How Artificial Intelligence Can Enhance the Diagnosis of Cardiac Amyloidosis: A Review of Recent Advances and Challenges

Cardiac amyloidosis (CA) is an underdiagnosed form of infiltrative cardiomyopathy caused by abnormal amyloid fibrils deposited extracellularly in the myocardium and cardiac structures. There can be high variability in its clinical manifestations, and diagnosing CA requires expertise and often thorough evaluation; as such, the diagnosis of CA can be challenging and is often delayed. The application of artificial intelligence (AI) to different diagnostic modalities is rapidly expanding and transforming cardiovascular medicine. Advanced AI methods such as deep-learning convolutional neural networks (CNNs) may enhance the diagnostic process for CA by identifying patients at higher risk and potentially expediting the diagnosis of CA. In this review, we summarize the current state of AI applications to different diagnostic modalities used for the evaluation of CA, including their diagnostic and prognostic potential, and current challenges and limitations.

A Novel Approach to Cardiac Magnetic Resonance Scar Characterization in Patients Affected by Cardiac Amyloidosis: A Pilot Study

Background and Objectives: Cardiac magnetic resonance (CMR) imaging has become an essential instrument in the study of cardiomyopathies; it has recently been integrated into the diagnostic workflow for cardiac amyloidosis (CA) with remarkable results. An additional emerging role is the stratification of the arrhythmogenic risk by scar analysis and the possibility of merging these data with electro-anatomical maps. This is made possible by using a software (ADAS 3D, Galgo Medical, Barcelona, Spain) able to provide 3D heart models by detecting fibrosis along the whole thickness of the myocardial walls. Little is known regarding the applications of this software in the wide spectrum of cardiomyopathies and the potential benefits have yet to be discovered. In this study, we tried to apply the ADAS 3D in the context of CA. Materials and Methods: This study was a retrospectively analysis of consecutive CMR imaging of patients affected by CA that were treated in our center (Marche University Hospital). Wherever possible, the data were processed with the ADAS 3D software and analyzed for a correlation between the morphometric parameters and follow-up events. The outcome was a composite of all-cause mortality, unplanned cardiovascular hospitalizations, sustained ventricular arrhythmias (VAs), permanent reduction in left ventricular ejection fraction, and pacemaker implantation. The secondary outcomes were the need for a pacemaker implantation and sustained VAs. Results: A total of 14 patients were deemed eligible for the software analysis: 8 patients with wild type transthyretin CA, 5 with light chain CA, and 1 with transthyretin hereditary CA. The vast majority of imaging features was not related to the composite outcome, but atrial wall thickening displayed a significant association with both the primary (p = 0.003) and the secondary outcome of pacemaker implantation (p = 0.003). The software was able to differentiate between core zones and border zones of scars, with the latter being the most extensively represented in all patients. Interestingly, in a huge percentage of CMR images, the software identified the highest degree of core zone fibrosis among the epicardial layers and, in those patients, we found a higher incidence of the primary outcome, without reaching statistical significance (p = 0.18). Channels were found in the scar zones in a substantial percentage of patients without a clear correlation with follow-up events. Conclusions: CMR imaging plays a pivotal role in cardiovascular diagnostics. Our analysis shows the feasibility and applicability of such instrument for all types of CA. We could not only differentiate between different layers of scars, but we were also able to identify the presence of fibrosis channels among the different scar zones. None of the data derived from the ADAS 3D software seemed to be related to cardiac events in the follow-up, but this might be imputable to the restricted number of patients enrolled in the study.

Novel echocardiographic pixel intensity quantification method for differentiating transthyretin cardiac amyloidosis from light chain cardiac amyloidosis and other phenocopies

AIMS

Differentiating cardiac amyloidosis (CA) subtypes is important considering the significantly different therapies for transthyretin (ATTR)-CA and light chain (AL)-CA. Therefore, an echocardiographic method to distinguish ATTR-CA from AL-CA would provide significant value. We assessed a novel echocardiographic pixel intensity method to quantify myocardial calcification to differentiate ATTR-CA from phenocopies of CA and from AL-CA, specifically.

METHODS AND RESULTS

167 patients with ATTR-CA (n=53), AL-CA (n=32), hypertrophic cardiomyopathy (n=37), and advanced chronic kidney disease (n=45) were retrospectively evaluated. The septal reflectivity ratio (SRR) was measured as the average pixel intensity of the visible anterior septal wall divided by the average pixel intensity of the visible posterior lateral wall. SRR and other myocardial strain-based echocardiographic measures were evaluated with receiver operator characteristic analysis to evaluate accuracy in distinguishing ATTR-CA from AL-CA and other forms of left ventricular hypertrophy. Mean septal reflectivity ratio (SRR) was significantly higher in the ATTR-CA cohort compared to the other cohorts (p <0.001). SRR demonstrated the largest AUC (0.91, p<0.0001) for distinguishing ATTR from all other cohorts and specifically for distinguishing ATTR-CA from AL-CA (AUC=0.90, p<0.0001, specificity 96%, sensitivity 63%). There was excellent inter- and intra-operator reproducibility with an ICC of 0.91 (p <0.001) and 0.89 (p <0.001), respectively.

CONCLUSION

The SRR is a reproducible and robust parameter for differentiating ATTR-CA from other phenocopies of CA and specifically ATTR-CA from AL-CA.

Coexistence of Light Chain and Transthyretin Cardiac Amyloidosis

Although most patients with cardiac amyloidosis are diagnosed with either light chain (AL) or transthyretin (ATTR) disease, coexisting amyloid subtypes can occur. We present three cases of coexisting AL and ATTR cardiac amyloidosis and demonstrate the importance of clinical history and endomyocardial biopsy in diagnosis of this rare entity.

Diagnostic Sensitivity of Abdominal Fat Aspiration Biopsy for Cardiac Amyloidosis: A Systematic Review and Meta-Analysis

Introduction. Cardiac amyloidosis is a lethal disease, the incidence of which is increasing every year. Early diagnosis and treatment are the keys to reducing the mortality of this disease. Methods. Relevant English literature published in Embase, PubMed, Cochrane Library, and Web of Science were searched until December 1, 2022. Meta-analysis was performed with Stata 17.0 software. Results. A total of 1060 patients with 5 articles were included in this study. The sensitivity of abdominal fat aspiration biopsy for the diagnosis of cardiac amyloidosis was 0.66 (0.48-0.84) and the sensitivity for light chain amyloidosis cardiomyopathy and transthyretin amyloidosis cardiomyopathy was 0.90 (0.80-0.97) and 0.39 (0.18-0.60), respectively. Conclusion. Abdominal fat aspiration biopsy has high sensitivity and clinical value in the diagnosis of light chain amyloidosis cardiomyopathy, whereas there are limitations in the diagnosis of transthyretin amyloidosis cardiomyopathy.

Chronic underlying gastrointestinal amyloidosis was revealed by cardiac echography: a case report from Syria

Introduction and importance

Amyloidosis is an infiltrative disease caused by the deposition of abnormal proteins. While cardiac amyloidosis is relatively common, gastrointestinal (GI) tract involvement is less frequent. In this case, the authors report a delayed diagnosis of systemic amyloidosis presenting mainly with digestive symptoms.

Case presentation

An 81-year-old male presented with the complaint of persistent diarrhoea for over a year and the progressive development of edemas during the last 4 months. Echocardiogram findings revealed the presence of the characteristic sparkling sign. The diagnosis of amyloidosis was confirmed by histopathological biopsies taken from the duodenum. Serum electrophoresis findings strongly suggested the possibility of plasma cell dyscrasia.

Clinical discussion

What distinguishes this case is that the suspicion of amyloidosis as the underlying cause of the diarrhoea did not arise until an incidental echocardiogram revealed cardiac hypertrophy and a sparkling appearance.

Conclusion

This case reminds us to consider amyloidosis as a possible underlying cause for unexplained gastrointestinal symptoms such as diarrhoea, especially in bad economic situations where the diagnosis of rare diseases may be delayed.

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.

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.

Correlation of 99mTc-DPD bone scintigraphy with histological amyloid load in patients with ATTR cardiac amyloidosis

BACKGROUND

The significance of measuring 99mTc-labelled-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) in transthyretin (ATTR) cardiac amyloidosis has not been adequately studied. This single-centre observational study evaluated the correlation between 99mTc-DPD scintigraphy and histological amyloid load in endomyocardial biopsy (EMB).

METHODS

Twenty-eight patients with biopsy-proven ATTR amyloidosis and concomitantly available 99mTc-DPD scintigraphy were included. Visual Perugini scoring, and (semi-)quantitative analysis of cardiac 99mTc-DPD uptake by planar whole-body imaging and single photon emission computed tomography (SPECT/CT) using regions of interest (ROI) were performed. From this, heart-to-whole-body ratio (H/WB) and heart-to-contralateral-chest ratio (H/CL) were calculated. The histological amyloid load was quantified using two different staining methods.

RESULTS

Increased cardiac tracer uptake was documented in all patients (planar: ROImean 129 ± 37 cps; SPECT/CT: ROImean 369 ± 142 cps). Histological amyloid load (19 ± 13%) significantly correlated with Perugini score (r = 0.69, p < .001) as well as with cardiac 99mTc-DPD uptake (planar: r = 0.64, p < .001; H/WB: r = 0.50, p = .014; SPECT/CT: r = 0.53, p = .008; H/CL: r = 0.43, p = .037) (results are shown for correlations with Congo Red-staining).

CONCLUSION

In ATTR, cardiac 99mTc-DPD uptake significantly correlated with histological amyloid load in EMB. Further studies are needed to implement thresholds in cardiac 99mTc-DPD uptake measurements for risk stratification and guidance of therapy.

Cardio-Hepatic Interaction in Cardiac Amyloidosis

Background: Congestion is associated with poor prognosis in cardiac amyloidosis (CA). The cardio-hepatic interaction and the prognostic impact of secondary liver affection by cardiac congestion in CA are poorly understood and require further characterisation. Methods: Participants of the amyloidosis cohort study AmyKoS at the Interdisciplinary Amyloidosis Centre of Northern Bavaria with proven transthyretin (ATTR-CA) and light chain CA (AL-CA) underwent serial work-up including laboratory tests, echocardiography, and in-depth hepatic assessment by vibration-controlled transient elastography (VCTE) and 13C-methacetin breath test. Results: In total, 74 patients with AL-CA (n = 17), ATTR-CA (n = 26) and the controls (n = 31) were analysed. ATTR-CA patients showed decreased microsomal liver function expressed by maximal percentage of dose rate (PDRpeak) related to hepatic congestion. Reduced PDRpeak in AL-CA could result from altered pharmacokinetics due to changed hepatic blood flow. Liver stiffness as a combined surrogate of chronic liver damage and congestion was identified as a predictor of all-cause mortality. Statistical modelling of the cardio-hepatic interaction revealed septum thickness, NT-proBNP and PDRpeak as predictors of liver stiffness in both CA subtypes; dilatation of liver veins and the fibrosis score FIB-4 were only significant for ATTR-CA. Conclusions: Non-invasive methods allow us to characterise CA-associated hepatic pathophysiology. Liver stiffness might be promising for risk stratification in CA.

Acute Exacerbation of Idiopathic Pulmonary Fibrosis With Concurrent Cardiac Amyloidosis: A Technetium Pyrophosphate Study

Amyloidosis presents a diagnostic challenge, particularly when concomitant with severe conditions like acute exacerbations of idiopathic pulmonary fibrosis (IPF). In this report, we detail the case of a 73-year-old patient with acute exacerbation of IPF and simultaneous emergence of cardiac amyloidosis. The patient's clinical journey began with persistent exertional dyspnea, progressing to hypoxemia on admission. Chest CT scans showed extensive ground-glass opacities, consolidations, and pre-existing honeycombing-like cysts and reticular shadows, accompanied by a right-sided pleural effusion. The therapeutic strategy for acute exacerbation of IPF encompassed methylprednisolone pulse therapy, tacrolimus, and nintedanib, augmented with intravenous immunoglobulin and recombinant thrombomodulin. Concurrently, heart failure with preserved ejection fraction was managed with a pharmacological trio: empagliflozin, diuretics, and eplerenone. A hypertrophied heart and low limb voltage prompted an investigation for cardiac amyloidosis, which 99mTechnetium pyrophosphate (99mTc-PYP) scintigraphy confirmed, yielding a probable diagnosis. Following steroid tapering, the patient was discharged home. This case prompted an investigation into the potential role of amyloidosis in pulmonary pathology. Our retrospective review of 10 patients, including four with cardiac amyloidosis, who underwent 99mTc-PYP scintigraphy, revealed a nonsignificant yet notable trend of increased pulmonary accumulation in cardiac amyloidosis cases (median (interquartile range): 5.4×104 (5.3-13.1×104) vs. 3.6×104 (2.4-5.1×104), p=0.0667). Notably, the pulmonary counts in this patient exceeded the negative cohort's mean values, hinting at a possible contribution of amyloid deposition to pulmonary pathology. This study, pioneering in evaluating lung field accumulation of 99mTc-PYP in cardiac amyloidosis, may provide novel insights into the influence of amyloidosis on pulmonary conditions.

Arrhythmias and Device Therapies in Cardiac Amyloidosis

Cardiac amyloidosis is caused by amyloid fibrils that deposit in the myocardial interstitium, causing restrictive cardiomyopathy and eventually death. The electromechanical, inflammatory, and autonomic changes due to amyloid deposition result in arrhythmias. Atrial fibrillation is by far the most common arrhythmia. The rate control strategy is generally poorly tolerated due to restrictive filling physiology and heart rate dependance, favoring adoption of the rhythm control strategy. Anticoagulation for stroke prophylaxis is warranted, irrespective of CHA2DS2-VASc score in patients with a favorable bleeding profile; data on left appendage closure devices are still insufficient. Ventricular arrhythmias are also not uncommon, and the role of implantable cardioverter-defibrillator in cardiac amyloidosis is controversial. There is no evidence of improvement in outcomes when used for primary prevention in these patients. Bradyarrhythmia is most commonly associated with sudden cardiac death in cardiac amyloidosis. Pacemaker implantation can help provide symptomatic relief but does not confer mortality benefit.

A wolf in sheep's clothing-aortic stenosis and cardiac amyloidosis: "RAISE"ing awareness in clinical practice

Aesop's fable of the wolf in sheep's clothing encourages us to look beneath the exterior appearance of a situation and evaluate the truth that lies beneath. This concept should be applied when managing older patients with severe aortic stenosis. This population of patients is increasingly being identified as having concomitant cardiac amyloidosis, which is an underrecognized cause of common cardiac conditions. The presence of cardiac amyloidosis negatively affects the outcome of patients with aortic stenosis, these patients undergo transcatheter aortic valve replacement (TAVR) with increasing frequency and have a significantly higher overall mortality rate than patients with aortic stenosis alone. Although left ventricular wall hypertrophy is expected in patients with aortic stenosis, it should not be assumed that this is caused only by aortic stenosis. A suspicion of cardiac amyloidosis should be raised in patients in whom the degree of hypertrophy is disproportionate to the degree of aortic stenosis severity. The remodeling, age, injury, systemic, and electrical (RAISE) score was developed to predict the presence of cardiac amyloidosis in patients with severe aortic stenosis. This article highlights the value of increased clinical suspicion, demonstrates the use of the multiparameter RAISE score in daily clinical practice, and illustrates the scoring system with case studies. In elderly patients being considered for TAVR, systematic testing for cardiac amyloidosis should be considered as part of the preoperative workup.

Delayed diagnosis of cardiac amyloidosis in a West African octogenarian

Left ventricular hypertrophy (LVH) is a common finding on cardiac imaging. Although there are multiple aetiologies for LVH, hypertension is frequently a presumed cause due to its high prevalence in the African region. Establishing a specific cause of LVH however requires thorough clinical evaluation with multimodality cardiac imaging playing a key role in the diagnostic pathway. We report on a case of a West African octogenarian who was treated presumptively for heart failure with preserved ejection fraction from hypertensive heart disease, based on his initial clinical presentation and echocardiographic findings three years earlier. By adopting a stepwise approach to his evaluation, including revisiting the history, and the application of multimodality cardiac imaging, the patient was diagnosed with cardiac amyloidosis.

Light-Chain (AL) Cardiac Amyloidosis Presenting as Heart Failure With Reduced Ejection Fraction

Systemic amyloidosis is caused by the extracellular deposition of misfolded proteins in various organs and usually leads to organ dysfunction. The two common subtypes include light-chain amyloidosis and transthyretin amyloidosis. Deposition of these proteins in the heart can lead to infiltrative and restrictive cardiomyopathy, commonly manifesting as heart failure with preserved ejection fraction. However, systolic heart failure with reduced ejection fraction is mainly seen in the advanced stages of the disease. Here, we present the case of a 53-year-old female who presented with new-onset heart failure with reduced ejection fraction with no prior symptoms or diagnosis of amyloidosis and diastolic dysfunction.

Rare c.302C>T TTR Variant Associated with Transthyretin Amyloidosis

Background and Objectives: Hereditary transthyretin amyloidosis (ATTRv) is a rare disease caused by pathogenic variants in the transthyretin (TTR) gene. More than 140 different disease-causing variants in TTR have been reported. Only a few individuals with a rare TTR variant, c.302C>T, p.(Ala101Val) (historically known as p.(Ala81Val)), primarily associated with cardiac ATTRv, have been described. Therefore, our aim was to analyze the clinical characteristics of individuals with the identified c.302C>T TTR variant at our center. Materials and Methods: We analyzed data from individuals with ATTRv who were diagnosed and treated at Vilnius University Hospital Santaros Klinikos. ATTRv was confirmed by negative hematological analysis for monoclonal protein, positive tissue biopsy or bone scintigraphy and a pathogenic TTR variant. Results: During 2018-2021, the TTR NM_000371.3:c.302C>T, NP_000362.1:p.(Ala101Val) variant was found in one individual in a homozygous state and in three individuals in a heterozygous state. The age of onset of symptoms ranged from 44 to 74 years. The earliest onset of symptoms was in the individual with the homozygous variant. A history of carpal tunnel syndrome was identified in two individuals. On ECG, three individuals had low QRS voltage in limb leads. All individuals had elevated NT-proBNP and hsTroponine I levels on baseline laboratory tests and concentric left ventricular hypertrophy on transthoracic echocardiography. The individual with the homozygous c.302C>T TTR variant had the most pronounced polyneuropathy with tetraparesis. Other patients with the heterozygous variant had more significant amyloid cardiomyopathy. When screening family members, the c.302C>T TTR variant was identified in two phenotypically negative relatives at the ages of 33 and 47 years. Conclusions: c.302C>T is a rare TTR variant associated with ATTRv cardiomyopathy. The homozygous state of this variant was not reported before, and is associated with earlier disease onset and neurological involvement compared to the heterozygote state.

Best Practices in Nuclear Imaging for the Diagnosis of Transthyretin Amyloid Cardiomyopathy (ATTR-CM) in KSA: The Eagle Eyes of Local Experts

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a complex and serious form of heart failure caused by the accumulation of transthyretin amyloid protein in the heart muscle. Variable symptoms of ATTR-CM can lead to a delayed diagnosis. Recognizing the diagnostic indicators is crucial to promptly detect this condition. A targeted literature review was conducted to examine the latest international consensus recommendations on a comprehensive diagnosis of ATTR-CM. Additionally, a panel consisting of nuclear medicine expert consultants (n = 10) and nuclear imaging technicians (n = 2) convened virtually from the Kingdom of Saudi Arabia (KSA) to formulate best practices for ATTR-CM diagnosis. The panel reached a consensus on a standard diagnostic pathway for ATTR-CM, which commences by evaluating the presence of clinical red flags and initiating a cardiac workup to assess the patient's echocardiogram. Cardiac magnetic resonance imaging may be needed, in uncertain cases. When there is a high suspicion of ATTR-CM, patients undergo nuclear scintigraphy and hematologic tests to rule out primary or light-chain amyloidosis. The expert panel emphasized that implementing best practices will support healthcare professionals in KSA to improve their ability to detect and diagnose ATTR-CM more accurately and promptly. Diagnosing ATTR-CM accurately and early can reduce morbidity and mortality rates through appropriate treatment.

Atrial Fibrillation in Patients with Hypertrophic Cardiomyopathy and Cardiac Amyloidosis: From Clinical Management to Catheter Ablation Indication

Atrial fibrillation (AF) is the most common arrhythmia in patients affected by cardiomyopathies. Reports estimate a prevalence of 27% in patients with hypertrophic cardiomyopathy (HCM) and 40% in patients with cardiac amyloidosis (CA). The presence of AF typically results in progressive functional decline, an increased frequency of hospitalizations for heart failure, and a higher thromboembolic risk. Medical management using mainly beta-blockers or amiodarone has produced variable outcomes and a high rate of recurrence. Catheter ablation reduces symptom burden and complications despite a moderate rate of recurrence. Recent evidence suggests that an early rhythm control strategy may lead to more favorable short- and long-term outcomes. In this review, we summarize contemporary data on the management of AF in patients with cardiomyopathy (HCM and CA) with particular reference to the timing and outcomes of ablation procedures.

Assessment of Tp-Te interval in patients with cardiac AL amyloidosis

BACKGROUND

Prolonged Tp-Te interval is strongly associated with fatal ventricular arrhythmias and mortality. This association has been demonstrated in various diseases. However, the current literature does not give any information on Tp-Te interval in cardiac amyloid light-chain (AL) amyloidosis.

METHODS

We retrospectively screened 116 cardiac AL amyloidosis patients and 35 patients were included in the study. Demographic, laboratory, 12-lead electrocardiographic (QTc, Tp-Te V1-V6) and transthoracic echocardiographic data of the patients were analysed and compared with 35 healthy controls.

RESULTS

QTc and Tp-Te V2-V5 were significantly prolonged in the cardiac AL amyloidosis group (p < 0.05). Also, there was a positive and statistically significant correlation between the parameters of QTc and Tp-Te V3-V6, and also between the parameters of interventricular septum thickness at enddiastole and Tp-Te V2-V5.

CONCLUSION

We present the first strong evidence of prolonged Tp-Te intervals in patients with cardiac AL amyloidosis. There may also be a relationship between prolonged Tp-Te interval and the development of arrhythmia in this patient group, as in some other groups. There is a need for prospective studies examining the relationship of prolonged Tp-Te interval with arrhythmias and its prognostic significance in cardiac AL amyloidosis.

Early diagnosis and management of cardiac amyloidosis: A clinical perspective

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

Case Report: Left bundle branch pacing in an amyloid light-chain cardiac amyloidosis patient with atrioventricular block

Introduction

Amyloid light-chain cardiac amyloidosis is a progressive infiltrative disease characterized by the deposition of amyloid fibrils in the cardiac tissue, which can cause serious atrioventricular block requiring pacemaker implantation. Left bundle branch pacing has emerged as an alternative method for delivering physiological pacing to achieve electrical synchrony of the left ventricle. However, left bundle branch pacing in patients with amyloid light-chain cardiac amyloidosis has not been studied in detail. Therefore, in this study, we present a case of left bundle branch pacing in a patient with amyloid light-chain cardiac amyloidosis.

Case summary

A 66-year-old male patient with amyloid light-chain cardiac amyloidosis presented with syncope for 1 month. Holter monitoring revealed intermittent third-degree atrioventricular block. Left bundle branch pacing was performed successfully. During the 1-year follow-up, it was observed that the left bundle branch capture threshold remained stable without any pacemaker-related complications or left ventricle systolic dysfunction, and there was no recurrence of syncope.

Conclusion

Left bundle branch pacing appears to be a safe and feasible option for patients with amyloid light-chain cardiac amyloidosis experiencing atrioventricular block.

Amyloid Burden Correlates with Electrocardiographic Findings in Patients with Cardiac Amyloidosis-Insights from Histology and Cardiac Magnetic Resonance Imaging

Cardiac amyloidosis (CA) is associated with several distinct electrocardiographic (ECG) changes. However, the impact of amyloid depositions on ECG parameters is not well investigated. We therefore aimed to assess the correlation of amyloid burden with ECG and test the prognostic power of ECG findings on outcomes in patients with CA. Consecutive CA patients underwent ECG assessment and cardiac magnetic resonance imaging (CMR), including the quantification of extracellular volume (ECV) with T1 mapping. Moreover, seven patients underwent additional amyloid quantification using immunohistochemistry staining of endomyocardial biopsies. A total of 105 CA patients (wild-type transthyretin: 74.3%, variant transthyretin: 8.6%, light chain: 17.1%) were analyzed for this study. We detected correlations of total QRS voltage with histologically quantified amyloid burden (r = -0.780, p = 0.039) and ECV (r = -0.266, p = 0.006). In patients above the ECV median (43.9%), PR intervals were significantly longer (p = 0.016) and left anterior fascicular blocks were more prevalent (p = 0.025). In our survival analysis, neither Kaplan-Meier curves (p = 0.996) nor Cox regression analysis detected associations of QRS voltage with adverse patient outcomes (hazard ratio: 0.995, p = 0.265). The present study demonstrated that an increased amyloid burden is associated with lower voltages in CA patients. However, baseline ECG findings, including QRS voltage, were not associated with adverse outcomes.

Resolution of Cardiac Infiltration Following Autologous Stem Cell Transplantation for AL Amyloidosis

A 43-year-old man presented with severe heart failure secondary to high-risk light chain cardiac amyloidosis. He underwent chemotherapy and autologous stem cell transplantation with complete hematologic response. Serial cardiac magnetic resonance imaging post-transplant demonstrated gradual normalization of biventricular function and myocardial T1, a surrogate measure of disease burden.

A single center experience

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.

Emerging Role of Scintigraphy Using Bone-Seeking Tracers for Diagnosis of Cardiac Amyloidosis: AJR Expert Panel Narrative Review

Amyloidoses are a complex group of clinical diseases that result from progressive organ dysfunction due to extracellular protein misfolding and deposition. The two most common types of cardiac amyloidosis are transthyretin amyloidosis (ATTR) and light-chain (AL) amyloidosis. Diagnosis of ATTR cardiomyopathy (ATTR-CM) is challenging owing to its phenotypic similarity to other more common cardiac conditions, the perceived rarity of the disease, and unfamiliarity with its diagnostic algorithms; endomyocardial biopsy was historically required for diagnosis. However, myocardial scintigraphy using bone-seeking tracers has shown high accuracy for detection of ATTR-CM and has become a key noninvasive diagnostic test for the condition, receiving support from professional society guidelines and transforming prior diagnostic paradigms. This AJR Expert Panel Narrative Review describes the role of myocardial scintigraphy using bone-seeking tracers in the diagnosis of ATTR-CM. The article summarizes available tracers, acquisition techniques, interpretation and reporting considerations, diagnostic pitfalls, and gaps in the current literature. The critical need for monoclonal testing of patients with positive scintigraphy results to differentiate ATTR-CM from AL cardiac amyloidosis is highlighted. Recent updates in guideline recommendations that emphasize the importance of a qualitative visual assessment are also discussed.

Transthyretin Cardiac Amyloidosis Disguised as Light Chain Amyloidosis or Multiple Myeloma?

We describe 2 challenging cases of cardiac transthyretin amyloidosis initially treated as cardiac amyloidosis light chain in the setting of active myeloma. Endomyocardial biopsy with mass spectrometry was essential to confirm the appropriate diagnosis to direct the treatment.

Cardiac Amyloidosis: Clinical Features, Pathogenesis, Diagnosis, and Treatment

Cardiac amyloidosis is a type of amyloidosis that deserves special attention as organ involvement significantly worsens the prognosis. Cardiac amyloidosis can be grouped under three main headings: immunoglobulin light chain (AL) amyloidosis that is dependent on amyloidogenic monoclonal light chain production; hereditary Transthyretin (TTR) amyloidosis that results from accumulation of mutated TTR; and wild-type (non-hereditary) TTR amyloidosis formerly known as senile amyloidosis. Although all three types cause morbidity and mortality due to severe heart failure when untreated, they contain differences in their pathogenesis, clinical findings, and treatment. In this article, the clinical features, pathogenesis, diagnosis, and treatment methods of cardiac amyloidosis will be explained with an overview, and an awareness will be raised in the diagnosis of this disease.

Caregiver's psychological well-being and quality of relationship with cardiac amyloidosis patients

Caregivers' psychological well-being is linked to the quality of care provided for familiar with chronic illness. Despite caregivers of cardiac patients present an impaired psychological well-being, less investigated is the psychological well-being of caregivers of individuals with a rare disease such as the Transthyretin Cardiac Amyloidosis (ATTR-CA). Specifically, given that no study explored the well-being of the caregiver and the caregiver-patient relationship, this study aimed to analyze the prevalence of anxiety and depression in ATTR-CA caregivers and if these disorders were associated with patient's and caregiver's characteristics. Fifty-eight dyad caregiver-ATTR-CA patients completed the Hospital Anxiety and Depression Scale and the Network of Relationships Inventory. Moreover, ATTR-CA patients completed the Kansas City Cardiomyopathy Questionnaire, while caregivers completed the Multidimensional Scale of Social Support. Results showed that anxious caregivers (44%) reported higher conflict with patients. They had ATTR-CA relatives with a worse perception of cardiac symptoms and higher anxiety and depression. Depressed caregivers (39%) reported higher conflict with ATTR-CA relatives and lower perceived social support. Caregiver reported a high prevalence of anxiety and depression associated with worse personal relational well-being and to patient's psycho-physical condition. The care of ATTR-CA patient should consider the caregiver well-being.

Myocardial structural and functional changes in cardiac amyloidosis: insights from a prospective observational patient registry

AIMS

The pathophysiological hallmark of cardiac amyloidosis (CA) is the deposition of amyloid within the myocardium. Consequently, extracellular volume (ECV) of affected patients increases. However, studies on ECV progression over time are lacking. We aimed to investigate the progression of ECV and its prognostic impact in CA patients.

METHODS AND RESULTS

Serial cardiac magnetic resonance (CMR) examinations, including ECV quantification, were performed in consecutive CA patients. Between 2012 and 2021, 103 CA patients underwent baseline and follow-up CMR, including ECV quantification. Median ECVs at baseline of the total (n = 103), transthyretin [(ATTR) n = 80], and [light chain (AL) n = 23] CA cohorts were 48.0%, 49.0%, and 42.6%, respectively. During a median period of 12 months, ECV increased significantly in all cohorts [change (Δ) +3.5% interquartile range (IQR): -1.9 to +6.9, P < 0.001; Δ +3.5%, IQR: -2.0 to +6.7, P < 0.001; and Δ +3.5%, IQR: -1.6 to +9.1, P = 0.026]. Separate analyses for treatment-naïve (n = 21) and treated (n = 59) ATTR patients revealed that the median change of ECV from baseline to follow-up was significantly higher among untreated patients (+5.7% vs. +2.3%, P = 0.004). Survival analyses demonstrated that median change of ECV was a predictor of outcome [total: hazard ratio (HR): 1.095, 95% confidence interval (CI): 1.047-1.0145, P < 0.001; ATTR: HR: 1.073, 95% CI: 1.015-1.134, P = 0.013; and AL: HR: 1.131, 95% CI: 1.041-1.228, P = 0.003].

CONCLUSION

The present study supports the use of serial ECV quantification in CA patients, as change of ECV was a predictor of outcome and could provide information in the evaluation of amyloid-specific treatments.

Lights and Shadows of Clinical Applications of Cardiac Scintigraphy with Bone Tracers in Suspected Amyloidosis

Radionuclide bone scintigraphy is the cornerstone of an imaging-based algorithm for accurate non-invasive diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). In patients with heart failure and suggestive echocardiographic and/or cardiac magnetic resonance imaging findings, the positive predictive value of Perugini grade 2 or 3 myocardial uptake on a radionuclide bone scan approaches 100% for the diagnosis of ATTR-CA as long as there is no biochemical evidence of a clonal dyscrasia. The technetium-labelled tracers that are currently validated for non-invasive diagnosis of ATTR-CA include pyrophosphate (99mTc-PYP); hydroxymethylene diphosphonate (99mTc-HMDP); and 3,3-diphosphono-1,2-propanodicarboxylate (99mTc-DPD). Although nuclear scintigraphy has transformed the contemporary diagnostic approach to ATTR-CA, a number of grey areas remains, including the mechanism for binding tracers to the infiltrated heart, differences in the kinetics and distribution of these radiotracers, differences in protocols of image acquisition worldwide, the clinical significance of extra-cardiac uptake, and the use of this technique for prognostic stratification, monitoring disease progression and assessing the response to disease-modifying treatments. This review will deal with the most relevant unmet needs and clinical questions concerning scintigraphy with bone tracers in ATTR-CA, providing expert opinions on possible future developments in the clinical application of these radiotracers in order to offer practical information for the interpretation of nuclear images by physicians involved in the care of patients with this ATTR-CA.

Hereditary Transthyretin Amyloidosis: How to Differentiate Carriers and Patients Using Speckle-Tracking Echocardiography

BACKGROUND

Hereditary transthyretin amyloidosis is a rare disease caused by transthyretin (TTR) gene mutations. The aim of our study was to identify early signs of cardiac involvement in patients with a TTR gene mutation in order to differentiate carriers from patients with neurological or cardiac disease.

METHODS

A case-control study was carried out on 31 subjects with the TTR mutation. Patients were divided into three groups: 23% with cardiac amyloidosis and polyneuropathy (group A), 42% with only polyneuropathy (group B) and 35% carriers (group C). Speckle-tracking echocardiography (left-ventricular global longitudinal strain-GLS, atrial stiffness) was performed in all patients. The apical/basal longitudinal strain ratio (SAB) and relative apical sparing (RAS) were assessed in all subjects.

RESULTS

Analyzing groups C and B, we only found a significant difference in the SAB (p-value 0.001) and RAS (p-value 0.039). These parameters were significantly more impaired in group A compared to group B (SAB p-value 0.008; RAS p-value 0.002). Also, atrial stiffness was significantly impaired in groups A and B compared to group C.

CONCLUSIONS

Our study suggests the diagnostic role of the SAB and RAS in cardiac amyloidosis. The SAB and RAS showed a gradual increase from carriers to patients with neurological and cardiac diseases. Thus, these parameters, in addition to atrial stiffness, could be used to monitor carriers. More extensive data are needed.

Heart of the Matter: Decoding the Underdiagnosed Cardiac Amyloidosis

Cardiac amyloidosis, a rare disorder marked by toxic amyloid protein deposition in the myocardium, contributes significantly to restrictive cardiomyopathy. We present an 85-year-old female diagnosed with amyloid transthyretin (ATTR) cardiac amyloidosis, emphasizing the under-recognition of this condition. The pathophysiology of cardiac amyloidosis involves misfolded protein accumulation, which impairs myocardial function. Differentiating AL and ATTR is crucial, with ATTR predominance. Diagnosis relies on echocardiography, cardiac magnetic resonance, nuclear imaging, and biomarker testing. A positive pyrophosphate (PYP) scan, compatible echocardiographic features, and the absence of systemic myeloma signs diagnose ATTR amyloidosis. Management includes heart failure treatment, arrhythmia control, and disease-modifying strategies like Tafamidis, Inotersen, and Patisiran. Genotyping guides prognostic and therapeutic considerations. Recognizing cardiac amyloidosis as an underlying cause of heart failure with preserved ejection fraction necessitates collaboration between cardiology and hematology. Improved awareness, innovative diagnostics, and targeted therapies are crucial to reduce diagnostic delays and enhance outcomes.

Recent Progress in the Development and Clinical Application of New Drugs for Transthyretin Cardiac Amyloidosis

ABSTRACT

Transthyretincardiac amyloidosis is a rare disease that has gained significant attention in recent years because of misfolding of transthyretin fibrils produced by the liver, leading to their deposition in the myocardium. The disease has an insidious onset, nonspecific clinical manifestations, and historically lacked effective drugs, making early diagnosis and treatment challenging. The survival time of patients largely depends on the extent of heart involvement at the time of diagnosis, and conventional treatments for cardiovascular disease do not provide significant benefits. Effective management of the disease requires treatment of its underlying cause. Orthotopic liver transplantation and combined hepato-heart transplantation have been clinically effective means of treating transthyretin cardiac amyloidosis mutants for many years. However, transplantation has many limitations in clinical practice. In recent years, the development of new drugs has brought new hope to patients. This review presents the latest advances in drug development and clinical application to provide a reference for clinicians managing transthyretin cardiac amyloidosis.

Myocardial Work Appraisal in Transthyretin Cardiac Amyloidosis and Nonobstructive Hypertrophic Cardiomyopathy

Global left ventricular (LV) myocardial work (MW) indexes can be recognized at ultrasound imaging from the LV pressure/global longitudinal strain (GLS) loop analysis. A total of 4 indexes, global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE), have been demonstrated to overcome the methodological limitations of GLS and provide useful information on myocardial dysfunction in some clinical settings. Although impaired MW indexes have been demonstrated in patients with transthyretin cardiac amyloidosis (ATTR) or with nonobstructive hypertrophic cardiomyopathy (HCM), there are no comparative studies at present. This study aimed to describe the characteristics of MW in both these clinical settings compared with patients with well-controlled hypertension (HTN). A total of 83 patients, 32 with ATTR (aged 70 ± 11 years, 32% mutated, 68% wild-type, 72% men), 29 with HCM (aged 57 ± 17 years), and 22 HTN controls (aged 56 ± 5.6 years, 59% men) were prospectively enrolled at 2 clinical centers. All participants had New York Heart Association class I or II. Overall, the LV mass index was greater in both study groups than in HTN, whereas the LV ejection fraction (EF) was significantly lower in ATTR compared with other groups. Based on this finding, patients with ATTR were further divided into 2 subgroups: ATTR1 (LVEF ≤0.50), n = 14 (44%) and ATTR2 (LVEF >0.50), n = 18 (56%). Overall, the GWI and GCW were lower in all ATTR patients (mostly in ATTR1) than in the other groups (p <0.001), whereas only small differences in GWE and none in GWW were found among the groups. Of interest, the pairwise comparison and receiver operating characteristic analysis in preserved LVEF patients showed that GWI was a better discriminator of ATTR2 from HCM patients than GLS, with the cut-off value ≤1,419 mm Hg% (89% sensitivity; 55% specificity; p = 0.013). In conclusion, MW analysis was confirmed to be a modern way to investigate myocardial function in patients with hypertrophic phenocopies. GWI and GCW were more impaired in patients with ATTR compared with HCM and HTN controls. Furthermore, this study likely revealed an additional discriminative value of GWI over GLS alone in preserved LVEF settings.

First description of Portuguese patients with cardiac amyloidosis and p.Val142Ile: more evidence of an "African variant" in Caucasians

Objectives. Hereditary transthyretin amyloidosis caused by the (ATTRv) p. Val142Ile variant is a common cause of cardiac amyloidosis among Western African countries and Afro-Americans populations. However, in recent years, Caucasian patients have been identified in greater numbers, raising the question of whether this variant has been undeappreciated in this population. We now have new cases of cardiac amyloidosis caused by the p.Val142Ile from a center in northern Portugal. In addition, we reviewed and discussed the published data concerning p.Val142Ile in Caucasians. Design. Patients diagnosed with cardiac amyloidosis underwent genetic testing using TTR gene sequencing and their relatives were recommended for genetic counsellingand testing if a pathogenic TTR variant was found. In our center, we reviewed the clinical data of patients who had the p.Val142Ile variant. A review of published cases of p.Val142Ile in Caucasians was also performed, to which our data was compared. Results. We found three ATTRv patients with the p.Val142Ile variant (one homozygotic), all Caucasian males with a median age at diagnosis of 69 years old. All of them had heart failure and arrhythmias. During the follow-up period, two patients died. There were 47 unrelated unrelated Caucasian cases of ATTRv p.Val142Ile variant reported worldwide until May 2022. Conclusions. Our findings add to the mounting evidence that the global prevalence of p.Val142Ile is likely understated. This highlights the importance of the systematic screening of the TTR gene in amyloidosis and phenocopies, as well as larger epidemiologic studies to determine the true ATTRv p.Val142Ile prevalence in non-African communities.

Comparison of cardio-focal and chest reconstruction of technetium-99m pyrophosphate scintigraphy for diagnosis of transthyretin cardiac amyloidosis: a quality assurance study

BACKGROUND

SPECT improves diagnostic specificity of Technetium-99m pyrophosphate (PYP) scintigraphy. Diagnostic performance of PYP data, reconstructed as either chest or cardio-focal SPECT is not known.

METHODS

In this quality assurance study, blinded evaluation of PYP SPECT/CT data from 102 Caucasian patients (mean age 76 ± 11 years, 67% men) was performed by two readers. Reader 1 reviewed planar and PYP chest SPECT, while reader 2 reviewed planar and cardio-focal PYP SPECT. Demographic, clinical, and other testing data were obtained from the electronic medical records.

RESULTS

A total of 41 patients (40%) were considered positive based on myocardial uptake on chest PYP SPECT. Of these, 98% of the patients had a Perugini score ≥ 2 on planar imaging. There was good agreement between the two readers for visual score ≥ 2 (k = .88, P < .001) and excellent agreement for myocardial uptake on tomographic imaging (98%, P < .001). Only one study was categorized as false negative by cardio-focal SPECT reconstruction. Non-diffuse myocardial uptake was identified in 22% of those with a positive PYP SPECT.

CONCLUSION

When read by experienced readers, chest and cardio-focal reconstruction of PYP SPECT have comparable diagnostic performance. A substantial proportion of patients with a positive PYP SPECT have a non-diffuse distribution of PYP. Given the possibility of misclassification of non-diffuse myocardial uptake on cardio-focal reconstruction alone, chest reconstruction of PYP scintigraphy should be strongly considered.

Value of nuclide scintigraphy in the diagnosis and prognosis of cardiac amyloidosis

Amyloidosis is a local or systemic disease caused by the deposition of misfolded proteins outside the cell, with rapid progression, and dire prognosis. Common types of cardiac amyloidosis are monoclonal immunoglobulin light chain amyloidosis (AL-CA) and transthyretin cardiac amyloidosis (ATTR-CA). Nuclear medicine examinations can be accurate, rapid, and non-invasive to help diagnose diseases and can effectively predict the prognosis of patients with CA. Technetium (99Tcm)-labeled bisphosphonate imaging has been included in the consensus of experts and has become the first-line imaging method for the diagnosis of ATTR-CA. 123I-metaiodoenzylguanidine (MIBG) as a norepinephrine analogue can effectively assess cardiac sympathetic innervation in patients with CA. Aβ- amyloid imaging agents such as 11C-pittsburgh compound B and 18F-flubetaben are expected to be new techniques for diagnosing AL-CA and incorporating them into cardiac staging systems for AL-CA patients in the future. New imaging agents such as 18F-NaF has been widely used in the diagnosis, treatment response monitoring, and prognosis assessment of CA. Summarizing the research value of nuclide imaging in CA may provide new ideas for clinical realization of early detection of CA and accurate assessment of disease prognosis.

Clinical Utility of Computed Tomography-Derived Myocardial Extracellular Volume Fraction: A Systematic Review and Meta-Analysis

BACKGROUND

Computed tomography (CT)-derived extracellular volume fraction (ECV) is a noninvasive method to quantify myocardial fibrosis. Although studies suggest CT is a suitable measure of ECV, clinical use remains limited.

OBJECTIVES

A meta-analysis was performed to determine the clinical value of CT-derived ECV in cardiovascular diseases.

METHODS

Electronic database searches of PubMed, Web of Science Core Collection, Cochrane advanced search, and EMBASE were performed. The most pivotal analysis entailed the comparison of ECV ascertained through CT-ECV among the control, aortic stenosis, and cardiac amyloidosis cohorts. The diagnostic test accuracy for detecting cardiac amyloidosis was assessed using summary receiver-operating characteristics curve.

RESULTS

Pooled CT-derived ECV values were 28.5% (95% CI: 27.3%-29.7%) in the control, 31.9 (95% CI: 30.2%-33.8%) in the aortic stenosis, and 48.9% (95% CI: 44.5%-53.3%) in the cardiac amyloidosis group. ECV was significantly elevated in aortic stenosis (P = 0.002; vs controls) but further elevated in cardiac amyloidosis (P < 0.001; vs aortic stenosis). CT-derived ECV had a high diagnostic accuracy for cardiac amyloidosis, with sensitivity of 92.8% (95% CI: 86.7%-96.2%), specificity of 84.8% (95% CI: 68.6%-93.4%), and area under the summary receiver-operating characteristic curve of 0.94 (95% CI: 0.88-1.00).

CONCLUSIONS

This study is the first comprehensive systematic review and meta-analysis of CT-derived ECV evaluation in cardiac disease. The high diagnostic accuracy of CT-ECV suggests the usefulness of CT-ECV in the diagnosis of cardiac amyloidosis in preoperative CT planning for transcatheter aortic valve replacement.

Case report]

The article presents a clinical case describing a complex differential diagnosis of cardiac amyloidosis types and verification of the diagnosis of AL-amyloidosis.

Cardiac Amyloid Quantification Using 124I-Evuzamitide (124I-P5+14) Versus 18F-Florbetapir: A Pilot PET/CT Study

BACKGROUND

Cardiac amyloid quantification could advance early diagnosis of amyloid cardiomyopathy (CMP) and treatment monitoring. However, current imaging tools are based on indirect measurements. 124I-evuzamitide is a novel pan-amyloid radiotracer binding to amyloid deposits from multiple amyloidogenic proteins. Its ability to quantify cardiac amyloid has not yet been investigated.

OBJECTIVES

The objectives of this pilot study were to quantify myocardial 124I-evuzamitide uptake and to compare its diagnostic value to 18F-florbetapir in participants with amyloid CMP and control subjects.

METHODS

This study included 46 participants: 12 with light-chain (AL) CMP, 12 with wild-type transthyretin (ATTRwt) CMP, 2 with hereditary amyloidosis, and 20 control subjects. All amyloidosis participants underwent positron emission tomography/computed tomography with 124I-evuzamitide and 18F-florbetapir. Control subjects underwent 124I-evuzamitide (n = 10) or 18F-florbetapir (n = 8) positron emission tomography/computed tomography. Left ventricular percent injected dose (LV% ID) was measured as mean activity concentration × myocardial volume/injected activity. High LV %ID was defined using Youden's index.

RESULTS

In CMP participants, median age was 74 years and 92% were men. 124I-evuzamitide LV %ID differed across groups: median AL-CMP 1.48 (IQR: 1.12-1.89), ATTRwt-CMP 2.12 (IQR: 1.66-2.47), and control subjects 0.00 (IQR: 0.00-0.01; overall P < 0.001). High LV %ID perfectly discriminated CMP from control subjects. Discrimination performance was similar for 18F-florbetapir LV %ID. Notably, for ATTRwt-CMP, LV %ID was higher with 124I-evuzamitide than 18F-florbetapir (P = 0.002). 124I-evuzamitide LV %ID was correlated with interventricular septum thickness (Spearman's ρ = 0.78) and LV global longitudinal strain (ρ = 0.54) from echocardiography, and with LV mass index (ρ = 0.82) and extracellular volume (ρ = 0.51) from cardiac magnetic resonance.

CONCLUSIONS

124I-evuzamitide demonstrates uptake by cardiac amyloid and accurately discriminates amyloid CMP from control subjects. In AL-CMP, discrimination performance is similar to 18F-florbetapir. In ATTRwt-CMP, performance may be better with 124I-evuzamitide. Moderate-to-strong correlations of 124I-evuzamitide uptake with cardiac structural and functional metrics suggest valid amyloid quantification. Hence, 124I-evuzamitide is a promising novel radiotracer to detect and quantify cardiac amyloid.

Molecular Imaging of Systemic and Cardiac Amyloidosis: Recent Advances and Focus on the Future

Myocardial infiltration by amyloid fibrils causes a severe and progressive form of heart failure. Until recently, this was not treatable. Several novel therapies have recently become available, increasing the urgency to make an accurate diagnosis, evaluate risk, and determine treatment response. Molecular imaging with positron-emitting amyloid tracers has a key emerging role in the evaluation and management of cardiac amyloidosis. In this review, we discuss molecular imaging of cardiac amyloidosis using amyloid PET tracers, including recent advances with a focus on the future.

Cardiac Amyloid Detection by PET/CT Imaging of Iodine (124I) Evuzamitide (124I-p5+14): A Phase 1/2 Study

BACKGROUND

The noninvasive detection of cardiac amyloid, as well as deposits in other vital organs, is critical for early diagnosis and quantitative disease monitoring. Positron emission tomography is an intrinsically quantitative imaging modality suitable for high-resolution amyloid detection.

OBJECTIVES

This study sought to evaluate the safety and efficacy of a novel amyloid-reactive peptide, designated p5+14, labeled with iodine-124 (124I), in patients with diverse types of systemic amyloidosis.

METHODS

In a single-site, open label phase 1/2 study (NCT03678259), the safety, biodistribution, and sensitivity of a single intravenous infusion of 124I-evuzamitide was assessed in patients with systemic amyloidosis (n = 50), asymptomatic transthyretin sequence variant carriers (n = 2), and healthy volunteers (n = 5). Subjects were administered 1.4 ± 0.2 mg of 124I-evuzamitide (71.5 ± 12.4 MBq) and positron emission tomography/x-ray computed tomography images acquired at 5.2 hours (Q25-Q75: 4.9-5.4 hours) postinfusion. Images were assessed visually and semi-quantitatively for positive uptake of radiotracer in the heart and other major organs.

RESULTS

Uptake of 124I-evuzamitide in the heart and other abdominothoracic organs was consistent with the patient's clinical presentation and the type of amyloidosis. The patient- and cardiac-associated sensitivity for imaging and clinical observations was 93.6% (95% CI: 82.8%-97.8%) and 96.2% (95% CI: 81.8%-99.8%), respectively. Semi-quantitative uptake of the radiotracer correlated significantly with serum N-terminal pro-B-type natriuretic peptide measurements in patients with light chain-associated amyloidosis. Cardiac uptake was not observed in any healthy volunteers. The agent was well tolerated, with 1 drug-related adverse event and no deaths.

CONCLUSIONS

124I-evuzamitide is an amyloid-binding radiotracer capable of detecting cardiac amyloid in patients with high sensitivity.

Diffuse Cardiac Uptake Misdiagnosed as Cardiac Amyloidosis in Bone Scan

In this presented case, a 77-year-old woman with an implanted prosthesis and ongoing knee pain underwent a bone scan using 99mTc-hydroxydiphosphonate (HDP) in suspicion for bone infection. An incidental finding from this scan revealed diffuse cardiac uptake, necessitating further diagnostic procedures to exclude the possibility of cardiac amyloidosis. In the subsequent 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scan and SPECT images, no perceptible cardiac uptake was observed at all. Upon retrospective review of the patient's medical records, she received 1000 mg of ferric carboxymaltose for iron-deficient anemia the day before the 99mTc-HDP bone scan. Therefore, it was assumed that the diffuse and temporary cardiac activity was due to the transient iron overload. We present and share these bone scan images in order to avoid possible future misinterpretation of cardiac amyloidosis.

Safety and Efficacy of Traditional Heart Failure Therapies in Patients With Cardiac Amyloidosis and Heart Failure

Randomized controlled trials have demonstrated mortality benefits for several medication classes in patients with heart failure (HF), especially with reduced ejection fraction (EF). However, the benefit of these traditional HF therapies in patients with HF from cardiac amyloidosis is unclear. our study aimed to evaluate the safety and efficacy of traditional HF therapies in patients with cardiac amyloidosis and HF with reduced EF or HF with mid-range EF (HFmrEF). We conducted a single-center retrospective study. Patients were included if they were diagnosed with cardiac amyloidosis and HF with reduced EF or HF with mid-range EF between January 2012 and 2022. The primary outcomes of interest were medication use patterns (for β blockers [BB], angiotensin-converting enzyme inhibitors [ACEI], angiotensin receptor blockers [ARBs], angiotensin receptor neprilysin inhibitors [ARNI], and mineralocorticoid receptor antagonists [MRAs]); potential medication side effects (symptomatic bradycardia, fatigue, hypotension, lightheadedness, and syncope); hospitalization; and death. The associations of BB, ACEI/ARB/ARNI, and MRA use with clinical outcomes were evaluated using Kaplan-Meier and Cox proportional hazards regression. A total of 82 patients met study criteria. At time of cardiac amyloidosis diagnosis, 63.4% were on a BB, 51.2% were on an ACEI/ARB/ARNI, and 43.9% were on an MRA. At last follow-up, 51.2% were on a BB, 35.4% were on an ACEI/ARB/ARNI, and 43.9% were on an MRA. There were no statistically significant differences in rates of potential medication side effects in patients on the medication class compared with those who were not. There was no association with hospitalization or mortality for baseline or follow-up BB, ACEI/ARB/ARNI, or MRA use. In conclusion, BBs, ACEI/ARB/ARNIs, and MRAs may be safely used in this population. However, their use does not appear to improve mortality or hospitalization.