Recent Advances and Current Dilemmas in the Diagnosis and Management of Transthyretin Cardiac Amyloidosis

Cardiac Amyloidosis: Clinical Features, Pathogenesis, Diagnosis, and Treatment

Cardiac amyloidosis is a type of amyloidosis that deserves special attention as organ involvement significantly worsens the prognosis. Cardiac amyloidosis can be grouped under three main headings: immunoglobulin light chain (AL) amyloidosis that is dependent on amyloidogenic monoclonal light chain production; hereditary Transthyretin (TTR) amyloidosis that results from accumulation of mutated TTR; and wild-type (non-hereditary) TTR amyloidosis formerly known as senile amyloidosis. Although all three types cause morbidity and mortality due to severe heart failure when untreated, they contain differences in their pathogenesis, clinical findings, and treatment. In this article, the clinical features, pathogenesis, diagnosis, and treatment methods of cardiac amyloidosis will be explained with an overview, and an awareness will be raised in the diagnosis of this disease.

A case of disappearing amyloid on technetium pyrophosphate scan

Technetium-99mm pyrophosphate (Tc-PYP) scintigraphy is a highly accurate non-invasive method for the diagnosis of transthyretin (ATTR) cardiac amyloidosis. Prognosis for this disease is improved following treatment with the transthyretin (TTR) stabilizer tafamidis. Although tafamidis slows disease progression, its effects on myocardial amyloid and Tc-PYP uptake remain unclear. We present a patient with ATTR cardiac amyloidosis who had a strongly positive initial Tc-PYP scan, with a dramatic decrease in Tc-PYP uptake on repeat scan after 3 years of tafamidis treatment. However, myocardial biopsy showed persistent diffuse amyloid deposits. This case highlights the need for further studies regarding the utility of serial Tc-PYP scans in monitoring the progress of ATTR cardiomyopathy.

Therapeutic value of tafamidis in patients with wild-type transthyretin amyloidosis (ATTRwt) with cardiomyopathy based on cardiovascular magnetic resonance (CMR) imaging

OBJECTIVES

The purpose of this study was to carefully analyse the therapeutic benefit of tafamidis in patients with wild-type transthyretin amyloidosis (ATTRwt) and cardiomyopathy (ATTRwt-CM) after one year of therapy based on serial multi-parametric cardiovascular magnetic resonance (CMR) imaging.

BACKGROUND

Non-sponsored data based on multi-parametric CMR regarding the effect of tafamidis on the cardiac phenotype of patients with ATTRwt-CM are not available so far.

METHODS

The present study comprised N = 40 patients with ATTRwt-CM who underwent two serial multi-parametric CMR studies within a follow-up period of 12 ± 3 months. Baseline (BL) clinical parameters, serum biomarkers and CMR findings were compared to follow-up (FU) values in patients treated "with" tafamidis 61 mg daily (n = 20, group A) and those "without" tafamidis therapy (n = 20, group B). CMR studies were performed on a 1.5-T system and comprised cine-imaging, pre- and post-contrast T1-mapping and additional calculation of extracellular volume fraction (ECV) values.

RESULTS

While left ventricular ejection fraction (LV-EF), left ventricular mass index (LVMi), left ventricular wall thickness (LVWT), native T1- and ECV values remained unchanged in the tafamidis group A, a slight reduction in LV-EF (p = 0.003) as well as a subtle increase in LVMi (p = 0.034), in LVWT (p = 0.001), in native T1- (p = 0.038) and ECV-values (p = 0.017) were observed in the untreated group B. Serum NT-proBNP levels showed an overall increase in both groups, however, with the untreated group B showing a relatively higher increase compared to the treated group A. Assessment of NYHA class did not result in significant intra-group differences when BL were compared with FU, but a trend to improvement in the treated group A compared to a worsening trend in the untreated group B (∆p = 0.005).

CONCLUSION

As expected, tafamidis does not improve cardiac phenotype in patients with ATTRwt-CM after one year of therapy. However, tafamidis seems to slow down cardiac disease progression in patients with ATTRwt-CM compared to those without tafamidis therapy based on multi-parametric CMR data already after one year of therapy.

Omega-3 PUFAs as a Dietary Supplement in Senile Systemic Amyloidosis

Eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6), two omega-3 poly-unsaturated fatty acids (PUFAs), are the main components in oil derived from fish and other marine organisms. EPA and DHA are commercially available as dietary supplements and are considered to be very safe and contribute to guaranteeing human health. Studies report that PUFAs have a role in contrasting neurodegenerative processes related to amyloidogenic proteins, such as β-amyloid for AD, α-synuclein in PD, and transthyretin (TTR) in TTR amyloidosis. In this context, we investigated if EPA and DHA can interact directly with TTR, binding inside the thyroxin-binding pockets (T₄BP) that contribute to the tetramer stabilization. The data obtained showed that EPA and DHA can contribute to stabilizing the TTR tetramer through interactions with T₄BP.

Cardiovascular Imaging in Cardio-Oncology: The Role of Echocardiography and Cardiac MRI in Modern Cardio-Oncology

Cardiovascular (CV) events are an increasingly common limitation of effective anticancer therapy. Over the last decade imaging has become essential to patients receiving contemporary cancer therapy. Herein we discuss the current state of CV imaging in cardio-oncology. We also provide a practical apparatus for the use of imaging in everyday cardiovascular care of oncology patients to improve outcomes for those at risk for cardiotoxicity, or with established cardiovascular disease. Finally, we consider future directions in the field given the wave of new anticancer therapies.

Suspicion, screening, and diagnosis of wild-type transthyretin amyloid cardiomyopathy: a systematic literature review

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt CM) is a more common disease than previously thought. Awareness of ATTRwt CM and its diagnosis has been challenged by its unspecific and widely distributed clinical manifestations and traditionally invasive diagnostic tools. Recent advances in echocardiography and cardiac magnetic resonance (CMR), non-invasive diagnosis by bone scintigraphy, and the development of disease-modifying treatments have resulted in an increased interest, reflected in multiple publications especially during the last decade. To get an overview of the scientific knowledge and gaps related to patient entry, suspicion, diagnosis, and systematic screening of ATTRwt CM, we developed a framework to systematically map the available evidence of (i) when to suspect ATTRwt CM in a patient, (ii) how to diagnose the disease, and (iii) which at-risk populations to screen for ATTRwt CM. Articles published between 2010 and August 2021 containing part of or a full diagnostic pathway for ATTRwt CM were included. From these articles, data for patient entry, suspicion, diagnosis, and screening were extracted, as were key study design and results from the original studies referred to. A total of 50 articles met the inclusion criteria. Of these, five were position statements from academic societies, while one was a clinical guideline. Three articles discussed the importance of primary care providers in terms of patient entry, while the remaining articles had the cardiovascular setting as point of departure. The most frequently mentioned suspicion criteria were ventricular wall thickening (44/50), carpal tunnel syndrome (42/50), and late gadolinium enhancement on CMR (43/50). Diagnostic pathways varied slightly, but most included bone scintigraphy, exclusion of light-chain amyloidosis, and the possibility of doing a biopsy. Systematic screening was mentioned in 16 articles, 10 of which suggested specific at-risk populations for screening. The European Society of Cardiology recommends to screen patients with a wall thickness ≥12 mm and heart failure, aortic stenosis, or red flag symptoms, especially if they are >65 years. The underlying evidence was generally good for diagnosis, while significant gaps were identified for the relevance and mutual ranking of the different suspicion criteria and for systematic screening. Conclusively, patient entry was neglected in the reviewed literature. While multiple red flags were described, high-quality prospective studies designed to evaluate their suitability as suspicion criteria were lacking. An upcoming task lies in defining and evaluating at-risk populations for screening. All are steps needed to promote early detection and diagnosis of ATTRwt CM, a prerequisite for timely treatment.

The discovery and development of transthyretin amyloidogenesis inhibitors: what are the lessons?

Transthyretin (TTR) is associated with several human amyloid diseases. Various kinetic stabilizers have been developed to inhibit the dissociation of TTR tetramer and the formation of amyloid fibrils. Most of them are bisaryl derivatives, natural flavonoids, crown ethers and carborans. In this review article, we focus on TTR tetramer stabilizers, genetic therapeutic approaches and fibril remodelers. The binding modes of typical bisaryl derivatives, natural flavonoids, crown ethers and carborans are discussed. Based on knowledge of the binding of thyroxine to TTR tetramer, many stabilizers have been screened to dock into the thyroxine binding sites, leading to TTR tetramer stabilization. Particularly, those stabilizers with unique binding profiles have shown great potential in developing the therapeutic management of TTR amyloidogenesis.

Recent Advances and Current Dilemmas in the Diagnosis and Management of Transthyretin Cardiac Amyloidosis

Cardiac amyloidosis (CA) is an increasingly recognized cause of heart failure, arrhythmias, and sudden cardiac death. While CA was previously rapidly fatal, recent advances in diagnosis and treatment have significantly improved outcomes. Advances in cardiac imaging and biomarkers have critically improved the accuracy and efficiency with which CA is diagnosed, even allowing for the noninvasive diagnosis of transthyretin CA. Cardiac magnetic resonance imaging, technetium nuclear imaging, echocardiography, and blood-based biomarkers have established important and complementary roles in the management and advancement of care. At the same time, the development of novel targeted amyloid therapies has allowed patients with CA to live longer and potentially achieve better quality of life. Still, despite this significant progress, there remain critical ongoing questions in the field. Accordingly, within this review we will highlight recent advances in cardiac imaging and therapeutics for CA, while focusing on key opportunities for further optimization of care and outcomes among this growing population. Specifically, we will discuss ongoing debates in the diagnosis of CA, including the interpretation of indeterminate cardiac imaging findings, the best technique to screen asymptomatic transthyretin amyloidosis gene mutation carriers for cardiac involvement, and the ideal method for monitoring response to CA treatment. We will additionally focus on recent advances in treatment for transthyretin amyloidosis-CA, including a discussion of available agents as well as highlighting ongoing clinical trials. Together, these data will allow clinicians to emerge with a greater understanding of the present and future of diagnosis, management, and potentially enhanced outcomes in this rapidly advancing field.