Identification of Transthyretin Cardiac Amyloidosis Using Serum Retinol-Binding Protein 4 and a Clinical Prediction Model

Clinical Use of Biomarkers in Cardiac Amyloidosis

Amyloidosis is a systemic condition characterized by multiple organs involvement. A multidisciplinary and multimodal approach in assessing patients is pivotal and recommended by the international scientific societies. Biomarkers represent an essential noninvasive tool to increase the suspicion of disease and orient further workup and clinical management of patients. This review provides an updated contemporary focus on the clinical use of biomarkers in cardiac amyloidosis, emphasizing their role in both the diagnostic and prognostic setting and discussing future perspective of emerging biomarkers.

Circulating transthyretin and retinol binding protein 4 levels among middle-age V122I TTR carriers in the general population

BACKGROUND

Hereditary transthyretin cardiac amyloidosis (ATTRv-CA) has a long latency phase before clinical onset, creating a need to identify subclinical disease. We hypothesized circulating transthyretin (TTR) and retinol binding protein 4 (RBP4) levels would be associated with TTR carrier status and correlated with possible evidence of subclinical ATTRv-CA.

METHODS

TTR and RBP4 were measured in blood samples from V122I TTR carriers and age-, sex- and race-matched non-carrier controls (1:2 matching) among Dallas Heart Study participants (phases 1 (DHS-1) and 2 (DHS-2)). Multivariable linear regression models determined factors associated with TTR and RBP4.

RESULTS

There were 40 V122I TTR carriers in DHS-1 and 54 V122I TTR carriers in DHS-2. In DHS-1 and DHS-2, TTR was lower in V122I TTR carriers (p < .001 for both), and RBP4 in DHS-2 was lower in V122I TTR carriers than non-carriers (p = .002). Among V122I TTR carriers, TTR was negatively correlated with markers of kidney function, and limb lead voltage (p < .05 for both) and TTR and RBP4 were correlated with atrial volume in DHS-2 (p < .05).

CONCLUSIONS

V122I TTR carrier status is independently associated with lower TTR and RBP4 in comparison with non-carriers. These findings support the hypothesis that TTR and RBP4 may correlate with evidence of subclinical ATTRv-CA.

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.

Hereditary transthyretin amyloidosis: a comprehensive review with a focus on peripheral neuropathy

Amyloidoses represent a group of diseases characterized by the pathological accumulation in the extracellular area of insoluble misfolded protein material called "amyloid". The damage to the tissue organization and the direct toxicity of the amyloidogenic substrates induce progressive dysfunctions in the organs involved. They are usually multisystem diseases involving several vital organs, such as the peripheral nerves, heart, kidneys, gastrointestinal tract, liver, skin, and eyes. Transthyretin amyloidosis (ATTR) is related to abnormalities of transthyretin (TTR), a protein that acts as a transporter of thyroxine and retinol and is produced predominantly in the liver. ATTR is classified as hereditary (ATTRv) and wild type (ATTRwt). ATTRv is a severe systemic disease of adults caused by mutations in the TTR gene and transmitted in an autosomal dominant manner with incomplete penetrance. Some pathogenic variants in TTR are preferentially associated with a neurological phenotype (progressive peripheral sensorimotor polyneuropathy); others are more frequently associated with restrictive heart failure. However, many mutations express a mixed phenotype with neurological and cardiological involvement. ATTRv is now a treatable disease. A timely and definite diagnosis is essential in view of the availability of effective therapies that have revolutionized the management of affected patients. The purpose of this review is to familiarize the clinician with the disease and with the correct diagnostic pathways in order to obtain an early diagnosis and, consequently, the possibility of an adequate treatment.

Tafamidis concentration required for transthyretin stabilisation in cerebrospinal fluid

BACKGROUND

Hereditary transthyretin (TTR) amyloidosis (ATTRv) initially presents as a polyneuropathy and/or a cardiomyopathy. Central nervous system (CNS) pathology in ATTRv amyloidosis, including focal neurological episodes, dementia, cerebrovascular bleeding, and seizures, appears around a decade later. Wild-type (WT) TTR amyloidosis (ATTRwt) causes a cardiomyopathy. CNS pathology risk likely also increases in these patients as cardiomyopathy progresses. Herein, we study tafamidis-mediated TTR kinetic stabilisation in cerebrospinal fluid (CSF).

METHODS

Varying tafamidis concentrations (50-1000 nM) were added to CSF from healthy donors or ATTRv patients, and TTR stabilisation was measured via the decrease in dissociation rate.

RESULTS

Tafamidis meglumine (Vyndaqel) can be dosed at 20 or 80 mg QD. The latter dose is bioequivalent to a 61 mg QD dose of tafamidis free acid (Vyndamax). The tafamidis CSF concentration in ATTRv patients on 20 mg Vyndaqel is ∼125 nM. By linear extrapolation, we expect a CSF concentration of ∼500 nM at the higher dose. When tafamidis is added to healthy donor CSF at 125 or 500 nM, the WT TTR dissociation rate decreases by 42% or 87%, respectively.

CONCLUSIONS

Tafamidis stabilises TTR in CSF to what is likely a clinically meaningful extent at CSF concentrations achieved by the normal tafamidis dosing regimen.

Design and Rationale the SCAN-MP (Screening for Cardiac Amyloidosis With Nuclear Imaging in Minority Populations) Study

Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is an important cause of heart failure in older individuals. Misfolding and deposition of transthyretin or prealbumin protein causes ATTR-CM in the context of a normal (wild-type) or variant TTR sequence. Variant ATTR-CM is most commonly caused by the substitution of valine for isoleucine at position 122 in transthyretin (Val122Ile or pV142I, almost exclusively observed in individuals of West African ancestry), demonstrated in 3.4% of self-identified Black individuals in the United States with an estimated 1.5 million carriers. Despite the large number of known pV142I carriers, the proportion of older Black patients with heart failure attributable to ATTR-CM remains unknown. Methods To address this knowledge gap, the SCAN-MP (Screening for Cardiac Amyloidosis with Nuclear Imaging in Minority Populations) study was funded by the National Institutes of Health/National Heart, Lung, and Blood Institute (R01HL139671) to enroll a targeted population of self-identified, community-dwelling Black or Caribbean Hispanic patients (many of whom are of West African ancestry) >60 years of age with heart failure and identify ATTR-CM by noninvasive nuclear imaging. The principal objective of SCAN-MP is to determine the prevalence of ATTR-CM in this population. Secondary objectives will explore TTR genotype, demographics, progression of variant versus wild-type ATTR-CM, and biochemical mechanisms of transthyretin amyloid fibril formation. Conclusions The SCAN-MP study is the largest, prospective study of cardiac amyloidosis in Black and Hispanic individuals. Both wild-type and variant ATTR-CM are now treatable with the US Food and Drug-approved drug tafamidis. The insights gained from SCAN-MP are likely to improve those at risk for or afflicted with ATTR-CM. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03812172.

Development and Validation of the HIV-CARDIO-PREDICT Score to Estimate the Risk of Cardiovascular Events in HIV-Infected Patients

IMPORTANCE

Commonly used risk assessment tools for cardiovascular disease might not be accurate for HIV-infected patients.

OBJECTIVE

We aimed to develop a model to accurately predict the 10-year cardiovascular disease (CV) risk of HIV-infected patients.

DESIGN

In this retrospective cohort study, adult HIV-infected patients seen at Boston Medical Center between March 2012 and January 2017 were divided into model development and validation cohorts.

SETTING

Boston Medical Center, a tertiary, academic medical center.

PARTICIPANTS

Adult HIV-infected patients, seen in inpatient and outpatient setting.

MAIN OUTCOMES AND MEASURES

We used logistic regression to create a prediction risk model for cardiovascular events using data from the development cohort. Using a point-based risk-scoring system, we summarized the relationship between risk factors and cardiovascular disease (CVD) risk. We then used the area under the receiver operating characteristics curve (AUC) to evaluate model discrimination. Finally, we tested the model using a validation cohort.

RESULTS

1914 individuals met the inclusion criteria. The model had excellent discrimination for CVD risk [AUC 0.989; (95% CI: 0.986-0.993)] and included the following 11 variables: male sex (95% CI: 2.53-3.99), African American race/ethnicity (95% CI: 1.50-3.13), current age (95% CI: 0.07-0.13), age at HIV diagnosis (95% CI: -0.10-(-0.02)), peak HIV viral load (95% CI: 9.89 × 10-7-3.00 × 10-6), nadir CD4 lymphocyte count (95% CI: -0.03-(-0.02)), hypertension (95% CI: 0.20-1.54), hyperlipidemia (95% CI: 3.03-4.60), diabetes (95% CI: 0.61-1.89), chronic kidney disease (95% CI: 1.26-2.62), and smoking (95% CI: 0.12-2.39). The eleven-parameter multiple logistic regression model had excellent discrimination [AUC 0.957; (95% CI: 0.938-0.975)] when applied to the validation cohort.

CONCLUSIONS AND RELEVANCE

Our novel HIV-CARDIO-PREDICT Score may provide a rapid and accurate evaluation of CV disease risk among HIV-infected patients and inform prevention measures.

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.

Whole Genome Association Study of the Plasma Metabolome Identifies Metabolites Linked to Cardiometabolic Disease in Black Individuals

Integrating genetic information with metabolomics has provided new insights into genes affecting human metabolism. However, gene-metabolite integration has been primarily studied in individuals of European Ancestry, limiting the opportunity to leverage genomic diversity for discovery. In addition, these analyses have principally involved known metabolites, with the majority of the profiled peaks left unannotated. Here, we perform a whole genome association study of 2,291 metabolite peaks (known and unknown features) in 2,466 Black individuals from the Jackson Heart Study. We identify 519 locus-metabolite associations for 427 metabolite peaks and validate our findings in two multi-ethnic cohorts. A significant proportion of these associations are in ancestry specific alleles including findings in APOE, TTR and CD36. We leverage tandem mass spectrometry to annotate unknown metabolites, providing new insight into hereditary diseases including transthyretin amyloidosis and sickle cell disease. Our integrative omics approach leverages genomic diversity to provide novel insights into diverse cardiometabolic diseases.

Transthyretin cardiac amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is an increasingly recognized cause of heart failure (HF) and mortality worldwide. Advances in non-invasive diagnosis, coupled with the development of effective treatments, have shifted ATTR-CA from a rare and untreatable disease to a relatively prevalent condition that clinicians should consider on a daily basis. Amyloid fibril formation results from age-related failure of homoeostatic mechanisms in wild-type ATTR (ATTRwt) amyloidosis (non-hereditary form) or destabilizing mutations in variant ATTR (ATTRv) amyloidosis (hereditary form). Longitudinal large-scale studies in the United States suggest an incidence of cardiac amyloidosis in the contemporary era of 17 per 100 000, which has increased from a previous estimate of 0.5 per 100 000, which was almost certainly due to misdiagnosis and underestimated. The presence and degree of cardiac involvement is the leading cause of mortality both in ATTRwt and ATTRv amyloidosis, and can be identified in up to 15% of patients hospitalized for HF with preserved ejection fraction. Associated features, such as carpal tunnel syndrome, can preceed by several years the development of symptomatic HF and may serve as early disease markers. Echocardiography and cardiac magnetic resonance raise suspicion of disease and might offer markers of treatment response at a myocardial level, such as extracellular volume quantification. Radionuclide scintigraphy with 'bone' tracers coupled with biochemical tests may differentiate ATTR from light chain amyloidosis. Therapies able to slow or halt ATTR-CA progression and increase survival are now available. In this evolving scenario, early disease recognition is paramount to derive the greatest benefit from treatment.

Relation of Body Mass Index to Transthyretin Cardiac Amyloidosis Particularly in Black and Hispanic Patients (from the SCAN-MP Study)

Heart failure with preserved ejection fraction is a heterogeneous clinical syndrome that includes distinct subtypes with different pathophysiologies, genetics, and treatment. Distinguishing heart failure with preserved ejection fraction caused by transthyretin cardiac amyloidosis (ATTR-CA) is critical given its specific treatment. We analyzed a single-center retrospective cohort to determine the association of body mass index (BMI) with a composite of either ATTR-CA or the valine-to-isoleucine substitution (Val122Ile) variant genotype (ATTR-CA+Val122Ile). These BMI differences were prospectively evaluated in the multicenter Screening for Cardiac Amyloidosis using nuclear imaging for Minority Populations (SCAN-MP) study of Black and Hispanic patients with heart failure. The association of BMI with ATTR-CA+Val122Ile was compared by Wilcoxon rank sum analysis and combined with age, gender, and maximum left ventricle wall thickness in multivariable logistic regression. In the retrospective analysis (n = 469), ATTR-CA+Val122Ile was identified in n = 198 (40%), who had a lower median BMI (25.8 kg/m², interquartile range [IQR] 23.4 to 28.9) than other patients (27.1 kg/m², IQR 23.9 to 32.0) (p <0.001). In multivariable logistic regression, BMI <30 kg/m² (odds ratio 2.6, 95% confidence interval 1.5 to 4.5) remained independently associated with ATTR-CA+Val122Ile with a greater association in Black and Hispanic patients (odds ratio 5.8, 95% confidence interval 1.7 to 19.6). In SCAN-MP (n = 201), 17 (8%) had either ATTR-CA (n = 10) or were Val122Ile carriers (n = 7) with negative pyrophosphate scans. BMI was lower (25.4 kg/m² [IQR 24.3 to 28.2]) in ATTR-CA+Val122Ile patients than in non-amyloid patients (32.7 kg/m² [28.3 to 38.6]) (p <0.001), a finding that persisted in multivariable analysis (p = 0.002). In conclusion, lower BMI is associated with ATTR-CA+Val122Ile in heart failure with increased left ventricle wall thickness, particularly in Black and Hispanic patients, and may aid in the identification of those benefiting from ATTR-CA evaluation.

New Advanced Imaging Parameters and Biomarkers-A Step Forward in the Diagnosis and Prognosis of TTR Cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative disorder characterized by extracellular myocardial deposits of amyloid fibrils, with poor outcome, leading to heart failure and death, with significant treatment expenditure. In the era of a novel therapeutic arsenal of disease-modifying agents that target a myriad of pathophysiological mechanisms, timely and accurate diagnosis of ATTR-CM is crucial. Recent advances in therapeutic strategies shown to be most beneficial in the early stages of the disease have determined a paradigm shift in the screening, diagnostic algorithm, and risk classification of patients with ATTR-CM. The aim of this review is to explore the utility of novel specific non-invasive imaging parameters and biomarkers from screening to diagnosis, prognosis, risk stratification, and monitoring of the response to therapy. We will summarize the knowledge of the most recent advances in diagnostic, prognostic, and treatment tailoring parameters for early recognition, prediction of outcome, and better selection of therapeutic candidates in ATTR-CM. Moreover, we will provide input from different potential pathways involved in the pathophysiology of ATTR-CM, on top of the amyloid deposition, such as inflammation, endothelial dysfunction, reduced nitric oxide bioavailability, oxidative stress, and myocardial fibrosis, and their diagnostic, prognostic, and therapeutic implications.

The revolution of ATTR amyloidosis in cardiology: certainties, gray zones and perspectives

Transthyretin (TTR) is a tetrameric protein synthesized mostly by the liver. As a result of gene mutations or as an ageing-related phenomenon, TTR molecules may misfold and deposit in the heart and in other organs as amyloid fibrils. Amyloid transthyretin cardiac amyloidosis (ATTR-CA) manifests typically as left ventricular pseudohypertrophy and/or heart failure with preserved ejection fraction and is an underdiagnosed disorder affecting quality of life and prognosis. This justifies the current search for novel tools for early diagnosis and accurate risk prediction, as well as for safe and effective therapies. In this review we will provide an overview of the main unsolved issues and the most promising research lines on ATTR-CA, ranging from the mechanisms of amyloid formation to therapies.

Critical Comparison of Documents From Scientific Societies on Cardiac Amyloidosis: JACC State-of-the-Art Review

Over the last year, 5 national or international scientific societies have issued documents regarding cardiac amyloidosis (CA) to highlight the emerging clinical science, raise awareness, and facilitate diagnosis and management of CA. These documents provide useful guidance for clinicians managing patients with CA, and all include: 1) an algorithm to establish a diagnosis; 2) an emphasis on noninvasive diagnosis with the combined use of bone scintigraphy and the exclusion of a monoclonal protein; and 3) indications for novel disease-modifying therapies for symptomatic CA, either with or without peripheral neuropathy. Nonetheless, the documents diverge on specific details of diagnosis, risk stratification, and treatment. Highlighting the similarities and differences of the documents by the 5 scientific societies with respect to diagnosis, risk stratification, and treatment offers useful insight into the knowledge gaps and unmet needs in the management of CA. An analysis of these documents, therefore, highlights "gray zones" requiring further investigation.

Clinical Clues and Diagnostic Workup of Cardiac Amyloidosis

Cardiac amyloidosis is increasingly recognized as an underlying cause of left ventricular wall thickening, heart failure, and arrhythmia with variable clinical presentation. Due to the subtle cardiac findings in early transthyretin cardiac amyloidosis and the availability of therapies that can modify but not reverse the disease progression, early recognition is vital. In light chain amyloidosis, timely diagnosis and treatment can significantly improve survival. In this manuscript, we review the clinical, imaging, and electrocardiographic clues that should raise suspicion for cardiac amyloidosis and provide a simplified diagnostic workup algorithm that ensures an accurate diagnosis. The evolution of the noninvasive diagnosis of cardiac amyloidosis has significantly influenced our understanding of disease prevalence, presentations, and outcomes. However, clinical recognition of clues and red flags remains the most important factor in advancing the care of patients with cardiac amyloidosis.

Adipokine Retinol Binding Protein 4 and Cardiovascular Diseases

The morbidity and mortality of cardiovascular diseases (CVDs) have been increasing year by year all over the world and expanding greatly to the younger population, which becomes the leading causes of death globally that threatens human life safety. Prediction of the occurrence of diseases by using risk related adverse events is crucial for screening and early detection of CVDs. Thus, the discovery of new biomarkers that related to risks of CVDs are of urgent in the field. Retinol-binding protein 4 (RBP4) is a 21-kDa adipokine, mainly secreted by adipocytes. Besides its well-established function in the induction of insulin resistance, it has also been found in recent years to be closely associated with CVDs and other risk factors, such as hypertension, coronary heart disease, heart failure, obesity, and hyperlipidemia. In this review, we mainly focus on the progress of research that establishes the correlation between RBP4 and CVDs and the corresponding major risk factors in recent years.

Motor Conduction Studies and Handgrip in Hereditary TTR Amyloidosis: Simple Tools to Evaluate the Upper Limbs

Purpose

Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv) is caused by mutations in the TTR gene, leading to misfolded monomers that aggregate generating amyloid fibrils. The clinical phenotype is heterogeneous, and characterized by a multisystemic disease affecting the sensorimotor and autonomic functions along with other organs.

Materials and Methods

All the patients were assessed by complete neurological assessment, neurophysiological evaluation, of the median nerve, and handgrip analysis. The data are presented as means and standard deviations. Parametric and non-parametric assessments have been performed to identify differences between groups. Pearson's correlation has been carried out when appropriate.

Results

Twenty patients with ATTRv (66.1 ± 8.4 years; eight females) and 30 controls (61.1 ± 11.6 years; 16 females) were enrolled. Handgrip strength was reduced in patients with ATTR in both right and left hands compared to the controls. Significant differences were found between patients and controls in the right (handgrip right, HGS_R TTR 21.1 ± 13 kg vs. HGS_R Control 29.4 ± 11.3 kg, p = 0.017) and left (handgrip left, HGS_L TTR 22.2 ± 10.7 kg. vs. HGS_L Control 31 ± 11.3 kg, p = 0.007). NIS and CMAP amplitude of the median nerve were related to HGS measures for both hands in patients with ATTRv.

Conclusions

The progression of bilateral carpal tunnel syndrome is related to neurophysiological data in the median nerve in ATTRv. Also, handgrip measures might represent an important tool for the assessment of disease progression in ATTRv. We propose using a combination of CMAP amplitude and HGS for the assessment of hand motor strength in ATTRv.

Whole Genome Sequence Analysis of the Plasma Proteome in Black Adults Provides Novel Insights Into Cardiovascular Disease

BACKGROUND

Plasma proteins are critical mediators of cardiovascular processes and are the targets of many drugs. Previous efforts to characterize the genetic architecture of the plasma proteome have been limited by a focus on individuals of European descent and leveraged genotyping arrays and imputation. Here we describe whole genome sequence analysis of the plasma proteome in individuals with greater African ancestry, increasing our power to identify novel genetic determinants.

METHODS

Proteomic profiling of 1301 proteins was performed in 1852 Black adults from the Jackson Heart Study using aptamer-based proteomics (SomaScan). Whole genome sequencing association analysis was ascertained for all variants with minor allele count ≥5. Results were validated using an alternative, antibody-based, proteomic platform (Olink) as well as replicated in the Multi-Ethnic Study of Atherosclerosis and the HERITAGE Family Study (Health, Risk Factors, Exercise Training and Genetics).

RESULTS

We identify 569 genetic associations between 479 proteins and 438 unique genetic regions at a Bonferroni-adjusted significance level of 3.8×10-11. These associations include 114 novel locus-protein relationships and an additional 217 novel sentinel variant-protein relationships. Novel cardiovascular findings include new protein associations at the APOE gene locus including ZAP70 (sentinel single nucleotide polymorphism [SNP] rs7412-T, β=0.61±0.05, P=3.27×10-30) and MMP-3 (β=-0.60±0.05, P=1.67×10-32), as well as a completely novel pleiotropic locus at the HPX gene, associated with 9 proteins. Further, the associations suggest new mechanisms of genetically mediated cardiovascular disease linked to African ancestry; we identify a novel association between variants linked to APOL1-associated chronic kidney and heart disease and the protein CKAP2 (rs73885319-G, β=0.34±0.04, P=1.34×10-17) as well as an association between ATTR amyloidosis and RBP4 levels in community-dwelling individuals without heart failure.

CONCLUSIONS

Taken together, these results provide evidence for the functional importance of variants in non-European populations, and suggest new biological mechanisms for ancestry-specific determinants of lipids, coagulation, and myocardial function.

Cardiovascular Involvement in Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is a systemic disorder resulting from the extracellular deposition of amyloid fibrils of misfolded transthyretin protein in the heart. ATTR-CA is a life-threatening disease, which can be caused by progressive deposition of wild type transthyretin (wtATTR) or by aggregation of an inherited mutated variant of transthyretin (mATTR). mATTR Is a rare condition transmitted in an autosomal dominant manner with incomplete penetrance, causing heterogenous phenotypes which can range from predominant neuropathic involvement, predominant cardiomyopathy, or mixed. Diagnosis of ATTR-CA is complex and requires integration of different imaging tools (echocardiography, bone scintigraphy, magnetic resonance) with genetics, clinical signs, laboratory tests, and histology. In recent years, new therapeutic agents have shown good efficacy and impact on survival and quality of life in this subset of patients, nevertheless patients affected by ATTR-CA may still carry an unfavorable prognosis, thus highlighting the need for new therapies. This review aims to assess cardiovascular involvement, diagnosis, and management of patients affected by ATTR-CA.

Transthyretin and retinol-binding protein as discriminators of diabetic retinopathy in type 1 diabetes mellitus

PURPOSE

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus (DM), which is still a major reason for blindness. Transthyretin (TTR) and retinol-binding protein (RBP) are thought to be related to the pathogenesis both in T2DM and T1DM. We aimed to investigate the association between serum levels of TTR, RBP, RBP/TTR ratio, and DR.

METHODS

This retrospective study involved 188 T1DM inpatients divided into two groups: patients with DR (n = 95) and patients without DR (n = 93). Data of serum levels on lipids and inflammation were collected. Multiple logistic regression analysis was performed to research the association between TTR, RBP, RBP/TTR, and diabetic retinopathy in T1DM.

RESULTS

Compared with patients without DR, those with DR have a higher level of TTR (207 versus 195 mg/L, p = 0.034) and RBP4 (36.85 versus 25.68 mg/L, p < 0.001). Significant differences were also observed between two groups with respect to body mass index (BMI), blood pressure (BP), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), homocysteine, apolipoprotein B (APOB), leucocyte, monocyte, neutrophil, and uric acid (p < 0.05 for all). TTR, RBP, and RBP/TTR were positively correlated with BP, BMI, TG, LDL, homocysteine, APOB, and uric acid. A multivariate logistic regression model revealed individuals with RBP4 level in the highest quartile had 58.95 times higher risk of developing diabetic retinopathy than those in the lowest quartile.

CONCLUSIONS

In conclusion, TTR, RBP, and RBP/TTR ratio are risk factors of DR in T1DM. They are potential markers and targets for diagnosis and treatment of DR.

Transthyretin Cardiac Amyloidosis and Novel Therapies to Treat This Not-so-rare Cause of Cardiomyopathy

Transthyretin cardiac amyloidosis (ATTR-CA) is typically a late-onset disease caused by the deposit of transthyretin amyloid fibrils throughout the heart. When this occurs, various cardiac sequelae can develop, including hypotension, conduction abnormalities, and valvular lesions. The cardiomyopathy caused by ATTR-CA (ATTR-CM) has proven difficult to treat. Until recently, symptomatic management was the only therapeutic option, and many therapies used to treat congestive heart failure were ineffective or even detrimental to patients with ATTR-CM. In addition, treatment was limited to heart and liver transplantation. As a result, prognosis was poor. Recently, a few drug therapies have come to light as potential treatment modalities for ATTR-CM, most notably tafamidis, sold under the brand names Vyndaqel and Vyndamax. After the phase III Transthyretin Amyloidosis Cardiomyopathy trial displayed the drug's efficacy, it was given breakthrough therapy designation and was approved by the Food and Drug Administration on May 6, 2019, for the treatment of ATTR-CA. This novel therapy, as well as various other therapies in the pipeline, such as inotersen and patisiran, provide hope where, until recently, there was little. Unfortunately, the exorbitant cost of these new therapies may present a barrier to long-term treatment for some patients. However, by further improving diagnostic algorithms and incorporating these new treatments into our existing therapeutic modalities, patients with ATTR-CA should be able to live far longer than previously expected. Finally, further research combining these novel treatment modalities must be done, as they may prove to be additive or even synergistic in their treatment of ATTR amyloidosis.

Genetic testing in ambulatory cardiology clinics reveals high rate of findings with clinical management implications

PURPOSE

Cardiovascular disease (CVD) is the leading cause of death in adults in the United States, yet the benefits of genetic testing are not universally accepted.

METHODS

We developed the "HeartCare" panel of genes associated with CVD, evaluating high-penetrance Mendelian conditions, coronary artery disease (CAD) polygenic risk, LPA gene polymorphisms, and specific pharmacogenetic (PGx) variants. We enrolled 709 individuals from cardiology clinics at Baylor College of Medicine, and samples were analyzed in a CAP/CLIA-certified laboratory. Results were returned to the ordering physician and uploaded to the electronic medical record.

RESULTS

Notably, 32% of patients had a genetic finding with clinical management implications, even after excluding PGx results, including 9% who were molecularly diagnosed with a Mendelian condition. Among surveyed physicians, 84% reported medical management changes based on these results, including specialist referrals, cardiac tests, and medication changes. LPA polymorphisms and high polygenic risk of CAD were found in 20% and 9% of patients, respectively, leading to diet, lifestyle, and other changes. Warfarin and simvastatin pharmacogenetic variants were present in roughly half of the cohort.

CONCLUSION

Our results support the use of genetic information in routine cardiovascular health management and provide a roadmap for accompanying research.

Inherited Neuromuscular Disorders: Which Role for Serum Biomarkers?

Inherited neuromuscular disorders (INMD) are a heterogeneous group of rare diseases that involve muscles, motor neurons, peripheral nerves or the neuromuscular junction. Several different lab abnormalities have been linked to INMD: sometimes they are typical of the disorder, but they usually appear to be less specific. Sometimes serum biomarkers can point out abnormalities in presymtomatic or otherwise asymptomatic patients (e.g., carriers). More often a biomarker of INMD is evaluated by multiple clinicians other than expert in NMD before the diagnosis, because of the multisystemic involvement in INMD. The authors performed a literature search on biomarkers in inherited neuromuscular disorders to provide a practical approach to the diagnosis and the correct management of INMD. A considerable number of biomarkers have been reported that support the diagnosis of INMD, but the role of an expert clinician is crucial. Hence, the complete knowledge of such abnormalities can accelerate the diagnostic workup supporting the referral to specialists in neuromuscular disorders.

Association of Low Plasma Transthyretin Concentration With Risk of Heart Failure in the General Population

Importance

Several lines of evidence support low plasma transthyretin concentration as an in vivo biomarker of transthyretin tetramer instability, a prerequisite for the development of both wild-type transthyretin cardiac amyloidosis (ATTRwt) and hereditary transthyretin cardiac amyloidosis (ATTRm). Both ATTRm and ATTRwt cardiac amyloidosis may manifest as heart failure (HF). However, whether low plasma transthyretin concentration confers increased risk of incident HF in the general population is unknown.

Objective

To evaluate whether low plasma transthyretin concentration is associated with incident HF in the general population.

Design, Setting, and Participants

This study included data from 2 similar prospective cohort studies of the Danish general population, the Copenhagen General Population Study (CGPS; n = 9582) and the Copenhagen City Heart Study (CCHS; n = 7385). Using these data, first, whether low concentration of plasma transthyretin was associated with increased risk of incident HF was tested. Second, whether genetic variants in TTR associated with increasing tetramer instability were associated with lower transthyretin concentration and with higher risk of HF was tested. Data were collected from November 2003 to March 2017 in the CGPS and from November 1991 to June 1994 in the CCHS; participants from both studies were observed for survival time end points until March 2017. Data were analyzed from March to June 2019.

Exposures

Transthyretin concentration at or below the 5th percentile, between the 5th and 95th percentile (reference), and greater than the 95th percentile; genetic variants in TTR.

Main Outcome and Measure

Incident HF identified using the Danish National Patient Registry.

Results

Of 9582 individuals in the CGPS, 5077 (53.0%) were women, and the median (interquartile range [IQR]) age was 56 (47-65) years. Of 7385 individuals in the CCHS, 4452 (60.3%) were women, and the median (IQR) age was 59 (46-70) years. During a median (IQR) follow-up of 12.6 (12.3-12.9) years and 21.7 (11.6-23.8) years, 441 individuals (4.6%) in the CGPS and 1122 individuals (15.2%) in the CCHS, respectively, developed HF. Baseline plasma transthyretin concentrations at or below the 5th percentile were associated with incident HF (CGPS: hazard ratio [HR], 1.6; 95% CI, 1.1-2.4; CCHS: HR, 1.4; 95% CI, 1.1-1.7). Risk of HF was highest in men with low transthyretin levels. Compared with p.T139M, a transthyretin-stabilizing variant, TTR genotype was associated with stepwise lower transthyretin concentrations for wild-type TTR (-16.5%), p.G26S (-18.1%), and heterozygotes for other variants (p.V142I, p.H110N, and p.D119N; -30.8%) (P for trend <.001). The corresponding HRs for incident HF were 1.14 (95% CI, 0.57-2.28), 1.29 (95% CI, 0.64-2.61), and 2.04 (95% CI, 0.54-7.67), respectively (P for trend = .04).

Conclusions and Relevance

In this study, lower plasma and genetically determined transthyretin concentrations were associated with a higher risk of incident HF, suggesting a potential mechanistic association between low transthyretin concentration as a marker of tetramer instability and incident HF in the general population.

Use of biomarkers to diagnose and manage cardiac amyloidosis

Amyloidoses are characterized by the tissue accumulation of misfolded proteins into insoluble fibrils. The two most common types of systemic amyloidosis result from the deposition of immunoglobulin light chains (AL) and wild-type or variant transthyretin (ATTRwt/ATTRv). Cardiac involvement is the main determinant of outcome in both AL and ATTR, and cardiac amyloidosis (CA) is increasingly recognized as a cause of heart failure. In CA, circulating biomarkers are important diagnostic tools, allow to refine risk stratification at baseline and during follow-up, help to tailor the therapeutic strategy and monitor the response to treatment. Among amyloid precursors, free light chains are established biomarkers in AL amyloidosis, while the plasma transthyretin assay is currently being investigated as a tool for supporting the diagnosis of ATTRv amyloidosis, predicting outcome and monitor response to novel tetramer stabilizers or small interfering RNA drugs in ATTR CA. Natriuretic peptides (NPs) and troponins are consistently elevated in patients with AL and ATTR CA. Plasma NPs, troponins and free light chains hold prognostic significance in AL amyloidosis, and are evaluated for therapy decision-making and follow-up, while the value of NPs and troponins in ATTR is less well established. Biomarkers can be usefully integrated with clinical and imaging variables at all levels of the clinical algorithm of systemic amyloidosis, from screening to diagnosis and prognosis, and treatment tailoring.

How to Identify Transthyretin Cardiac Amyloidosis at an Early Stage

Cardiac involvement of systemic amyloidosis is preferentially observed in patients with amyloid light chain amyloidosis or transthyretin amyloidosis (ATTR). Owing to the development of diagnostic modalities and changes in recognition by physicians, transthyretin cardiac amyloidosis (ATTR-CA) is now understood to be a more common cause of heart failure than previously thought. Recent progress in disease-modifying therapeutic interventions, such as transthyretin stabilizers, has resulted in ATTR-CA changing from an incurable disease to a curable disease. These interventions are particularly effective in patients with mild symptoms of heart failure, thus indicating that early detection and a precise diagnosis are important for improving the prognosis. In this review article, we summarize the recent reports of early screening of ATTR-CA and describe some important points regarding the making of a precise diagnosis, especially focusing on histological evaluations.

DISCOVERY: prevalence of transthyretin (TTR) mutations in a US-centric patient population suspected of having cardiac amyloidosis

BACKGROUND

Hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) is a multisystem disease that presents with polyneuropathy and/or cardiomyopathy.

METHODS

DISCOVERY, a multicenter screening study, enrolled patients with clinically suspected cardiac amyloidosis to determine the frequency of transthyretin (TTR) mutations and assess disease characteristics.

RESULTS

Of 1007 patients, the majority were from the US (84%), Black/African American (56%), male (63%), and with a mean (standard deviation) age of 65 (13) years. Among 1001 patients with genotyping results, 74 (7%) had a pathogenic TTR mutation (71/836 [8%] from the US). Val122Ile was the most common mutation, found in 11% of Black/African American patients overall; Black/African American ethnicity was an independent predictor of having a pathogenic TTR mutation. Additional independent predictors of such mutations in the total population and Black/African American group were interventricular septum thickness, low electrocardiogram voltage, and age.

CONCLUSIONS

Pathogenic TTR mutations occurred in 8% of US patients with suspected cardiac amyloidosis. Most mutations were Val122Ile, almost exclusively found in Black/African American patients. Disease often remains undetected until advanced and difficult to treat, therefore, clinicians should assess at-risk patients for hATTR amyloidosis as early as possible.

Transthyretin amyloid cardiomyopathy: An uncharted territory awaiting discovery

Transthyretin amyloid cardiomyopathy (ATTR-AC) is an under-recognized and underdiagnosed disease. Although traditionally considered a rare condition, the epidemiology of the disease is rapidly changing due to the possibility of non-invasive diagnosis through cardiac scintigraphy with bone tracers and novel disease-modifying treatments providing survival advantages. Nevertheless, many questions and grey areas have to be addressed, such as the natural history of ATTR-AC, the role and implications of genotype-phenotype interactions, the best clinical management, prognostic stratification and the most appropriate treatments, including those already recommended for patients with heart failure. Clinicians have to cope with old beliefs and evolving concepts in ATTR-AC. A wide horizon of possibilities for physicians of many specialties is unfolding and awaits discovery.

Cardiac Amyloidosis: Evolving Diagnosis and Management: A Scientific Statement From the American Heart Association

Transthyretin amyloid cardiomyopathy (ATTR-CM) results in a restrictive cardiomyopathy caused by extracellular deposition of transthyretin, normally involved in the transportation of the hormone thyroxine and retinol-binding protein, in the myocardium. Enthusiasm about ATTR-CM has grown as a result of 3 simultaneous areas of advancement: Imaging techniques allow accurate noninvasive diagnosis of ATTR-CM without the need for confirmatory endomyocardial biopsies; observational studies indicate that the diagnosis of ATTR-CM may be underrecognized in a significant proportion of patients with heart failure; and on the basis of elucidation of the mechanisms of amyloid formation, therapies are now approved for treatment of ATTR-CM. Because therapy for ATTR-CM may be most effective when administered before significant cardiac dysfunction, early identification of affected individuals with readily available noninvasive tests is essential. This scientific statement is intended to guide clinical practice and to facilitate management conformity by covering current diagnostic and treatment strategies, as well as unmet needs and areas of active investigation in ATTR-CM.

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.

Tenosynovial and Cardiac Amyloidosis in Patients Undergoing Carpal Tunnel Release

BACKGROUND

Patients with cardiac amyloidosis often have carpal tunnel syndrome that precedes cardiac manifestations by several years. However, the prevalence of cardiac involvement at the time of carpal tunnel surgery has not been established.

OBJECTIVES

The authors sought to identify the prevalence and type of amyloid deposits in patients undergoing carpal tunnel surgery and evaluate for cardiac involvement. The authors also sought to determine if patients with soft tissue transthyretin (TTR) amyloid had abnormal TTR tetramer kinetic stability.

METHODS

This was a prospective, cross-sectional, multidisciplinary study of consecutive men age ≥50 years and women ≥60 years undergoing carpal tunnel release surgery. Biopsy specimens of tenosynovial tissue were obtained and stained with Congo red; those with confirmed amyloid deposits were typed with mass spectrometry and further evaluated for cardiac involvement with biomarkers, electrocardiography, echocardiography with longitudinal strain, and technetium pyrophosphate scintigraphy. Additionally, serum TTR concentration and tetramer kinetic stability were examined.

RESULTS

Of 98 patients enrolled (median age 68 years, 51% male), 10 (10.2%) had a positive biopsy for amyloid (7 ATTR, 2 light chain [AL], 1 untyped). Two patients were diagnosed with hereditary ATTR (Leu58His and Ala81Thr), 2 were found to have cardiac involvement (1 AL, 1 ATTR wild-type), and 3 were initiated on therapy. In those patients who had biopsy-diagnosed ATTR, there was no difference in plasma TTR concentration or tetramer kinetic stability.

CONCLUSIONS

In a cohort of patients undergoing carpal tunnel release surgery, Congo red staining of tenosynovial tissue detected amyloid deposits in 10.2% of patients. Concomitant cardiac evaluation identified patients with involvement of the myocardium, allowing for implementation of disease-modifying therapy. (Carpal Tunnel Syndrome and Amyloid Cardiomyopathy; NCT02792790).

Expert Consensus Recommendations for the Suspicion and Diagnosis of Transthyretin Cardiac Amyloidosis

Cardiomyopathy is a manifestation of transthyretin amyloidosis (ATTR), which is an underrecognized systemic disease whereby the transthyretin protein misfolds to form fibrils that deposit in various tissues and organs. ATTR amyloidosis is debilitating and associated with poor life expectancy, especially in those with cardiac dysfunction, but a variety of treatment options have recently become available. Considered a rare disease, ATTR amyloidosis may be more prevalent than thought, particularly in older persons. Diagnosis is often delayed because of a lack of disease awareness and the heterogeneity of symptoms at presentation. Given the recent availability of effective treatments, early recognition and diagnosis are especially critical because treatment is likely more effective earlier in the disease course. The Amyloidosis Research Consortium recently convened a group of experts in ATTR amyloidosis who, through an iterative process, agreed on best practices for suspicion, diagnosis, and characterization of disease. This review describes these consensus recommendations for ATTR associated with cardiomyopathy as a resource to aid cardiologists and others in the recognition and diagnosis of ATTR associated with cardiomyopathy. Included in this review is an overview of red flag signs and symptoms and a recommended diagnostic approach, including testing for monoclonal protein, scintigraphy, or biopsy and, if ATTR associated with cardiomyopathy is identified, TTR genotyping.

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.

Use of Serum Transthyretin as a Prognostic Indicator and Predictor of Outcome in Cardiac Amyloid Disease Associated With Wild-Type Transthyretin

BACKGROUND

Wild-type transthyretin amyloidosis (ATTRwt), an underappreciated cause of heart failure in older adults, is challenging to diagnose and monitor in the absence of validated, disease-specific biomarkers. We examined the prognostic use and survival association of serum TTR (transthyretin) concentration in ATTRwt.

METHODS AND RESULTS

Patients with biopsy-proven ATTRwt were retrospectively identified. Serum TTR, cardiac biomarkers, and echocardiographic parameters were assessed at baseline and follow-up evaluations. Statistical analyses included Kaplan-Meier method, Cox proportional hazard survival models, and receiver-operating characteristic curve analysis. Median serum TTR concentration at presentation was 23 mg/dL (n=116). Multivariate predictors of shorter overall survival were decreased TTR, left ventricular ejection fraction and elevated cTn-I (cardiac troponin I); an inclusive model demonstrated superior accuracy in 4-year survival prediction by receiver-operating characteristic curve analysis (area under the curve, 0.77). TTR values lower than the normal limit, <18 mg/dL, were associated with shorter survival (2.8 versus 4.1 years; P=0.03). Further, TTR values at 1- and 2-year follow-ups were significantly lower (P<0.001) in untreated patients (n=23) compared with those treated with TTR stabilizer, diflunisal (n=12), after baseline evaluation. During 2-year follow-up, unchanged TTR corresponded to increased cTn-I (P=0.006) in untreated patients; conversely, the diflunisal-treated group showed increased TTR (P=0.001) and stabilized cTn-I and left ventricular ejection fraction at 1 year.

CONCLUSIONS

In this series of biopsy-proven ATTRwt, lower baseline serum TTR concentration was associated with shorter survival as an independent predictor of outcome. Longitudinal analysis demonstrated that decreasing TTR corresponded to worsening cardiac function. These data suggest that TTR may be a useful prognostic marker and predictor of outcome in ATTRwt.

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.