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Cardiac amyloidosis is increasingly recognized as a treatable form of heart failure. Highly effective specific therapies have recently become available for the 2 most frequent forms of cardiac amyloidosis: immunoglobulin light chain amyloidosis and transthyretin (ATTR) amyloidosis. Nevertheless, initiation of specific therapies requires recognition of cardiac amyloidosis and appropriate characterization of the amyloid type. Although noninvasive diagnosis is possible for ATTR cardiac amyloidosis, histological demonstration and typing of amyloid deposits is still required for a substantial number of patients with ATTR and in all patients with light chain amyloidosis and other rarer forms of cardiac amyloidosis. Amyloid histological typing can be performed using different techniques: mass spectrometry, immunohistochemistry, and immunoelectron microscopy. This review describes which patients require histological confirmation of cardiac amyloidosis along with when and how to type amyloid deposits in histologic specimens. Furthermore, it covers the characteristics and limitations of the different typing methods that are available in clinical practice., Competing Interests: Funding Support and Author Disclosures This study has been partially supported by Instituto de Salud Carlos III through the projects “PI18/0765 and PI20/01379” (cofunded by European Regional Development Fund/European Social Fund “A way to make Europe”/“Investing in your future”). The Centro Nacional de Investigaciones Cardiovasculares is supported by the Instituto de Salud Carlos III, the Ministerio de Ciencia e Innovación, the Pro-Centro Nacional de Investigaciones Cardiovasculares Foundation, and the Severo Ochoa grant (CEX2020-001041-S). This work was also supported by grants from the Italian Ministry of Health (Ricerca Finalizzata, grant #GR-2018-12368387), the Italian Ministry of Research and Education (PRIN 20207XLJB2), Cancer Research UK 4013 (C355/A26819), Fundación Científica Asociación Española Contra el Cáncer, and AIRC under the Accelerator Award Program. The authors have reported that they have no relationships relevant to the content of this paper to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Transthyretin amyloid cardiomyopathy is characterized by the deposition of misfolded monomeric transthyretin (TTR) in the heart. Acoramidis is a high-affinity TTR stabilizer that acts to inhibit dissociation of tetrameric TTR and leads to more than 90% stabilization across the dosing interval as measured ex vivo., Methods: In this phase 3, double-blind trial, we randomly assigned patients with transthyretin amyloid cardiomyopathy in a 2:1 ratio to receive acoramidis hydrochloride at a dose of 800 mg twice daily or matching placebo for 30 months. Efficacy was assessed in the patients who had an estimated glomerular filtration rate of at least 30 ml per minute per 1.73 m 2 of body-surface area. The four-step primary hierarchical analysis included death from any cause, cardiovascular-related hospitalization, the change from baseline in the N-terminal pro-B-type natriuretic peptide (NT-proBNP) level, and the change from baseline in the 6-minute walk distance. We used the Finkelstein-Schoenfeld method to compare all potential pairs of patients within strata to generate a P value. Key secondary outcomes were death from any cause, the 6-minute walk distance, the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary, and the serum TTR level., Results: A total of 632 patients underwent randomization. The primary analysis favored acoramidis over placebo (P<0.001); the corresponding win ratio was 1.8 (95% confidence interval [CI], 1.4 to 2.2), with 63.7% of pairwise comparisons favoring acoramidis and 35.9% favoring placebo. Together, death from any cause and cardiovascular-related hospitalization contributed more than half the wins and losses to the win ratio (58% of all pairwise comparisons); NT-proBNP pairwise comparisons yielded the highest ratio of wins to losses (23.3% vs. 7.0%). The overall incidence of adverse events was similar in the acoramidis group and the placebo group (98.1% and 97.6%, respectively); serious adverse events were reported in 54.6% and 64.9% of the patients., Conclusions: In patients with transthyretin amyloid cardiomyopathy, the receipt of acoramidis resulted in a significantly better four-step primary hierarchical outcome containing components of mortality, morbidity, and function than placebo. Adverse events were similar in the two groups. (Funded by BridgeBio Pharma; ATTRibute-CM ClinicalTrials.gov number, NCT03860935.)., (Copyright © 2024 Massachusetts Medical Society.)

Importance: Tafamidis has been shown to improve survival in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) compared with placebo. However, its effect on cardiac function has not been fully characterized., Objective: To examine the effect of tafamidis on cardiac function in patients with ATTR-CM., Design, Setting, and Participants: This was an exploratory, post hoc analysis of the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT), a multicenter, international, double-blind, placebo-controlled phase 3 randomized clinical trial conducted from December 2013 to February 2018. The ATTR-ACT included 48 sites in 13 counties and enrolled patients aged 18 to 90 years with ATTR-CM. Data were analyzed from July 2018 to September 2023., Intervention: Patients were randomized to tafamidis meglumine, 80 mg or 20 mg, or placebo for 30 months., Main Outcomes and Measures: Patients were categorized based on left ventricular (LV) ejection fraction at enrollment as having heart failure with preserved ejection fraction (≥50%), mildly reduced ejection fraction (41% to 49%), or reduced ejection fraction (≤40%). Changes from baseline to month 30 in LV ejection fraction, LV stroke volume, LV global longitudinal strain, and the ratio of early mitral inflow velocity to septal and lateral early diastolic mitral annular velocity (E/e') were compared in patients receiving tafamidis, 80 mg, vs placebo., Results: A total of 441 patients were randomized in ATTR-ACT, and 436 patients had available echocardiographic data. Of 436 included patients, 393 (90.1%) were male, and the mean (SD) age was 74 (7) years. A total of 220 (50.5%), 119 (27.3%), and 97 (22.2%) had heart failure with preserved, mildly reduced, and reduced LV ejection fraction, respectively. Over 30 months, there was less pronounced worsening in 4 of the echocardiographic measures in patients receiving tafamidis, 80 mg (n = 176), vs placebo (n = 177) (least squares mean difference: LV stroke volume, 7.02 mL; 95% CI, 2.55-11.49; P = .002; LV global longitudinal strain, -1.02%; 95% CI, -1.73 to -0.31; P = .005; septal E/e', -3.11; 95% CI, -5.50 to -0.72; P = .01; lateral E/e', -2.35; 95% CI, -4.01 to -0.69; P = .006)., Conclusions and Relevance: Compared with placebo, tafamidis, 80 mg, attenuated the decline of LV systolic and diastolic function over 30 months in patients with ATTR-CM. Approximately half of patients had mildly reduced or reduced LV ejection fraction at enrollment, suggesting that ATTR-CM should be considered as a possible diagnosis in patients with heart failure regardless of underlying LV ejection fraction., Trial Registration: ClinicalTrials.gov Identifier: NCT01994889.

Background: Conventional right ventricle (RV) pacemaker stimulation has been associated with worse clinical outcomes in patients with cardiac amyloidosis (CA). Left bundle branch area pacing (LABPP) has been suggested as a promising alternative. We sought to assess the safety, feasibility, and outcomes of LABPP in patients with CA., Methods: We retrospectively analyzed echocardiography and pacing parameters and clinical outcomes in 23 consecutive patients with CA and LBBAP implanted from June 2020 to October 2022., Results: LBBAP was successfully performed in 22 over 23 patients (19 male, 78.6 ± 11.7 years, 20 ATTR, mean LVEF 45.5 ± 16.2%). After the procedure, 9 patients showed Qr pattern and 11 a qR pattern in V1 on ECG. Average procedure time was 67 ± 28 min. After 7.7 ± 5.2 months follow-up, no procedure-related complications had occurred. Although, a significant reduction in QRS width (p = .001) was achieved, we did not observe significant changes in LVEF and Nt ProBNP at 6 months of follow-up. Pacing parameters were stable during follow-up: LBB capture threshold and R wave amplitude were 1.0 ±  0.5 V and 10.6 ± 6.0 mV versus 0.8 ±  0.1 V, p = .21 and 10.6 ± 5.1 mV (p = .985) at follow up., Conclusion: LBBAP is safe and feasible pacing technique for patients with CA. LBBAP is associated with significant narrowing of QRSd without worsening in LVEF and Nt-proBNP., (© 2023 Wiley Periodicals LLC.)

Over the last year, 5 national or international scientific societies have issued documents regarding cardiac amyloidosis (CA) to highlight the emerging clinical science, raise awareness, and facilitate diagnosis and management of CA. These documents provide useful guidance for clinicians managing patients with CA, and all include: 1) an algorithm to establish a diagnosis; 2) an emphasis on noninvasive diagnosis with the combined use of bone scintigraphy and the exclusion of a monoclonal protein; and 3) indications for novel disease-modifying therapies for symptomatic CA, either with or without peripheral neuropathy. Nonetheless, the documents diverge on specific details of diagnosis, risk stratification, and treatment. Highlighting the similarities and differences of the documents by the 5 scientific societies with respect to diagnosis, risk stratification, and treatment offers useful insight into the knowledge gaps and unmet needs in the management of CA. An analysis of these documents, therefore, highlights "gray zones" requiring further investigation., Competing Interests: Funding Support and Author Disclosures Prof Rapezzi has served as a speaker and has received consulting fees from Pfizer, Alnylam, and Eidos; and has received research grant support to his institution from Pfizer. Prof Emdin, Drs Vergaro and Aimo has received consulting income from Pfizer; and their institution has received clinical trial funding from Pfizer. Dr Sinagra has served as a consultant for Novartis, AstraZeneca, Dompè, Impulse Dynamics, and Biotronik; and has received fees at congresses from Novartis, Bayer, AstraZeneca, Boston Scientific, Vifor Pharma, Menarini, and Akcea Therapeutics. Dr Merlo has received fees at congresses for Pfizer and Vifor Pharma; and has received research grant support from Pfizer. Dr Fontana has served as a consultant for Pfizer, Intellia, Alnylam, Ionis, Janssen, Novo Nordisk, and Akcea; and has received research grants from Pfizer and Eidos. Dr Maurer has received grant support from NIH R01HL139671, R21AG058348, and K24AG036778; has received consulting income from Intellia, Novo-Nordisk, Pfizer, Eidos, Prothena, Akcea, and Alnylam; and his institution has received clinical trial funding from Pfizer, Prothena, Eidos, and Alnylam. Dr Garcia-Pavia has served as a speaker and received consulting fees from Pfizer, Alnylam, Akcea, Neuroimmune, and Eidos; and has received research grant support to his institution from Pfizer. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Cardiac amyloidosis is a serious and progressive infiltrative disease that is caused by the deposition of amyloid fibrils at the cardiac level. It can be due to rare genetic variants in the hereditary forms or as a consequence of acquired conditions. Thanks to advances in imaging techniques and the possibility of achieving a non-invasive diagnosis, we now know that cardiac amyloidosis is a more frequent disease than traditionally considered. In this position paper the Working Group on Myocardial and Pericardial Disease proposes an invasive and non-invasive definition of cardiac amyloidosis, addresses clinical scenarios and situations to suspect the condition and proposes a diagnostic algorithm to aid diagnosis. Furthermore, we also review how to monitor and treat cardiac amyloidosis, in an attempt to bridge the gap between the latest advances in the field and clinical practice., (© European Society of Cardiology 2021 This article has been co-published with permission in European Heart Journal (published by Oxford University Press on behalf of European Society of Cardiology) and European Journal of Heart Failure (published by John Wiley & Sons Ltd on behalf of European Society of Cardiology) These articles are identical except for minor stylistic and spelling differences in keeping with each journal’s style. Either citation can be used when citing this article.)

Cardiac amyloidosis is a serious and progressive infiltrative disease that is caused by the deposition of amyloid fibrils at the cardiac level. It can be due to rare genetic variants in the hereditary forms or as a consequence of acquired conditions. Thanks to advances in imaging techniques and the possibility of achieving a non-invasive diagnosis, we now know that cardiac amyloidosis is a more frequent disease than traditionally considered. In this position paper the Working Group on Myocardial and Pericardial Disease proposes an invasive and non-invasive definition of cardiac amyloidosis, addresses clinical scenarios and situations to suspect the condition and proposes a diagnostic algorithm to aid diagnosis. Furthermore, we also review how to monitor and treat cardiac amyloidosis, in an attempt to bridge the gap between the latest advances in the field and clinical practice., (© European Society of Cardiology 2021.)

Introduction and Objectives: Cardiac amyloidosis (CA) is produced by amyloid fiber deposition in the myocardium. The most frequent forms are those caused by light chains (AL) and transthyretin (ATTR). Our objective was to describe the diagnosis, treatment and outcomes of CA in a specialized Spanish center., Methods: We included all patients diagnosed with CA in Hospital Universitario Puerta de Hierro Majadahonda from May 2008 to September 2018. We analyzed their clinical characteristics, outcomes, and survival., Results: We included 180 patients with CA, of whom 64 (36%) had AL (50% men; mean age, 65±11 years) and 116 had ATTR (72% men; mean age 79±11 years; 18 with hereditary ATTR). The most common presentation was heart failure in both groups (81% in AL and 45% in ATTR, P <.01). Other forms of presentation in ATTR patients were atrial arrhythmias (16%), conduction disorders (6%), and incidental finding (6%); 70 patients (40%), had a previous alternative cardiac diagnosis. Diagnosis was noninvasive in 75% of ATTR patients. Diagnostic delay was higher in ATTR (2.8±4.3 vs 0.6±0.7 years, P <.001), but mortality was greater in AL patients (48% vs 32%, P=.028). Independent predictors of mortality were AL subtype (HR, 6.16; 95%CI, 1.56-24.30; P=.01), female sex (HR, 2.35; 95%CI, 1.24-4.46; P=.01), and NYHA functional class III-IV (HR, 2.07; 95%CI, 1.11-3.89; P=.02)., Conclusions: CA is a clinical challenge, with wide variability in its presentation depending on the subtype, leading to diagnostic delay and high mortality. Improvements are needed in the early diagnosis and treatment of these patients., (Copyright © 2020 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.)

Carpal tunnel syndrome (CTS) is a common finding among patients with cardiac amyloidosis. We sought to determine the prevalence of cardiac amyloidosis in patients who had undergone CTS surgery. From 2005 to 2014, 308 patients ≥ 60 years underwent CTS surgery. Of these, 233 (76%) agreed to participate in the study and 101 (73 ± 8 years; 68% females) showed left ventricular hypertrophy (LVH) ≥ 12 mm and underwent additional studies to diagnose AL and ATTR amyloidosis. Based on complementary studies, three patients were diagnosed with cardiac amyloidosis (two wild-type ATTR and one AL). The three patients showed bilateral CTS with no occupational risk factors. Prevalence of cardiac amyloidosis in the overall cohort was only 1.2% (3/233), but among patients with LVH and bilateral CTS, the prevalence was 5.5% (3/55) and 13.6% (3/22) if cases with an occupational risk factor were excluded. Cardiac amyloidosis should be excluded in the presence of bilateral CTS and particularly if an occupational risk factor is absent.

INTRODUCTION: Transthyretin amyloidosis (ATTR amyloidosis) is primarily associated with a cardiac or neurologic phenotype, but a mixed phenotype is increasingly described. METHODS: This study describes the mixed phenotype cohort in the Transthyretin Amyloidosis Outcomes Survey (THAOS). THAOS is an ongoing, longitudinal, observational survey of patients with ATTR amyloidosis, including both hereditary (ATTRv) and wild-type disease, and asymptomatic carriers of pathogenic transthyretin variants. Baseline characteristics of patients with a mixed phenotype (at enrollment or reclassified during follow-up) are described (data cutoff: January 4, 2022). RESULTS: Approximately one-third of symptomatic patients (n = 1185/3542; 33.5%) were classified at enrollment or follow-up as mixed phenotype (median age, 66.5 years). Of those, 344 (29.0%) were reclassified to mixed phenotype within a median 1-2 years of follow-up. Most patients with mixed phenotype had ATTRv amyloidosis (75.7%). The most frequent genotypes were V30M (38.9%) and wild type (24.3%). CONCLUSIONS: These THAOS data represent the largest analysis of a real-world mixed phenotype ATTR amyloidosis population to date and suggest that a mixed phenotype may be more prevalent than previously thought. Patients may also migrate from a primarily neurologic or cardiologic presentation to a mixed phenotype over time. These data reinforce the need for multidisciplinary evaluation at initial assessment and follow-up of all patients with ATTR amyloidosis. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00628745.

Abstract Introduction Transthyretin amyloidosis (ATTR amyloidosis) is primarily associated with a cardiac or neurologic phenotype, but a mixed phenotype is increasingly described. Methods This study describes the mixed phenotype cohort in the Transthyretin Amyloidosis Outcomes Survey (THAOS). THAOS is an ongoing, longitudinal, observational survey of patients with ATTR amyloidosis, including both hereditary (ATTRv) and wild-type disease, and asymptomatic carriers of pathogenic transthyretin variants. Baseline characteristics of patients with a mixed phenotype (at enrollment or reclassified during follow-up) are described (data cutoff: January 4, 2022). Results Approximately one-third of symptomatic patients (n = 1185/3542; 33.5%) were classified at enrollment or follow-up as mixed phenotype (median age, 66.5 years). Of those, 344 (29.0%) were reclassified to mixed phenotype within a median 1–2 years of follow-up. Most patients with mixed phenotype had ATTRv amyloidosis (75.7%). The most frequent genotypes were V30M (38.9%) and wild type (24.3%). Conclusions These THAOS data represent the largest analysis of a real-world mixed phenotype ATTR amyloidosis population to date and suggest that a mixed phenotype may be more prevalent than previously thought. Patients may also migrate from a primarily neurologic or cardiologic presentation to a mixed phenotype over time. These data reinforce the need for multidisciplinary evaluation at initial assessment and follow-up of all patients with ATTR amyloidosis. Trial Registration ClinicalTrials.gov: NCT00628745.

Abstract Background Transthyretin amyloidosis (ATTR amyloidosis) is a progressive, multisystemic, life-threatening disease resulting from the deposition of variant or wild-type (ATTRwt amyloidosis) transthyretin amyloid fibrils in various tissues and organs. Methods Established in 2007, the Transthyretin Amyloidosis Outcomes Survey (THAOS) is the largest ongoing, global, longitudinal, observational study of patients with ATTR amyloidosis, including both hereditary and wild-type disease, and asymptomatic carriers of pathogenic TTR mutations. This analysis describes the baseline characteristics of symptomatic patients and asymptomatic gene carriers enrolled in THAOS since its inception in 2007 (data cutoff: August 1, 2022), providing a consolidated overview of 15-year data from the THAOS registry. Results This analysis included 4428 symptomatic patients and 1707 asymptomatic gene carriers. The majority of symptomatic patients were male (70.8%) with a mean (standard deviation [SD]) age at symptom onset of 56.6 (17.9) years. Compared with the 14-year analysis, V30M remained the most prevalent genotype in Europe (62.2%), South America (78.6%), and Japan (74.2%) and ATTRwt remained most common in North America (56.2%). Relative to the 14-year analysis, there was an increase of mixed phenotype (from 16.6 to 24.5%) and a reduction of predominantly cardiac phenotype (from 40.7 to 31.9%). The proportion of patients with predominantly neurologic phenotype remained stable (from 40.1 to 38.7%). Asymptomatic gene carriers were 58.5% female with a mean age at enrollment of 41.9 years (SD 15.5). Conclusions This overview of > 6000 patients enrolled over 15 years in THAOS represents the largest registry analysis of ATTR amyloidosis to date and continues to emphasize the genotypic and phenotypic heterogeneity of the disease. Nearly a quarter of the symptomatic population within THAOS was mixed phenotype, underscoring the need for multidisciplinary management of ATTR amyloidosis. Trial registration ClinicalTrials.gov Identifier: NCT00628745.

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive and fatal condition that requires early diagnosis, management, and specific treatment. The availability of new disease-modifying therapies has made successful treatment a reality. Transthyretin amyloid cardiomyopathy can be either age-related (wild-type form) or caused by mutations in the TTR gene (genetic, hereditary forms). It is a systemic disease, and while the genetic forms may exhibit a variety of symptoms, a predominant cardiac phenotype is often present. This document aims to provide an overview of ATTR-CM amyloidosis focusing on cardiac involvement, which is the most critical factor for prognosis. It will discuss the available tools for early diagnosis and patient management, given that specific treatments are more effective in the early stages of the disease, and will highlight the importance of a multidisciplinary approach and of specialized amyloidosis centres. To accomplish these goals, the World Heart Federation assembled a panel of 18 expert clinicians specialized in TTR amyloidosis from 13 countries, along with a representative from the Amyloidosis Alliance, a patient advocacy group. This document is based on a review of published literature, expert opinions, registries data, patients’ perspectives, treatment options, and ongoing developments, as well as the progress made possible via the existence of centres of excellence. From the patients’ perspective, increasing disease awareness is crucial to achieving an early and accurate diagnosis. Patients also seek to receive care at specialized amyloidosis centres and be fully informed about their treatment and prognosis.