Transthyretin (TTR) cardiac amyloidosis

Novel technique and assessment of available three-dimensional delivery sheath for endomyocardial biopsy during cardiac device implantation

BACKGROUND

Early cardiomyopathy diagnosis allows timely treatment and may help resolve problems that occur after cardiac implantable electronic device (CIED) implantation.

OBJECTIVE

To describe a novel technique for endomyocardial biopsy (EMB) using a three-dimensional (3D) delivery sheath during CIED implantation. Additionally, we investigated 3D delivery sheath characteristics using sheath deflection during bioptome insertion.

METHODS

This study of 20 patients undergoing CIED implantation analyzed the EMB success rate and pathological findings. Fluoroscopic images assessed 3D delivery sheath characteristics before and after bioptome insertion in three sheaths. CIEDs were implanted for sick sinus syndrome (n=3), atrioventricular conduction disorder (n=16), and left ventricular dysfunction (n=1). Fluoroscopic verification was performed using right anterior oblique (RAO) and left anterior oblique (LAO) views. EMB was performed with Selectra 3D (BIOTRONIK), CSP Locator 3D (Abbott) and SSPC (Boston Scientific) (12, 4, and 4 patients, respectively). The distance moved toward the right ventricular apex (RVA) in RAO was defined as Dis-RAO (mm) and that moved toward the RVA in LAO was defined as Dis-LAO (mm).

RESULTS

Among the three sheaths, only the CSP Locator 3D and Selectra 3D showed significant differences in Dis-RAO (13.2±2.0mm vs. 19.8±3.8mm, p<0.01) and Dis-LAO (8.1±1.3mm vs. 15.3±3.9mm, p<0.01). A total of 77 EMB samples from 20 patients were collected without any complication, and four patients (20%) were diagnosed with cardiac amyloidosis (CA) based on pathological findings.

CONCLUSIONS

All 3D delivery sheaths were safe and effective for performing EMB from the RVS during CIED implantation, enabling early CA diagnosis in 20% of patients.

Electrocardiographic abnormalities attributable to infiltrative cardiomyopathies: review and prevalence in patients with congestive heart failure

BACKGROUND

The electrocardiogram (ECG) is routinely used in patients with suspected infiltrative cardiomyopathies; heart diseases characterized by the abnormal deposition of pathological substances in the myocardium. This study presents a review of ECG features attributable to various infiltrative cardiomyopathies and analyzes the prevalence and overlap of electrocardiographic abnormalities in patients with adjudicated CHF.

RESULTS

The study included 573 consecutive CHF patients without severe aortic stenosis, further stratified by LV hypertrophy (LVH) and preserved or decreased LV ejection fraction. Comprehensive ECG analysis revealed at least one ECG abnormality typically associated with infiltrative cardiomyopathies in 95% of patients, and more than one ECG abnormality in 70%. An average number of ECG abnormalities was 2.2 ± 1.2 per patient. There was substantial overlap in ECG abnormalities in individual patients, particularly those attributable to Fabry's disease and hemochromatosis (51.5%) or cardiac amyloidosis (46.1%), and hemochromatosis and cardiac amyloidosis (44.2%). Prevalence of various ECG abnormalities was similar across various patient demographics and co-morbidities, including LVH status and/or history of CAD which did not increase the number of ECG abnormalities (2.155 ± 1.238 vs. 2.228 ± 1.192 in patients without CAD history, p = 0.969). Patients with reduced LV ejection fraction had a higher prevalence of widened QRS and premature ventricular complexes.

CONCLUSION

ECG abnormalities attributable to infiltrative cardiomyopathies are common in heart failure patients, with a significant overlap in findings classically attributed to various infiltrative cardiomyopathies. The presence of LVH and decreased LV ejection fraction do not significantly affect the prevalence of ECG abnormalities.

Role of Biomarkers in Early Diagnosis and Prognosis of Cardiac Amyloidosis: A Systematic Review and Meta-Analysis

BACKGROUND

Cardiac amyloidosis is characterized by amyloid fibril deposition in the heart, leading to restrictive cardiomyopathy and heart failure. Early diagnosis and monitoring are crucial for effective management. This systematic review and meta-analysis evaluates the utility of various biomarkers in the early detection, disease progression, and prognosis of cardiac amyloidosis.

METHODS

We conducted a comprehensive search of PubMed, Scopus, and Web of Science databases for studies published between 2000 and 2024 that assessed the diagnostic and prognostic value of biomarkers in cardiac amyloidosis. Data were extracted and analyzed to determine the sensitivity, specificity, and prognostic significance of each biomarker. The correlation between biomarker levels and imaging findings was also explored.

RESULTS

A total of 45 studies were included in the meta-analysis. NT-proBNP and troponins had high sensitivity and specificity for early diagnosis of cardiac amyloidosis. Novel biomarkers, such as serum amyloid P component and light-chain assays, showed promise in distinguishing between amyloidosis subtypes and predicting disease progression. However, significant variability existed in the correlation between biomarkers and imaging findings.

CONCLUSIONS

Biomarkers are crucial for early diagnosis and prognosis of cardiac amyloidosis. NT-proBNP and troponins are well-established markers, while novel biomarkers offer additional insights into disease progression and subtype differentiation.

Cardiovascular Risk Factors and Genetic Risk in Transthyretin V142I Carriers

BACKGROUND

Nearly 3% to 4% of Black individuals in the United States carry the transthyretin V142I variant, which increases their risk of heart failure. However, the role of cardiovascular (CV) risk factors (RFs) in influencing the risk of clinical outcomes among V142I variant carriers is unknown.

OBJECTIVES

This study aimed to assess the impact of CV RFs on the risk of heart failure in V142I carriers.

METHODS

This study included self-identified Black individuals without prevalent heart failure from 6 TOPMed (Trans-Omics for Precision Medicine) cohorts, the REGARDS (Reasons for Geographic And Racial Differences in Stroke) study, and the All of Us Research Program. The cohort was stratified based on the V142I genotype and the number of CV RFs (hypertension, diabetes, obesity, and hypercholesterolemia). Adjusted Cox models were used to assess the association of heart failure with the V142I genotype and CV RF profile, taking noncarriers with a favorable CV RF profile as reference.

RESULTS

The cross-sectional analysis, including 1,625 V142I carriers among 48,365 Black individuals, found that the prevalence of CV RFs did not vary by V142I carrier status. In the longitudinal analysis, there were 587 (3.2%) V142I carriers among 18,407 Black individuals (median age: 60 years [Q1-Q3: 52-68 years], 63.0% female). Among carriers, the heart failure risk was attenuated with a favorable (0 or 1 RF) CV RF profile (adjusted HR: 2.26; 95% CI: 1.58-3.23) compared with an unfavorable (3 or 4 RFs) CV RF profile (adjusted HR: 4.14; 95% CI: 2.79-6.14).

CONCLUSIONS

A favorable CV RF profile lowers but does not abrogate V142I variant-associated heart failure risk. This study highlights the importance of having a favorable CV RF profile among V142I carriers for risk reduction of heart failure.

Diagnostic and therapeutic challenges in rapidly progressing cardiac amyloidosis: a literature review based on case report

INTRODUCTION

Cardiac amyloidosis is a rarely reported and potentially fatal variant of the systemic disease. Its early diagnosis could potentially lead to significantly improved clinical outcomes.

CASE PRESENTATION

A 56-year-old female presented with dyspnea and palpitations. Her physical exam and non-invasive evaluation with cardiac magnetic resonance imaging (CMRI) revealed restrictive cardiomyopathy, and the bone marrow biopsy results showed systemic amyloidosis.

DISCUSSION

The diagnosis of cardiac amyloidosis is not always straightforward, and delay can cause the progression of the disease and an increased risk of morbidity and mortality. Electrocardiograms, echocardiograms, cardiac magnetic resonance imaging, and histopathologic evaluation are the main methods for diagnosing cardiac amyloidosis. The treatment consists of controlling heart failure symptoms and disease-modifying interventions, including medical and surgical therapeutic methods.

CLINICAL LEARNING POINT (CONCLUSION)

Cardiac involvement is the main cause of death in systemic amyloidosis. Early suspicion, diagnosis, and treatment are crucial in improving patients' survival. CMRI can play an essential role in the diagnosis of cardiac Amyloidosis. A graphical abstract is provided for visual summary.

ATTRv-V30M amyloid fibrils from heart and nerves exhibit structural homogeneity

Amyloidogenic transthyretin (ATTR) amyloidosis is a systemic disease characterized by the deposition of amyloid fibrils made of transthyretin. Transthyretin is primarily produced in tetrameric form by the liver, but also by retinal epithelium and choroid plexus. The deposition of these fibrils in the myocardium and peripheral nerves causes cardiomyopathies and neuropathies, respectively. Using cryoelectron microscopy (cryo-EM), we investigated fibrils extracted from cardiac and nerve tissues of an ATTRv-V30M patient. We found consistent fibril structures from both tissues, similar to cardiac fibrils previously described, but different from vitreous humor fibrils of the same genotype. Our findings, along with previous ATTR fibrils structural studies, suggest a uniform fibrillar architecture across different tissues when transthyretin originates from the liver. This study advances our understanding of how deposition and production sites influence fibril structure in ATTRv-V30M amyloidosis.

Pharmacological management of transthyretin amyloid cardiomyopathy: a scoping review

AIMS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is characterized by the accumulation of transthyretin (TTR) protein in the myocardium. The aim of this scoping review is to provide a descriptive summary of the clinical trials and observational studies that evaluated the clinical efficacy and safety of various agents used in ATTR-CM, with a goal of identifying the contemporary gaps in literature and to reveal future research opportunities.

METHODS AND RESULTS

The search was performed in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search using several databases for observational and clinical trials investigating the treatment modalities for ATTR-CM was undertaken. We extracted data including study characteristics, primary endpoints, and adverse events from each study. A total of 19 studies were included in our scoping review. Out of which, 8 were clinical trials and 11 were observational analyses. The drugs evaluated included tafamadis, acoramidis, revusiran, doxycycline and tauroursodeoxycholic acid and doxycycline, diflusinil, inotersan, eplontersen, and patisiran. Tafamidis has shown to be efficacious in the management of ATTR-CM, particularly when initiated at earlier stages. RNA interference and antisense oligonucleotide drugs have shown promising impacts on quality of life. Additionally, this review identified gaps in the literature, particularly among long-term outcomes, comparative effectiveness, and the translation of research into economic contexts.

CONCLUSION

Multiple pharmacological options are potential disease-modifying therapies for ATTR-CM. However, many gaps exist in the understanding of these various drug therapies, warranting further research. The future directions for management of ATTR-CM are promising in regard to improving prognostic implications.

Prospective Multicenter Screening With High-Sensitivity Cardiac Troponin T for Wild-Type Transthyretin Cardiac Amyloidosis in Outpatient and Community-Based Settings

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) was proposed as a simple and useful diagnostic tool for cardiac amyloidosis (CA). We performed exploratory systemic screening using hs-cTnT to detect wild-type transthyretin CA (ATTRwt-CA) in outpatient and community-based settings.

METHODS AND RESULTS

This study was a prospective multicenter study including 8 internal medicine clinics in Kochi Prefecture, Japan. Consecutive individuals aged ≥70 years who visited those clinics as outpatients were enrolled. Patients with a prior diagnosis of CA or a history of heart failure hospitalization were excluded. We measured hs-cTnT levels in the enrolled individuals at each clinic, and those with elevated hs-cTnT levels (≥0.03ng/mL) received further detailed examination, including remeasurement of hs-cTnT. The diagnosis of ATTRwt-CA was confirmed by biopsy-proven transthyretin. Of 1,141 individuals enrolled in the study, 55 (4.8%) had elevated hs-cTnT levels. Of the 33 patients who underwent further examination, 22 had elevated hs-cTnT levels at remeasurement. Finally, 2 men were diagnosed with ATTRwt-CA. The prevalence of ATTRwt-CA was 9.1% (2/22) among patients with elevated hs-cTnT levels at two examinations, and at least 0.18% (2/1,141) in the whole study population.

CONCLUSIONS

Measurement of hs-cTnT will help to screen for patients with undiagnosed ATTRwt-CA in primary care practice.

Automated Neural Architecture Search for Cardiac Amyloidosis Classification from [18F]-Florbetaben PET Images

Medical image classification using convolutional neural networks (CNNs) is promising but often requires extensive manual tuning for optimal model definition. Neural architecture search (NAS) automates this process, reducing human intervention significantly. This study applies NAS to [18F]-Florbetaben PET cardiac images for classifying cardiac amyloidosis (CA) sub-types (amyloid light chain (AL) and transthyretin amyloid (ATTR)) and controls. Following data preprocessing and augmentation, an evolutionary cell-based NAS approach with a fixed network macro-structure is employed, automatically deriving cells' micro-structure. The algorithm is executed five times, evaluating 100 mutating architectures per run on an augmented dataset of 4048 images (originally 597), totaling 5000 architectures evaluated. The best network (NAS-Net) achieves 76.95% overall accuracy. K-fold analysis yields mean ± SD percentages of sensitivity, specificity, and accuracy on the test dataset: AL subjects (98.7 ± 2.9, 99.3 ± 1.1, 99.7 ± 0.7), ATTR-CA subjects (93.3 ± 7.8, 78.0 ± 2.9, 70.9 ± 3.7), and controls (35.8 ± 14.6, 77.1 ± 2.0, 96.7 ± 4.4). NAS-derived network performance rivals manually determined networks in the literature while using fewer parameters, validating its automatic approach's efficacy.

Tafamidis medication adherence and persistence in patients with transthyretin amyloid cardiomyopathy in Japan

AIMS

This study aimed to describe baseline characteristics and adherence among patients with transthyretin amyloid cardiomyopathy (ATTR-CM) treated with tafamidis (VYNDAQEL®) in Japan using the Japanese Medical Data Vision (MDV) database.

METHODS AND RESULTS

This study was a non-interventional, retrospective cohort study of adult (≥18 years old) patients in the Japanese MDV claims database diagnosed with ATTR-CM and with at least two tafamidis prescriptions of dose strength 4 × 20 mg/day between 1 March 2019 and 31 August 2021. The date of the first prescription was defined as the index date, with follow-up time defined as the time between the first and last prescription plus the days' supply from the last refill. Baseline characteristics were assessed during a 12 month pre-index period. Adherence was measured using two metrics: (i) the modified medication possession ratio (mMPR), calculated by taking the sum of days supplied for all fills within the follow-up period, divided by the number of days of follow-up, and reported as a percentage, with patients classified as adherent with an mMPR of ≥80%, and (ii) the proportion of days covered (PDC), calculated by taking the total number of days' supply dispensed during the follow-up period divided by the number of days of follow-up, adjusting for any days' supply overlap. A total of 210 patients were identified; the mean (standard deviation) age of the cohort was 77 (5.9) years, and the majority (89%) were male. The most common baseline cardiovascular comorbidities were heart failure (85%), ischaemic heart disease (66%), hypertensive diseases (49%), and diabetes (35%); 75% of patients received heart failure medications in the 12 months prior to index, with the most common being beta-blockers (49%), diuretics (48%), angiotensin receptor blockers (30%), angiotensin-converting enzyme inhibitors (22%), and sodium-glucose cotransporter-2 inhibitors (8.1%). Over an average 14 month follow-up, mean mMPR was 96% with a median of 100% [inter-quartile range (IQR): 97-101%]; 93% of patients were adherent (defined as an mMPR ≥ 80%). In the same follow-up period, mean PDC was 93.6% with a median of 99% (IQR: 93-100%). Persistence was high with 78% of patients having a 0 day gap between prescription refills.

CONCLUSIONS

This study found high adherence rates to tafamidis in this real-world Japanese patient population. Adherence rates in this study were similar to those reported by the tafamidis clinical trial and a previously published US commercial claims adherence analysis. Further studies should be conducted to assess the impact of real-world adherence on real-world outcomes.

DPD Quantification Correlates With Extracellular Volume and Disease Severity in Wild-Type Transthyretin Cardiac Amyloidosis

Background

The pathophysiological hallmark of wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is the deposition of amyloid within the myocardium.

Objectives

This study aimed to investigate associations between quantitative cardiac 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) uptake and myocardial amyloid burden, cardiac function, cardiac biomarkers, and clinical status in ATTRwt-CM.

Methods

Forty ATTRwt-CM patients underwent quantitative DPD single photon emission computed tomography/computed tomography to determine the standardized uptake value (SUV) retention index, cardiac magnetic resonance imaging to determine extracellular volume (ECV) and cardiac function (RV-LS), and assessment of cardiac biomarkers (N-terminal prohormone of brain natriuretic peptide [NT-proBNP], troponin T) and clinical status (6-minute walk distance [6MWD], National Amyloidosis Centre [NAC] stage). ATTRwt-CM patients were divided into 2 cohorts based on median SUV retention index (low uptake: <5.19 mg/dL, n = 20; high uptake: ≥5.19 mg/dL, n = 20). Linear regression models were used to assess associations of the SUV retention index with variables of interest and the Mann-Whitney U or chi-squared test to compare variables between groups.

Results

ATTRwt-CM patients (n = 40) were elderly (78.0 years) and predominantly male (75.0%). Univariable linear regression analyses revealed associations of the SUV retention index with ECV (r = 0.669, β = 0.139, P < 0.001), native T1 time (r = 0.432, β = 0.020, P = 0.005), RV-LS (r = 0.445, β = 0.204, P = 0.004), NT-proBNP (log10) (r = 0.458, β = 2.842, P = 0.003), troponin T (r = 0.422, β = 0.048, P = 0.007), 6MWD (r = 0.385, β = -0.007, P = 0.017), and NAC stage (r = 0.490, β = 1.785, P = 0.001). Cohort comparison demonstrated differences in ECV (P = 0.001), native T1 time (P = 0.013), RV-LS (P = 0.003), NT-proBNP (P < 0.001), troponin T (P = 0.046), 6MWD (P = 0.002), and NAC stage (I: P < 0.001, II: P = 0.030, III: P = 0.021).

Conclusions

In ATTRwt-CM, quantitative cardiac DPD uptake correlates with myocardial amyloid load, longitudinal cardiac function, cardiac biomarkers, exercise capacity, and disease stage, providing a valuable tool to quantify and monitor cardiac disease burden.

Outcomes of patients with cardiac amyloidosis undergoing percutaneous left atrial appendage occlusion

BACKGROUND

There is limited data on the safety and efficacy of left atrial appendage occlusion (LAAO) devices in patients with cardiac amyloidosis. We examined the outcomes of patients with cardiac amyloidosis undergoing LAAO device implantation in a nationally representative cohort of patients.

METHODS

The National Readmissions Database (NRD) was analyzed from 2016 to 2019 to identify patients ≥ 18 years old with atrial fibrillation (AF) undergoing LAAO. Patients were divided into those with cardiac amyloidosis and those without cardiac amyloidosis. A multivariable logistic regression model was utilized to assess the independent association of cardiac amyloidosis with in-hospital, 30-day/90-day/180-day outcomes after adjusting for confounders.

RESULTS

Our cohort included 54,900 LAAO implantation procedures, of which 220 (0.4%) had cardiac amyloidosis. Patients with cardiac amyloidosis had a lower proportion of women and a lower prevalence of comorbidities including anemia, obesity, diabetes, and peripheral vascular disorders but a higher prevalence of stroke, as compared to those without cardiac amyloidosis. On multivariable analysis, cardiac amyloidosis was associated with significantly higher odds of peri-procedural major adverse events (adjusted odds ratio [aOR]: 2.69; 95% confidence interval [CI]: 1.41-5.14; p<0.01) and neurological complications (aOR: 5.48; 95% CI: 2.47-12.8; p<0.01). There was no difference in the odds of other peri-procedural complications, in-hospital mortality, hospital resource utilization, and 30/90/180-day all-cause/bleeding/stroke-related readmissions between both groups.

CONCLUSION

Patients with cardiac amyloidosis undergoing LAAO device implantation have an increased risk of peri-procedural complications without any difference in bleeding/stroke-related readmissions. These hypothesis-generating findings need validation in future prospective studies.

Safety assessment of Tafamidis: a real-world pharmacovigilance study of FDA adverse event reporting system (FAERS) events

OBJECTIVE

Tafamidis-associated adverse events (AEs) were investigated retrospectively by data mining the US Food and Drug Administration Adverse Event Reporting System (FAERS) to inform clinical safety.

METHODS

Data were gathered from the FAERS database, which spans the second quarter of 2019 to the fourth quarter of 2023. A total number of 8532 reports of Tafamidis-related adverse events were detected after evaluating 8,432,351 data. Disproportionality analyses were used to quantify the signal and assess the significance of Tafamidis-associated AEs using four algorithms, including the reporting odds ratio (ROR), the proportional reporting ratio (PRR), the multi-item gamma Poisson shrinker (MGPS) and the Bayesian confidence propagation neural network (BCPNN).

RESULTS

Among the 8532 reports of AEs with Tafamidis as the primary suspected drug, Tafamidis-induced AEs were identified as occurring in 27 system organ classes (SOC). A total of 207 Tafamidis-induced AEs were detected which simultaneously complied with the four algorithms. Our analysis also identified new adverse reactions including Hypoacusis, Deafness, and Essential hypertension. The median onset of adverse reactions associated with Tafamidis was 180 days (interquartile range [IQR] 51-419 days).

CONCLUSION

Tafamidis is a drug that has shown favorable safety and tolerability results in clinical trials. However, a number of adverse reactions associated with Tafamidis have been identified through analysis of the FAERS database. In clinical applications, it is recommended to closely monitor patients' hearing while using Tafamidis. In addition, it is hoped that further experimental and clinical studies will be conducted in the future to understand the mechanism of occurrence between Tafamidis and adverse reactions such as primary hypertension, hyperlipidemia, and height reduction.

A Snapshot of the Most Recent Transthyretin Stabilizers

In recent years, several strategies have been developed for the treatment of transthyretin-related amyloidosis, whose complex clinical manifestations involve cardiomyopathy and polyneuropathy. In view of this, transthyretin stabilizers represent a major cornerstone in treatment thanks to the introduction of tafamidis into therapy and the entry of acoramidis into clinical trials. However, the clinical treatment of transthyretin-related amyloidosis still presents several challenges, urging the development of new and improved therapeutics. Bearing this in mind, in this paper, the most promising among the recently published transthyretin stabilizers were reviewed. Their activity was described to provide some insights into their clinical potential, and crystallographic data were provided to explain their modes of action. Finally, structure-activity relationship studies were performed to give some guidance to future researchers aiming to synthesize new transthyretin stabilizers. Interestingly, some new details emerged with respect to the previously known general rules that guided the design of new compounds.

Diflunisal versus tafamidis on neuropathy and cardiomyopathy in hereditary transthyretin amyloidosis

OBJECTIVES

Hereditary transthyretin (TTR) amyloidosis (ATTRv) is frequently complicated by polyneuropathy (ATTRv-PN) and cardiomyopathy (ATTRv-CM). The long-term efficacy of diflunisal on both polyneuropathy and cardiomyopathy in ATTRv patients, especially those with non-V30M genotypes, has not been fully investigated and compared with that of tafamidis.

METHODS

We compared the structural and biochemical characteristics of A97S-TTR complexed with tafamidis with those of diflunisal, and prospectively followed up and compared the progression of polyneuropathy and cardiomyopathy between ATTRv-PN patients taking diflunisal and those taking tafamidis.

RESULTS

Both diflunisal and tafamidis effectively bind to the two thyroxine-binding sites at the A97S-TTR dimer-dimer interface and equally and almost sufficiently reduce amyloid fibril formation. Thirty-five ATTRv-PN patients receiving diflunisal and 22 patients receiving tafamidis were enrolled. Compared with no treatment, diflunisal treatment significantly delayed the transition of FAP Stage 1 to 2 and Stage 2 to 3 and decreased the deterioration in parameters of the ulnar nerve conduction study (NCS). The progression of FAP stage or NCS parameters did not differ between patients treated with diflunisal and those treated with tafamidis. Both diflunisal and tafamidis treatments significantly decreased radiotracer uptake on 99mTc-PYP SPECT and stabilized cardiac wall thickness and blood pro-B-type natriuretic peptide levels. No significant adverse events occurred during diflunisal or tafamidis treatment.

INTERPRETATIONS

The binding patterns of both tafamidis and diflunisal to A97S-TTR closely resembled those observed in the wild type. Diflunisal can effectively delay the progression of polyneuropathy and cardiomyopathy with similar efficacy to tafamidis and may become a cost-effective alternative treatment for late-onset ATTRv-PN.

Inverse correlation between age of onset and myocardial amyloid deposition quantified by 99mTc-PYP scintigraphy in patients with wild-type transthyretin amyloid cardiomyopathy

OBJECTIVE

Wild-type transthyretin amyloidosis cardiomyopathy (ATTRwt-CM) is increasingly recognized as a contributing factor to cardiac insufficiency in the elderly population. We aimed to identify the factors affecting age of onset of ATTRwt-CM, encompassing the assessment of amyloid deposition in myocardial tissue through the use of 99mTc-pyrophosphate (PYP) and clinical parameters.

METHODS

A retrospective investigation involving a consecutive cohort of 107 cases, each having been diagnosed with ATTRwt-CM confirmed through histopathological and genetic analysis, was performed. All patients underwent PYP scintigraphy, and the heart-to-contralateral (H/CL) ratio was calculated to measure amyloid deposition in the myocardium. Univariate and multivariate analyses were performed to identify independent predictors of the age of onset of ATTRwt-CM, considering the H/CL ratio and various clinical risk factors for heart failure.

RESULTS

Gender (p = 0.03), Creatinine (Cr) (r = 0.32, p < 0.01), hemoglobin (Hb) (r =  - 0.44, p < 0.01), albumin (Alb) (r =  - 0.32, p < 0.01), brain natriuretic peptide (BNP) (r = 0.21, p = 0.03), low-density lipoprotein-cholesterol (LDL-C) (r =  - 0.27, p < 0.01), and H/CL ratio (r =  - 0.44, p < 0.01) were all significantly associated with the onset age. In multiple regression analysis, the independent predictive factors for the onset age of ATTRwt-CM were identified as the H/CL ratio (p < 0.01), Hb (p < 0.01), and Cr (p < 0.01).

CONCLUSION

The H/CL ratio, Hb, and Cr independently affect age of onset in patients with ATTRwt-CM. The H/CL ratio is inversely correlated with age of onset, and may be the sole factor in the development of heart failure in early onset patients, while it may have a synergistic effect on heart failure with anemia and renal dysfunction in late-onset patients.

Transthyretin amyloidosis cardiomyopathy in Greece: Clinical insights from the National Referral Center

BACKGROUND

Clinical characteristics and outcomes of patients with transthyretin amyloidosis cardiomyopathy (ATTR-CM) vary by region, necessitating the acquisition of country-specific evidence for proper management.

METHODS

This is an observational study including sequential patients presenting in the Amyloidosis Reference Center of Greece, from 01/2014 to 12/2022. ATTR-CM was diagnosed by positive scintigraphy and exclusion of light-chain amyloidosis or positive biopsy typing. Genetic testing was performed in all cases.

RESULTS

In total, 109 ATTR-CM patients were included (median age, 81 years) of which 15 carried TTR mutations (27% Val30Met). Most patients (82%) presented with heart failure and 59% with atrial fibrillation, while 10% had aortic stenosis. Importantly, 78 (71.6%) had clinically significant extracardiac manifestations (45% musculoskeletal disorder, 40% peripheral neuropathy, and 33% gastrointestinal symptoms). Sixty-five (60%) received disease-specific treatment with tafamidis. Estimated median survival was 48 months; advanced NYHA class, National Amyloidosis Center stage, eGFR<45 ml/kg/1.73 m2, NT-pro-BNP>5000 pg/mL were associated with worse survival, while tafamidis treatment was associated with improved survival in patients with IVS≥ 12 mm.

DISCUSSION

These are the first data describing the characteristics, management, and outcomes of patients with ATTR-CM in Greece, which could influence local guidelines.

Effect of Diflunisal in Patients with Transthyretin Cardiomyopathy: A Pilot Study

Background: ATTR-CM is becoming more prevalent, and disease-modifying therapy has been investigated in recent years with promising results. Diflunisal has shown TTR-stabilizing properties assessed by biomarkers and echocardiography, but there are no trials addressing the evolution of morphological changes with CMR. Methods and Results: AMILCA-DIFLU is an exploratory pilot study prospective, single-center, non-randomized, open-label clinical trial. Patients diagnosed with ATTR-CM underwent clinical, functional, biochemical and imaging assessment before and one year after diflunisal therapy initiation. Of the twelve ATTR-CM patients included, only nine patients completed treatment and study protocol in 12 months. To increase the sample size, we included seven real-world patients with one year of diflunisal treatment. Among the group of patients who completed treatment, diflunisal therapy did not show improvement in cardiac disease status as assessed by many cardiac and inflammatory biomarkers, 6MWT and CMR parameters after one year of treatment. However, a non-significant trend towards stabilization of CMR parameters such as LVEF, ECV and T2 at one year was found. When comparing the group of patients who completed diflunisal therapy and those who did not, a significant decrease in the distance performed in the 6MWT was found in the group of patients who completed treatment at one year (-14 ± 81.8 vs. -173 ± 122.2; p = 0.032). Diflunisal was overall well tolerated, showing only a statistically significant worsening in renal function in the group of diflunisal-treatment patients with no clinical relevance or need for treatment discontinuation. Conclusions: In patients with ATTR-CM, treatment with diflunisal was overall well tolerated and tended to stabilize or slow down amyloid cardiac disease progression assessed by CMR parameters, cardiac and inflammatory biomarkers and functional capacity.

Mechanisms of damage and therapies for cardiac amyloidosis: a role for inflammation?

The term cardiac amyloidosis (CA) refers to the accumulation of extracellular amyloid deposits in the heart because of different conditions often affecting multiple organs including brain, kidney and liver. Notably, cardiac involvement significantly impacts prognosis of amyloidosis, with cardiac biomarkers playing a pivotal role in prognostic stratification. Therapeutic management poses a challenge due to limited response to conventional heart failure therapies, necessitating targeted approaches aimed at preventing, halting or reversing amyloid deposition. Mechanisms underlying organ damage in CA are multifactorial, involving proteotoxicity, oxidative stress, and mechanical interference. While the role of inflammation in CA remains incompletely understood, emerging evidence suggests its potential contribution to disease progression as well as its utility as a therapeutic target. This review reports on the cardiac involvement in systemic amyloidosis, its prognostic role and how to assess it. Current and emerging therapies will be critically discussed underscoring the need for further efforts aiming at elucidating CA pathophysiology. The emerging evidence suggesting the contribution of inflammation to disease progression and its prognostic role will also be reviewed possibly offering insights into novel therapeutic avenues for CA.

Transthyretin amyloid cardiomyopathy: Literature review and red-flag symptom clusters for each cardiology specialty

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is a progressive and infiltrative cardiac disorder that may cause fatal consequences if left untreated. The estimated survival time from diagnosis is approximately 3-6 years. Because of the non-specificity of initial symptom manifestation and insufficient awareness among treating physicians, approximately one-third of patients with ATTRwt-CM are initially misdiagnosed with other cardiac diseases. Although heart failure (HF) is the most common initial manifestation of ATTRwt-CM, observed in nearly 70% of affected patients, patients may also present with other cardiologic symptoms, such as atrial fibrillation (AF) and aortic stenosis (AS). This non-specific and diverse nature of the initial ATTRwt-CM presentation indicates that various cardiology subspecialties are involved in patient diagnosis and management. Standard guideline-directed pharmacological treatment for HF is not recommended for patients with ATTRwt-CM because of its limited effectiveness. However, no established algorithms are available regarding HF management in this patient population. This literature review provides an overview of the red flags for ATTRwt-CM and research findings regarding HF management in this patient population. In addition to commonly recognized red flags for ATTRwt-CM (e.g., HF, AF and severe AS), published literature identified potential red flags such as coronary microvascular dysfunction. For HF management in patients with ATTRwt-CM, the use of mineralocorticoid receptor antagonists (MRAs) was reported as a well-tolerated option associated with a low discontinuation rate and reduced mortality. Although there is no concrete evidence for recommendations against sodium-glucose cotransporter 2 inhibitor (SGLT2i) administration, research supporting its use is limited to small-scale studies. Robust evidence is lacking for AF ablation, implantable cardioverter-defibrillators and cardiac resynchronization therapy. Based on the published findings and our clinical experience as Japanese ATTRwt-CM experts, red-flag symptom clusters for each cardiology specialty (HF, arrhythmia and ischaemia/structural heart disease) and a treatment scheme for HF management are presented. As this research area remains at an exploratory stage, our observations would require further discussion among experts worldwide.

Role of endogenous T1ρ and its dispersion imaging in differential diagnosis of cardiac amyloidosis

BACKGROUND

Cardiovascular magnetic resonance (CMR) has demonstrated excellent performance in the diagnosis of cardiac amyloidosis (CA). However, misdiagnosis occasionally occurs because the morphological and functional features of CA are non-specific. This study was performed to determine the value of non-contrast CMR T1ρ in the diagnosis of CA.

METHODS

This prospective study included 45 patients with CA, 30 patients with hypertrophic cardiomyopathy (HCM), and 10 healthy controls (HCs). All participants underwent cine (whole heart), T1ρ mapping, pre- and post-contrast T1 mapping imaging (three slices), and late gadolinium enhancement using a 3T whole-body magnetic resonance imaging system. All participants underwent T1ρ at two spin-locking frequencies: 0 and 298 Hz. Extracellular volume (ECV) maps were obtained using pre- and post-contrast T1 maps. The myocardial T1ρ dispersion map, termed myocardial dispersion index (MDI), was also calculated. All parameters were measured in the left ventricular myocardial wall. Participants in the HC group were scanned twice on different days to assess the reproducibility of T1ρ measurements.

RESULTS

Excellent reproducibility was observed upon evaluation of the coefficient of variation between two scans (T1ρ [298 Hz]: 3.1%; T1ρ [0 Hz], 2.5%). The ECV (HC: 27.4 ± 2.8% vs HCM: 32.6 ± 5.8% vs CA: 46 ± 8.9%; p < 0.0001), T1ρ [0 Hz] (HC: 35.8 ± 1.7 ms vs HCM: 40.0 ± 4.5 ms vs CA: 51.4 ± 4.4 ms; p < 0.0001) and T1ρ [298 Hz] (HC: 41.9 ± 1.6 ms vs HCM: 48.8 ± 6.2 ms vs CA: 54.4 ± 5.2 ms; p < 0.0001) progressively increased from the HC group to the HCM group, and then the CA group. The MDI progressively decreased from the HCM group to the HC group, and then the CA group (HCM: 8.8 ± 2.8 ms vs HC: 6.1 ± 0.9 ms vs CA: 3.4 ± 2.1 ms; p < 0.0001). For differential diagnosis, the combination of MDI and T1ρ [298 Hz] showed the greatest sensitivity (98.3%) and specificity (95.5%) between CA and HCM, compared with the native T1 and ECV.

CONCLUSION

The T1ρ and MDI approaches can be used as non-contrast CMR imaging biomarkers to improve the differential diagnosis of patients with CA.

In-hospital outcomes among amyloidosis patients with atrial fibrillation: A propensity score-matched analysis

Background

The impact of atrial fibrillation (AF) among patients with amyloidosis on in-hospital outcomes is not well-established. We aimed to examine in-hospital outcomes among patients admitted with a primary diagnosis of AF with and without amyloidosis.

Methods and Results

We queried the Nationwide Readmissions Database to compare the in-hospital outcomes among AF patients with and without amyloidosis. Our study demonstrated that in-hospital all-cause mortality, adverse events, and 30-day readmission were comparable between the two groups.

Conclusions

Patients with AF and concurrent amyloidosis did not have worse in-hospital outcomes than those with AF alone.

Cerebrovascular Involvement in Transthyretin Amyloid Cardiomyopathy

Background: Intracardiac thrombosis is common in transthyretin amyloid cardiomyopathy (ATTR-CM), and patients are at risk for thromboembolic events. However, silent cerebral infarcts and the extent of cerebral small vessel disease in patients with cardiac amyloidosis are unknown. Methods: Thirty-two consecutively selected ATTR-CM patients were prospectively studied by cerebral magnetic resonance imaging (cMRI) and compared with 43 CHA2DS2-VASc-matched controls (Co). Structural clinical standard cMRI sequences and features of cerebral vessel involvement were included and quantified by two board certified neuroradiologists in consensus blinded to clinical status. Group differences were estimated using generalized (logistic) linear regression models adjusting for vascular risk factors based on the CHA2DS2-VASc score. Results: The median CHA2DS2-VASc score was 4 for ATTR-CM and Co (p = 0.905). There were no differences between groups in the frequency of current or former smokers (p = 0.755), body-mass-index > 30 (p = 0.106), and hyperlipidemia (p = 0.869). The number of territorial infarcts (4 vs. 0, p = 0.018) was higher in ATTR-CM compared to Co, as was the mean number of cerebral microbleeds (1.4 vs. 0.3, p ≤ 0.001) and the number of Virchow-Robin spaces (43.8 vs. 20.6, p ≤ 0.001). Lacunar lesion presence was higher in ATTR-CM (6 vs. 2, p = 0.054). CHA2DS2-VASc score, atrial fibrillation, anticoagulation, and the interaction term of CHA2DS2-VASc score and atrial fibrillation did not affect the probability of a territorial ischemic lesion or lacunar lesion in logistic regression modeling. Conclusions: In patients with ATTR-CM free from clinically apparent neurological symptoms, cMRI revealed unreported significant small cerebral vessel disease and territorial ischemia. Our findings may support low thresholds for anticoagulation and cMRI in patients with ATTR-CM.

Pericardial Disease in Cardiac Amyloidosis: A Comprehensive Review

In patients with cardiac amyloidosis, pericardial involvement is common, with up to half of patients presenting with pericardial effusions. The pathophysiological mechanisms of pericardial pathology in cardiac amyloidosis include chronic elevations in right-sided filling pressures, myocardial and pericardial inflammation due to cytotoxic effects of amyloid deposits, and renal involvement with subsequent uremia and hypoalbuminemia. The pericardial effusions are typically small; however, several cases of life-threatening cardiac tamponade with hemorrhagic effusions have been described as a presenting clinical scenario. Constrictive pericarditis can also occur due to amyloidosis and its identification presents a clinical challenge in patients with cardiac amyloidosis who concurrently manifest signs of restrictive cardiomyopathy. Multimodality imaging, including echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging, is useful in the evaluation and management of this patient population. The recognition of pericardial effusion is important in the risk stratification of patients with cardiac amyloidosis as its presence confers a poor prognosis. However, specific treatment aimed at the effusions themselves is seldom indicated. Cardiac tamponade and constrictive pericarditis may necessitate pericardiocentesis and pericardiectomy, respectively.

Tafamidis therapy in transthyretin amyloid cardiomyopathy: a narrative review from clinical trials and real-world evidence

BACKGROUND

Amyloidosis is a heterogeneous group of disorders caused by the extracellular deposition of insoluble misfolded proteins, leading to end-organ damage. Transthyretin amyloid cardiomyopathy (ATTR-CM) is a subtype in which a protein known as transthyretin accumulates within the heart tissue, progressively resulting in restrictive cardiomyopathy and heart failure. Due to the progressive nature of ATTR-CM, clinical management requires efficacious regimens to manage the debilitating condition and Tafamidis shows promising results in this regard.

MAIN BODY

ATTR-CM poses a significant challenge due to its nature and limited therapeutic options. Tafamidis is a novel therapy designed to stabilize the transthyretin tetramers, inhibiting the formation of amyloid fibrils. It has emerged as a promising treatment and the only FDA-approved drug for ATTR-CM. Tafamidis' role in slowing disease progression and improving outcomes in patients with ATTR-CM has been demonstrated in the major randomized control trial ATTR-ACT with promising open-label extension studies, some still ongoing. Additionally, real-world evidence supports its use in clinical practice, showing its role in reducing morbidity and mortality associated with this condition. Clinical evidence shows its efficacy in improving symptoms and cardiac function in patients. Case studies also reveal significant benefits to patients like reducing myocardial damage, reversal of atrial fibrillation, and resolution of heart failure symptoms. Real-world outcomes and clinical trials show a consistent reduction in amyloid deposition, cardiovascular-related hospitalizations, and all-cause mortality with Tafamidis therapy.

CONCLUSION

Tafamidis is an essential component of the treatment of ATTR-CM and this narrative review synthesizes the current evidence regarding safety, efficacy, and utilization in real practice. While it shows promising effects, its effectiveness may also vary and high cost precludes real-world large-scale studies. Overall, Tafamidis emerges as a valuable therapeutic option for managing ATTR-CM.

Cardiac Amyloidosis Mimicking Non-ST-Segment Myocardial Infarction: A Case Report

Cardiac amyloidosis is a rare but increasingly recognized condition characterized by the deposition of amyloid fibrils in cardiac tissue, leading to structural and functional heart impairment. This infiltrative cardiomyopathy often mimics more common cardiac conditions, posing significant diagnostic challenges. Particularly deceptive is its presentation as non-ST-segment elevation myocardial infarction (NSTEMI), where the clinical overlap necessitates considering amyloidosis in differential diagnoses. A 75-year-old male presented with muscle weakness, respiratory infection symptoms, and elevated cardiac enzymes. His history included a recent hospitalization for NSTEMI, with normal coronary angiography. Initial evaluations showed elevated troponin and CRP levels. A comprehensive cardiac assessment revealed a dilated ascending aorta, moderate systolic dysfunction (left ventricular ejection fraction (LV-EF), 47%), and asymmetrical interventricular septal thickening, suggesting hypertrophic cardiomyopathy or amyloidosis. The patient improved and was referred for further specialized care. Cardiac amyloidosis can mimic acute coronary syndrome (ACS), presenting with chest pain and elevated cardiac biomarkers. Differentiation is critical as amyloidosis involves myocardial infiltration by amyloid proteins, leading to restrictive cardiomyopathy. Advanced imaging techniques like cardiac MRI and nuclear scintigraphy are essential for accurate diagnosis and appropriate management, impacting therapeutic strategies and patient outcomes.

Six-minute walk test as clinical end point in cardiomyopathy clinical trials, including ATTR-CM: a systematic literature review

Aim: The six-minute walk test (6MWT) is a common measure of functional capacity in patients with heart failure (HF). Primary clinical study end points in cardiomyopathy (CM) trials, including transthyretin-mediated amyloidosis with CM (ATTR-CM), are often limited to hospitalization and mortality. Objective: To investigate the relationship between the 6MWT and hospitalization or mortality in CM, including ATTR-CM. Method: A PRISMA-guided systematic literature review was conducted using search terms for CM, 6MWT, hospitalization and mortality. Results: Forty-one studies were identified that reported 6MWT data and hospitalization or mortality data for patients with CM. The data suggest that a greater 6MWT distance is associated with a reduced risk of hospitalization or mortality in CM. Conclusion: The 6MWT is an accepted alternative end point in CM trials, including ATTR-CM.

Carpal Tunnel Syndrome and Transthyretin Amyloidosis in the All of Us Research Program

OBJECTIVE

To evaluate the association of carpal tunnel syndrome (CTS) with incident heart failure and incident amyloidosis and to assess the risk of CTS in pathogenic TTR genetic variant carriers.

METHODS

This prospective cohort study included multiethnic US adults 18 years of age and older without prevalent heart failure and amyloidosis with available genotypic data from the All of Us Research Program. The primary outcomes were incident heart failure and incident amyloidosis. The association of incident heart failure and incident amyloidosis with CTS was assessed using multivariable adjusted Cox models accounting for age, sex, race and ethnicity, obesity, hypertension, diabetes, statin use, and smoking status.

RESULTS

Of the 166,987 individuals included, the median age was 54 (38 to 66) years; 105,279 (63.0%) were female, and 92,780 (55.6%) were non-Hispanic White individuals; CTS was identified in 12,407 (7.4%) individuals. Compared with individuals without CTS, the adjusted hazard ratio for incident heart failure was 1.13 (95% CI, 1.02 to 1.26) in individuals with CTS. The risk of amyloidosis was ∼3-fold higher (adjusted hazard ratio, 2.86; 95% CI, 1.71 to 4.77) in individuals with CTS compared with those without CTS. Individuals carrying a pathogenic TTR variant had an approximately 40% higher risk (adjusted hazard ratio, 1.38; 95% CI, 1.16 to 1.65) for development of CTS compared with noncarriers.

CONCLUSION

Cardiac amyloidosis screening programs may use CTS as a sentinel event and use genetic testing to identify individuals at a higher risk of TTR amyloidosis.

Challenges associated with managing treatment complications in an older patient with cardiac amyloidosis

BACKGROUND

Amyloidosis, particularly wild-type transthyretin amyloidosis (ATTRwt), is an increasingly recognized cause of heart failure with preserved ejection fraction in the aging population. The complexity of managing ATTRwt in older patients underscores the necessity for individualized treatment approaches, yet clinical guidelines are lacking. This case report contributes to the understanding of ATTRwt management in the elderly, emphasizing the intricacies of medication tolerance and therapeutic decision-making.

CASE PRESENTATION

An 83-year-old Korean man with a history of hypertension presented with dyspnea and peripheral edema. Investigations including electrocardiography, transthoracic echocardiography, cardiac magnetic resonance, and Technetium pyrophosphate scintigraphy led to a diagnosis of ATTRwt cardiac amyloidosis. Initial management with heart failure medications, including an angiotensin-converting enzyme inhibitor, diuretic, and mineralocorticoid receptor antagonist, was modified due to evolving clinical presentations, such as hypotension and onset of atrial fibrillation. Challenges included intolerance to beta-blockers and bleeding complications from direct oral anticoagulant therapy. The patient's treatment journey highlighted the need for personalized management strategies in older ATTRwt patients.

CONCLUSIONS

This case illustrates the challenges in diagnosing and managing ATTRwt amyloidosis in the elderly, particularly the complexities in medication management due to the patient's age, comorbid conditions, and side effects. It underscores the importance of a tailored approach in managing ATTRwt in older populations and highlights the need for ongoing research and development of treatment strategies tailored to this demographic.

Hereditary transthyretin cardiac amyloidosis proven by endomyocardial biopsy: a single-centre retrospective study and literature review

BACKGROUND

This study aimed to report the genotypes and phenotypes of hereditary transthyretin cardiac amyloidosis (hATTR-CA) in a Western Chinese cohort and review the genetic profiles of this disorder in the Chinese population.

METHODS

Transthyretin (TTR) gene sequencing of probands diagnosed with TTR cardiac amyloidosis and their relatives was performed at West China Hospital of Sichuan University from January 2018 to December 2021. All patients underwent endomyocardial biopsy for light and electron microscopy examinations. Clinical and essential examination materials were retrospectively collected and analysed.

RESULTS

TTR gene alteration was demonstrated in five probands and their two relatives. Three TTR variants were identified, namely, Ser23Asn, Glu54Leu and Thr60Ala. This study is the first to report Glu54Leu as pathogenic mutations in Chinese hATTR-CA patients. The Ser23Asn mutation was the most common mutation in this cohort. Five probands, including two males and three females, were all ethnic Han-Chinese. The median age at diagnosis and delay in diagnosis (interval from onset to diagnosis) was 56 years (range, 54-69 years) and 8 years (range, from 1 to 30 years), respectively. Three cases showed a defined family history of amyloidosis. Endomyocardial biopsies and TTR immunohistochemistry showed positive results in all patients. Two probands died 17.0 months and 21.0 months after diagnosis.

CONCLUSIONS

We identified one novel TTR variants causing hATTR-CA in the West Han Chinese population. To avoid misdiagnosis or delayed diagnosis of hATTR-CA, TTR genotypic screening and endomyocardial biopsy should be performed as soon as possible in cases with heightened clinical suspicion.

EstimATTR: A Simplified, Machine-Learning-Based Tool to Predict the Risk of Wild-Type Transthyretin Amyloid Cardiomyopathy

BACKGROUND

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM), an increasingly recognized cause of heart failure (HF), often remains undiagnosed until later stages of the disease.

METHODS AND RESULTS

A previously developed machine learning algorithm was simplified to create a random forest model based on 11 selected phenotypes predictive of ATTRwt-CM to estimate ATTRwt-CM risk in hypothetical patient scenarios. Using U.S. medical claims datasets (IQVIA), International Classification of Diseases codes were extracted to identify a training cohort of patients with ATTRwt-CM (cases) or nonamyloid HF (controls). After assessment in a 20% test sample of the training cohort, model performance was validated in cohorts of patients with International Classification of Diseases codes for ATTRwt-CM or cardiac amyloidosis vs nonamyloid HF derived from medical claims (IQVIA) or electronic health records (Optum). The simplified model performed well in identifying patients with ATTRwt-CM vs nonamyloid HF in the test sample, with an accuracy of 74%, sensitivity of 77%, specificity of 72%, and area under the curve of 0.82; robust performance was also observed in the validation cohorts.

CONCLUSIONS

This simplified machine learning model accurately estimated the empirical probability of ATTRwt-CM in administrative datasets, suggesting it may serve as an easily implementable tool for clinical assessment of patient risk for ATTRwt-CM in the clinical setting.

BRIEF LAY SUMMARY

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM for short) is a frequently overlooked cause of heart failure. Finding ATTRwt-CM early is important because the disease can worsen rapidly without treatment. Researchers developed a computer program that predicts the risk of ATTRwt-CM in patients with heart failure. In this study, the program was used to check for 11 medical conditions linked to ATTRwt-CM in the medical claims records of patients with heart failure. The program was 74% accurate in identifying ATTRwt-CM in patients with heart failure and was then used to develop an educational online tool for doctors (the wtATTR-CM estimATTR).

Early diagnosis and management of cardiac amyloidosis: A clinical perspective

Cardiac amyloidosis multidisciplinary team (MDT). We propose the creation of a multidisciplinary team (MDT) for cardiac amyloidosis in which internal medicine physicians could take a lead role in coordinating other specialists involved in patient care. Created with BioRender.com.

Case Report: A rare transthyretin mutation p.D58Y in a Chinese case of transthyretin amyloid cardiomyopathy

Hereditary transthyretin amyloid (ATTRv) cardiomyopathy (CM) is caused by mutations in the TTR gene. TTR mutations contribute to TTR tetramer destabilization and dissociation, leading to excessive deposition of insoluble amyloid fibrils in the myocardium and finally resulting in cardiac dysfunction. In this article, we report a case of a Chinese patient with transthyretin mutation p.D58Y and provide detailed information on cardiac amyloidosis, including transthoracic echocardiography, cardiac magnetic resonance, and SPECT imaging for the first time. Our report aims to provide a better understanding of ATTR genotypes and phenotypes.

Multi-organ structural homogeneity of amyloid fibrils in ATTRv-T60A amyloidosis patients, revealed by Cryo-EM

ATTR amyloidosis is a degenerative disorder characterized by the systemic deposition of the protein transthyretin. These amyloid aggregates of transthyretin (ATTR) can deposit in different parts of the body causing diverse clinical manifestations. Our laboratory aims to investigate a potential relationship between the different genotypes, organ of deposition, clinical phenotypes, and the structure of ATTR fibrils. Using cryo-electron microscopy, we have recently described how the neuropathic related mutations ATTRv-I84S and ATTRv-V122∆ can drive structural polymorphism in ex vivo fibrils. Here we question whether the mutation ATTRv-T60A, that commonly triggers cardiac and neuropathic symptoms, has a similar effect. To address this question, we extracted and determined the structure of ATTR-T60A fibrils from multiple organs (heart, thyroid, kidney, and liver) from the same patient and from the heart of two additional patients. We have found a consistent conformation among all the fibril structures, acquiring the "closed-gate morphology" previously found in ATTRwt and others ATTRv related to cardiac or mixed manifestations. The closed-gate morphology is composed by two segments of the protein that interact together forming a polar channel, where the residues glycine 57 to isoleucine 68 act as a gate of the polar cavity. Our study indicates that ATTR-T60A fibrils present in peripheral organs adopt the same structural conformation in all patients, regardless of the organ of deposition.

ATTRv-V30M Type A amyloid fibrils from heart and nerves exhibit structural homogeneity

ATTR amyloidosis is a systemic disease characterized by the deposition of amyloid fibrils made of transthyretin, a protein integral to transporting retinol and thyroid hormones. Transthyretin is primarily produced by the liver and circulates in blood as a tetramer. The retinal epithelium also secretes transthyretin, which is secreted to the vitreous humor of the eye. Because of mutations or aging, transthyretin can dissociate into amyloidogenic monomers triggering amyloid fibril formation. The deposition of transthyretin amyloid fibrils in the myocardium and peripheral nerves causes cardiomyopathies and neuropathies, respectively. Using cryo-electron microscopy, here we determined the structures of amyloid fibrils extracted from cardiac and nerve tissues of an ATTRv-V30M patient. We found that fibrils from both tissues share a consistent structural conformation, similar to the previously described structure of cardiac fibrils from an individual with the same genotype, but different from the fibril structure obtained from the vitreous humor. Our study hints to a uniform fibrillar architecture across different tissues within the same individual, only when the source of transthyretin is the liver. Moreover, this study provides the first description of ATTR fibrils from the nerves of a patient and enhances our understanding of the role of deposition site and protein production site in shaping the fibril structure in ATTRv-V30M amyloidosis.

Aging in Heart Failure: Embracing Biology Over Chronology: JACC Family Series

Age is among the most potent risk factors for developing heart failure and is strongly associated with adverse outcomes. As the global population continues to age and the prevalence of heart failure rises, understanding the role of aging in the development and progression of this chronic disease is essential. Although chronologic age is on a fixed course, biological aging is more variable and potentially modifiable in patients with heart failure. This review describes the current knowledge on mechanisms of biological aging that contribute to the pathogenesis of heart failure. The discussion focuses on 3 hallmarks of aging-impaired proteostasis, mitochondrial dysfunction, and deregulated nutrient sensing-that are currently being targeted in therapeutic development for older adults with heart failure. In assessing existing and emerging therapeutic strategies, the review also enumerates the importance of incorporating geriatric conditions into the management of older adults with heart failure and in ongoing clinical trials.

Effects of tafamidis on the left ventricular and left atrial strain in patients with wild-type transthyretin cardiac amyloidosis

AIMS

Although tafamidis is used in patients with wild-type transthyretin cardiac amyloidosis (ATTRwt-CA), its specific effect on cardiac function is unclear. Thus, this study aimed to investigate the effect of tafamidis on left atrial (LA) and left ventricular function using speckle-tracking echocardiography for 1 year of treatment in patients with ATTRwt-CA.

METHODS AND RESULTS

We included 23 patients (mean age, 76 years) with ATTRwt-CA confirmed via biopsy. We analysed the left ventricular and LA strain using 2D speckle-tracking echocardiography and compared these parameters before and 1 year after starting treatment with tafamidis between 16 patients with sinus rhythm (SR) and 7 patients with atrial fibrillation (AF). In ATTRwt-CA patients with SR, LA reservoir strain significantly improved by 1-year tafamidis treatment (10.5 ± 5.0% to 11.9 ± 5.3%, P = 0.0307) although global longitudinal strain (GLS) did not (-10.6 ± 3.1% to -11.3 ± 3.0%, P = 0.0608). In contrast, LA reservoir strain was not significantly changed (5.4 ± 2.9% to 4.9 ± 1.7%, P = 0.4571), and GLS deteriorated (-8.4 ± 2.3% to -6.8 ± 1.4%, P = 0.0267) in ATTRwt-CA patients with AF.

CONCLUSION

LA function improved with tafamidis treatment in ATTRwt-CA patients with SR but not left ventricular function. However, these cardiac functions did not improve with tafamidis treatment in ATTRwt-CA patients with AF.

Therapeutic approaches in proteinopathies

A family of maladies known as amyloid disorders, proteinopathy, or amyloidosis, are characterized by the accumulation of abnormal protein aggregates containing cross-β-sheet amyloid fibrils in many organs and tissues. Often, proteins that have been improperly formed or folded make up these fibrils. Nowadays, most treatments for amyloid illness focus on managing symptoms rather than curing or preventing the underlying disease process. However, recent advances in our understanding of the biology of amyloid diseases have led to the development of innovative therapies that target the emergence and accumulation of amyloid fibrils. Examples of these treatments include the use of small compounds, monoclonal antibodies, gene therapy, and others. In the end, even if the majority of therapies for amyloid diseases are symptomatic, greater research into the biology behind these disorders is identifying new targets for potential therapy and paving the way for the development of more effective treatments in the future.

Chest pain in a patient with transthyretin cardiac amyloidosis: A case report

Key Clinical Message

Patients with transthyretin cardiac amyloidosis (ATTR-CM) commonly present with dyspnea, fatigue, and edema. In our case, the main presentation was exertional angina, which was atypical in patients with ATTR-CM and should be paid more attention to.

Abstract

A 54-year-old woman was admitted with a complaint of exertional chest pain, and she had a history of hypertension. The results of the electrocardiogram and echocardiography revealed the clues of cardiac amyloidosis, and the patient was finally diagnosed with transthyretin cardiac amyloidosis, then she received tafamidis, and the symptoms improved significantly.

Prevalence of transthyretin amyloid cardiomyopathy in pacemaker patients

AIMS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is characterized by increased wall thickness, diastolic dysfunction and progressive heart failure symptoms. The disease may infiltrate the conduction system leading to conduction disturbances requiring an implantation of permanent cardiac pacemaker (PM), but the extent is unknown. Here, we report the prevalence of ATTR-CM in patients ≥65 years with PM.

METHODS AND RESULTS

In this prospective, cross-sectional single-centre study patients were recruited from our out-patient pacemaker clinic. Eligibility criteria were age above 65 years, permanent cardiac pacemaker and competent to give informed consent. Patients underwent echocardiography at the pacemaker visit and were referred to 99mTc-DPD-scintigraphy (DPD) and blood samples if septum thickness was ≥12 mm, defined as left ventricular hypertrophy (LVH). Fifty eight of the 128 patients had LVH on echocardiography. Eleven patients had a DPD-scintigraphy based diagnosis of ATTR-CM, which represent 19% of patients with LVH and 9% of the total cohort. Patients diagnosed with ATTR-CM had higher concentrations of cardiac biomarkers (P < 0.001), higher E/E' (P = 0.001), and lower global longitudinal strain (P = 0.003) on echocardiography and more heart failure symptoms (P = 0.001).

CONCLUSIONS

The prevalence of ATTR-CM in elderly patients with PM and LVH on echocardiography was 19%.

Significant tricuspid regurgitation is associated with adverse outcomes in patients with transthyretin amyloid cardiomyopathy

Objectives

Patients diagnosed with transthyretin amyloid cardiomyopathy (ATTR-CM) often experience poor outcomes due to the development of heart failure (HF). Tricuspid regurgitation (TR) has been found to be correlated with adverse outcomes in patients with HF. This study aims to assess whether the presence of significant TR is associated to adverse cardiac outcomes in patients diagnosed with ATTR-CM.

Materials and methods

Retrospective study of ATTR-CM patients enrolled in the Institutional Registry of Amyloidosis (NCT01347047). Patients were categorized based on the presence of significant TR (moderate or severe according to current guidelines criteria) or absence of significant TR. All patients were followed up for 2 years to assess the incidence of the composite outcome of death or HF hospitalization.

Results

A total of 93 ATTR-CM patients were included. The mean age at diagnosis was 82.5 [IQR 75 - 86] years, 86% were male, and the mean left ventricular ejection fraction was 52% [IQR 43 - 60]. Among them, 32.3% (n = 30) patients had significant TR. Patients with significant TR had higher NTpro-BNP values (5308 vs 2454, pg/mL, p = 0.004), and a lower left ventricular ejection fraction (44 vs. 56%, p = 0.0002) compared to patients without significant TR. The incidence of the primary outcome was higher in patients with significant TR (77% vs. 30%, p<0.001). In a multivariate Cox regression analysis, only NTpro-BNP, as a numerical variable (HR 1.00, 95% CI 1.00005-1.0002, p = 0.001), and significant TR (HR 2.23, 95% CI 1.12-4.42, p=0.021) were independently associated with the composite outcome of death or HF hospitalization.

Conclusions

In patients diagnosed with ATTR-CM, the presence of significant TR was associated with worse outcomes.

Performance of 99mTc-PYP scintigraphy in the diagnosis of hereditary transthyretin cardiac amyloidosis

OBJECTIVE

Most reported research has primarily investigated wild-type transthyretin cardiac amyloidosis (ATTRwt-CA). However, the application of bone scintigraphy for hereditary transthyretin cardiac amyloidosis (ATTRv-CA) has not been systematically investigated. Therefore, in this study, we aimed to evaluate the diagnostic value of 99mTc-PYP scintigraphy in ATTRv-CA.

METHODS

Fifty-four patients were enrolled in a highly suspected cardiac amyloidosis cohort. Transthyretin (TTR) gene characteristics were summarized in the ATTRv-CA group. In 99mTc-PYP scintigraphy, the diagnostic efficiency of the visual score (VGS) and heart-to-contralateral chest (H/CL) ratio were evaluated. Furthermore, the interobserver consistency among the diagnosticians was investigated.

RESULTS

Twenty-eight patients were diagnosed with ATTRv-CA with eight genotypes. The Ala97Ser genotype accounts for 46% (n = 13) with a mean age of disease onset, definite diagnosis, and interval of 61.6 ± 1.9, 66.5 ± 1.3, and 4.0 (3.0, 6.2) years, respectively. Their VGS is Grade 3, and their H/CL ratio is higher than that of the non-Ala97Ser group, but no statistical significance exists (mean H/CL: 1.95 ± 0.06 vs. 1.87 ± 0.02, p = 0.844). Additionally, ATTRv-CA patients showed VGS ≥ 2, and mean H/CL ratio of 2.09 ± 0.06. The sensitivity and specificity of VGS were 100% and 65%, respectively. And the interobserver consistency analysis of VGS showed the intraclass correlation coefficient is 0.522. The best cutoff value of H/CL ratio was 1.51 (AUC = 0.996), and the diagnostic consistency of H/CL (bias: 0.018) was high.

CONCLUSIONS

Ala97Ser is the most common genotype in ATTRv-CA in our cohort, with characteristics of later onset and rapid progression, but delayed diagnosis and extensive 99mTc-PYP uptake. Overall, ATTRv-CA patients showed moderate-to-extensive myocardial 99mTc-PYP uptake. Additionally, VGS carries subjectivity, low specialty and interobserver consistency. But H/CL exhibit high diagnostic efficacy and interobserver consistency. The H/CL ratio is more useful than VGS.

Cardiac Amyloidosis Due to Transthyretin Protein: A Review

Importance

Systemic amyloidosis from transthyretin (ATTR) protein is the most common type of amyloidosis that causes cardiomyopathy.

Observations

Transthyretin (TTR) protein transports thyroxine (thyroid hormone) and retinol (vitamin A) and is synthesized predominantly by the liver. When the TTR protein misfolds, it can form amyloid fibrils that deposit in the heart causing heart failure, heart conduction block, or arrhythmia such as atrial fibrillation. The biological processes by which amyloid fibrils form are incompletely understood but are associated with aging and, in some patients, affected by inherited variants in the TTR genetic sequence. ATTR amyloidosis results from misfolded TTR protein deposition. ATTR can occur in association with normal TTR genetic sequence (wild-type ATTR) or with abnormal TTR genetic sequence (variant ATTR). Wild-type ATTR primarily manifests as cardiomyopathy while ATTR due to a genetic variant manifests as cardiomyopathy and/or polyneuropathy. Approximately 50 000 to 150 000 people in the US have heart failure due to ATTR amyloidosis. Without treatment, heart failure due to ATTR amyloidosis is associated with a median survival of approximately 5 years. More than 130 different inherited genetic variants in TTR exist. The most common genetic variant is Val122Ile (pV142I), an allele with an origin in West African countries, that is present in 3.4% of African American individuals in the US or approximately 1.5 million persons. The diagnosis can be made using serum free light chain assay and immunofixation electrophoresis to exclude light chain amyloidosis combined with cardiac nuclear scintigraphy to detect radiotracer uptake in a pattern consistent with amyloidosis. Loop diuretics, such as furosemide, torsemide, and bumetanide, are the primary treatment for fluid overload and symptomatic relief of patients with ATTR heart failure. An ATTR-directed therapy that inhibited misfolding of the TTR protein (tafamidis, a protein stabilizer), compared with placebo, reduced mortality from 42.9% to 29.5%, reduced hospitalizations from 0.7/year to 0.48/year, and was most effective when administered early in disease course.

Conclusions and Relevance

ATTR amyloidosis causes cardiomyopathy in up to approximately 150 000 people in the US and tafamidis is the only currently approved therapy. Tafamidis slowed progression of ATTR amyloidosis and improved survival and prevented hospitalization, compared with placebo, in people with ATTR-associated cardiomyopathy.

Characterization of Transthyretin Mutation G47V Associated with Hereditary Cardiac Amyloidosis

INTRODUCTION

Amyloidosis caused by TTR mutations (ATTRv) is a rare inherited and autosomal dominant disease. More than 150 mutants of TTR have been reported, whereas some of them remain to be investigated.

METHODS

A 52-year-old male presented with heart failure and clinically diagnosed ATTR cardiac amyloidosis (ATTR-CA) was recruited. Whole-exome sequencing (WES) was performed. Biochemical and biophysical experiments characterized protein stability using urea-mediated tryptophan fluorescence. Drug response was analyzed by fibril formation assay. Finally, tetramer TTR concentration in patient's serum sample was measured by ultra-performance liquid chromatography (UPLC).

RESULTS

For the proband, WES revealed a mutation (c.200G>T; p.Gly67Val and referred to as G47V) in TTR gene. Biochemical and biophysical kinetics study showed that the thermodynamic stability of G47V-TTR (Cm = 2.4 m) was significantly lower than that of WT-TTR (Cm = 3.4 m) and comparable to that of L55P-TTR (Cm = 2.3 m), an early age-of-onset mutation. G47V:WT-TTR heterozygous tetramer kinetic stability (t1/2 = 1.4 h) was further compromised compared to that of the homozygous G47V-TTR (t1/2 = 3.1 h). Among three small molecule stabilizers, AG10 exhibited the best inhibition of the fibrillation of G47V-TTR homozygous protein. Using a UPLC assay, nearly 40% of TTR in this patient was calculated to be non-tetrameric.

CONCLUSION

In this work, we reported a patient presented early onset of clinically typical ATTR-CA due to G47V-TTR mutation. Our work for the first time not only characterized the biochemical properties of G47V-TTR mutation, but also provided hints for the pathogenicity of this mutation.

Outcomes of Octogenarian Patients Treated with Tafamidis for Transthyretin Amyloid Cardiomyopathy

Patients with transthyretin amyloid cardiomyopathy (ATTR-CM) benefit from disease-modifying agents such as tafamidis. However, the survival benefit of tafamidis in elderly patients (age ≥80 years) is not reported. This study aimed to assess the survival of patients with ATTR-CM aged 80 years and older who were treated with tafamidis compared with patients aged <80 years. We conducted a retrospective analysis of patients with ATTR-CM who underwent tafamidis treatment, aged 45 to 97 years at the time of diagnosis between January 1, 2008, and May 31, 2021. A total of 484 patients were included, with 208 in the ≥80 years group and 276 in the <80 years group. The cohort was followed up for mortality outcomes, and hazard ratios with 95% confidence intervals were calculated. After a median follow-up of 18.5 months, 72 deaths were recorded in the entire cohort. Kaplan-Meier curves showed no differences in survival probability between the 2 groups at 30 months (p for log-rank test = 0.76). The survival rates for patients aged ≥80 years who underwent treatment at 1, 2, 3, 4, and 5 years were 94.7%, 86.0%, 77.0%, 77.0%, and 38.5%, respectively. The corresponding rates for patients aged <80 years who underwent treatment were 93.2, 84.8, 74.4, 68.2, and 64.6%, respectively. In the multivariable analysis, the hazard ratio (95% confidence interval) of the mortality comparing treatment patients aged ≥80 years with those aged <80 years was 0.81 (0.41 to 1.61). In conclusion, tafamidis treatment is associated with similar reductions in mortality in older and younger patients with ATTR-CM.

Cardiac MRI T1 and T2 Mapping as a Quantitative Imaging Biomarker in Transthyretin Amyloid Cardiomyopathy

RATIONALE AND OBJECTIVES

This study aimed to assess the utility of cardiac magnetic resonance imaging (MRI) T1 and T2 mapping as quantitative imaging biomarkers in transthyretin amyloid cardiomyopathy (ATTR-CM).

MATERIALS AND METHODS

This study retrospectively evaluated 74 patients with confirmed wild-type ATTR-CM who underwent cardiac MRI, 99mTc-labeled pyrophosphate (99mTc-PYP) scintigraphy, and echocardiography. We assessed the quantitative disease parameters, for example, left ventricular ejection fraction (LVEF), and global longitudinal strain (GLS) by echocardiography, native T1, extracellular volume fraction (ECV), and native T2 value by cardiac MRI, heart-to-contralateral ratio (H/CL) by 99mTc-PYP, and high-sensitive cardiac troponin T. Myocardial native T2 of ≥50 ms was defined as myocardial edema. Correlations between the disease's quantitative parameters were evaluated, and the ECV was compared to other parameters in ATTR-CM with/without myocardial edema.

RESULTS

ECV in all patients with ATTR-CM revealed a strong correlation with native T1 (r = 0.62), a moderate correlation with hs-TnT (r = 0.59), LVEF (r = -0.48), GLS (r = 0.58), and H/CL (r = 0.48). Correlations between ECV and other quantitative parameters decreased in ATTR-CM with myocardial edema except for H/CL. Meanwhile, the correlations increased in ATTR-CM without myocardial edema.

CONCLUSION

The presence of myocardial edema affected the interpretation of ECV assessment, although ECV can be a comprehensive imaging biomarker for ATTR-CM. ECV showed a significant correlation with various quantitative disease parameters and can be a reliable disease monitoring marker in patients with ATTR-CM when myocardial edema was excluded.

Current Perspectives on Atrial Amyloidosis: A Narrative Review

Amyloidosis is a systemic disease caused by low molecular weight protein accumulation in the extracellular space, which can lead to different degrees of damage, depending of the organ or tissue involved. The condition is defined cardiac amyloidosis (CA) when heart is affected, and it is associated with an unfavorable outcome. Different types of CA have been recognized, the most common (98%) are those associated with deposition of light chain (AL-CA), and the form secondary to transthyretin deposit. The latter can be classified into two types, a wild type (transthyretin amyloidosis wild type (ATTRwt)-CA), which mainly affects older adults, and the hereditary or variant type (ATTRh-CA or ATTRv-CA), which instead affects more often young people and is associated with genetic alterations. The atrial involvement can be isolated or linked to CA with a nonspecific clinical presentation represented by new onset atrial fibrillation (AF), diastolic dysfunction and heart failure with preserved ejection fraction, or thromboembolism and stroke. Untreated patients have a median survival rate of 9 years for AL-CA and 7 years for ATTR-CA. By contrast, AL-CA and ATTR-CA treated patients have a median survival rate of 24 and 10 years, respectively. Atrial involvement in CA is a common but poor studied event, and alterations of performance can anticipate the anatomical damage. Recently, numerous advances have been made in the diagnostic field with improvements in the available techniques. An early diagnosis therefore allows a more effective therapeutic strategy with a positive impact on prognosis and mortality rate. A multimodality approach to the diagnosis of atrial involvement from CA is therefore recommended, and standard echocardiography, advanced Doppler-echocardiography (DE) and cardiac magnetic resonance (CMR) can be useful to detect early signs of CA and to estabilish an appropriate treatment.

Biochemical and biophysical properties of a rare TTRA81V mutation causing mild transthyretin amyloid cardiomyopathy

AIMS

We conducted a presentation on an 84-year-old male patient who has been diagnosed with TTRA81V (p. TTRA101V) hereditary transthyretin cardiac amyloidosis (hATTR-CM). In order to establish its pathogenicity, we extensively investigated the biochemical and biophysical properties of the condition.

METHODS AND RESULTS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an increasingly acknowledged progressive infiltrative cardiomyopathy that leads to heart failure and potentially fatal arrhythmias. Gaining a comprehensive understanding of the biochemical and biophysical characteristics of genetically mutated TTR proteins serves as the fundamental cornerstone for delivering precise medical care to individuals affected by ATTR. Laboratory assessments indicated a brain natriuretic peptide of 200.12 ng/L (normal range: 0-100 ng/L) and high-sensitivity cardiac troponin I of 0.189 μg/L (normal range: 0-0.1 μg/L). Echocardiography identified left atrial enlargement, symmetrical left ventricular hypertrophy (16 mm septal and 16 mm posterior wall), and a left ventricular ejection fraction of 56%. Cardiac-enhanced magnetic resonance imaging revealed subendocardial late gadolinium enhancement. Tc-99m-PYP nuclear scintigraphy confirmed grade 3 myocardial uptake, showing an increased heart-to-contralateral ratio (H/CL = 2.33). Genetic testing revealed a heterozygous missense mutation in the TTR gene (c.302C>T), resulting in an alanine-to-valine residue change (p. Ala81Val, following the first 20 residues of signal sequence nomenclature). Biochemical analysis of this variant displayed compromised kinetic stability in both the TTRA81V:WT (wild-type) heterozygote protein (half-life, t1/2  = 21 h) and the TTRA81V homozygote protein (t1/2  = 17.5 h). The kinetic stability fell between that of the TTRWT (t1/2  = 42 h) and the early-onset TTRL55P mutation (t1/2  = 4.4 h), indicating the patient's late-onset condition. Kinetic stabilizers (Tafamidis, Diflunisal, and AG10) all exhibited the capacity to inhibit TTRA81V acid- and mechanical force-induced fibril formation, albeit less effectively than with TTRWT. Chromatographic assessment of the patient's serum TTR tetramers indicated a slightly lower concentration (3.0 μM) before oral administration of Tafamidis compared with the normal range (3.6-7.2 μM).

CONCLUSIONS

We identified a patient with hATTR-CM who possesses a rare TTRA81V mutation solely associated with cardiac complications. The slightly reduced kinetic stability of this mutation indicates its late-onset nature and contributes to the gradual progression of the disease.

Generation of two induced pluripotent stem cell lines from hereditary amyloidosis patients with polyneuropathy carrying heterozygous transthyretin (TTR) mutation

Hereditary transthyretin amyloidosis with polyneuropathy (ATTR-PN) results from specific TTR gene mutations. In this study, we generated two induced pluripotent stem cell (iPSC) lines derived from ATTR-PN patients with heterozygous TTR gene mutations (Ala97Ser and Phe64Leu). These iPSC lines exhibited normal morphology, karyotype, high pluripotency marker expression, and differentiation into cells representing all germ layers. The generation of these iPSC lines serve as a valuable tool for investigating the mechanisms of ATTR-PN across various cell types and facilitating patient-specific in vitro amyloidosis modeling.