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Introduction. A clinical case of an 80-year-old patient with clinical and instrumental manifestations of amyloidosis caused by the deposition of non-mutant (“wild type”) transthyretin (Amyloidosis “wild type” TransThyRetin, ATTRwt) is described. A special feature of this case was the diagnosis of amyloidosis at the same time as the identification of symmetrical polyarthritis.Aim. To present an example of successful diagnosis and timely treatment of ATTRwt amyloidosis.Materials and methods. Male patient (80 years old) consulted a rheumatologist in an outpatient clinic with complaints of weakness and pain in the muscles of the upper and lower extremities, swelling and soreness of both wrist joints; with manifestations of multiple tunnel syndromes (ulnar canal, Guyon canals, bilateral carpal tunnel syndrome). In addition, the patient had a heart involvement which appeared as left ventricle hypertrophy, paroxysmal form of atrial fibrillation, chronic heart failure with preserved ejection fraction, intraventricular conduction defect and low QRS voltage. Due to the presence of cardiac manifestations along with neuropathy, transthyretinic amyloidosis was suspected.Results. Polyneuropathy was confirmed by the results of electroneuromyography. AL-amyloidosis (immunoglobulin Light chain Amyloidosis) is excluded due to the absence of monoclonal proteins in the blood. The diagnosis was confirmed by the results of scintigraphy with with labeled technetium-99m pyrophosphate. Intensive accumulation of radiopharmaceutical was detected in the myocardium of the left ventricle. The study also confirmed the presence of polyarthritis, manifested by increased accumulation, in the area of the I metatarsophalangeal joint on the left, both wrist, shoulder and knee joints. The hereditary nature of ATTR amyloidosis was excluded by the results of genetic analysis, which did not reveal mutations in the transthyretin gene. The singularity of this case was in development of a symmetrical polyarthritis during amyloidosis manifestation. Pathogenetic therapy with tafamidis was initiated. Arthritis regressed after starting treatment with methotrexate.Conclusion. Transthyretin amyloidosis is a chronic progressive life-threatening disease caused by the formation and deposition of transthyretin-derived amyloid fibrils. The variety of amyloid tropicity to various organs and tissues leads to it phenotypic heterogeneity, which makes it difficult to make a diagnosis on early stages. However, the detection of «red flags» symptoms signaling the presence of transthyretin amyloidosis can shorten the time before initiation of targeted treatment, contributing to the improvement of the patient’s quality of life.

Amyloidosis is a group of diseases characterized by accumulation of a protein of a specific fibrillar structure in the interstitium of various organs and tissues. The concept of amyloidosis unites more than 30 different pathophysiological conditions, each of which is based on abnormal synthesis of 30 different precursor proteins. However, 95% of amyloid cardiomyopathies are associated with just two proteins: a protein derived from light chains of immunoglobulins and a protein called transthyretin. Determination of the precursor protein is a cornerstone of management of patients with amyloid cardiomyopathy. Transthyretin is a carrier protein of thyroxine, retinol and other substances, that performs vital functions. For hereditary or age-related reasons, TTR misfolding occurs in the liver. The resulting monomers, entering blood, form toxic intermediate products and amyloid fibrils. Cardiac amyloidosis (or amyloid cardiomyopathy) used to be considered a rare disease. In the recent past, possibilities of therapy for cardiac amyloidosis were limited by prescription of diuretics, mineralocorticoid receptor antagonists and anticoagulants, since other drugs are not tolerated well by patients or are tolerated in minimal doses. Advent of the first drug specific for treatment of transthyretin amyloid cardiomyopathy in Russia increased a need of awareness of ATTR-CM among general practitioners and cardiologists, and introduction of modern diagnostic algorithms for this disease. Timely detection and competent differential diagnosis of ATTR-CM from other types of amyloid cardiomyopathy can play a decisive role in the prognosis of this disease. Tafamidis is a treatment that was shown to reduce mortality and CV-related hospitalization in ATTR-CM patients.

The article presents the case report of a rare hereditary form of systemic ATTR-amyloidosis in Russian patient with a discussion of approaches to the diagnosis and treatment of this form, also based on the own experience in the management of such patients. Modern ideas about the pathogenesis of the disease as well as detailed information about the clinical manifestations of amyloid cardiopathy and of other organs are presented. The nature of structural and hemodynamic changes in the heart is discussed on the basis of experience, including own, ultrasound examination of the heart in patients with amyloidosis, especially the article focuses the reader's attention on the true infiltrative nature of transtiretin amyloid cardiopathy in contrast to AL-amyloidosis, in which there is a significant inflammatory component that determines a more unfavorable natural course of AL-amyloidosis of the heart. The article discusses the differential diagnosis of different types of amyloidosis, the diagnostic difficulties associated with weak congophilia of transtiretin amyloidosis and at the same time substantiates the need for morphological verification of the diagnosis. Modern methods of treatment of ATTR-amyloidosis are discussed.