Serum levels of NT-proBNP as surrogate for cardiac amyloid burden: new evidence from gadolinium-enhanced cardiac magnetic resonance imaging in patients with amyloidosis

Clinical and imaging characteristics of patients with cardiac amyloidosis- a single center observational study

Amyloidosis is a disease characterized by the deposition of protein fibrils. Cardiac involvement is a significant factor in determining prognosis. This study aimed to examine the clinical profile, outcomes, and long-term mortality rates in patients with transthyretin (ATTR) and amyloid light-chain (AL) amyloidosis. The retrospective cohort study included 94 patients with amyloidosis (69 with AL and 25 with ATTR amyloidosis) diagnosed between 2010 and 2022. The study involved multimodality imaging (ECG, echocardiography and cardiac magnetic resonance (CMR) data and survival analyses. Patients with ATTR amyloidosis were older and had a higher proportion of males compared to those with AL amyloidosis. Cardiac involvement was more prevalent in the ATTR group, including atrial fibrillation (AF), while pleural and pericardial effusion were more frequent in the AL group. Biomarkers such as NT-proBNP and troponin T were significantly elevated in both groups and were associated with all-cause mortality only in univariate analyses. CMR data, especially typical late gadolinium enhancement (LGE) was not associated with increased mortality, while pleural effusion and left atrial dilatation on echocardiography were identified as powerful predictors of mortality. In conclusion, both AL and ATTR amyloidosis exhibited poor outcomes. Cardiac involvement, particularly dilated left atrium and pleural effusion on echocardiography were associated with an increased risk of mortality, while typical LGE on CMR was not.

High-Sensitivity Cardiac Troponin T to Exclude Cardiac Involvement in TTR Variant Carriers and ATTRv Amyloidosis Patients

(1) Background: Individuals carrying a pathogenic transthyretin gene variant (TTRv) are at high risk for developing hereditary transthyretin (ATTRv) amyloidosis and are routinely screened for the development of cardiomyopathy (ATTRv-CM). This study aims to evaluate whether the cardiac biomarkers N-terminal pro B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) can be used to rule out ATTRv-CM. (2) Methods: In this retrospective case-control study, data from 46 ATTRv-CM patients and 101 TTRv carriers and ATTRv amyloidosis patients without cardiomyopathy were included. Binary logistic regression models were used to assess the ability of NT-proBNP and hs-cTnT to predict the diagnosis of ATTRv-CM. An optimal cutoff for the relevant biomarker(s) was determined based on a sensitivity of ≥99% and the highest possible percentage of additional tests avoided (%ATA) in the index dataset. (3) Results: Hs-cTnT demonstrated the highest predictive capabilities for ATTRv-CM. The addition of NT-proBNP did not improve the predictive model. A hs-cTnT cutoff of <6 ng/L resulted in a 97% sensitivity and a negative predictive value of 95% with a %ATA of 30% in the validation dataset. (4) Conclusion: In conclusion, hs-cTnT is a useful biomarker for excluding cardiac involvement in TTRv carriers and ATTRv amyloidosis patients and it has the potential to prevent unnecessary diagnostic procedures.

Identification of wild-type transthyretin cardiac amyloidosis in patients with carpal tunnel syndrome surgery (CACTuS)

AIMS

Wild-type transthyretin cardiac amyloidosis (ATTRwt) is an infiltrative cardiomyopathy with a poor prognosis. The condition is associated with carpal tunnel syndrome (CTS), which often precedes the ATTRwt diagnosis by several years. The aim of the study was (i) to screen patients with a recent history of CTS for ATTRwt using red flags, (ii) to determine whether patients with screened ATTRwt had less advanced disease compared with patients with clinical ATTRwt, and (iii) to assess the sensitivity and specificity of known red flags in ATTRwt.

METHODS AND RESULTS

Patients aged ≥60 years at the time of CTS surgery were invited for screening. Red flags were defined as elevated biomarker levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) or cardiac troponin, an electrocardiogram pattern associated with ATTRwt, left ventricular hypertrophy (LVH), and impaired longitudinal strain with apical sparring. All patients with a red flag were referred for a diagnostic scintigraphy. Patients with ATTRwt diagnosed by screening were compared with patients with clinical ATTRwt (n = 51) matched by age, gender, and CTS surgery. Among the 120 enrolled subjects (mean age 74.5 years, 90% male), the suspicion of ATTR was raised in 67 (55.8%), and 10 (8.3%) were diagnosed with ATTRwt. Patients identified with ATTRwt were predominantly asymptomatic and had mildly elevated NT-proBNP, mildly increased LVH, preserved left ventricular ejection fraction, and systolic longitudinal function, which differed significantly from clinical ATTRwt controls (P < 0.001).

CONCLUSIONS

The study found an ATTRwt prevalence of 8.3% in a population of age and gender-selected patients with a recent history of CTS. The identified patients with ATTRwt had less structural and functional cardiac involvement than clinical ATTRwt controls.

Update on Disease-Specific Biomarkers in Transthyretin Cardiac Amyloidosis

PURPOSE OF REVIEW

Transthyretin cardiac amyloidosis (ATTR-CM) is an infiltrative cardiomyopathy and an increasingly recognized cause of morbidity and mortality. There remains substantial delay between initial symptoms and diagnosis. With the recent emergence of various targeted therapies proven to reduce morbidity and mortality, there is an imperative to diagnose subclinical disease. Biomarkers may be well-suited for this role.

RECENT FINDINGS

Conventional markers of heart failure, such as natriuretic peptides and cardiac troponins, and estimated glomerular filtration rate are associated with risk in ATTR-CM. Circulating transthyretin (TTR) levels parallel TTR kinetic stability, correlate with disease severity, and may serve as indirect markers of ATTR-CM disease activity and response to targeted treatment. There is also growing evidence for the correlation of TTR to retinol-binding protein 4, a biomarker which independently associates with this disease. The rate-limiting step for ATTR pathogenesis is dissociation of the TTR homotetramer, which may be quantified using subunit exchange to allow for early risk assessment, prognostication, and assessment of treatment response. The protein species that result from the dissociation and misfolding of TTR are known as nonnative transthyretin (NNTTR). NNTTR is quantifiable via peptide probes and is a specific biomarker whose reduction is positively correlated with improvement in neuropathic ATTR amyloidosis. Neurofilament light chain (NfL) is released into the blood after axonal damage and correlates with neuropathic ATTR amyloidosis, but its clinical use in ATTR-CM is uncertain. Conventional markers of heart failure, transthyretin, retinol-binding protein 4, transthyretin kinetic stability, nonnative transthyretin, peptide probes, and neurofilament light chain have potential as biomarkers to enable early, subclinical diagnosis in patients with transthyretin cardiac amyloidosis.

Prevalence and Risk Factors of Cardiac Amyloidosis in Heart Failure: A Systematic Review and Meta-Analysis

AIMS

Heart failure (HF) is one of the leading causes of mortality worldwide. Heart failure is also one of the most common presentations of cardiac amyloidosis (CA). Contemporary epidemiological data of CA in HF patients is lacking. Hence, this systematic review and meta-analysis was conducted to determine the prevalence of amyloidosis in HF patients, and to clarify the risk factors of concomitant CA and HF.

METHODS

A systematic review and meta-analysis was performed. Studies were retrieved from Medline, EMBASE, Scopus and Cochrane library. The search was not restricted in time, type or language of publication. The prevalence of CA in HF grouped according to diagnostic techniques and risk factors of CA with HF was analysed.

RESULTS

Eleven (11) studies were included, involving 3,303 patients. The pooled prevalence of CA in HF was 13.7%. The overall prevalence of CA in HF with preserved ejection fraction was 15.1%, and that of HF with reduced ejection fraction was 11.3%. The main factors associated with the diagnosis of CA in HF included older age, males, raised NT pro-BNP, increased interventricular septal thickness in diastole, apical sparing, and reduced left ventricular systolic function.

CONCLUSION

A high index of clinical suspicion is required to identify HF patients with CA. Supportive investigations may be helpful when clinically correlated. A considerable proportion of HF patients have CA and certain risk factors may be helpful in increasing suspicions of CA in HF.

Red flags for the diagnosis of cardiac amyloidosis: simple suggestions to raise suspicion and achieve earlier diagnosis

Cardiac amyloidosis is an infiltrative disease characterized by extracellular deposition of insoluble amyloid fibrils in the heart leading to organ dysfunction. Despite recent diagnostic advances, the diagnosis of cardiac amyloidosis is often delayed or even missed. Furthermore, a long diagnostic delay is associated with adverse outcomes, with the early diagnosed patients showing the longest survival. In this narrative review we aimed to summarize the 'red flags' that may facilitate the correct diagnosis. The red flags may be classified as clinical, biohumoral, electrocardiographic, echocardiographic, and cardiac magnetic resonance features and should promptly raise the suspicion of cardiac amyloidosis in order to start a correct diagnostic pathway and targeted treatment strategies that may improve patients' outcomes.

Proposed Cardiac End Points for Clinical Trials in Immunoglobulin Light Chain Amyloidosis: Report From the Amyloidosis Forum Cardiac Working Group

Immunoglobulin light chain amyloidosis is a rare, multisystemic, phenotypically heterogenous disease affecting cardiovascular, renal, neurological, and gastrointestinal systems to varying degrees. Its underlying cause is a plasma cell dyscrasia characterized by misfolding of monoclonal immunoglobulin light chains which leads to aggregation and deposition of insoluble amyloid fibrils in target organs. Prognosis is primarily dependent on extent of cardiac involvement and depth of hematologic response to treatment. To facilitate development of new therapies, a public-private partnership was formed between the nonprofit Amyloidosis Research Consortium and the US Food and Drug Administration Center for Drug Evaluation and Research. In 2020, the Amyloidosis Forum launched an initiative to identify novel/composite end points and analytic strategies to expedite clinical trials for development of new therapies for the primary hematologic disorder and organ system manifestations. Specialized working groups identified organ-specific end points; additional working groups reviewed health-related quality of life measures and statistical approaches to data analysis. Each working group comprised amyloidosis experts, patient representatives, statisticians, and representatives from the Food and Drug Administration, the UK Medicines and Healthcare Products Regulatory Agency, and pharmaceutical companies. This review summarizes the proceedings and recommendations of the Cardiac Working Group. Using a modified Delphi method, the group identified, reviewed, and prioritized cardiac end points relevant to immunoglobulin light chain amyloidosis in the context of an antiplasma cell therapy. Prioritized cardiovascular end points included overall survival, hospitalization, N-terminal pro-B-type natriuretic peptide level, 6-minute walk test, Kansas City Cardiac Questionnaire, and cardiac deterioration progression-free survival. These recommended components will be further explored through evaluation of clinical trial datasets and formal guidance from regulatory authorities.

Diagnostic Role of NT-proBNP in Patients with Cardiac Amyloidosis Involvement: A Meta-Analysis

Fundamento

A amiloidose é definida como um distúrbio caracterizado pela deposição de material proteico amiloide extracelular nos tecidos.

Objetivos

O N-terminal pró-peptídeo natriurético tipo-B (NT-proBNP) é usado para prever a amiloidose cardíaca (AC), mas seu efeito diagnóstico no comprometimento por AC ainda não é claro, especialmente em termos de especificidade e sensibilidade.

Métodos

Foi feita uma busca de literatura nos bancos de dados Pubmed, Embase e a biblioteca Cochrane, e o QUADAS 2 foi utilizado para avaliação da qualidade. O comando Midas no Stata 12.0 foi usado para analisar os indicadores dos sujeitos. O teste Q de Cochran e o I² foram usados como testes de heterogeneidade, e a heterogeneidade significativa foi definida como p <0,05 e/ou I² >50%. A análise de correlação de Spearman foi usada para avaliar o efeito de limiar, e o viés da publicação foi avaliado pelo teste de assimetria. A significância estatística foi definida em p <0,05.

Resultados

Como resultados, 10 conjuntos de dados de 7 estudos foram incluídos para análise, apresentando alta qualidade metodológica e pequenos vieses de confusão. A sensibilidade e a especificidade do NT-proBNP no diagnóstico do comprometimento cardíaco para pacientes com amiloidose foram 0,93 e 0,84, respectivamente. As curvas ROC também sugeriram uma validade diagnóstica alta do NT-proBNP com AUC de 0,95. Um nomograma de Fagan demonstrou que as probabilidades de NT-proBNP positivo e negativo no avanço do comprometimento por AC eram de 90% e 8%, respectivamente. O gráfico de funil de Deek não sugeriu viés significativo de publicação entre os estudos incluídos, e os resultados foram estáveis e confiáveis.

Conclusões

O NT-proBNP desempenha um papel positivo no diagnóstico precoce do comprometimento por AC, com alta sensibilidade e especificidade.

Hereditary transthyretin amyloidosis overview

Hereditary amyloidogenic transthyretin (ATTRv) amyloidosis is a rare autosomal dominantly inherited disorder caused by mutations in the transthyretin (TTR) gene. The pathogenetic model of ATTRv amyloidosis indicates that amyloidogenic, usually missense, mutations destabilize the native TTR favouring the dissociation of the tetramer into partially unfolded species that self-assemble into amyloid fibrils. Amyloid deposits and monomer-oligomer toxicity are the basis of multisystemic ATTRv clinical involvement. Peripheral nervous system (autonomic and somatic) and heart are the most affected sites. In the last decades, a better knowledge of pathomechanisms underlying the disease led to develop novel and promising drugs that are rapidly changing the natural history of ATTRv amyloidosis. Thus, clinicians face the challenge of timely diagnosis for addressing patients to appropriate treatment. As well, the progressive nature of ATTRv raises the issue of presymptomatic testing and risk management of carriers. The main aim of this review was to focus on what we know about ATTRv so far, from pathogenesis to clinical manifestations, diagnosis and hence patient's monitoring and treatment, and from presymptomatic testing to management of carriers.

Prevalence and outcomes of concomitant cardiac amyloidosis and aortic stenosis: A systematic review and meta-analysis

BACKGROUND

Cardiac amyloidosis (CA) is an increasingly recognised condition in patients with aortic stenosis (AS). However, there is large variation in the reported prevalence figures, due to differences in populations and diagnostic methods. We aimed to investigate the prevalence, risk factors and outcomes of concomitant CA and AS.

METHODS

We performed a systematic review and meta-analysis of the literature searched on Medline, EMBASE, Scopus and CENTRAL. We analysed the prevalence of CA in AS grouped according to diagnostic techniques, and the risk factors and outcomes of concomitant CA and AS was analysed in AS patients referred for surgical or transcatheter aortic valve replacement (AVR).

RESULTS

A total of 21 studies were included, involving 4,243 patients. The pooled prevalence of CA in patients with AS was 14.4%, with substantial heterogeneity. The pooled prevalence of AS in CA was 8.7%, with substantial heterogeneity. Patients with both AS and CA had higher all-cause mortality than those with AS or CA alone. In AS patients requiring AVR, CA was associated with increasing age, male sex, higher NT-proBNP levels, increased interventricular septal end diastole thickness and lower left ventricular ejection fraction. Concomitant AS and CA was associated with increased all-cause mortality and pacemaker implantation post-procedure. Study limitations included the heterogeneity of results and the fair to good quality of studies published.

CONCLUSION

Overall, a substantial proportion of patients with AS may have CA, and they have poorer prognosis. A high degree of clinical suspicion is needed to identify "red flags" and perform appropriate diagnostic imaging.

Elevated interleukin-6 levels are associated with impaired outcome in cardiac transthyretin amyloidosis

BACKGROUND

Elevated interleukin (IL)-6-levels have been described in familial variant transthyretin amyloidosis (ATTRv) associated polyneuropathy and heart failure. However, IL-6 in cardiac ATTR amyloidosis (ATTR-CM) and its prognostic value have not been investigated yet.

AIM

We aim to study the correlation between IL-6 levels with clinical presentation (Gillmore-class) and outcome [heart transplantation or death (htx/death)], or the combined endpoint of cardiac decompensation or htx/death in ATTR-CM.

METHODS

IL-6 levels of 106 ATTR-CM patients [54 wild-type ATTRwt, 52 ATTRv-CM], 15 asymptomatic carriers of ATTR mutations (aATTRv-CM) and 27 healthy donors were quantified using Luminex technology. Statistical analysis was performed using parametric survival regression models.

RESULTS

We found that IL-6 levels from wild-type ATTR patients were significantly elevated compared to healthy controls, while aATTRv-CM carriers and ATTRv-CM patients did not show a significant difference. IL-6 levels showed significantly higher values in increasing Gillmore classes. Univariate analyses revealed association of low IL-6 levels with cardiac decompensation and htx/death [odds ratio: 0.26 (0.09-0.72), P = 0.01] and htx/death [odds ratio: 0.15 (0.04-0.58), P = 0.006]. However, in the multivariate model, no significant improvement of risk prediction was seen for IL-6, while established prognostic factors were significantly associated with outcome.

CONCLUSION

Raised IL-6 levels correlate with clinical presentation and are associated with worse outcome in ATTR-CM but do not improve stratification in addition to established risk factors.

Diagnostic and prognostic value of cardiac imaging in amyloidosis

Amyloidosis is an infiltrative disease caused by extracellular protein deposition that has accumulated a lot of scientific production in recent years. Different types of amyloidosis can affect the heart. Transthyretin amyloidosis and light chain amyloidosis are the two most common types of cardiac amyloidosis. These entities have a poor prognosis, so accurate diagnostic techniques are imperative for determining an early therapeutic approach. Recent advances in cardiac imaging and diagnostic strategies show that these tools are safe and can avoid the use of invasive diagnostic techniques to histological confirmation, such as endomyocardial biopsy. We performed a review on the diagnostic and prognostic implications of different cardiac imaging techniques in cardiac amyloidosis. We mainly focus on reviewing echocardiography, cardiac magnetic resonance, computed tomography and nuclear imaging techniques and the different safety measurements that can be done with each of them.

Keys to early diagnosis of cardiac amyloidosis: red flags from clinical, laboratory and imaging findings

Cardiac involvement in systemic amyloidosis, due either to immunoglobulin light-chain or transthyretin amyloidosis, influences clinical presentation and is a strong predictor of unfavourable outcome. Until recently considered as a rare, incurable disease, cardiac amyloidosis, is still mis/underdiagnosed, although treatments effective in improving patient survival are now available for both subtypes, including chemotherapy regimens for immunoglobulin light-chain amyloidosis and tetramer stabiliser for transthyretin amyloidosis. Achieving a timely diagnosis allows initiating life-saving therapies and requires the early recognition of clinical, laboratory and imaging signs of cardiac involvement, some of them may be apparent well before the disease becomes clinically manifest. Given the systemic nature of amyloidosis, a close interaction among experts in multiple specialties is also required, including cardiologists, nephrologists, haematologists, neurologists, radiologists, nuclear medicine specialists and internists. As an increased awareness about disease presentation is required to ameliorate diagnostic performance, we aim to provide the clinician with a guide to the screening and early diagnosis of cardiac amyloidosis, and to review the clinical, biohumoral and instrumental ‘red flags’ that should raise the suspicion of cardiac amyloidosis.

Advances in the diagnosis and treatment of transthyretin amyloidosis with cardiac involvement

Amyloidosis is caused by extracellular deposition of insoluble abnormal fibrils constituted by misfolded proteins, which can modify tissue anatomy and hinder the function of multiple organs including the heart. Amyloidosis that can affect the heart includes mostly systemic amyloidosis (amyloid light chain, AL) and transthyretin amyloidosis (ATTR). The latter can be acquired in elderly patients (ATTRwt), or be inherited in younger individuals (ATTRm). The diagnosis is demanding given the high phenotypic heterogeneity of the disease. Therefore, "red flags," which are suggestive features giving support to diagnostic suspicion, are extremely valuable. However, the lack of broad awareness among clinicians represents a major obstacle for early diagnosis and treatment of ATTR. Furthermore, recent implementation of noninvasive diagnostic techniques has revisited the need for endomyocardial biopsy (EMB). In fact, unlike AL amyloidosis, which requires tissue confirmation and typing for diagnosis, ATTR can now be diagnosed noninvasively with the combination of bone scintigraphy and the absence of a monoclonal protein. Securing the correct diagnosis is pivotal for the newly available therapeutic options targeting both ATTRm and ATTRwt, and are directed to either stabilization of the abnormal protein or the reduction of the production of transthyretin. The purpose of this article is to review the contemporary aspects of diagnosis and management of transthyretin amyloidosis with cardiac involvement, summarizing also the recent therapeutic advances with tafamidis, patisiran, and inotersen.

Diagnosis and Treatment of Hereditary Transthyretin Amyloidosis (hATTR) Polyneuropathy: Current Perspectives on Improving Patient Care

Hereditary transthyretin amyloidosis (hATTR) with polyneuropathy (formerly known as Familial Amyloid Polyneuropathy) is a rare disease due to mutations in the gene encoding transthyretin (TTR) and characterized by multisystem extracellular deposition of amyloid, leading to dysfunction of different organs and tissues. hATTR amyloidosis represents a diagnostic challenge for neurologists considering the great variability in clinical presentation and multiorgan involvement. Generally, patients present with polyneuropathy, but clinicians should consider the frequent cardiac, ocular and renal impairment. Especially a hypertrophic cardiomyopathy, even if usually latent, is identifiable in at least 50% of the patients. Therapeutically, current available options act at different stages of TTR production, including synthesis inhibition (liver transplantation and/or gene-silencing drugs) or tetramer TTR stabilization (TTR stabilizers), increasing survival at different disease stages.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/n8sg_YlGJiA

Cardiac amyloidosis: An underdiagnosed/underappreciated disease

Cardiac amyloidosis or amyloid cardiomyopathy (ACM), commonly resulting from extracellular deposition of amyloid fibrils consisted of misfolded immunoglobulin light chain (AL) or transthyretin (TTR) protein, is an underestimated cause of heart failure and cardiac arrhythmias. Among the three types of cardiac amyloidosis (wild-type or familial TTR and light-chain), the wild-type (Wt) TTR-related amyloidosis (ATTR) is an increasingly recognized cause of heart failure with preserved ejection fraction (HFpEF), and amyloidosis should be considered in the differential diagnosis of this heart failure group of patients. Recent advances in the diagnosis and drug treatment of ACM have ushered in a new era in early disease detection and better management of these patients. Certain clues in cardiac and extracardiac manifestations of ACM may heighten clinical suspicion and guide further confirmatory testing. Newer noninvasive imaging methods (strain echocardiography, cardiac magnetic resonance and bone scintigraphy) may obviate the need for endomyocardial biopsy in ATTR patients, while newer targeted therapies may alter the adverse prognosis in these patients. Early recognition of ACM is crucial in halting the disease process before irreversible organ damage occurs. Chemotherapy and stem-cell transplantation combined with immunomodulatory therapy may also favorably affect the course and prognosis of light chain ACM. Finally, in select patients with end-stage disease, heart transplantation may render results comparable to non-ACM patients. All these issues are herein reviewed.

Diagnosis of cardiac amyloidosis: a systematic review on the role of imaging and biomarkers

BACKGROUND

Cardiac Amyloidosis (CA) pertains to the cardiac involvement of a group of diseases, in which misfolded proteins deposit in tissues and cause progressive organ damage. The vast majority of CA cases are caused by light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR). The increased awareness of these diseases has led to an increment of newly diagnosed cases each year.

METHODS

We performed multiple searches on MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews. Several search terms were used, such as "cardiac amyloidosis", "diagnostic modalities cardiac amyloidosis" and "staging cardiac amyloidosis". Emphasis was given on original articles describing novel diagnostic and staging approaches to the disease.

RESULTS

Imaging techniques are indispensable to diagnosing CA. Novel ultrasonographic techniques boast high sensitivity and specificity for the disease. Nuclear imaging has repeatedly proved its worth in the diagnostic procedure, with efforts now focusing on standardization and quantification of amyloid load. Because the latter would be invaluable for any staging system, those spearheading research in magnetic resonance imaging of the disease are also trying to come up with accurate tools to quantify amyloid burden. Staging tools are currently being developed and validated for ATTR CA, in the spirit of the acclaimed Mayo Staging System for AL.

CONCLUSION

Cardiac involvement confers significant morbidity and mortality in all types of amyloidosis. Great effort is made to reduce the time to diagnosis, as treatment in the initial stages of the disease is tied to better prognosis. The results of these efforts are highly sensitive and specific diagnostic modalities that are also reasonably cost effective.

Recent advances in the noninvasive strategies of cardiac amyloidosis

The heart, like any organ in the body, is susceptible to amyloid deposition. Although more than 30 types of protein can cause amyloidosis, only two types commonly deposit in the ventricular myocardium: amyloid light chain and amyloid transthyretin. Amyloid cardiomyopathy is usually a major determinant of patient outcomes, and the diagnosis of heart involvement can be often relatively under-diagnosed, owing to nonspecific presenting symptoms and signs at a subclinical stage. The diagnosis of cardiac amyloidosis is usually performed by endomyocardial biopsy; however, the invasive nature and related high-risk complications restrict its wide use in clinical settings. Recently, with the advent of innovative techniques used for evaluating cardiac amyloidosis, noninvasive methods become increasingly important, especially in earlier diagnosis, distinguishing typing, risk prediction and response to treatment. Here, we will review recent developments in the noninvasive methods used in the assessment of cardiac amyloidosis, focused on the laboratory biomarkers and imaging modalities.

Cardiac amyloidosis: pathogenesis, clinical context, diagnosis and management options

Amyloidosis covers a group of disorders that can manifest in virtually any organ system in the body and is thought to be secondary to misfolding of extracellular proteins with subsequent deposition in tissues. The precursor protein that is produced in excess defines the specific amyloid type. This requires histopathological confirmation using Congo-red dye with its characteristic demonstration of green birefringence under cross-polarized light. There are three main types of amyloidosis associated with cardiac involvement: light-chain (AL), familial or senile (ATTR), and secondary (AA) amyloidosis. The frequency of cardiac involvement and prognosis varies among each type. Amyloid cardiomyopathy commonly manifests as heart failure and the presenting features are usually dyspnoea, oedema, angina, pre-syncope and syncope. The diagnosis of cardiac amyloidosis is very hard and can easily be misdiagnosed. Although the imaging studies (such as echocardiography and cardiovascular magnetic resonance) may guide the diagnosis, tissue biopsy is needed for confirmation. Management of cardiac amyloidosis initially is to treat the underlying heart failure. Pacemaker implantation is usually required in patients with any conduction abnormalities. Transplantation is the next step with worsening heart failure. However, the aim of any treatment in amyloidosis, irrespective of type, is to prevent further deposition of amyloid while managing concurrent symptoms. In this manuscript, we will discuss the pathogenesis of cardiac amyloidosis, diagnostic methods and management options.

Amyloid cardiomyopathy

Amyloidosis is a heterogeneous group of diseases characterized by the deposition of amyloid. It is caused by extracellular deposition of insoluble fibrils with beta-pleated sheet configuration. The protein misfolding abnormalities result in amyloid fibrils and may manifest as primary, secondary, or familial amyloidosis. Amyloid deposition can occur in multiple organs (eg, heart, liver, kidney, skin, eyes, lungs, nervous system) resulting in a variety of clinical manifestations. Cardiac involvement can occur as part of a systemic disease or as a localized phenomenon. Cardiac involvement in all types of amyloidosis represents a major negative prognostic factor. Early diagnosis, multi-disciplinary cooperation and proper therapy are key aspects of care for patients with amyloid cardiomyopathy. Early diagnosis is crucial, especially in AL amyloidosis, as patients with advanced heart disease are unsuitable candidates for modern, effective hematological treatment including autologous stem cell transplantation. Despite signal development in diagnostics and therapy, the prognosis for patients with advanced cardiac involvement remains poor. This article is an overview of amyloidosis, providing information about the characteristics of cardiac amyloidosis, and present a structured approach to diagnosis, treatment and prognosis of this condition.

Quantitative assessment of systolic and diastolic function in patients with LGE negative systemic amyloidosis using CMR

OBJECTIVES

In clinical routine myocardial affection in amyloidosis is assessed by qualitative late gadolinium enhancement (LGE). Recent studies suggest that early cardiac involvement in amyloidosis may be overlooked by qualitative LGE assessment. The aim of this study was to assess possible early cardiac involvement in LGE negative AL patients by means of systolic and diastolic strain assessment and quantitative enhancement.

METHODS

51 individuals (17 Patients with LGE positive light-chain amyloidosis (AL) (Group A), 17 Patients with LGE negative systemic AL (Group B), and 17 healthy controls (Group C)) were investigated. SSFP-Cine sequences were acquired in short axis slices as well as horizontal long axis views. Standard CMR parameters as well as Feature Tracking (FT) derived systolic and diastolic circumferential and longitudinal strain parameters were calculated. Additionally, contrast enhanced MRI images were analyzed to quantitatively determine the extent of enhancement.

RESULTS

AL patients with and without LGE both had significantly lower early diastolic strain rate (EDSR) values and peak systolic longitudinal strain (PSLS) values than healthy controls (EDSR: Group A 63.1±17.6; Group B: 74.46±11.8; Group C: 86.82±12.7; F(2.48)=10.7 p<0.001); (PSLS: Group A: -13.44±1.9%; Group B: -20.31±1.2%; Group C: -23.11±1.4%; F(2.48)=167.6; p<0.001). Analysis of quantitative LGE enhancement revealed increased enhancement in qualitative LGE negative AL patients compared to healthy controls (Group A: 19.6±8.9%; Group B: 8.2±3.9%; Group C: 2.4±1.3% F(2.48)=52.2; p<0.001).

CONCLUSION

CMR strain analysis detects early systolic and diastolic strain impairment in AL patients lacking qualitative LGE enhancement.

Diagnosis, Prognosis, and Therapy of Transthyretin Amyloidosis

Transthyretin amyloidosis is a fatal disorder that is characterized primarily by progressive neuropathy and cardiomyopathy. It occurs in both a mutant form (with autosomal dominant inheritance) and a wild-type form (with predominant cardiac involvement). This article guides clinicians as to when the disease should be suspected, describes the appropriate diagnostic evaluation for those with known or suspected amyloidosis, and reviews the interventions currently available for affected patients.

Comparison of different types of cardiac amyloidosis by cardiac magnetic resonance imaging

OBJECTIVES

We sought to determine cardiac morphological and functional differences between light-chain (AL), mutant-type transthyretin (ATTRmt) and wild-type TTR (ATTRwt) amyloidosis using contrast-enhancement cardiac magnetic resonance imaging (CE-CMR). Finally, we attempted to establish the diagnostic and prognostic impact of these findings.

INTRODUCTION

The most common forms of cardiac amyloid are AL and ATTR amyloidosis, but the clinical courses of these variants are quite heterogeneous. While CE-CMR is used to evaluate patients with cardiac amyloidosis, its ability to predict prognosis in these patients is debatable.

METHODS

About 130 patients with cardiac amyloidosis (AL, n = 62; ATTRmt, n = 30, ATTRwt, n = 33) were assessed by CE-CMR (cardiac morphology, cardiac function, late gadolinium enhancement).

RESULTS

Left ventricular (LV) mass, basal and mid-ventricular maximal wall thickness, and thickness of the inter-atrial septum were higher in ATTRwt when compared to AL and ATTRmt amyloidosis. Tricuspid annular excursion was lower in ATTRwt amyloidosis than in AL amyloidosis. CE was observed in 94.6% of the patients (AL 80.6%; ATTRmt 90%; ATTRwt 87.9%) with significant differences in quality and intensity between the groups. Differentiation of amyloid types was achieved by combination of age, number of organs, the presence of inferolateral CE-CMR, thickness of inter-atrial septum and troponin T. Overall 1-year-survival rates were 93.3, 93.9 and 70.5% in ATTRwt, ATTRmt and AL amyloidosis, respectively. LV mass, mitral annular excursion and NT-proBNP in AL amyloidosis, LV mass maximal apical wall thickness and troponin T in ATTRwt amyloidosis, and finally NT-proBNP and renal function in ATTRmt amyloidosis were independent predictors of outcome.

CONCLUSIONS

This study demonstrates that CE-CMR can highlight morphological and functional differences between different types of cardiac amyloidosis. In addition, CE-CMR and cardiac biomarkers provide useful prognostic information in patients with cardiac amyloidosis.

The "Wagshurst study": p.Val40Ile transthyretin gene variant causes late-onset cardiomyopathy

BACKGROUND

Transthyretin-related amyloidosis (ATTR) is characterized by a wide heterogeneity of genotypes and predominantly neurological and cardiac phenotypes. This study aims to characterize a cohort of patients with the rare transthyretin (TTR) Val20Ile (p.TTRVal40Ile) variant.

METHODS AND RESULTS

This study comprises a single-center cohort of 59 individuals subsequently evaluated for TTRVal20Ile variant due to clinical (n = 13) or predictive (n = 46) reasons. All patients were mainly related to Wagshurst, a small village in the South of Germany. Clinical assessment was performed by neurological evaluation, echocardiography, electrocardiography, cardiac biomarkers, cardiac MRI (n = 13), and (99m)Tc-DPD scintigraphy (n = 16). The rare TTRVal20Ile variant was found in 41 patients; evidence of cardiac amyloidosis was present in 22 patients. Evidence of pulmonary involvement was obtained by (99m)Tc-DPD scintigraphy in eight patients. No further organ involvement was observed in any of the patients carrying TTRVal20Ile variant. Correlation of inter-ventricular septum thickness as well as decrease of left ventricular longitudinal contractility with age was observed. Moreover, thickness of inter-ventricular septum correlated with NT-proBNP plasma levels and decrease in mitral annular plane systolic excursion. Cardiac manifestation started during the early sixth life decade indicated by higher left ventricular septum thickness and NT-proBNP plasma levels as compared to patients in fifth decade of life. All patients of the seventh and eighth life decade (n = 10) presented with cardiac amyloidosis. During median follow-up of 26 (0-108) months, eight patients underwent heart transplantation with 1-year mortality rate of 25%.

CONCLUSIONS

This large cohort of individuals carrying the TTRVal20Ile mutation reveals a predominantly cardiac phenotype with high penetrance and late onset of symptoms. Cardiac manifestation progressed to end-stage heart failure within a few years, finally requiring heart transplantation with promising long-term survival rates.

Osteopontin: a novel predictor of survival in patients with systemic light-chain amyloidosis

BACKGROUND

Troponin-T (cTnT) and NT-proBNP provide prognostic information in light-chain amyloidosis (AL). Thus, these biomarkers are widely used in clinical routine for risk stratification. Recently, plasma level of osteopontin (OPN), a secreted phosphoglycoprotein expressed by a variety of cell types, has been reported as a risk predictor in various cardiovascular diseases.

METHODS

OPN was determined retrospectively in 150 consecutive patients newly diagnosed with AL amyloidosis. All patients were evaluated according to a routine protocol including electrocardiography, echocardiography and laboratory testing.

RESULTS

Mean OPN was 591 ± 37 ng/mL. Cardiac involvement was established in 83 (55.3%). Median OPN plasma level were associated with number of organs involved, renal function, eligibility for high-dose melphalan chemotherapy and autologous stem cell transplantation, and severity of cardiac amyloidosis. Median follow-up was 19.2 months. 1-year all-cause-survival was 83.4%. The cut-offs discriminating 1-year all-cause-mortality for NT-proBNP, troponin T, and OPN were 2544 ng/L, 0.035 µg/L, and 426.8 ng/mL, respectively. Outcome was worse in patients with biomarkers above the individual ROC derived cut-off. A significant improvement of survival was observed in patients with cTNT >0.035 µg/L or NT-proBNP >2544 ng/L and OPN below ROC-derived cut-off of 426.8 ng/mL as compared to patients with OPN above 426.8 ng/L. No further discrimination was achieved by OPN in the cohorts of low troponin T or low NT-proBNP, respectively. Separate multivariate models identified OPN (cut-off 426.8 ng/mL) and troponin T (cut-off 0.035 µg/L) as independent predictors of all-cause-mortality.

CONCLUSIONS

These data demonstrated that OPN appears to be a valuable marker in the clinical routine for evaluation of patients with AL amyloidosis, especially if it is used in combination with cTNT and/or NT-proBNP.

Cardiac amyloidosis without increased left ventricular wall thickness

OBJECTIVES

To determine how often left ventricular wall thickness (LVWT) is normal and to assess the effect of LVWT on clinical outcomes of patients with immunoglobulin light chain (AL) cardiac amyloidosis.

PATIENTS AND METHODS

A total of 117 patients with systemic AL amyloidosis were retrospectively categorized from April 1, 1995, to September 15, 2012; group A included cardiac amyloidosis patients with an LVWT greater than 12 mm (45 patients); group B, cardiac amyloidosis patients with an LVWT of 12 mm or less (25 patients); and group C, no evidence of cardiac amyloidosis (47 patients). We compared echocardiographic parameters and survival rates among the 3 groups.

RESULTS

No differences were found between groups A and B in the following parameters: left ventricular ejection fraction (median, 56% [interquartile range (IQR), 46%-63%] vs 56% [IQR, 49%-63%], P=.76), left arterial volume index (median, 44.5 [IQR, 38.5-59.7] vs 43.9 [IQR, 33.8-57.1] mL/m(2), P=.79), e' (median, 0.04 [IQR, 0.03-0.05] vs 0.05 [IQR, 0.04-0.06] m/s, P=.10), and E/e' (early diastolic mitral inflow velocity (E)/e') (median, 18.4 [IQR, 12.0-23.3] vs 18.0 [IQR, 13.6-25.0], P=.98). Patients in group C exhibited significantly different values for these parameters (median, 65% [IQR, 61%-69%], 23.4 [IQR, 18.0-29.0] mL/m(2), 0.08 [IQR, 0.06-0.09] m/s, and 8.8 [IQR, 7.2-10.5], respectively; all P<.001). The survival rates were statistically different, with median survival times of 422, 729, and 2080 days in groups A, B, and C, respectively (P=.002). Using multivariate Cox proportional hazards regression analysis, we found that age, an N-terminal pro-B-type natriuretic peptide level of 1800 pg/mL or greater, E/e', and complete hematologic remission were significant predictors of survival.

CONCLUSIONS

A third of patients with AL cardiac amyloidosis were diagnosed as having an LVWT of 12 mm or less. Because appropriate therapy can improve the survival of patients with AL cardiac amyloidosis, early detection by sensitive diagnostic methods should be pursued even when LVWT is not increased.

Noninvasive risk stratification of patients with transthyretin amyloidosis

OBJECTIVES

We sought to evaluate noninvasive parameters by electrocardiography, echocardiography, technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) scintigraphy, and cardiac magnetic resonance for the prediction of all-cause mortality in patients with cardiac transthyretin amyloidosis (ATTR).

BACKGROUND

ATTR may present with highly variable symptoms, including polyneuropathy and cardiomyopathy, the latter being associated with a poor outcome. However, data on noninvasive risk stratification of ATTR are limited.

METHODS

A total of 70 patients with ATTR were evaluated by echocardiography, cardiac biomarkers, and (99m)Tc-DPD scintigraphy. Cardiac magnetic resonance was performed in 30 patients. Echocardiographic findings and plasma levels of biomarkers were correlated with results of quantitative analysis of scintigraphy using a region-of-interest technique (whole-body as well as heart tracer retention). Receiver-operating characteristic (ROC) analysis was performed to calculate a cutoff value of (99m)Tc-DPD scintigraphy for heart retention for the diagnosis of cardiac amyloid involvement with the highest sensitivity and specificity. Univariate and multivariate analyses were performed in patients with cardiac involvement (n = 60) to determine noninvasive predictors of all-cause mortality.

RESULTS

Scintigraphy findings correlated with morphological (interventricular septum thickness, left ventricular hypertrophy index) as well as functional (mitral annular systolic velocity, mitral/tricuspid annular plane systolic excursion) findings, cardiac biomarkers, renal function, and late gadolinium enhancement. The ROC-derived cutoff for the detection of cardiac amyloidosis by scintigraphic heart tracer retention was 4.8%. Univariate Cox regression revealed N-terminal pro-B-type natriuretic peptide, troponin T, mitral annular plane systolic excursion, and left ventricular hypertrophy index as predictors of all-cause mortality. However, on multivariate analysis, troponin T remained the only independent predictor of survival. The ROC-derived cutoff value of troponin T predicting all-cause mortality with the highest sensitivity (80.0%) and specificity (68.7%) was 0.0375 ng/l.

CONCLUSIONS

Quantitative analysis of tracer retention is capable of characterizing the severity of cardiac involvement in ATTR. By multivariate analysis, troponin T remained the only independent predictor of survival.

Effects of tafamidis on transthyretin stabilization and clinical outcomes in patients with non-Val30Met transthyretin amyloidosis

This phase II, open-label, single-treatment arm study evaluated the pharmacodynamics, efficacy, and safety of tafamidis in patients with non-Val30Met transthyretin (TTR) amyloidosis. Twenty-one patients with eight different non-Val30Met mutations received 20 mg QD of tafamidis meglumine for 12 months. The primary outcome, TTR stabilization at Week 6, was achieved in 18 (94.7%) of 19 patients with evaluable data. TTR was stabilized in 100% of patients with non-missing data at Months 6 (n = 18) and 12 (n = 17). Exploratory efficacy measures demonstrated some worsening of neurological function. However, health-related quality of life, cardiac biomarker N-terminal pro-hormone brain natriuretic peptide, echocardiographic parameters, and modified body mass index did not demonstrate clinically relevant worsening during the 12 months of treatment. Tafamidis was well tolerated. In conclusion, our findings suggest that tafamidis 20 mg QD effectively stabilized TTR associated with several non-Val30Met variants.

Role of natriuretic peptide to predict cardiac abnormalities in patients with hereditary transthyretin amyloidosis

BACKGROUND

Familial amyloid polyneuropathy (FAP) mainly targets the peripheral nervous system and heart. Early noninvasive detection of cardiac impairment is critical for therapeutic management.

AIM

To assess if amino-terminal pro-brain natriuretic peptide (NT-proBNP) or troponin T (cTnT) can predict echocardiographic left-ventricle (LV) impairment in FAP.

METHODS

Thirty-six asymptomatic carriers and patients with FAP had echocardiographic measurement of left-ventricular (LV) systolic function, hypertrophy (LVH) and estimation of filling pressure (FP).

RESULTS

Overall, median age, NT-proBNP, and LV ejection fraction were, respectively, 59 years (41-74), 323 pg/ml (58-1960), and 60% (51-66). Twelve patients had increased cTnT. Prevalence of ATTR gene mutations was 53% for Val30Met. Four individuals were asymptomatic, 6 patients had isolated neurological clinical signs, and 26 had echo-LV abnormalities. The ROC curve identified NT-proBNP patients with echo-LV abnormalities (area: 0.92; (0.83-0.99), p = 0.001) at a threshold >82 pg/ml with a sensitivity of 92%, and a specificity of 90%. Increased in NT-proBNP occurred in patients with SD and/or LVH with or without increase in FP. Elevated cTnT (>0.01 ng/ml) was only observed in patients with LVH and systolic dysfunction, with or without FP.

CONCLUSION

In FAP, NT-proBNP was associated with cardiac impairment suggesting that NT-proBNP could be used in carriers or in FAP patients with only neurologic symptoms for identifying the appropriate time to start cardiac echocardiographic assessment and follow-up. cTnT identified patients with severe cardiac disease.

Transthyretin familial amyloid polyneuropathy

TTR FAP is characterized by phenotypic and genotypic heterogeneity. The severity of polyneuropathy along with autonomic dysfunction and heart involvement makes it a life-threatening disease. This protein is mainly produced by the liver. Molecular genetic testing is essential in the diagnostic strategy. TTR-Val30Met is the most frequent substitution, resulting in a guanine to cytosine mutation in exon 2 of the gene. It is virtually the only variant detected in Portugal, Brazil, and Sweden. By contrast, as many as 30 different TTR variants are reported in Japan and in other European countries. A less severe phenotype with late onset has been reported. Diagnosis should be performed as early as possible since upcoming pharmacological therapeutic approaches are now available, in addition to liver transplantation.

Overexpression of human amyloidogenic light chains causes heart failure in embryonic zebrafish: a preliminary report

AL cardiomyopathy leading to heart failure (HF) represents a significant cause of morbidity and mortality in systemic amyloidosis. However, the paucity of robust in vivo models of AL-induced cardiac dysfunction has limited our ability to probe the mechanisms of AL heart disease. To address this problem, we have developed a model of AL HF in zebrafish embryos by injection of in vitro transcribed mRNA encoding amyloidogenic light chain (aLC) into fertilized oocytes. We demonstrate that expression of aLC causes cardiomyopathy in developing zebrafish without significantly impairing extracardiac development. The cardiac ventricle of embryos expressing aLC exhibit impaired contractility, smaller size, and increased myocardial thickness which result in congestion and edema, features paralleling the clinical manifestations of amyloid cardiomyopathy. Phosphorylated p38, a marker of oxidative stress, was increased in response to aLC expression. No evidence of amyloid fibril deposition was identified. Thus, expression of aLC mRNA in zebrafish results in cardio toxic effects without fibril deposition. This is consistent with prior evidence indicating that aLC oligomers mediate cardiac dysfunction in vitro. This model will allow exploration of amyloid pathophysiology and testing of interventions to reduce and reverse the deleterious effects of amyloidosis on myocardial function.

Longitudinal left ventricular function for prediction of survival in systemic light-chain amyloidosis: incremental value compared with clinical and biochemical markers

OBJECTIVES

The aim of the study was to determine whether longitudinal left ventricular (LV) function provides prognostic information in a large cohort of patients with systemic light-chain (AL) amyloidosis.

BACKGROUND

AL amyloidosis is associated with a high incidence of cardiovascular events. Reduced myocardial longitudinal function is one of the hallmarks of myocardial involvement in this rare disease.

METHODS

Two hundred six consecutive patients with biopsy-proven AL amyloidosis were investigated in this prospective observational study. Echocardiographic imaging parameters, mean tissue Doppler-derived longitudinal strain (LS), and two-dimensional global longitudinal strain (2D-GLS) of the LV, cardiac serological biomarkers, and comprehensive clinical disease characteristics were assessed. The primary endpoint was all-cause mortality or heart transplantation.

RESULTS

After a median follow-up of 1207 days, LS and 2D-GLS were significant predictors of survival in AL amyloidosis. The cutoff values discriminating survivors from nonsurvivors were -10.65% for LS and -11.78% for 2D-GLS. In a multivariable echocardiographic Cox model, only diastolic dysfunction and 2D-GLS remained as independent predictors of survival. In comprehensive clinical models, 2D-GLS (p < 0.0001), diastolic dysfunction (p < 0.01), the pathologic free light chains (p < 0.05), cardiac troponin-T (cTnT) (p < 0.01), and the Karnofsky index (p < 0.001) remained as independent predictors. 2D-GLS delineated a superior prognostic value compared with that derived from pathologic free light chains or cTnT in patients evaluated before firstline chemotherapy (n = 113; p < 0.0001), and remained the only independent predictor besides the Karnofsky index in subjects with preserved LV ejection fraction (≥50%; n = 127; p < 0.01). LS and 2D-GLS both offered significant incremental information (p < 0.001) for the assessment of outcome compared with clinical variables (age, Karnofsky index, and New York Heart Association functional class) and serological biomarkers.

CONCLUSIONS

In the largest serial investigation reported so far, reduced LV longitudinal function served as an independent predictor of survival in AL amyloidosis and offered incremental information beyond standard clinical and serological parameters.

Green tea halts progression of cardiac transthyretin amyloidosis: an observational report

Background

Treatment options in patients with amyloidotic transthyretin (ATTR) cardiomyopathy are limited. Epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea (GT), inhibits fibril formation from several amyloidogenic proteins in vitro. Thus, it might also halt progression of TTR amyloidosis. This is a single-center observational report on the effects of GT consumption in patients with ATTR cardiomopathy.

Methods

19 patients with ATTR cardiomyopathy were evaluated by standard blood tests, echocardiography, and cardiac MRI (n = 9) before and after consumption of GT and/or green tea extracts (GTE) for 12 months.

Results

Five patients were not followed up for reasons of death (n = 2), discontinuation of GT/GTE consumption (n = 2), and heart transplantation (n = 1). After 12 months no increase of left ventricular (LV) wall thickness and LV myocardial mass was observed by echocardiography. In the subgroup of patients evaluated by cardiac MRI a mean decrease of LV myocardial mass (−12.5 %) was detected in all patients. This was accompanied by an increase of mean mitral annular systolic velocity of 9 % in all 14 patients. Total cholesterol (191.9 ± 8.9 vs. 172.7 ± 9.4 mg/dL; p < 0.01) and LDL cholesterol (105.8 ± 7.6 vs. 89.5 ± 8.0 mg/dL; p < 0.01) decreased significantly during the observational period. No serious adverse effects were reported by any of the participants.

Conclusions

Our observation suggests an inhibitory effect of GT and/or GTE on the progression of cardiac amyloidosis. We propose a randomized placebo-controlled investigation to confirm our observation.

Electronic supplementary material

The online version of this article (doi:10.1007/s00392-012-0463-z) contains supplementary material, which is available to authorized users.