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

Cardiac amyloidosis: A diagnostic challenge

Cardiac amyloidosis is indeed a condition characterized by the deposition of amyloid proteins in the myocardium, leading to thickening and stiffening of the heart muscle. These abnormal protein deposits can interfere with the heart's normal functioning and may pose diagnostic challenges due to its varied clinical presentation and resemblance to other heart condition. Here, we present a case of 55-year-old female patient of uncontrolled hypertensions for 15 years. About 15 years ago, she presented with chest pain and was diagnosed with cardiomyopathy (CM) characterized by low left ventricle (LV) function of unknown cause. Despite being on antihypertensive treatment, the patient continued to experience chest heaviness with persistent elevate blood pressure. An echocardiogram revealed increased LV septal wall thickness, valvular thickening, and biatrial dilation. Subsequently, cardiac magnetic resonance imaging (CMR) was performed, which revealed left atrium enlargement and asymmetrical myocardial wall thickening, particularly at the septum. White blood axial image revealed thickened inter atrial septum, while late gadolinium enhancement (LGE) magnetic resonance (LGE MR) images showed patchy LGE at the base relative to the apex of the myocardium, highlighting the base-to-apex gradient, subendocardial pattern enhancement at apical lateral wall, and transmural pattern enhancement of the mid anteroseptal and inferoseptal wall. Additionally, a short axis time to invert T1 scout image of left ventricle displayed an abnormal nulling pattern initially in the myocardium, followed by the blood pool, and finally the spleen. These findings collectively led to the diagnosis of cardiac amyloidosis.

Global epidemiology of heart failure

Heart failure (HF) is a heterogeneous clinical syndrome marked by substantial morbidity and mortality. The natural history of HF is well established; however, epidemiological data are continually evolving owing to demographic shifts, advances in treatment and variations in access to health care. Although the incidence of HF has stabilized or declined in high-income countries over the past decade, its prevalence continues to increase, driven by an ageing population, an increase in risk factors, the effectiveness of novel therapies and improved survival. This rise in prevalence is increasingly noted among younger adults and is accompanied by a shift towards HF with preserved ejection fraction. However, disparities exist in our epidemiological understanding of HF burden and progression in low-income and middle-income countries owing to the lack of comprehensive data in these regions. Therefore, the current epidemiological landscape of HF highlights the need for periodic surveillance and resource allocation tailored to geographically vulnerable areas. In this Review, we highlight global trends in the burden of HF, focusing on the variations across the spectrum of left ventricular ejection fraction. We also discuss evolving population-based estimates of HF incidence and prevalence, the risk factors for and aetiologies of this disease, and outcomes in different geographical regions and populations.

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.

Right Ventricular to Pulmonary Artery Uncoupling Is Associated With Impaired Exercise Capacity in Patients With Transthyretin Cardiac Amyloidosis

BACKGROUND

Exercise capacity is related to mortality and morbidity in heart failure (HF) patients. Determinants of exercise capacity in transthyretin cardiac amyloidosis (ATTR-CA) have not been established.

METHODS AND RESULTS

This single-center study retrospectively evaluated ATTR-CA patients and patients with non-amyloidosis HF with preserved/mildly reduced ejection fraction (HFpEF/HFmrEF) (n=32 and n=51, respectively). In the ATTR-CA group, the median age was 75.5 years (interquartile range [IQR] 71.3-78.8 years), 90.6% were male, and the median left ventricular (LV) ejection fraction was 53.5% (IQR 41.4-65.6%). Cardiopulmonary exercise tests revealed a median peak oxygen consumption and anaerobic threshold of 15.9 (IQR 11.6-17.4) and 10.6 (IQR 8.5-12.0] mL/min/kg, respectively, and ventilatory efficiency (minute ventilation/carbon dioxide production [V̇E/V̇CO2] slope) of 35.5 (IQR 32.0-42.5). Among exercise variables, V̇E/V̇CO2slope has the greatest prognostic value. Univariate analysis revealed a significant correlation between V̇E/V̇CO2slope and age, LV global longitudinal strain, tricuspid annular plain systolic excursion/pulmonary arterial systolic pressure (TAPSE/PASP) ratio, and mixed venous oxygen saturation. In multivariate analyses, the TAPSE/PASP ratio was an independent predictor of V̇E/V̇CO2slope (95% confidence interval -44.5, -10.8; P=0.0067). In non-amyloidosis HFpEF/HFmrEF patients, the TAPSE/PASP ratio was not independently correlated with V̇E/V̇CO2slope.

CONCLUSIONS

Right ventricular-pulmonary artery coupling estimated by the TAPSE/PASP ratio determines exercise capacity in ATTR-CA patients. This highlights the importance of early therapeutic intervention against underappreciated right ventricular dysfunction associated with ATTR-CA.

Multi-modality artificial intelligence-based transthyretin amyloid cardiomyopathy detection in patients with severe aortic stenosis

PURPOSE

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a frequent concomitant condition in patients with severe aortic stenosis (AS), yet it often remains undetected. This study aims to comprehensively evaluate artificial intelligence-based models developed based on preprocedural and routinely collected data to detect ATTR-CM in patients with severe AS planned for transcatheter aortic valve implantation (TAVI).

METHODS

In this prospective, single-center study, consecutive patients with AS were screened with [99mTc]-3,3-diphosphono-1,2-propanodicarboxylic acid ([99mTc]-DPD) for the presence of ATTR-CM. Clinical, laboratory, electrocardiogram, echocardiography, invasive measurements, 4-dimensional cardiac CT (4D-CCT) strain data, and CT-radiomic features were used for machine learning modeling of ATTR-CM detection and for outcome prediction. Feature selection and classifier algorithms were applied in single- and multi-modality classification scenarios. We split the dataset into training (70%) and testing (30%) samples. Performance was assessed using various metrics across 100 random seeds.

RESULTS

Out of 263 patients with severe AS (57% males, age 83 ± 4.6years) enrolled, ATTR-CM was confirmed in 27 (10.3%). The lowest performances for detection of concomitant ATTR-CM were observed in invasive measurements and ECG data with area under the curve (AUC) < 0.68. Individual clinical, laboratory, interventional imaging, and CT-radiomics-based features showed moderate performances (AUC 0.70-0.76, sensitivity 0.79-0.82, specificity 0.63-0.72), echocardiography demonstrated good performance (AUC 0.79, sensitivity 0.80, specificity 0.78), and 4D-CT-strain showed the highest performance (AUC 0.85, sensitivity 0.90, specificity 0.74). The multi-modality model (AUC 0.84, sensitivity 0.87, specificity 0.76) did not outperform the model performance based on 4D-CT-strain only data (p-value > 0.05). The multi-modality model adequately discriminated low and high-risk individuals for all-cause mortality at a mean follow-up of 13 months.

CONCLUSION

Artificial intelligence-based models using collected pre-TAVI evaluation data can effectively detect ATTR-CM in patients with severe AS, offering an alternative diagnostic strategy to scintigraphy and myocardial biopsy.

Circulating ECM proteins decorin and alpha-L-iduronidase differentiate ATTRwt-CM from ATTRwt-negative HFpEF/HFmrEF

AIMS

Wild-type transthyretin cardiac amyloidosis (ATTRwt-CM) is an under-recognized aetiology of heart failure (HF), necessitating early detection for timely treatment. Our study aimed to differentiate patients with ATTRwt-CM from ATTRwt-negative HFpEF/HFmrEF patients by identifying and validating circulating protein biomarkers. In addition, we measured the same biomarkers in patients with cardiomyopathy due to light chain amyloidosis (AL)-CM to gain disease-specific insights.

METHODS AND RESULTS

In this observational study, serum concentrations of 363 protein biomarkers were measured in a discovery cohort consisting of 73 ATTRwt-CM, 55 AL-CM, and 59 ATTRwt-negative HFpEF/HFmrEF patients, using multiplex proximity extension assays. Sparse partial least squares analyses showed overlapping ATTRwt-CM and AL-CM biomarker profiles with clear visual differentiation from ATTRwt-negative patients. Pathway analyses with g:Profiler revealed significantly up-regulated proteoglycans (PG) and cell adhesion pathways in both ATTRwt-CM and AL-CM. Penalized regression analysis revealed that the proteoglycan decorin (DCN), lysosomal hydrolase alpha-L-iduronidase (IDUA) and glycosyl hydrolase galactosidase β-1 (GLB-1) most effectively distinguished ATTRwt-CM from ATTRwt-negative patients (R2 = 0.71). In a prospective validation cohort of 35 ATTRwt-CM patients and 25 ATTRwt-negative patients, DCN and IDUA significantly predicted ATTRwt-CM in the initial analysis (DCN: OR 3.3, IDUA: OR 0.4). While DCN remained significant after correcting for echocardiographic parameters, IDUA did not. DCN showed moderate discriminative ability (AUC, 0.74; 95% CI, 0.61-0.87; sensitivity, 0.91; specificity, 0.52) as did IDUA (AUC, 0.78; 95% CI, 0.65-0.91; sensitivity, 0.91; specificity, 0.61). A model combining clinical factors (AUC 0.92) outperformed DCN but not IDUA, a combination of the biomarkers was not significantly better. Neither DCN nor IDUA correlated with established disease markers.

CONCLUSION

ATTRwt-CM has a distinctly different biomarker profile compared with HFpEF/HFmrEF, while ATTRwt-CM patients share a similar biomarker profile with AL-CM patients characterized by up-regulation of proteoglycans and cell-adhesion pathways. The biomarkers DCN and IDUA show the potential to serve as an initial screening tool for ATTTRwt-CM. Further research is needed to determine the clinical usefulness of these and other extracellular matrix components in identifying ATTRwt-CM.

The Mayo ATTR-CM score versus other diagnostic scores and cardiac biomarkers in patients with suspected cardiac amyloidosis

AIMS

Several scores were developed to help the diagnosis of cardiac amyloidosis (CA). The most recent one, being the Mayo transthyretin amyloidosis cardiomyopathy (ATTR-CM) score, was not externally validated. We compared the diagnostic performance of the ATTR-CM score with previous tools (increased wall thickness [IWT] score, AMYLoidosis Index [AMYLI] score, and cardiac biomarkers) in a cohort of patients evaluated for a suspicion of CA.

METHODS AND RESULTS

We analysed 362 consecutive patients referred to a third-level centre for suspected CA. Overall, 132 (36%) had transthyretin CA (ATTR-CA), and 91 (25%) immunoglobulin light chain CA (AL-CA); CA was excluded in 139 (38%). ATTR-CM score had a good diagnostic performance to distinguish ATTR-CA from AL-CA or no CA, with an area under the curve (AUC) of 0.795 (95% confidence interval [CI] 0.747-0.842, p < 0.001), and ATTR-CA from no CA (AUC 0.822, 95% CI 0.774-0.871, p < 0.001). Results were consistent in both patients with preserved (AUC 0.787, 95% CI 0.726-0.848, p < 0.001), and reduced or mildly reduced ejection fraction (AUC 0.790, 95% CI 0.709-0.871, p < 0.001). The ATTR-CM score showed a better discrimination compared to IWT and AMYLI score to distinguish ATTR-CA from AL-CA or no CA (p = 0.002), but not to distinguish ATTR-CA from no CA (p = 0.270). Diagnostic accuracy was significantly higher for the ATTR-CM score as compared to the rule-in cut-off of high-sensitivity troponin T.

CONCLUSION

The Mayo ATTR-CM score has a good performance in identifying patients with ATTR-CA, with also better discrimination power when compared to other scores and biomarkers.

Transthyretin amyloid cardiomyopathy in severe aortic stenosis submitted to valve replacement: a multicenter study

Aim: To evaluate the prevalence of TTR amyloid cardiomyopathy (ATTR-CM) in severe aortic stenosis (SAS) patients, and to determine the independent predictors of major adverse events (MAE).Patients & methods: 91 SAS patients >65 years with an interventricular septum thickness ≥12.5 mm were referred for aortic valve replacement (AVR). 99mTc-DPD scintigraphy was applied to diagnose ATTR-CM, in the absence of monoclonal protein.Results: ATTR-CM was found in 11%. 78% of patients underwent AVR, but only 2 had ATTR-CM. There were no significant differences in the composite of all cause-mortality or cardiovascular hospitalizations. Lower left ventricle ejection fraction and not performing AVR were independent predictors of MAE.Conclusion: Not performing AVR was an independent predictor of MAE, regardless the ATTR-CM diagnosis.

Diagnostic performance and relationships of structural parameters and strain components for the diagnosis of cardiac amyloidosis with MRI

PURPOSE

The purpose of this study was to evaluate the diagnostic performance and relationships of cardiac MRI structural parameters and strain components in patients with cardiac amyloidosis (CA) and to estimate the capabilities of these variables to discriminate between CA and non-amyloid cardiac hypertrophy (NACH).

MATERIALS AND METHODS

Seventy patients with CA (56 men; mean age, 76 ± 10 [standard deviation] years) and 32 patients (19 men; mean age, 63 ± 10 [standard deviation] years) with NACH underwent cardiac MRI. Feature tracking (FT) global longitudinal strain (GLS), radial strain (GRS), circumferential strain (GCS), strain AB ratio (apical strain divided by basal strain), myocardial T1, myocardial T2 and extracellular volume (ECV) were calculated. Comparisons between patients with CA and those with NACH were made using Mann-Whitney rank sum test. The ability of each variable to discriminate between CA and NACH was estimated using area under the receiver operating characteristic curve (AUC).

RESULTS

Patients with CA had higher median GLS (-7.0% [Q1, -9.0; Q3, -5.0]), higher median GCS (-12.0% [Q1, -15.0; Q3, -9.0]), and lower median GRS (16.5% [Q1, 13.0; Q3, 23.0]) than those with NACH (-9.0% [Q1, -11.0; Q3, -8.0]; -17.0% [Q1, -20.0; Q3, -14.0]; and 25.5% [Q1, 16.0; Q3, 31.5], respectively) (P < 0.001 for all). Median myocardial T1 and ECV were significantly higher in patients with CA (1112 ms [Q1, 1074; Q3, 1146] and 47% [Q1, 41; Q3, 55], respectively) than in those with NACH (1056 ms [Q1, 1011; Q3, 1071] and 28% [Q1, 26; Q3, 30], respectively) (P < 0.001). Basal ECV showed the best performance for the diagnosis of CA (AUC = 0.975; 95% confidence interval [CI]: 0.947-1). No differences in AUC were found between AB ratio of GRS (0.843; 95% CI: 0.768-0.918) and basal myocardial T1 (0.834; 95% CI: 0.741-0.928) for the diagnosis of CA (P = 0.81). The combination of the AB ratio of FT-GRS and basal myocardial T1 had a diagnostic performance not different from that of basal ECV (P = 0.06).

CONCLUSION

ECV outperforms FT-strain for the diagnosis of CA with cardiac MRI. The AB ratio of FT-GRS associated with myocardial T1 provides diagnostic performance similar to that achieved by ECV.

Improving care for systemic light-chain amyloidosis patients: is a multidisciplinary approach best?

INTRODUCTION

Light chain (AL) amyloidosis is a rare and complex disease which can affect various systems of the body. In common with many rare and multisystemic diseases, the breadth of diagnostic, clinical, and supportive expertise required to care for such patients is best met by a multidisciplinary team.

AREAS COVERED

We outline different phases of the patients' journey, including diagnosis, staging, treatment, and response assessment, to highlight common clinical issues best resolved by a multidisciplinary approach.

EXPERT OPINION

To extend the benefit of multidisciplinary care to the majority of patients with AL amyloidosis, innovative healthcare models such as telehealth and multisite multidisciplinary team meetings need to be implemented. The need for a multidisciplinary approach where such a wide array of healthcare skills is required also highlights the shortcomings of our current diagnostic and monitoring assays. Better access to diagnostic and subtyping assays is necessary. The ability to characterize and measure the causative amyloidogenic light chain as well as imaging techniques to accurately diagnose and monitor response to therapy is also needed and is currently an area of research focus.

Precision Genetic Therapies: Balancing Risk and Benefit in Patients with Heart Failure

PURPOSE OF REVIEW

Precision genetic medicine is evolving at a rapid pace and bears significant implications for clinical cardiology. Herein, we discuss the latest advancements and emerging strategies in gene therapy for cardiomyopathy and heart failure.

RECENT FINDINGS

Elucidating the genetic architecture of heart failure has paved the way for precision therapies in cardiovascular medicine. Recent preclinical studies and early-phase clinical trials have demonstrated encouraging results that support the development of gene therapies for heart failure arising from a variety of etiologies. In addition to the discovery of new therapeutic targets, innovative delivery platforms are being leveraged to improve the safety and efficacy of cardiac gene therapies. Precision genetic therapy represents a potentially safe and effective approach for improving outcomes in patients with heart failure. It holds promise for radically transforming the treatment paradigm for heart failure by directly targeting the underlying etiology. As this new generation of cardiovascular medicines progress to the clinic, it is especially important to carefully evaluate the benefits and risks for patients.

Temporal Outcomes of Patients Diagnosed With Transthyretin Cardiac Amyloidosis

BACKGROUND

Transthyretin cardiac amyloidosis (ATTR-CA) is increasingly recognized. Clinical outcomes have evolved over time amid changes in the diagnostic pathway and advances in therapeutics. We sought to evaluate clinical outcomes over time of patients with ATTR-CA with access to disease-modifying therapy.

METHODS AND RESULTS

This is a retrospective cohort study of 419 patients diagnosed with ATTR-CA during 2001-2021, comparing clinical characteristics across eras. The primary end point was composite all-cause mortality or orthotopic heart transplantation (OHT). Time-to-event analysis was performed using Cox proportional hazard modeling controlling for differences among cohorts. Patients diagnosed in the more recent years had higher median age (2017-2021, 78 years; 2014-2016, 75 years; 2001-2013, 74 years) and more often had wild-type ATTR (81.9% vs 82.5% vs 56.4%), but less severe phenotypes as evidenced by more individuals with Columbia stage I disease (47.6% vs 35.9% vs 22.4%), owing to lower biomarkers, more patients in New York Heart Association functional classes I and II (68.9% vs 47.6% vs 43.6%), and lower use of loop diuretics (67.0% vs 78.6% vs 89.1%). Over time, patients were treated more frequently with tafamidis (74% vs 37% vs 32%). On multivariable analysis, greater Columbia score (hazard ratio 1.42, 95% confidence interval 1.30-1.54, P < .001) was predictive of death or OHT, whereas tafamidis (hazard ratio 0.31, 95% confidence interval 0.22-0.44, P < .001) was associated with greater survival and freedom from OHT.

CONCLUSIONS

Patients recently diagnosed with ATTR-CA have earlier stage disease and substantially lower mortality. Tafamidis is associated with significantly improved survival and freedom from OHT.

Navigating the penetrance and phenotypic spectrum of inherited cardiomyopathies

Inherited cardiomyopathies are genetic diseases that can lead to heart failure and sudden cardiac death. These conditions tend to run in families, following an autosomal dominant pattern where first-degree relatives have a 50% chance of carrying the pathogenic variant. Despite significant advancements and increased accessibility of genetic testing, accurately predicting the phenotypic expression of these conditions remains challenging due to the inherent variability in their clinical manifestations and the incomplete penetrance observed. This poses challenges in providing patient care and effectively communicating the potential risk of future disease to patients and their families. To address these challenges, this review aims to synthesize the available evidence on penetrance, expressivity, and factors influencing disease expression to improve communication and risk assessment for patients with inherited cardiomyopathies and their family members.

Thromboembolic and bleeding risk in cardiac amyloidosis

Cardiac amyloidosis represents a spectrum of conditions characterized by the accumulation of insoluble fibrils, resulting in progressive deposition and myocardial dysfunction. The exact mechanisms contributing to the heightened risk of thromboembolic events and bleeding tendencies in cardiac amyloidosis remain unclear. Proteins such as transthyretin in transthyretin amyloidosis and light chains in light-chain amyloidosis, along with acute phase proteins in amyloid A (AA) amyloidosis, play complex roles in the coagulation cascade, affecting both coagulation initiation and fibrinolysis regulation. The increased occurrence of atrial fibrillation, systolic and diastolic left ventricular dysfunction, and atrial myopathy in patients with cardiac amyloidosis may predispose them to thrombus formation. This predisposition can occur regardless of sinus rhythm status or even with proper anticoagulant management. Bleeding events are often linked to amyloid deposits around blood vessels, which may increase capillary fragility and cause coagulation disturbances, leading to unstable international normalized ratio levels during anticoagulant therapy. Thus, comprehensive risk assessment for both thrombotic and hemorrhagic complications, especially before commencing anticoagulant therapy, is imperative. This review will explore the essential pathophysiological, epidemiologic, and clinical aspects of thromboembolic and bleeding risk in cardiac amyloidosis, evaluating the existing evidence and uncertainties regarding thrombotic and bleeding risk assessment and antithrombotic treatment.

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.

Radionuclide Imaging of Cardiac Amyloidosis: An Update and Future Aspects

Cardiac amyloidosis (CA) is caused by the misfolding, accumulation and aggregation of proteins into large fibrils in the extracellular compartment of the myocardium, leading to restrictive cardiomyopathy, heart failure and death. The major forms are transthyretin (ATTR) CA and light-chain (AL) CA, based on the respective precursor protein. Each of them requires early diagnosis for a timely treatment initiation that will improve patient outcomes. For this, radionuclide imaging is essentially used as single-photon emission computed tomography (SPECT) with bone-avid radiotracers or as positron emission tomography (PET) with amyloid-binding radiotracers. Both offer unprecedented specificity for the diagnostic of CA. SPECT has even revolutionized the diagnosis of ATTR-CA by making it non-invasive. Indeed, SPECT has now entered the standard diagnostic pathway to CA and has led to earlier diagnosis of the disease. SPECT also modified the epidemiology of ATTR-CA, highlighting that the disease is much more frequent than previously believed, and showing that ATTR-CA plays a substantial role in HFpEF and aortic stenosis, particularly among elderly patients. In parallel, amyloid-binding radiotracers for PET have accumulated a substantial amount of evidence, but are not approved for clinical use in CA yet. Further studies are needed to refine acquisition protocols and validate results in broader populations. Unlike bone-avid SPECT radiotracers, PET radiotracers have been specifically created to bind to amyloid fibrils. Thus, PET is the only imaging method that is truly specific for amyloid deposits and very sensitive to any amyloid type. Indeed, PET can not only detect ATTR-CA, but also AL-CA and rare hereditary forms. For both SPECT and PET, advances in quantitation of myocardial uptake have generated more granular and reproducible findings, paving the way for progress in earlier diagnosis, risk stratification and therapeutic response monitoring. Encouraging findings have shown that SPECT and PET are sensitive to early CA when other diagnostic methods are negative. Both radionuclide imaging techniques can predict adverse outcomes, but more evidence is needed to determine how to use them in conjunction with usual prognostic staging scores. Studies on follow-up imaging after therapy suggested that SPECT and PET can capture myocardial changes in CA, but again, more data are needed to meaningfully interpret such changes. Based on all these promising results, radionuclide imaging has the potential to further impact the landscape of CA in diagnosis, prognosis and follow-up, but also to substantially contribute to the assessment of novel therapies that will improve the lives of patients with CA.

Cardiopulmonary exercise testing in transthyretin amyloid cardiomyopathy patients: a long-term follow-up study

AIMS

Patients with transthyretin amyloid cardiomyopathy (ATTR-CM) experience reduced functional capacity. We evaluated changes in functional capacity over extensive follow-up using cardiopulmonary exercise testing (CPX).

METHODS

ATTR-CM patients underwent CPX and blood testing at baseline, first [V1, 8 (6-10) months] and second follow-up (V2) at 35 (26-41) months after start of disease-specific therapy.

RESULTS

We included 34 ATTR-CM patients, aged 77 (±6) years (88.2% men). CPX showed two patterns with functional capacity improvement at V1 and deterioration at V2. Peak work capacity ( P = 0.005) and peak oxygen consumption (VO 2 , P = 0.012) increased at V1 compared with baseline and decreased at V2. The ventilation to carbon dioxide relationship slope (VE/VCO 2 ) increased at V2 compared with baseline and V1 ( P = 0.044). A cut-off for peak VO 2 at 14 ml/kg·min showed more events (composite of death and heart failure hospitalization): less than 14 vs. greater than 14 ml/kg·min ( P  = 0.013). Cut-offs for VE/VCO 2 slope at 40 showed more events greater than 40 vs. less than 40 ( P  = 0.009).

CONCLUSION

ATTR-CM patients showed an improvement and deterioration in the short-term and long-term follow-up, respectively, with a better prognosis for those with peak VO 2 above 14 ml/kg·min and for a VE/VCO 2 slope below 40.

Treatment of transthyretin cardiac amyloidosis

PURPOSE OF REVIEW

Tafamidis is currently the only approved disease-modifying treatment for ATTR-CM. However, there have been important developments in the treatment of ATTR-CM, as the results of two phase 3 trials were published and several other trials are in their final stages. In this review, we summarize current and future therapies for ATTR-CM.

RECENT FINDINGS

Recently, acoramidis, a TTR stabilizer has been proven to be effective in reducing mortality and morbidity compared to placebo in the ATTRibute-CM trial. Additionally, patisiran, an RNA silencer, preserved functional capacity and quality of life compared to placebo in the APOLLO-B trial. However, the FDA declined to approve patisiran for ATTR-CM. The results of phase 1 trial of ALXN2220, an antiamyloid antibody raise hope for reversal of myocardial damage by amyloid depletion. Phase 3 trials evaluating the efficacy of different RNA silencers, gene editing with CRISPR-Cas9, and other anti-amyloid antibodies are ongoing.

SUMMARY

Therapies targeting different mechanism in the pathophysiology of ATTR-CM provide new alternatives for treating patients with ATTR-CM. Future research should focus on comparing their effectiveness, the potential of combined treatment with agents from different classes and on identifying the patients who will benefit most from each class of medication.

First report of the clinical characteristics and outcomes of cardiac amyloidosis in Saudi Arabia

AIMS

Cardiac amyloidosis (CA) is a potentially fatal multisystemic disease that remains significantly underdiagnosed, particularly in the Middle East. This study aims to evaluate the prevalence and clinical characteristics of CA in a high-risk population at a tertiary centre in Saudi Arabia.

METHODS

This cross-sectional, retrospective, single-centre study was conducted at a tertiary hospital in Riyadh, Saudi Arabia. We reviewed the medical records of heart failure patients seen between August 2018 and July 2022 who exhibited red flags for CA and subsequently underwent CA screening. Red flags that prompted the workup included at least two of the following factors: the presence of unilateral or bilateral carpal tunnel syndrome, a family history of transthyretin amyloid (ATTR) amyloidosis and specific electrocardiographic features (relative/absolute low QRS voltage, pseudoinfarct pattern and atrioventricular/interventricular conduction abnormalities). Echocardiographic red flags included mainly increased wall thickness (≥12 mm), significant diastolic dysfunction, reduced left ventricular (LV) longitudinal function, right ventricular (RV) dysfunction and elevated right atrial (RA)/pulmonary artery (PA) pressure. Cardiac magnetic resonance (CMR) red flags included aspects similar to those in an echocardiogram as well as a subendocardial or transmural late gadolinium enhancement (LGE) pattern. These patients were assessed for CA through technetium-99m pyrophosphate ([99mTc]Tc-PYP) bone scintigraphy, serum and urine protein electrophoresis with immunofixation and a serum-free light chain assay.

RESULTS

A total of 177 patients were screened, of which 21.0 (11.9%) patients were diagnosed with transthyretin amyloid CA (ATTR-CA) and 13 (7.3%) patients were diagnosed with light chain CA (AL-CA). Compared with patients with negative/equivocal [99mTc]Tc-PYP scans (grades 0-1), patients with positive [99mTc]Tc-PYP scans (grades 2-3) were older (78.0 vs. 68.0 years, P < 0.001), had higher levels of troponin (P = 0.003) and N-terminal pro-brain natriuretic peptide (NT-proBNP) (P < 0.001), had a higher LV mass index (P < 0.001), displayed a more depressed global longitudinal strain (GLS) (P < 0.001) with a greater prevalence of a relative apical sparing pattern (P < 0.001) and demonstrated a higher incidence of first-degree atrioventricular block (P = 0.008) and low voltage patterns on electrocardiography (P < 0.001). Patients with ATTR-CA and AL-CA were more likely to have a subendocardial or transmural LGE pattern on CMR (P < 0.001) and had a significantly lower overall survival (P < 0.001) when compared with other heart failure aetiologies.

CONCLUSIONS

This is the first study to describe the clinical characteristics and outcomes of CA in the Middle East and Saudi Arabia. The prevalence of CA among screened heart failure patients here aligns with major international studies, suggesting significant underdiagnosis in the region. Therefore, larger multicentric studies and regional screening programmes are urgently needed to accurately characterize the epidemiology and outcomes of CA in the Middle East.

Tracking the pre-clinical progression of transthyretin amyloid cardiomyopathy using artificial intelligence-enabled electrocardiography and echocardiography

Background and Aims

Diagnosing transthyretin amyloid cardiomyopathy (ATTR-CM) requires advanced imaging, precluding large-scale testing for pre-clinical disease. We examined the application of artificial intelligence (AI) to echocardiography (TTE) and electrocardiography (ECG) as a scalable strategy to quantify pre-clinical trends in ATTR-CM.

Methods

Across age/sex-matched case-control datasets in the Yale-New Haven Health System (YNHHS) we trained deep learning models to identify ATTR-CM-specific signatures on TTE videos and ECG images (area under the curve of 0.93 and 0.91, respectively). We deployed these across all studies of individuals referred for cardiac nuclear amyloid imaging in an independent population at YNHHS and an external population from the Houston Methodist Hospitals (HMH) to define longitudinal trends in AI-defined probabilities for ATTR-CM using age/sex-adjusted linear mixed models, and describe discrimination metrics during the early pre-clinical stage.

Results

Among 984 participants referred for cardiac nuclear amyloid imaging at YNHHS (median age 74 years, 44.3% female) and 806 at HMH (69 years, 34.5% female), 112 (11.4%) and 174 (21.6%) tested positive for ATTR-CM, respectively. Across both cohorts and modalities, AI-defined ATTR-CM probabilities derived from 7,423 TTEs and 32,205 ECGs showed significantly faster progression rates in the years before clinical diagnosis in cases versus controls (p time × group interaction ≤0.004). In the one-to-three-year window before cardiac nuclear amyloid imaging sensitivity/specificity metrics were estimated at 86.2%/44.2% [YNHHS] vs 65.7%/65.5% [HMH] for AI-Echo, and 89.8%/40.6% [YNHHS] vs 88.5%/35.1% [HMH] for AI-ECG.

Conclusions

We demonstrate that AI tools for echocardiographic videos and ECG images can enable scalable identification of pre-clinical ATTR-CM, flagging individuals who may benefit from risk-modifying therapies.

Transthyretin cardiac amyloid: Broad heart failure phenotypic spectrum and implications for diagnosis

AIMS

Transthyretin cardiac amyloidosis (ATTR-CA) is most often associated with heart failure with preserved ejection fraction (HFpEF). However, patients may present with impaired systolic function at the time of diagnosis, which has not been widely investigated. We sought to explore the prevalence of various heart failure (HF) phenotypes and their associated clinical characteristics at the time of ATTR-CA diagnosis.

METHODS

We performed a single-centre retrospective cohort study of consecutive patients with ATTR-CA evaluated between February 2016 and December 2022. Data on patient demographics, comorbidities, imaging and laboratory findings were compared across HF phenotypes (age: 78.1 ± 8.6 years, with 91.1% male). A total of 21.6% (n = 46) presented with heart failure with reduced ejection fraction (HFrEF), 17.8% (n = 38) with heart failure with mildly reduced ejection fraction (HFmrEF) and 60.6% (n = 129) with HFpEF at the time of diagnosis with ATTR-CA. Those presenting with HFrEF or HFmrEF were more likely to be African American and had significantly worse New York Heart Association (NYHA) functional class, higher N-terminal pro-brain natriuretic peptide (NT-proBNP) and higher serum creatinine levels as compared with those with HFpEF.

CONCLUSIONS

Although ATTR-CA is traditionally thought to be seen primarily among patients with HFpEF, our data suggest that ATTR-CA has a higher prevalence among patients with HFrEF, which underscores the importance of heightened clinical suspicion regardless of ejection fraction when considering ATTR-CA. Furthermore, although comorbidities are similar, patients with HFmrEF and HFrEF had a worse symptom burden.

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.

Prevalence and characteristics of patients with incidental cardiac uptake on bone scintigraphy

BACKGROUND

Bone scintigraphy is emerging as a confirmatory diagnostic tool for transthyretin cardiac amyloidosis (ATTR-CA). This study aimed to investigate the frequency and clinical characteristics of patients with incidental cardiac uptake and incidental ATTR-CA on bone scintigraphy.

METHODS

All bone scintigraphic studies performed at a tertiary teaching hospital between 2011 and 2022 were reviewed retrospectively. Patients who underwent bone scintigraphy to confirm ATTR-CA were excluded. Patients with cardiac uptake of grade 2 or 3 were included and divided into two groups: possible ATTR-CA group and noncardiac amyloidosis (non-CA) group.

RESULTS

Of the 61,432 bone scintigraphic studies performed on 32,245 patients, 23 (0.07%) had grade 2 or 3 cardiac uptake. Nine of 23 patients (39.1%) were assigned to the non-CA group because they showed cardiac uptake from definite other causes or focal uptake that did not match CA. The remaining 14 patients (60.9%) were classified as the possible ATTR-CA group, and five patients were referred to cardiologists and finally diagnosed with ATTR-CA. Two patients were treated with tafamidis. Patients in the ATTR-CA group were significantly older and had a less frequent history of end-stage renal disease than those in the non-CA group. Other characteristics were comparable in both groups.

CONCLUSIONS

Although incidental ATTR-CA in patients undergoing bone scintigraphy for noncardiac reasons is uncommon, if cardiac uptake is observed in elderly patients without metastatic calcification associated with end-stage renal disease, further diagnostic work-up for ATTR-CA as a cause of undiagnosed heart failure should be considered.

Transthyretin amyloid cardiomyopathy among patients with heart failure and preserved ejection fraction: the AMY score

AIMS

Transthyretin 'wild-type' amyloid cardiomyopathy (ATTRwt-CM) is a differential diagnosis of heart failure with preserved ejection fraction (HFpEF). The clinical work-up for ATTRwt-CM is challenging. Considering a combination of clinical variables specific for ATTRwt-CM might aid in identifying patients at risk.

METHODS AND RESULTS

Sixty patients (78 ± 6 years, 8% female) were diagnosed with ATTRwt-CM by endomyocardial biopsy. Preserved ejection fraction (LVEF >45%) was present in 41 of the patients. Those were 1:1 propensity score age- and sex-matched to a cohort of patients with HFpEF. ATTRwt-CM patients had less obesity (P = 0.01) and higher septal thickness (IVSd, P < 0.01) as well as more diastolic dysfunction (E/e', P < 0.01). On multivariable regression IVSd > 14 mm, E/e' > 14 and absence of obesity (P > 0.01 for all) were identified as predictors for ATTRwt-CM. A weighted point-based score was derived with IVSd > 14 mm = 1 point; absence of obesity = 2 points; and E/e' > 14 = 3 points. Area under the curve (AUC) for the summation score was 0.91 (0.84-0.97, P < 0.01) and a score of more than 3 points predicted ATTRwt-CM with good sensitivity (78%) and specificity (90%). The score was validated in an external cohort of 142 patients with ATTRwt-CM and 419 HFpEF patients showing sufficient accuracy (AUC 0.91, 0.88-0.94, P < 0.01). A value greater than 3 points demonstrated a high sensitivity (93%) and a negative predictive value of 97%.

CONCLUSIONS

A score based on basic clinical and echocardiographic features helps to distinguish ATTRwt-CM from typical HFpEF. This could facilitate the diagnostic work-up for these patients and enable earlier disease screening on a large scale.

Atrial Fibrillation as a Prognostic Factor for All-Cause Mortality in Patients With Transthyretin Amyloid Cardiomyopathy

Background

Atrial fibrillation/atrial flutter (AF/AFL) are common manifestations of transthyretin amyloid cardiomyopathy (ATTR-CM) but have not been found to be predictive of mortality.

Objectives

This analysis aimed to examine whether baseline or historical AF/AFL at enrollment was prognostic for all-cause mortality.

Methods

In the ATTR-ACT (Tafamidis in Transthyretin Cardiomyopathy Clinical Trial), a 30-month study of tafamidis vs placebo for ATTR-CM, AF/AFL was evaluated as an independent prognostic factor for all-cause mortality using Cox proportional hazards modelling. The impact of AF/AFL on tafamidis efficacy was explored by adding an interaction term for AF/AFL status and treatment.

Results

ATTR-ACT enrolled 441 patients with ATTR-CM (median age 75 years; 90% male); 314 (71.2%) had baseline or historical AF/AFL at enrollment. AF/AFL was an independent prognostic factor for all-cause mortality after adjusting for covariates prespecified in the ATTR-ACT model (treatment, genotype, New York Heart Association functional class; HR: 0.550; 95% CI: 0.368-0.821) but not in an expanded stepwise model selection analysis including 23 covariates (blood urea nitrogen and N-terminal pro-B-type natriuretic peptide concentration, 6-minute walk test distance, genotype, treatment, and global longitudinal strain were prognostic [P < 0.01]). The interactions between tafamidis treatment and AF/AFL for all-cause mortality (P = 0.33) and changes in Kansas City Cardiomyopathy Questionnaire Overall Summary score (P = 0.83) and 6-minute walk test distance (P = 0.82) were not significant.

Conclusions

In ATTR-ACT, baseline or historical AF/AFL was prognostic for all-cause mortality in analyses with limited adjustment but not after accounting for additional indicators of disease severity. Baseline or historical AF/AFL did not impact the efficacy of tafamidis treatment. (Safety and Efficacy of Tafamidis in Patients With Transthyretin Cardiomyopathy [ATTR-ACT]; NCT01994889).

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.

A bibliometric analysis of light chain amyloidosis from 2005 to 2024: research trends and hot spots

Background

Light chain (AL) amyloidosis stands as the most prevalent subtype of systemic amyloidosis, encompassing a group of rare diseases. Here, we evaluated the scientific landscape of AL amyloidosis to investigate research trends and identify hotspots within the field.

Methods

Relevant studies on AL amyloidosis published over the past two decades were retrieved from the Web of Science Core Collection. The publications between 2005 and 2024 were subjected to bibliometric analyses, leveraging tools including CiteSpace, VOSviewer, RStudio and MS Excel to analyse and visualize the annual publication trend, co-occurrence patterns, collaborative networks among countries, organizations, and authors. Burst keywords and references were also examined to obtain the research history, and emerging hotspots.

Results

The bibliometric analysis included 2,864 articles published between 2005 and 2024. The most productive journal is Amyloid-Journal of Protein Folding Disorders. The United States, along with several developed nations, emerges as a dominant force in international AL amyloidosis research. "AL amyloidosis" and "cardiac amyloidosis" were the primary hotspots over the past two decades, and "Biomarkers," "Cardiac amyloidosis," and "treatment" would be future trends.

Conclusion

This bibliometric analysis examined the research developments in AL amyloidosis over the past two decades using bibliometric software. Recent research in this field primarily focuses on two main areas: clinical diagnosis and treatment of AL amyloidosis, as well as cardiac amyloidosis. Emphasis is placed on understanding the mechanisms underlying immunoglobulin light chain aggregation and deposition to mitigate organ involvement.

Recent advances in the diagnostic methods and therapeutic strategies of transthyretin cardiac amyloidosis

Cardiac amyloidosis is a progressive disease characterized by the buildup of amyloid fibrils in the extracellular space of the heart. It is divided in 2 main types, immunoglobulin light chain amyloidosis and transthyretin amyloidosis (ATTR), and ATTR amyloidosis is further divided in 2 subtypes, non-hereditary wild type ATTR and hereditary mutant variant amyloidosis. Incidence and prevalence of ATTR cardiac amyloidosis is increasing over the last years due to the improvements in diagnostic methods. Survival rates are improving due to the development of novel therapeutic strategies. Tafamidis is the only disease-modifying approved therapy in ATTR amyloidosis so far. However, the most recent advances in medical therapies have added more options with the potential to become part of the therapeutic armamentarium of the disease. Agents including acoramidis, eplontersen, vutrisiran, patisiran and anti-monoclonal antibody NI006 are being investigated on cardiac function in large, multicenter controlled trials which are expected to be completed within the next 2-3 years, providing promising results in patients with ATTR cardiac amyloidosis. However, further and ongoing research is required in order to improve diagnostic methods that could provide an early diagnosis, as well as survival and quality of life of these patients.

Effect of beta-blockade on mortality in patients with cardiac amyloidosis: A systematic review and meta-analysis

AIMS

The efficacy of beta-blockers in cardiac amyloidosis (CA) is unclear, and concerns persist that neurohormonal blockade could worsen symptoms of heart failure. We aimed to assess whether beta-blocker therapy is associated with improved survival in patients with CA.

METHODS AND RESULTS

We conducted a systematic review and meta-analysis to examine the impact of beta-blocker therapy on mortality in patients with CA. A search of MEDLINE and EMBASE was performed in August 2023. Data were extracted from observational studies and synthesized with pooling and random effects meta-analysis. Thirteen studies including 4215 patients with CA were incorporated in this review (3688 transthyretin amyloid cardiomyopathy (ATTR-CM), 502 light chain amyloid cardiomyopathy (AL-CM), 25 not specified; age 74.8 ± 5.5 years, 76% male). Over half of the cohort (52%) received beta-blockers and the rate of beta-blocker withdrawal was 28%. All-cause mortality was 33% (range: 13-51%) after a median follow-up ranging from 13 to 36 months. There was an inverse association between the pooled risk of mortality and the use of beta-blocker therapy at any time point (RR 0.48, 95% CI 0.29-0.80, I2 = 83%, P = 0.005, seven studies). There was no association between mortality and beta-blocker use (RR 0.65, 95% CI 0.29-1.47, I2 = 88%, P = 0.30) in the three studies that only included patients with ATTR-CM. The three studies that included patients with both ATTR-CM and AL demonstrated an association of beta-blocker use with reduced mortality (OR 0.43, 95% CI 0.29-0.63, I2 = 4%, P < 0.001). The only study that solely included 53 patients with AL-CM, demonstrated improved survival among the 53% who were able to tolerate beta-blocker therapy (RR 0.26, 95% CI 0.08-0.79, P = 0.02). The absence of information on staging of CA is an important limitation of this study.

CONCLUSIONS

Treatment with beta-blockers may be associated with a survival benefit in patients with CA, but these findings are subject to selection and survivor biases. Definitive prospective randomized trials of conventional heart failure therapies are needed in CA.

Diastolic dysfunction in Alzheimer's disease model mice is associated with Aβ-amyloid aggregate formation and mitochondrial dysfunction

Alzheimer's Disease (AD) is a progressive neurodegenerative disease caused by the deposition of Aβ aggregates or neurofibrillary tangles. AD patients are primarily diagnosed with the concurrent development of several cardiovascular dysfunctions. While few studies have indicated the presence of intramyocardial Aβ aggregates, none of the studies have performed detailed analyses for pathomechanism of cardiac dysfunction in AD patients. This manuscript used aged APPSWE/PS1 Tg and littermate age-matched wildtype (Wt) mice to characterize cardiac dysfunction and analyze associated pathophysiology. Detailed assessment of cardiac functional parameters demonstrated the development of diastolic dysfunction in APPSWE/PS1 Tg hearts compared to Wt hearts. Muscle function evaluation showed functional impairment (decreased exercise tolerance and muscle strength) in APPSWE/PS1 Tg mice. Biochemical and histochemical analysis revealed Aβ aggregate accumulation in APPSWE/PS1 Tg mice myocardium. APPSWE/PS1 Tg mice hearts also demonstrated histopathological remodeling (increased collagen deposition and myocyte cross-sectional area). Additionally, APPSWE/PS1 Tg hearts showed altered mitochondrial dynamics, reduced antioxidant protein levels, and impaired mitochondrial proteostasis compared to Wt mice. APPSWE/PS1 Tg hearts also developed mitochondrial dysfunction with decreased OXPHOS and PDH protein complex expressions, altered ETC complex dynamics, decreased complex activities, and reduced mitochondrial respiration. Our results indicated that Aβ aggregates in APPSWE/PS1 Tg hearts are associated with defects in mitochondrial respiration and complex activities, which may collectively lead to cardiac diastolic dysfunction and myocardial pathological remodeling.

Developing a genetic testing panel for evaluation of morbidities in kidney transplant recipients

Cardiovascular disease, infection, malignancy, and thromboembolism are major causes of morbidity and mortality in kidney transplant recipients (KTR). Prospectively identifying monogenic conditions associated with post-transplant complications may enable personalized management. Therefore, we developed a transplant morbidity panel (355 genes) associated with major post-transplant complications including cardiometabolic disorders, immunodeficiency, malignancy, and thrombophilia. This gene panel was then evaluated using exome sequencing data from 1590 KTR. Additionally, genes associated with monogenic kidney and genitourinary disorders along with American College of Medical Genetics (ACMG) secondary findings v3.2 were annotated. Altogether, diagnostic variants in 37 genes associated with Mendelian kidney and genitourinary disorders were detected in 9.9% (158/1590) of KTR; 25.9% (41/158) had not been clinically diagnosed. Moreover, the transplant morbidity gene panel detected diagnostic variants for 56 monogenic disorders in 9.1% KTRs (144/1590). Cardiovascular disease, malignancy, immunodeficiency, and thrombophilia variants were detected in 5.1% (81), 2.1% (34), 1.8% (29) and 0.2% (3) among 1590 KTRs, respectively. Concordant phenotypes were present in half of these cases. Reviewing implications for transplant care, these genetic findings would have allowed physicians to set specific risk factor targets in 6.3% (9/144), arrange intensive surveillance in 97.2% (140/144), utilize preventive measures in 13.2% (19/144), guide disease-specific therapy in 63.9% (92/144), initiate specialty referral in 90.3% (130/144) and alter immunosuppression in 56.9% (82/144). Thus, beyond diagnostic testing for kidney disorders, sequence annotation identified monogenic disorders associated with common post-transplant complications in 9.1% of KTR, with important clinical implications. Incorporating genetic diagnostics for transplant morbidities would enable personalized management in pre- and post-transplant care.

Rare Variant of Hereditary Amyloid Transthyretin Cardiomyopathy Secondary to Ser97Tyr Mutation

Hereditary transthyretin amyloidosis (hATTR) is an autosomal dominant, adult-onset disease that stems from point mutations in the TTR gene encoding the protein transthyretin. The disease is progressive and life-threatening and is associated with amyloid deposits in multiple organs including the heart, kidney, skin, eyes, nervous system, and gastrointestinal tract. Genotypic and phenotypic heterogeneity is a characteristic hallmark of hereditary transthyretin amyloidosis. Herein, we present a rare variant of hATTR cardiomyopathy secondary to Ser97Tyr mutation, having been documented only in a handful of families previously. This case serves as a valuable opportunity to elucidate the clinico-pathogenesis of this disease, highlight the aggressive nature of this genetic mutation (c.290C>A; p.Ser97Tyr), and document the response to the latest advances in treatment currently available.

A review regarding the article 'Prevalence of Valvular Heart Disease in Cardiac Amyloidosis and Impact on Survival'

Cardiac amyloidosis (CA) is a condition characterized by the accumulation of amyloid fibrils in the heart muscle, resulting in an infiltrative cardiomyopathy. The presence of amyloid protein can impact different parts of the heart, including the valves. Limited data is available on the prevalence and prognostic significance of valvular heart disease (VHD) in CA. However, advancements in imaging technology have allowed for accurate noninvasive diagnosis of CA, eliminating the need for confirmatory endomyocardial biopsy and improving our understanding of this dual pathology. The development of targeted drug therapies for CA and transcatheter valve replacement or repair for VHD has significantly improved the prognosis for patients with both conditions. This review will discuss the findings of this original research and provide an overview of current researches on VHD in CA, as well as the progress in diagnosing and treating CA with VHD.

Cardiovascular Magnetic Resonance in the Management of Cardiac Amyloidosis: Current and Future Clinical Applications

Cardiac magnetic resonance represents the gold standard imaging technique to assess cardiac volumes, wall thickness, mass, and systolic function but also to provide noninvasive myocardial tissue characterization across almost all cardiac diseases. In patients with cardiac amyloidosis, increased wall thickness of all heart chambers, a mildly reduced ejection fraction and occasionally pleural and pericardial effusion are the characteristic morphologic anomalies. The typical pattern after contrast injection is represented by diffuse areas of late gadolinium enhancement, which can be focal and patchy in very early stages, circumferential, and subendocardial in intermediate stages or even diffuse transmural in more advanced stages.

Amyloidosis and Amyloidogenesis: One Name, Many Diseases

Amyloidosis is a heterogenous group of disorders, caused by the deposition of insoluble fibrils derived from misfolded proteins in the extracellular space of various organs. These proteins have an unstable structure that causes them to misfold, aggregate, and deposit as amyloid fibrils with the pathognomonic histologic property of green birefringence when viewed under cross-polarized light after staining with Congo red. Amyloid fibrils are insoluble and degradation-resistant; resistance to catabolism results in progressive tissue amyloid accumulation. The outcome of this process is organ disfunction independently from the type of deposited protein, however there can be organ that are specifically targeted from certain proteins.

Clinical Use of Biomarkers in Cardiac Amyloidosis

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

Prevalence and clinical outcomes of isolated or combined moderate to severe mitral and tricuspid regurgitation in patients with cardiac amyloidosis

AIMS

Evidence on the epidemiology and prognostic significance of mitral regurgitation (MR) and tricuspid regurgitation (TR) in patients with cardiac amyloidosis (CA) is scarce.

METHODS AND RESULTS

Overall, 538 patients with either transthyretin (ATTR, n = 359) or immunoglobulin light-chain (AL, n = 179) CA were included at three Italian referral centres. Patients were stratified according to isolated or combined moderate/severe MR and TR. Overall, 240 patients (44.6%) had no significant MR/TR, 112 (20.8%) isolated MR, 66 (12.3%) isolated TR, and 120 (22.3%) combined MR/TR. The most common aetiologies were atrial functional MR, followed by primary infiltrative MR, and secondary TR due to right ventricular (RV) overload followed by atrial functional TR. Patients with isolated or combined MR/TR had a more frequent history of heart failure (HF) hospitalization and atrial fibrillation, worse symptoms, and higher levels of NT-proBNP as compared to those without MR/TR. They also presented more severe atrial enlargement, atrial peak longitudinal strain impairment, left ventricular (LV) and RV systolic dysfunction, and higher pulmonary artery systolic pressures. TR carried the most advanced features. After adjustment for age, sex, CA subtypes, laboratory, and echocardiographic markers of CA severity, isolated TR and combined MR/TR were independently associated with an increased risk of all-cause death or worsening HF events, compared to no significant MR/TR [adjusted HR 2.75 (1.78-4.24) and 2.31 (1.44-3.70), respectively].

CONCLUSION

In a large cohort of patients with CA, MR, and TR were common. Isolated TR and combined MR/TR were associated with worse prognosis regardless of CA aetiology, LV, and RV function, with TR carrying the highest risk.

Efficacy of Computed Tomography-Based Evaluation of Myocardial Extracellular Volume Combined With Red Flags for Early Screening of Concealed Cardiac Amyloidosis in Patients With Atrial Fibrillation

BACKGROUND

The prevalence of transthyretin amyloid cardiomyopathy (ATTR-CM) in atrial fibrillation (AF) patients remains unclear. We explored the efficacy of computed tomography-based myocardial extracellular volume (CT-ECV) combined with red flags for the early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.

METHODS AND RESULTS

Patients referred for AF ablation at Oita University Hospital were prescreened using the red-flag signs defined by echocardiographic or electrocardiographic findings, medical history, symptoms, and blood biochemical findings. Myocardial CT-ECV was quantified in red flag-positive patients using routine pre-AF ablation planning cardiac CT with the addition of delayed-phase cardiac CT scans. Patients with high (>35%) ECV were evaluated using technetium pyrophosphate (99 mTc-PYP) scintigraphy. A cardiac biopsy was performed during the planned AF ablation procedure if 99 mTc-PYP scintigraphy was positive. Between June 2022 and June 2023, 342 patients were referred for AF ablation. Sixty-seven (19.6%) patients had at least one of the red-flag signs. Myocardial CT-ECV was evaluated in 57 patients because of contraindications to contrast media, revealing that 16 patients had high CT-ECV. Of these, 6 patients showed a positive 99 mTc-PYP study, and 6 patients were subsequently diagnosed with wild-type ATTR-CM via cardiac biopsy and genetic testing.

CONCLUSIONS

CT-ECV combined with red flags could contribute to the systematic early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.

Analysis of post-market adverse events of tafamidis base on the FDA adverse event reporting system

Tafamidis is the world's first and only oral drug approved to treat the rare disease transthyretin amyloid cardiomyopathy (ATTR-CM). Medicines are known to have different adverse reactions during the course of treatment. However, the current limited clinical studies did not identify significant adverse drug reactions to tafamidis. Tafamidis has been on the market for 5 years now, a large number of adverse drug event (ADE) reports with tafamidis as the primary suspected drug have been reported in the United Food and Drug Administration's adverse event reporting system (FAERS). We retrieved 8170 adverse event reports in FAERS with tafamidis as the first suspected drug, and mined these reports for positive signals to perform risk warnings for potentially possible adverse events with tafamidis. We found that a large number of adverse events associated with the primary disease were reported due to insufficient awareness of ATTR among the reporters, leading to a large number of positive signals reported in the cardiac disorders system. We also found that tafamidis has the potential to cause an adverse event risks of ear and labyrinth disorders system and urinary tract infection bacterial, which deserve continued clinical attention.

Delayed Diagnosis of Cardiac Amyloidosis Masked by Chronic Coronary Artery Disease and Ischemic Cardiomyopathy: A Case Report of an Overlooked and Underdiagnosed Etiology

Cardiac amyloidosis (CA) is an infiltrative disease of the heart characterized by the deposition of insoluble protein aggregates in the myocardium. There are two subtypes of CA, and they are named after the misfolded protein. Transthyretin cardiac amyloidosis (ATTR-CA) is caused by the accumulation of the tetrameric transthyretin protein produced in the liver, and light-chain cardiac amyloidosis (AL-CA) occurs due to circulating abnormal light-chain deposition. Disease manifestation can be very non-specific, and there can be overlap with other cardiac processes. This often leads to a delay in diagnosis and a poor prognosis. Here, we present a case of delayed diagnosis of CA spanning over several years that required a multidisciplinary approach but ultimately resulted in fatality six years after the initial diagnosis.

Anticoagulation in Atrial Fibrillation Associated With Cardiac Amyloidosis: A Narrative Review

Cardiac amyloidosis (CA) involves the abnormal deposition and accumulation of amyloid proteins in the heart muscle. A hallmark of disease progression is declining heart function, which can lead to structural irregularities, arrhythmias, and ultimately heart failure. Atrial fibrillation (AF) is the most common arrhythmia that presents in CA patients, and this arrhythmia is significant because it can moderately increase the risk of patients developing intracardiac thrombi, thereby putting them at risk for thromboembolic events. The management of this complication entails the use of anticoagulants like vitamin K antagonists and direct oral anticoagulants to reduce the risk of thrombus formation. This article seeks to review AF in CA and the use of anticoagulation therapy for the management and reduction of thromboembolic risk. The major conclusions of this review are centered around the need for safe administration of anticoagulant therapy to CA patients, regardless of their CHA2DS2-VASc risk score. This review highlights the importance of taking a multidisciplinary or collaborative approach to CA treatment to ensure that all aspects of this multifaceted disease can be properly managed while minimizing adverse events like bleeding risk and drug-drug interactions.

Gait abnormalities in older adults with transthyretin cardiac amyloidosis

BACKGROUND

Transthyretin cardiac amyloidosis (ATTR cardiac amyloidosis) is caused by variant (ATTRv) or wild type (ATTRwt) transthyretin. While gait abnormalities have been studied in younger patients with ATTRv amyloidosis, research on gait in older adults with ATTR cardiac amyloidosis is lacking. Given ATTR cardiac amyloidosis' association with neuropathy and orthopedic manifestations, we explore the gait in this population.

METHODS

Twenty-eight older male ATTR cardiac amyloidosis patients and 11 healthy older male controls walked overground with and without a dual cognitive task. Gait parameters: stride width, length, velocity and stance time percentage were measured using an instrumented mat. ATTR amyloidosis patients were further categorized based on clinical and functional assessments.

RESULTS

We found significant gait differences between ATTR cardiac amyloidosis patients and healthy controls; patients had more variable, slower, narrower and shorter strides, with their feet spending more time in contact with the ground as opposed to in swing. However, the observed gait differences did not correlate with clinical and functional measures of ATTR cardiac amyloidosis severity.

CONCLUSIONS

Our results suggest that gait analysis could be a complementary tool for characterizing ATTR cardiac amyloidosis patients and may inform clinical care as it relates to falls, management of anticoagulation, and functional independence.

Artificial Intelligence Assists in the Early Identification of Cardiac Amyloidosis

A 69-year-old female presented with symptomatic atrial fibrillation. Cardiac amyloidosis was suspected due to an artificial intelligence clinical tool applied to the presenting electrocardiogram predicting a high probability for amyloidosis, and the subsequent unexpected finding of left atrial appendage thrombus reinforced this clinical suspicion. This facilitated an early diagnosis by the biopsy of AL cardiac amyloidosis and the prompt initiation of targeted therapy. This case highlights the utilization of an AI clinical tool and its impact on clinical care, particularly for the early detection of a rare and difficult to diagnose condition where early therapy is critical.

Diagnostic Pitfall and Clinical Characteristics of Variant Versus Wild-Type Transthyretin Amyloid Cardiomyopathy in Asian Population: The Korean Nationwide Cohort Study

BACKGROUND

Transthyretin amyloidosis cardiomyopathy (ATTR-CM) is an under-recognized cause of heart failure (HF) with clinical phenotypes that vary across regions and genotypes. We sought to characterize the clinical characteristics of ATTR-CM in Asia.

METHODS

Data from a nationwide cohort of patients with ATTR-CM from six major tertiary centres in South Korea were analysed between 2010 and 2021. All patients underwent clinical evaluation, biochemical laboratory tests, echocardiography, and transthyretin (TTR) genotyping at the time of diagnosis. The study population comprised 105 Asian ATTR-CM patients (mean age: 69 years; male: 65.7%, wild-type ATTR-CM: 41.9%).

RESULTS

Among our cohort, 18% of the patients had a mean left ventricular (LV) wall thickness < 12 mm. The diagnosis of ATTR-CM increased notably during the study period (8 [7.6%] during 2010-2013 vs. 22 [21.0%] during 2014-2017 vs. 75 [71.4%] during 2018-2021). Although the duration between symptom onset and diagnosis did not differ, the proportion of patients with HF presenting mild symptoms increased during the study period (25% NYHA class I/II between 2010-2013 to 77% between 2018-2021). In contrast to other international registry data, male predominance was less prominent in wild-type ATTR-CM (68.2%). The distribution of TTR variants was also different from Western countries and from Japan. Asp38Ala was the most common mutation.

CONCLUSION

A nationwide cohort of ATTR-CM exhibited less male predominance, a proportion of patients without increased LV wall thickness, and distinct characteristics of genetic mutations, compared to cohorts in other parts of the world. Our results highlight the ethnic variation in ATTR-CM and may contribute to improving the screening process for ATTR-CM in the Asian population.

Cardiac amyloidosis at a glance

Amyloidosis can affect any organ in the body by deposition of amyloid fibrils. When these aggregate in the heart, it leads to cardiac amyloidosis a life-threatening and progressive disease. Although considered a rare condition, advances in imaging techniques and raised awareness have shown that it might be more frequent than has been historically estimated. Cardiac amyloidosis can be hereditary or occur as a consequence of the ageing process but, regardless of type, patients experience a heavy symptomatic burden. This article provides an overview of its pathophysiology, signs and symptoms and how any nurse can look for the main red flags in clinical practice. Early referral for specialist care can have a significant impact on disease progression and patient quality of life.