Serum neurofilament light chain levels correlate with small fiber related parameters in patients with hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN).

BACKGROUND: Recent evidence suggests that both serum neurofilament light chain (sNfL) levels and small fiber related diagnostic variables may be valuable disease biomarkers of hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN). Our study aimed to explore the relations between sNfL and small fiber related skin biopsy and quantitative sensory testing (QST) parameters in a cohort of ATTRv-PN patients and pre-symptomatic carriers. METHODS: We retrospectively analyzed data from 13 ATTRv patients and 21 pre-symptomatic carriers who underwent sNfL dosage, skin biopsy, and QST, and analyzed correlations between sNFL, intraepidermal nerve fiber density (IENFD), and cold (CDT) and warm detection thresholds (WDT). RESULTS: Both sNfL and small fiber related parameters significantly differed between carriers and patients (sNfL: p < 0.0001; IENFD: p = 0.0008; CDT, WDT: < 0.0001). sNFL levels were normal in all carriers, altered in 85% of patients, negatively correlated with distal IENFD (r = -0.47, p = 0.005), and significantly correlated with CDT (r = -0.68; p < 0.0001) and WDT (r = 0.57; p < 0.0001). CONCLUSIONS: Our study showed that sNfL reliably discriminates symptomatic ATTRv-PN patients from pre-symptomatic carriers, and found significant relations between sNfL, skin biopsy, and QST small fiber related parameters, suggesting that sNfL might be a valuable biomarker of peripheral nerve involvement in ATTRv-PN and a supportive criterion for symptomatic disease transition.

Data-independent acquisition mass spectrometry reveals comprehensive plasma protein profiles in the natural history of patients with hereditary transthyretin amyloidosis (ATTRv).

OBJECTIVES: Hereditary transthyretin amyloidosis (ATTRv) is a rare, fatal, autosomal dominant disease with more than 140 mutations discovered. Three phenotypes of amyloid infiltration are neuropathy (ATTRv-PN), cardiopathy (ATTRv-CM), and neuropathy + cardiopathy (ATTRv-MIX). The lack of ATTR-specific biomarkers, difficulties in biopsy evidence, and limited known pathogenic mechanisms have made diagnosis difficult. Newly emerging noninvasive measures for monitoring progression and disease-modifying therapies have improved early diagnosis and patient management. METHODS: Our research applies the latest technology, Data-Independent Acquisition-Based Quantitative Proteomics (DIA), to reveal comprehensive plasma protein profiles in the natural history of Chinese patients with hereditary transthyretin amyloidosis (ATTRv). We analyzed differentially expressed proteins (DEPs) in three phenotypes (ATTRv-PN, ATTRv-CM, and ATTRv-MIX). RESULTS: Serum samples were collected from a total of 18 patients (6 ATTRv-PN, 5 ATTRv-CM, and 7 ATTRv-MIX patients) and 20 healthy participants as a control group. Combined with the results of the proteomic and bioinformatic analyses, we found 30 DEPs and protein interaction networks clustered in KRT family proteins and DSC3 between ATTRv-PN and the control, which were rich in the estrogen signaling pathway and the cell adhesion molecule (CAM) pathway. CONCLUSION: This study demonstrates a global and significant proteomic profile in different stages of ATTRv.

Patisiran, an RNAi Therapeutic, for Hereditary Transthyretin Amyloidosis.

BACKGROUND: Patisiran, an investigational RNA interference therapeutic agent, specifically inhibits hepatic synthesis of transthyretin. METHODS: In this phase 3 trial, we randomly assigned patients with hereditary transthyretin amyloidosis with polyneuropathy, in a 2:1 ratio, to receive intravenous patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks. The primary end point was the change from baseline in the modified Neuropathy Impairment Score+7 (mNIS+7; range, 0 to 304, with higher scores indicating more impairment) at 18 months. Other assessments included the Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) questionnaire (range, -4 to 136, with higher scores indicating worse quality of life), 10-m walk test (with gait speed measured in meters per second), and modified body-mass index (modified BMI, defined as [weight in kilograms divided by square of height in meters]×albumin level in grams per liter; lower values indicated worse nutritional status). RESULTS: A total of 225 patients underwent randomization (148 to the patisiran group and 77 to the placebo group). The mean (±SD) mNIS+7 at baseline was 80.9±41.5 in the patisiran group and 74.6±37.0 in the placebo group; the least-squares mean (±SE) change from baseline was -6.0±1.7 versus 28.0±2.6 (difference, -34.0 points; P<0.001) at 18 months. The mean (±SD) baseline Norfolk QOL-DN score was 59.6±28.2 in the patisiran group and 55.5±24.3 in the placebo group; the least-squares mean (±SE) change from baseline was -6.7±1.8 versus 14.4±2.7 (difference, -21.1 points; P<0.001) at 18 months. Patisiran also showed an effect on gait speed and modified BMI. At 18 months, the least-squares mean change from baseline in gait speed was 0.08±0.02 m per second with patisiran versus -0.24±0.04 m per second with placebo (difference, 0.31 m per second; P<0.001), and the least-squares mean change from baseline in the modified BMI was -3.7±9.6 versus -119.4±14.5 (difference, 115.7; P<0.001). Approximately 20% of the patients who received patisiran and 10% of those who received placebo had mild or moderate infusion-related reactions; the overall incidence and types of adverse events were similar in the two groups. CONCLUSIONS: In this trial, patisiran improved multiple clinical manifestations of hereditary transthyretin amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO ClinicalTrials.gov number, NCT01960348 .).

Inotersen Treatment for Patients with Hereditary Transthyretin Amyloidosis.

BACKGROUND: Hereditary transthyretin amyloidosis is caused by pathogenic single-nucleotide variants in the gene encoding transthyretin ( TTR) that induce transthyretin misfolding and systemic deposition of amyloid. Progressive amyloid accumulation leads to multiorgan dysfunction and death. Inotersen, a 2'- O-methoxyethyl-modified antisense oligonucleotide, inhibits hepatic production of transthyretin. METHODS: We conducted an international, randomized, double-blind, placebo-controlled, 15-month, phase 3 trial of inotersen in adults with stage 1 (patient is ambulatory) or stage 2 (patient is ambulatory with assistance) hereditary transthyretin amyloidosis with polyneuropathy. Patients were randomly assigned, in a 2:1 ratio, to receive weekly subcutaneous injections of inotersen (300 mg) or placebo. The primary end points were the change in the modified Neuropathy Impairment Score+7 (mNIS+7; range, -22.3 to 346.3, with higher scores indicating poorer function; minimal clinically meaningful change, 2 points) and the change in the score on the patient-reported Norfolk Quality of Life-Diabetic Neuropathy (QOL-DN) questionnaire (range, -4 to 136, with higher scores indicating poorer quality of life). A decrease in scores indicated improvement. RESULTS: A total of 172 patients (112 in the inotersen group and 60 in the placebo group) received at least one dose of a trial regimen, and 139 (81%) completed the intervention period. Both primary efficacy assessments favored inotersen: the difference in the least-squares mean change from baseline to week 66 between the two groups (inotersen minus placebo) was -19.7 points (95% confidence interval [CI], -26.4 to -13.0; P<0.001) for the mNIS+7 and -11.7 points (95% CI, -18.3 to -5.1; P<0.001) for the Norfolk QOL-DN score. These improvements were independent of disease stage, mutation type, or the presence of cardiomyopathy. There were five deaths in the inotersen group and none in the placebo group. The most frequent serious adverse events in the inotersen group were glomerulonephritis (in 3 patients [3%]) and thrombocytopenia (in 3 patients [3%]), with one death associated with one of the cases of grade 4 thrombocytopenia. Thereafter, all patients received enhanced monitoring. CONCLUSIONS: Inotersen improved the course of neurologic disease and quality of life in patients with hereditary transthyretin amyloidosis. Thrombocytopenia and glomerulonephritis were managed with enhanced monitoring. (Funded by Ionis Pharmaceuticals; NEURO-TTR ClinicalTrials.gov number, NCT01737398 .).

A multi-modal diagnostic model improves detection of cardiac amyloidosis among patients with diagnostic confirmation by cardiac biopsy.

BACKGROUND: Timely recognition of cardiac amyloidosis is clinically important, but the diagnosis is frequently delayed. OBJECTIVES: We sought to identify a multi-modality approach with the highest diagnostic accuracy in patients evaluated by cardiac biopsy, the diagnostic gold standard. METHODS: Consecutive patients (N = 242) who underwent cardiac biopsy for suspected amyloidosis within an 18-year period were retrospectively identified. Cardiac biomarker, ECG, and echocardiography results were examined for correlation with biopsy-proven disease. A prediction model for cardiac amyloidosis was derived using multivariable logistic regression. RESULTS: The overall cohort was characterized by elevated BNP (median 727 ng/mL), increased left ventricular wall thickness (IWT; median 1.7 cm), and reduced voltage-to-mass ratio (median 0.06 mm/[g/m2]). One hundred and thirteen patients (46%) had either light chain (n = 53) or transthyretin (n = 60) amyloidosis by cardiac biopsy. A prediction model including age, relative wall thickness, left atrial pressure by E/e', and low limb lead voltage (<0.5 mV) showed good discrimination for cardiac amyloidosis with an optimism-corrected c-index of 0.87 (95% CI 0.83-0.92). The diagnostic accuracy of this model (79% sensitivity, 84% specificity) surpassed that of traditional screening parameters, such as IWT in the absence of left ventricular hypertrophy on ECG (98% sensitivity, 20% specificity) and IWT with low limb lead voltage (49% sensitivity, 91% specificity). CONCLUSION: Among patients with an advanced infiltrative cardiomyopathy phenotype, traditional biomarker, ECG, and echocardiography-based screening tests have limited individual diagnostic utility for cardiac amyloidosis. A prediction algorithm including age, relative wall thickness, E/e', and low limb lead voltage improves the detection of cardiac biopsy-proven disease.

Hereditary transthyretin amyloidosis: current treatment.

PURPOSE OF REVIEW: Hereditary transthyretin amyloidosis (ATTRv) is a rare autosomal dominant, life-threatening disease. Until recently only early stages of ATTRv-PN (polyneuropathy) had access to disease-modifying therapy (DMT), whereas there was no specific treatment for ATTRv-CM (cardiomyopathy). This review updates our knowledge about results of three phase 3 clinical trials, expert's consensus for early diagnosis and emerging biomarkers. RECENT FINDINGS: Two phase 3 studies using RNAi and antisense oligonucleotides (ASO) were successful. Primary endpoints were progression of neuropathic score mNIS +7 and quality of Life (QOL) in a population of ATTRv-PN at different levels of severity. They knock downed circulating amyloidogenic mutant and wild-type TTR. Safety concerned ASO with a risk of thrombocytopenia. RNAi showed possible reversibility of the disease. Phase 3 ATTRACT trial-tested tafamidis versus placebo in patients with ATTRv-CM and ATTRwt-CM and showed a significant reduction of all-cause mortality and rates of cardiovascular-related hospitalizations. All three drugs obtained marketing authorization by European Medicines Agency (EMA) and Food and drug administration (FDA). Early diagnosis criteria for ATTRv-PN and ATTRv-CM are available. Ongoing clinical trials for ATTRv are presented. New biomarkers are plasma neurofilament light chain, intraepidermal nerve fiber density. SUMMARY: The majority of patients with ATTRv may have now access to a DMT. Criteria for early diagnosis are available.

Clinical, histopathological, and in silico pathogenicity analyses in a pedigree with familial amyloidosis of the Finnish type (Meretoja syndrome) caused by a novel gelsolin mutation.

Purpose: Familial amyloidosis of the Finnish type (FAF) is an inherited amyloidosis arising from mutations in the gelsolin protein (GSN). The disease includes facial paralysis, loose skin, and lattice corneal dystrophy. To date, FAF has been invariably associated with substitution of Asp214 in GSN. We describe the clinical, histopathological, and genetic features of a family with FAF due to a novel GSN mutation. Methods: Five affected adult individuals in a three-generation FAF pedigree were included in the study. Histopathological analysis was performed on an eyelid skin biopsy from one patient. Genetic analysis included next-generation sequencing (NGS) and Sanger sequencing for confirmation of the GSN variant. Several tools for in silico analysis of pathogenicity for the novel variant and to predict the effect of the amino acid replacement on protein stability were used. Results: Three older adult affected patients exhibited corneal lattice dystrophy, cutis laxa, and facultative peripheral neuropathy. Two younger adult individuals presented only with corneal amyloid deposits. NGS identified a heterozygous GSN c.1631T>G transversion, predicting a novel p.Met544Arg mutation. All in silico tools indicated that p.Met544Arg is deleterious for GSN functionality or stability. Conclusions: The results expand the molecular spectrum of GSN-linked systemic amyloidosis. The novel p.Met544Arg pathogenic variant is predicted to affect gelsolin function, presumably by impairing a potential calcium-sensitive, actin-binding region.

Phase 3 Multicenter Study of Revusiran in Patients with Hereditary Transthyretin-Mediated (hATTR) Amyloidosis with Cardiomyopathy (ENDEAVOUR).

PURPOSE: The Phase 3 ENDEAVOUR study evaluated revusiran, an investigational RNA interference therapeutic targeting hepatic transthyretin (TTR) production, for treating cardiomyopathy caused by hereditary transthyretin-mediated (hATTR) amyloidosis. METHODS: Patients with hATTR amyloidosis with cardiomyopathy were randomized 2:1 to receive subcutaneous daily revusiran 500 mg (n = 140) or placebo (n = 66) for 5 days over a week followed by weekly doses. Co-primary endpoints were 6-min walk test distance and serum TTR reduction. RESULTS: Revusiran treatment was stopped after a median of 6.71 months; the study Sponsor prematurely discontinued dosing due to an observed mortality imbalance between treatment arms. Eighteen (12.9%) patients on revusiran and 2 (3.0%) on placebo died during the on-treatment period. Most deaths in both treatment arms were adjudicated as cardiovascular due to heart failure (HF), consistent with the natural history of the disease. A post hoc safety investigation of patients treated with revusiran found that, at baseline, a greater proportion of those who died were ≥ 75 years and showed clinical evidence of more advanced HF compared with those who were alive throughout treatment. Revusiran pharmacokinetic exposures and TTR lowering did not show meaningful differences between patients who died and who were alive. Revusiran did not deleteriously affect echocardiographic parameters, cardiac biomarkers, or frequency of cardiovascular and HF hospitalization events. CONCLUSIONS: Causes for the observed mortality imbalance associated with revusiran were thoroughly investigated and no clear causative mechanism could be identified. Although the results suggest similar progression of cardiac parameters in both treatment arms, a role for revusiran cannot be excluded. CLINICAL TRIAL REGISTRATION: NCT02319005.

Disease-Specific Biomarkers in Transthyretin Cardiac Amyloidosis.

PURPOSE OF REVIEW: Transthyretin amyloidosis is an increasingly recognized cause of restrictive cardiomyopathy related to amyloid fibril deposition in cardiac tissues. As treatment therapies have emerged for transthyretin amyloidosis (ATTR), so has interest in using biomarkers to identify disease prior to advanced presentation. RECENT FINDINGS: Lower levels of transthyretin and retinol binding protein-4 have been demonstrated in patients with pathogenic mutations of transthyretin either with or without clinical disease. Levels associate with the severity of mutations as well as response to treatment with transthyretin stabilizers or small interfering RNA molecules which silence transthyretin production. Transthyretin stability is the rate limiting step of amyloid fibril formation and directly measuring transthyretin kinetic stability has the potential to identify patients as risk as well as therapeutic response to treatment regardless of pathogenic or wild-type genetics. In addition, non-antibody protein-based peptide probes have been developed that directedly measure misfolded transthyretin oligomers due to transthyretin breakdown. Although promising, both TTR kinetic and protein peptide probes remain in early stages of clinical investigation. Transthyretin, retinol binding protein-4, transthyretin kinetic stability, and protein-based peptide probes have potential as biomarkers to facilitate an earlier ATTR diagnosis for patients with pathogenic transthyretin mutations.

Amyloid cardiomyopathy in a large integrated health care system.

BACKGROUND: Light Chain (AL) and transthyretin (ATTR) amyloidosis are the most common forms of amyloid cardiomyopathy. Population based studies describing the epidemiology and clinical features of amyloid cardiomyopathy are often based in tertiary medical centers and thus may be limited by referral bias. METHODS AND RESULTS: We performed a cohort study of 198 patients diagnosed and treated in the Kaiser Permanente Northern California health care system who had a confirmed diagnosis of cardiac amyloidosis between 2001 and 2016. Associations between demographic, clinical, laboratory and imaging data and patient outcomes were quantified using multivariable Cox proportional hazard models for both the AL and ATTR groups. The average length of follow up was 2.8 years (SD 2.9 years) and overall survival was 69.1 percent at one year and 35.4 percent at five years. In the AL group, lower left ventricular ejection fraction (HR 1.33 per 5-point decrease, P < .001), coronary artery disease (HR 3.56, P < .001), and diabetes mellitus (HR 3.19, P < .001) were associated with all-cause mortality. Increasing age at the time of diagnosis with associated with higher all-cause mortality in both the AL and ATTR groups. Higher levels of B-type natriuretic peptide were associated with all-cause mortality in both groups: Top quartile BNP HR 6.17, P < .001 for AL and HR 8.16, P = .002 for ATTR. CONCLUSIONS: This study describes a large cohort of patients with amyloid cardiomyopathy derived from a community based, integrated healthcare system and describes demographic, clinical, and laboratory characteristics associated with mortality and heart failure hospitalization. In this population, coronary artery disease, diabetes mellitus, and high BNP levels were strongly associated with mortality.

Inflammatory profiling of patients with familial amyloid polyneuropathy.

BACKGROUND: Familial amyloid polyneuropathy (FAP) or ATTRv (amyloid TTR variant) amyloidosis is a fatal hereditary disease characterized by the deposition of amyloid fibrils composed of transthyretin (TTR). The current diagnosis of ATTRv relies on genetic identification of TTR mutations and on Congo Red-positive amyloid deposits, which are absent in most ATTRv patients that are asymptomatic or early symptomatic, supporting the need for novel biomarkers to identify patients in earlier disease phases allowing disease control. METHODS: In an effort to search for new markers for ATTRv, our group searched for nine inflammation markers in ATTRv serum from a cohort of 28 Brazilian ATTRv patients. RESULTS: We found that the levels of six markers were increased (TNF-α, IL-1ß, IL-8, IL-33, IFN-ß and IL-10), one had decreased levels (IL-12) and two of them were unchanged (IL-6 and cortisol). Interestingly, asymptomatic patients already presented high levels of IL-33, IL-1ß and IL-10, suggesting that inflammation may take place before fibril deposition. CONCLUSIONS: Our findings shed light on a new, previously unidentified aspect of ATTRv, which might help define new criteria for disease management, as well as provide additional understanding of ATTRv aggressiveness.

Combination of Commonly Examined Parameters Is a Useful Predictor of Positive 99 mTc-Labeled Pyrophosphate Scintigraphy Findings in Elderly Patients With Suspected Transthyretin Cardiac Amyloidosis.

BACKGROUND: A recent study revealed a high prevalence of transthyretin (TTR) cardiac amyloidosis (CA) in elderly patients. 99 mTc-labeled pyrophosphate (99 mTc-PYP) scintigraphy is a remarkably sensitive and specific modality for TTR-CA, but is only available in specialist centres; thus, it is important to raise the pretest probability. The aim of this study was to evaluate the characteristics of patients with 99 mTc-PYP positivity and make recommendations about patient selection for 99 mTc-PYP scintigraphy.Methods and Results:We examined 181 consecutive patients aged ≥70 years who underwent 99 mTc-PYP scintigraphy at Kumamoto University Hospital between January 2012 and December 2018. Logistic regression analyses showed that high-sensitivity cardiac troponin T (hs-cTnT) ≥0.0308 ng/mL, left ventricular posterior wall thickness ≥13.6 mm, and wide QRS (QRS ≥120 ms) were strongly associated with 99 mTc-PYP positivity. We developed a new index for predicting 99 mTc-PYP positivity by adding 1 point for each of the 3 factors. The 99 mTc-PYP positive rate increased by a factor of 4.57 for each 1-point increase (P<0.001). Zero points corresponded to a negative predictive value of 87% and 3 points corresponded to a positive predictive value of 96% for 99 mTc-PYP positivity. CONCLUSIONS: The combination of biochemical (hs-cTnT), physiological (wide QRS), and structural (left ventricular posterior wall thickness) findings can raise the pretest probability for 99 mTc-PYP scintigraphy. It can assist clinicians in determining management strategies for elderly patients with suspected CA.

Plasma neurofilament light chain concentration is increased and correlates with the severity of neuropathy in hereditary transthyretin amyloidosis.

Hereditary transthyretin amyloidosis (ATTRm) causes a disabling peripheral neuropathy as part of a multisystem disorder. The recent development of highly effective gene silencing therapies has highlighted the need for effective biomarkers of disease activity to guide the decision of when to start and stop treatment. In this study, we measured plasma neurofilament light chain (pNfL) concentration in 73 patients with ATTR and found that pNfL was significantly raised in ATTRm patients with peripheral neuropathy compared to healthy controls. Furthermore, pNFL correlated with disease severity as defined by established clinical outcome measures in patients for whom this information was available. These findings suggest a potential role of pNfL in monitoring disease activity and progression in ATTRm patients.

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.

Serum Proteomic Variability Associated with Clinical Phenotype in Familial Transthyretin Amyloidosis (ATTRm).

Transthyretin (TTR), normally a plasma circulating protein, can become misfolded and aggregated, ultimately leading to extracellular deposition of amyloid fibrils usually targeted to heart or nerve tissues. Referred to as TTR-associated amyloidoses (ATTR), this group of diseases is frequently life threatening and fatal if untreated. ATTR, caused by amyloid-forming variant TTR proteins (ATTRm) that arise from point mutations in the TTR gene, were classically referred to as familial amyloid cardiomyopathy (FAC) or familial amyloid polyneuropathy (FAP), reflecting the clinical phenotype. FAC and FAP are pathologies that can be challenging to diagnose as there are no definitive biomarkers of disease; moreover, disease-specific measures of progression are lacking, and treatment options are limited. Thus, the discovery of sensitive and specific indicators of disease has the potential to improve recognition, enable accurate measurement of amyloid progression and response to treatment, and reveal key information regarding FAC and FAP pathobiological mechanisms. In this study, the goal was to investigate serum proteomic features unique to FAC and FAP types of ATTRm. Multiple-reaction monitoring mass spectrometry (MRM-MS), a powerful technique in profiling proteomes, was used to measure the serum concentrations of 160 proteins in samples from FAC and FAP patients. Results were compared to data from healthy control sera obtained from individuals matched to age (≥60 years), gender (male), and race (Caucasian). Proteomic analyses of ATTRm (FAC and FAP) and control samples showed significant concentration differences in 107 of 192 (56%) of the serum proteins that were studied. In comparing FAC to FAP, differences in concentrations as well as interactions and functions of several proteins were identified as unique to each disease; significantly lower levels of TTR were specific to FAC, but not to FAP. Annotated functional clustering identified extracellular region, signal, and signal peptide as terms common to FAC and FAP. Conversely, disulfide bond was unique to FAC; secreted, glycosylation site: N-linked, glycosylation, glycoprotein, polymorphism, and sequence variant were associated solely with FAP. Predicted protein-protein associations in FAC were seen for reaction, binding, and activation processes; no associations were found in FAP. This study demonstrates significant proteomic differences between ATTRm patient and control sera, as well as ATTRm phenotype-associated variations in the circulating levels of several proteins including TTR. The identification of serum proteins unique to FAC and FAP may have diagnostic and prognostic utility and could possibly provide important clues about disease mechanisms.

Blood Proteomic Profiling in Inherited (ATTRm) and Acquired (ATTRwt) Forms of Transthyretin-Associated Cardiac Amyloidosis.

Transthyretin-associated forms of cardiac amyloidosis are fatal protein misfolding diseases that can be inherited (ATTRm) or acquired (ATTRwt). An accurate diagnosis of ATTR amyloidosis can be challenging as biopsy evidence, usually from the affected organ, is required. Precise biomarkers for ATTR disease identification and monitoring are undiscovered, disease-specific therapeutic options are needed, and the current understanding of ATTR molecular pathogenesis is limited. The aim of this study was to investigate and compare the serum proteomes in ATTRm and ATTRwt cardiac amyloidosis to identify differentially expressed blood proteins that were disease-specific. Using multiple-reaction monitoring mass spectrometry (MRM-MS), the concentrations of 160 proteins were analyzed in serum samples from ATTRm and ATTRwt patients, and a healthy control group. Patient and control sera were matched to age (≥60 years), gender (male), and race (Caucasian). The circulating concentrations of 123/160 proteins were significantly different in patient vs control sera; TTR and retinol-binding protein (RBP4) levels were significantly decreased (p < 0.03) in ATTRm compared to controls. In ATTRm, 14/123 proteins were identified as unique to that group and found generally to be lower than controls; moreover, the concentrations of RBP4 and 6 other proteins in this group were significantly different (p < 0.04) compared to ATTRwt. Predicted interactions among the 14 proteins unique to ATTRm were categorized as reaction and binding associations. Alternatively, 27 proteins were found to be unique to ATTRwt with associated interactions defined as activation, catalysis, and inhibition, in addition to reaction and binding. This study demonstrates significant proteomic differences between ATTR patient and control sera, and disease-associated variations in circulating levels of several proteins including TTR and RBP4. The identification of serum proteins unique to ATTRm and ATTRwt cardiac amyloidosis may have diagnostic and prognostic utility, and may provide important clues about disease mechanisms.

Heart Failure Resulting From Age-Related Cardiac Amyloid Disease Associated With Wild-Type Transthyretin: A Prospective, Observational Cohort Study.

BACKGROUND: Heart failure caused by wild-type transthyretin amyloidosis (ATTRwt) is an underappreciated cause of morbidity and mortality in the aging population. The aims of this study were to examine features of disease and to characterize outcomes in a large ATTRwt cohort. METHODS AND RESULTS: Over 20 years, 121 patients with ATTRwt were enrolled in a prospective, observational study. Median age at enrollment was 75.6 years (range, 62.6-87.8 years); 97% of patients were white. The median survival, measured from biopsy diagnosis, was 46.69 months (95% confidence interval, 41.95-56.77); 78% of deaths were attributable to cardiac causes. By Kaplan-Meier analysis, 5-year survival was 35.7% (95% confidence interval, 25-46). Impaired functional capacity (mean Vo2max, 13.5 mL·kg(-1)·min(-1)) and atrial fibrillation (67%) were common clinical features. Multivariate predictors of reduced survival were elevated serum brain natriuretic peptide (482 ± 337 pg/mL) and uric acid (8.2 ± 2.6 mg/dL), decreased left ventricular ejection fraction (50% median; range, 10%-70%), and increased relative wall thickness (0.75 ± 0.19). CONCLUSIONS: In this series of patients with biopsy-proven ATTRwt, poor functional capacity and atrial arrhythmias were common clinical features. Elevated brain natriuretic peptide and uric acid, decreased left ventricular ejection fraction, and increased relative wall thickness were associated with limited survival of only 35.7% at 5 years for the group as a whole. These data establish the natural history of ATTRwt, provide statistical basis for the design of future interventional clinical trials, and highlight the need for more sensitive diagnostic tests and disease-specific treatments for this disease.

The Utility of 99mTc-DPD Scintigraphy in the Diagnosis of Cardiac Amyloidosis: An Australian Experience.

BACKGROUND: The uptake of bone-seeking radiotracers in the amyloid heart is well recognised. 99mTc-DPD has been shown to be highly sensitive for cardiac transthyretin (ATTR) amyloid in an overseas population, but is not registered for use in Australia. We explored its utility as a diagnostic tool within our population. METHODS: Patients diagnosed with AL and ATTR (wild-type and inherited) cardiac amyloidosis were prospectively recruited from the Princess Alexandra Hospital Amyloidosis Centre. Patients underwent injection with 99mTc-DPD then planar whole body imaging was performed at 5 minutes post-injection (soft tissue phase) and 3 hours (bone phase). A myocardial SPECT and low amperage CT were acquired after the late whole-body scan. Scans were analysed by two nuclear imaging specialists. Intensity of cardiac 99mTc-DPD uptake was graded as 0 to 3 in accordance with previous criteria, and semiquantitative analysis was performed using a heart to whole body ratio (H:WB) on the 3-hour scan. Patients also underwent electrocardiography and transthoracic echocardiography, and blood samples were taken for troponin I and brain natriuretic peptide levels, to assess for any correlation with DPD uptake. RESULTS: Twenty-one patients (8 AL and 13 ATTR) completed the study. Median age was 58 and 70 years for AL and ATTR patients respectively, and 19 (90.5%) were male. 99mTc-DPD scintigraphy was positive in 2 (25%) of AL, and 13 (100%) of ATTR patients. Grade of cardiac uptake, and mean H:WB (0.1249 v. 0.0794) was greater in the ATTR cohort (p-value<0.001 and 0.001 respectively). No statistically significant correlation was identified between H:WB and echocardiographic parameters. There was a significant positive correlation between H:WB and the PR interval on ECG (p=0.026). CONCLUSIONS: 99mTc-DPD scintigraphy is highly sensitive for the diagnosis of cardiac ATTR amyloid, but less so for AL amyloid.

Acute cardiac failure secondary to senile systemic amyloidosis.

Hereditary or senile transthyretin (TTR) cardiac amyloidosis is a rare and underestimated cause of heart failure in old patients. New diagnostic methods, particularly cardiac MRI and proteomic analysis, have been recently developed that enable both earlier identification and development of specific treatments.We report a case of cardiac amyloidosis revealed through late-onset heart failure.