Résumé
Transthyretin cardiac amyloidosis (ATTR-CA) is caused by the deposition of transthyretin(TTR) in the myocardial interstitium. Its clinical manifestations are mainly heart failure and arrhythmia, leading to poor life quality and low survival rate. Diagnosis is often delayed or missed due to the lack of disease awareness, the non-specific clinical symptom presentation of the disease, and inadequacy of non-invasive diagnostic methods and medications in the past. The recent availability of effective treatments makes the early recognition and diagnosis especially critical, because treatment is likely more effective earlier in the disease course. Therefore, it is crucial to establish a diagnosis and treatment strategy to facilitate the rapid and accurate identification of the disease. Based on the advances in research and experiences gained ATTR-CA, our team has developed a consensus on diagnosis and treatment for the disease. In this article, we interpret the key points and present the update of diagnostic process, providing clinicians with an overview of key aspects of ATTR-CA in China.
Résumé
Hypertrophic cardiomyopathy (HCM) is cardiomyopathy with a clinical phenotype of cardiac hypertrophy. The etiology includes genetically defective encoding sarcomeres, congenital metabolic diseases such as lysosomal storage diseases, systemic amyloidosis such as transthyretin amyloidosis(ATTR), and Fabry disease. Previous therapies did not target the etiology and pathogenesis and therefore were less effective. In recent years, treatments targeting different mechanisms of myocardial hypertrophy have achieved good results. Mavacamten can reduce myocardial contractility by inhibiting ATP activity, thereby significantly improving left ventricular outflow tract(LVOT) obstruction, cardiac contractility, ventricular tension, and limitting myocardial damage. By inhibiting the dissociation of transthyretin(TTR) and subsequent formation and deposition of the amyloid fibril, tafamidis can reduce the mortality and morbidity of patients with transthyretin cardiac amyloidosis(ATTR-CA). Gene silencing and gene editing technology can reduce abnormal TTR levels. Synthesis of α-galactosidase A by gene recombination technology in vitro can effectively reduce left ventricular mass index(LVMi), improve cardiac function, reduce angina attacks and decrease mortality of Fabry disease.
Résumé
Transthyretin cardiac amyloidosis myocardiopathy （ATTR-CM） is an infiltrative cardiomyopathy characterized by the deposition of amyloidogenic material in the myocardial interstitium due to the misfolding of monomers following the dissociation of unstable transthyretin （TTR） tetramers. Previous treatments for ATTR-CM lacked specificity，primarily targeting symptomatic management of heart failure and arrhythmias. In recent years，researchers have developed two major classes of drugs addressing the pathogenesis of ATTR-CM. The first class stabilizes TTR tetramer structure （such as tafamidis and acoramidis）， while the second class interferes with TTR synthesis （such as patisiran）. Among these，tafamidis has been confirmed as the only currently effective treatment for ATTR-CM，while other drugs are still in clinical trial stages with limited clinical evidence. Concerning the management of comorbidities in ATTR-CM，treatment mainly focuses on common cardiac comorbidities （such as heart failure and arrhythmias）. Traditional drugs used to improve heart failure prognosis （such as β-blockers and renin-angiotensin- receptor blocker），have not demonstrated prognosis improvement in ATTR-CM patients and may even lead to adverse reactions. For ATTR-CM patients with concurrent atrial fibrillation，anticoagulation therapy is recommended to prevent thrombus formation，and amiodarone can be used for rhythm control. Despite significant advancements in pharmaceutical treatments for ATTR-CM，the overall prognosis remains poor，necessitating further research into the pathogenesis and target development to enhance the prognosis of ATTR-CM patients.
Résumé
Transthyretin cardiac amyloidosis (ATTR-CM) is a rare and under-recognized disorder characterized by the aggregation of transthyretin-derived insoluble amyloid fibrils in the myocardium. Heterogeneity of symptoms at presentation, makes its diagnosis often delayed. An expert panel gathered on a virtual platform across India to conduct a meeting for developing a guiding tool for ATTR-CM diagnosis. The panel recommended younger age (40 years) for suspecting ATTR-CM and thick-walled non-dilated hypokinetic ventricle was considered as one of the important red flags. Electrocardiogram (ECG) and echocardiography (ECHO) findings were recommended as primary tests to raise the suspicion while nuclear scintigraphy and hematological tests were recommended to confirm the diagnosis and rule out amyloid light-chain (AL) amyloidosis. Cardiac magnetic resonance (CMR) and biopsy were recommended in case of ambiguity in the presence of red flags. Considering the lack of expert guidelines in the Indian scenario, a standardized diagnostic algorithm was also proposed.