation, or peripheral neuropathy in a patient with cardiomyopathy creates a differential diagnosis between the major types of CA: amyloidosis light chains (AL), amyloidosis transthyretin (ATTR) and amyloidosis A (AA).

Objectives: To demonstrate the utility of the Western blotting (WB)-based amyloid typing method in patients diagnosed with cardiac amyloidosis where the type of amyloid was not obvious based on the clinical context.

Methods: Congo red positive endomyocardial biopsy specimens were studied in patients where the type of amyloid was uncertain. Amyloid proteins were extracted and identified by WB. Mass spectrometry (MS) of the electrophoretically resolved protein-in-gel bands was used for confirmation of WB data.

Results: WB analysis allowed differentiation between AL, AA, and ATTR in cardiac biopsies based on specific immunoreactivity of the electrophoretically separated proteins and their characteristic molecular weight. The obtained results were confirmed by MS.

Conclusions: WB-based amyloid typing method is cheaper and more readily available than the complex and expensive gold standard techniques such as MS analysis or immunoelectron microscopy. Notably, it is more sensitive and specific than the commonly used immunohistochemical techniques and may provide an accessible diagnostic service to patients with amyloidosis in Israel.