Cardiac Amyloidosis: Updates in Imaging

Prevalence of transthyretin amyloid cardiomyopathy in patients admitted for acute heart failure

INTRODUCTION

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed cause of AHF that benefits from a specific approach. The aim was to determine the prevalence of ATTR-CM among patients hospitalized for AHF.

METHODS

A prospective study was conducted on consecutive patients aged 60 or older admitted for acute AHF without cardiogenic shock.

RESULTS

The study included 103 patients, a total of 16 patients (15.5 %) were compatible with ATTR-CM. The ATTR-CM group showed a higher septal wall thickness (18.1 mm vs. 11.8 mm; P = 0.001), lower systolic excursion of the tricuspid annular plane (15 mm vs. 18.3 mm, P = 0.014), and S wave of the right ventricle (8 cm/s vs. 9.2 cm/s P=0.032).

CONCLUSION

ATTR-CM is an underdiagnosed condition, there are some variables associated with its diagnosis. The coexistence with other comorbidities causing AHF, highlights the importance of considering screening for this cardiomyopathy in adults hospitalized for AHF.

[Current role of imaging techniques in cardiac amyloidosis]

Cardiac amyloidosis (CA) is an underdiagnosed disease and, if left untreated, rapidly fatal. Emerging therapies for CA increase the urgency of developing non-invasive diagnostic methods for its early detection and for monitoring therapeutic response. Classic imaging features on echocardiography and cardiac magnetic resonance, although typical for cardiac amyloidosis, are not specific enough to distinguish light chain amyloidosis from transthyretin. Myocardial bone-avid radiotracer uptake is highly specific for transthyretin cardiac amyloidosis when plasma cell dyscrasia has been excluded; it is now replacing the need for biopsy in many patients. Detection of early cardiac amyloidosis, quantitation of its burden, and assessment of response to therapy are important next steps for imaging to advance the evaluation and management of cardiac amyloidosis.

Comparison of left ventricular global and segmental strain parameters by cardiovascular magnetic resonance tissue tracking in light-chain cardiac amyloidosis and hypertrophic cardiomyopathy

Background

Apical sparing of left ventricular (LV) strain can occur in light-chain cardiac amyloidosis (AL-CA). We employed indicators of the strain ratio of the apex to base (RAB) and the relative apical sparing of strain (RAS) on the basis of LV global and segmental strain to distinguish AL-CA from hypertrophic cardiomyopathy (HCM).

Methods

In all, 36 AL-CA patients, 37 HCM patients, and 36 healthy controls underwent 3.0 T cardiac magnetic resonance (CMR) examination. We compared LV strain parameters from CMR tissue tracking (CMR-TT), including global and segmental peak radial strain (PRS), peak circumferential strain (PCS), and peak longitudinal strain (PLS); the peak systolic strain rate in radial, circumferential, and longitudinal directions (PSSR_R, PSSR_C, PSSR_L); and the peak diastolic strain rate in radial, circumferential, and longitudinal directions (PDSR_R, PDSR_C, PDSR_L). We also assessed the values of RAB and RAS. Differences in all groups were compared using an independent t-test and a nonparametric rank sum test.

Results

In the comparison of global strain parameters, all the peak strain, systolic, and diastolic peak strain rates of the AL-CA group significantly decreased compared with those of the HCM and healthy control groups (all P<0.001). The values of PSSR in all directions were lower in the AL-CA than in the HCM patients (PSSR_R, P<0.001; PSSR_C, P=0.004; PSSR_L, P=0.010) . In the analysis of segmental strain parameters, all peak strains in the basal segment showed significant differences between the AL-CA and HCM groups (all P<0.001). Some strain rate parameters in the basal segment were also noted to be significantly different (PSSR_R, P<0.001; PSSR_L, P<0.001; PDSR_R, P=0.015; PDSR_C, P=0.020). Both the RAB and RAS of peak strain in all directions showed significant differences between the AL-CA and HCM groups (all P<0.001). The RAB of the radial and circumferential PSSR showed statistical differences between the 2 groups (P<0.001 and P=0.001). The RAS in the radial direction of both the PSSR and PDSR was statistically different (P=0.003 and P=0.012).

Conclusions

The CMR-TT technique can be used to quantitatively compare global and segmental strain differences between AL-CA and HCM. In addition, RAB and RAS are reliable parameters for assessing the apical sparing pattern and thus, for distinguishing AL-CA from HCM.

Role of Diphosphonates Bone Scintigraphy in Correlation with Biomarkers for a Personalized Approach to ATTR Cardiac Amyloidosis in North-Eastern Romania

Transthyretin cardiac amyloidosis (ATTR) is a rare cardiac protein deposition disease characterized by progressive thickening of both ventricles, the inter-atrial-ventricular septum and the atrioventricular valves. The gold standard method for diagnosing this rare pathology is endomyocardial biopsy. If this method cannot be used, the alternative is a mixture of clinical and paraclinical tests. Over the course of five years, we examined 58 patients suspected of cardiac amyloidosis based on electrocardiography and ultrasonography criteria, who had been sent for bone scintigraphy in order to determine the presence of ATTR cardiac amyloidosis. However, the final diagnosis was set by correlating the bone scan with genetic testing, free light chain dosage or soft tissue biopsy. Based on the final diagnosis we analyzed the patients' predominant biomarkers in order to determine a possible correlation between them. This analysis is designed to help the general practitioner set a possible cardiac amyloidosis diagnosis.

Non-LGE Cardiac Magnetic Resonance Imaging in Patients with Cardiac Amyloidosis

Cardiac involvement is the leading cause of death in patients with cardiac amyloidosis. Early recognition is crucial as it can significantly change the course of the disease. Until now, the imaging modality of choice for diagnosing cardiac amyloidosis has been cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement (LGE). LGE-CMR in patients with cardiac amyloidosis reveals characteristic LGE patterns that lead to a diagnosis while also correlating well with disease prognosis. However, LGE-CMR has numerous drawbacks that the newer CMR modality, T1 mapping, aims to improve. T1 mapping can be further subdivided into native T1 mapping, which does not require the use of contrast, and ECV measurement, which requires the use of contrast. Numerous T1 mapping techniques have been developed, each one with its own advantages and disadvantages when it comes to procedure difficulty and image quality. A literature review to identify relevant published articles was performed by two authors. This review aimed to present the value of T1 mapping in diagnosing cardiac amyloidosis, quantifying the amyloid burden, and evaluating the prognosis of patients with amyloidosis with cardiac involvement.

Prevalence and Risk Factors of Cardiac Amyloidosis in Heart Failure: A Systematic Review and Meta-Analysis

AIMS

Heart failure (HF) is one of the leading causes of mortality worldwide. Heart failure is also one of the most common presentations of cardiac amyloidosis (CA). Contemporary epidemiological data of CA in HF patients is lacking. Hence, this systematic review and meta-analysis was conducted to determine the prevalence of amyloidosis in HF patients, and to clarify the risk factors of concomitant CA and HF.

METHODS

A systematic review and meta-analysis was performed. Studies were retrieved from Medline, EMBASE, Scopus and Cochrane library. The search was not restricted in time, type or language of publication. The prevalence of CA in HF grouped according to diagnostic techniques and risk factors of CA with HF was analysed.

RESULTS

Eleven (11) studies were included, involving 3,303 patients. The pooled prevalence of CA in HF was 13.7%. The overall prevalence of CA in HF with preserved ejection fraction was 15.1%, and that of HF with reduced ejection fraction was 11.3%. The main factors associated with the diagnosis of CA in HF included older age, males, raised NT pro-BNP, increased interventricular septal thickness in diastole, apical sparing, and reduced left ventricular systolic function.

CONCLUSION

A high index of clinical suspicion is required to identify HF patients with CA. Supportive investigations may be helpful when clinically correlated. A considerable proportion of HF patients have CA and certain risk factors may be helpful in increasing suspicions of CA in HF.

Neurological manifestations of hereditary transthyretin amyloidosis: a focus on diagnostic delays

BACKGROUND

The recent availability of disease-modifying therapies for hereditary transthyretin amyloid (ATTRv) amyloidosis warrants urgency for earlier diagnosis and timely identification of active disease state among genetic carriers.

METHODS

We reviewed clinical neurological data of all patients with ATTRv amyloidosis with initial visits at our amyloidosis centre between January 2016 and December 2018. We abstracted the signs and symptoms of neurological manifestations, as well as rates and patterns of diagnostic testing.

RESULTS

Of 92 patients with 19 different transthyretin (TTR) mutations, 66 and 36% had symptoms attributed to large-fibre and small-fibre neuropathy, respectively, compared to 75 and 66% with corresponding examination findings. Thirty-six patients with V122I ATTR mutation had asymptomatic polyneuropathy identified on neurological examination, eight without concurrent cardiac disease. Seventy-three percent of patients had symptoms of carpal tunnel syndrome (CTS), while 26% had dysautonomia. The average delays between the onset of symptoms of large fibre neuropathy (LFN) or CTS to ATTRv amyloidosis diagnosis were 2.9 and 6.7 years, respectively.

DISCUSSION

Our study found higher rates of polyneuropathy by examination than patient-reported symptoms, especially among those with V122I TTR amyloidosis, signalling asymptomatic polyneuropathy. Our findings suggest the need for routine neurological examinations and other testing for genetic carriers to achieve earlier identification of active disease state.

Suspicion, screening, and diagnosis of wild-type transthyretin amyloid cardiomyopathy: a systematic literature review

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt CM) is a more common disease than previously thought. Awareness of ATTRwt CM and its diagnosis has been challenged by its unspecific and widely distributed clinical manifestations and traditionally invasive diagnostic tools. Recent advances in echocardiography and cardiac magnetic resonance (CMR), non-invasive diagnosis by bone scintigraphy, and the development of disease-modifying treatments have resulted in an increased interest, reflected in multiple publications especially during the last decade. To get an overview of the scientific knowledge and gaps related to patient entry, suspicion, diagnosis, and systematic screening of ATTRwt CM, we developed a framework to systematically map the available evidence of (i) when to suspect ATTRwt CM in a patient, (ii) how to diagnose the disease, and (iii) which at-risk populations to screen for ATTRwt CM. Articles published between 2010 and August 2021 containing part of or a full diagnostic pathway for ATTRwt CM were included. From these articles, data for patient entry, suspicion, diagnosis, and screening were extracted, as were key study design and results from the original studies referred to. A total of 50 articles met the inclusion criteria. Of these, five were position statements from academic societies, while one was a clinical guideline. Three articles discussed the importance of primary care providers in terms of patient entry, while the remaining articles had the cardiovascular setting as point of departure. The most frequently mentioned suspicion criteria were ventricular wall thickening (44/50), carpal tunnel syndrome (42/50), and late gadolinium enhancement on CMR (43/50). Diagnostic pathways varied slightly, but most included bone scintigraphy, exclusion of light-chain amyloidosis, and the possibility of doing a biopsy. Systematic screening was mentioned in 16 articles, 10 of which suggested specific at-risk populations for screening. The European Society of Cardiology recommends to screen patients with a wall thickness ≥12 mm and heart failure, aortic stenosis, or red flag symptoms, especially if they are >65 years. The underlying evidence was generally good for diagnosis, while significant gaps were identified for the relevance and mutual ranking of the different suspicion criteria and for systematic screening. Conclusively, patient entry was neglected in the reviewed literature. While multiple red flags were described, high-quality prospective studies designed to evaluate their suitability as suspicion criteria were lacking. An upcoming task lies in defining and evaluating at-risk populations for screening. All are steps needed to promote early detection and diagnosis of ATTRwt CM, a prerequisite for timely treatment.

Imaging-Guided Treatment for Cardiac Amyloidosis

Purpose of Review

This review will explore the role of cardiac imaging in guiding treatment in the two most commonly encountered subtypes of cardiac amyloidosis (immunoglobulin light-chain amyloidosis [AL] and transthyretin amyloidosis [ATTR]).

Recent Findings

Advances in multi-parametric cardiac imaging involving a combination of bone scintigraphy, echocardiography and cardiac magnetic resonance imaging have resulted in earlier diagnosis and initiation of treatment, while the evolution of techniques such as longitudinal strain and extracellular volume quantification allow clinicians to track individuals’ response to treatment. Imaging developments have led to a deeper understanding of the disease process and treatment mechanisms, which in combination result in improved patient outcomes.

Summary

The rapidly expanding treatment regimens for cardiac amyloidosis have led to an even greater reliance on cardiac imaging to help establish an accurate diagnosis, monitor treatment response and aid the adjustment of treatment strategies accordingly.

New Advanced Imaging Parameters and Biomarkers—A Step Forward in the Diagnosis and Prognosis of TTR Cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an infiltrative disorder characterized by extracellular myocardial deposits of amyloid fibrils, with poor outcome, leading to heart failure and death, with significant treatment expenditure. In the era of a novel therapeutic arsenal of disease-modifying agents that target a myriad of pathophysiological mechanisms, timely and accurate diagnosis of ATTR-CM is crucial. Recent advances in therapeutic strategies shown to be most beneficial in the early stages of the disease have determined a paradigm shift in the screening, diagnostic algorithm, and risk classification of patients with ATTR-CM. The aim of this review is to explore the utility of novel specific non-invasive imaging parameters and biomarkers from screening to diagnosis, prognosis, risk stratification, and monitoring of the response to therapy. We will summarize the knowledge of the most recent advances in diagnostic, prognostic, and treatment tailoring parameters for early recognition, prediction of outcome, and better selection of therapeutic candidates in ATTR-CM. Moreover, we will provide input from different potential pathways involved in the pathophysiology of ATTR-CM, on top of the amyloid deposition, such as inflammation, endothelial dysfunction, reduced nitric oxide bioavailability, oxidative stress, and myocardial fibrosis, and their diagnostic, prognostic, and therapeutic implications.

Cardiac Amyloidosis: A Review of Current Imaging Techniques

Systemic amyloidosis is a rare, heterogenous group of diseases characterized by extracellular infiltration and deposition of amyloid fibrils. Cardiac amyloidosis (CA) occurs when these fibrils deposit within the myocardium. Untreated, this inevitably leads to progressive heart failure and fatality. Historically, treatment has remained supportive, however, there are now targeted disease-modifying therapeutics available to patients with CA. Advances in echocardiography, cardiac magnetic resonance (CMR) and repurposed bone scintigraphy have led to a surge in diagnoses of CA and diagnosis at an earlier stage of the disease natural history. CMR has inherent advantages in tissue characterization which has allowed us to better understand the pathological disease process behind CA. Combined with specialist assessment and repurposed bone scintigraphy, diagnosis of CA can be made without the need for invasive histology in a significant proportion of patients. With existing targeted therapeutics, and novel agents being developed, understanding these imaging modalities is crucial to achieving early diagnosis for patients with CA. This will allow for early treatment intervention, accurate monitoring of disease course over time, and thereby improve the length and quality of life of patients with a disease that historically had an extremely poor prognosis. In this review, we discuss key radiological features of CA, focusing on the two most common types; immunoglobulin light chain (AL) and transthyretin (ATTR) CA. We highlight recent advances in imaging techniques particularly in respect of their clinical application and utility in diagnosis of CA as well as for tracking disease change over time.

Convolutional Neural Networks for Fully Automated Diagnosis of Cardiac Amyloidosis by Cardiac Magnetic Resonance Imaging

Aims: We tested the hypothesis that artificial intelligence (AI)-powered algorithms applied to cardiac magnetic resonance (CMR) images could be able to detect the potential patterns of cardiac amyloidosis (CA). Readers in CMR centers with a low volume of referrals for the detection of myocardial storage diseases or a low volume of CMRs, in general, may overlook CA. In light of the growing prevalence of the disease and emerging therapeutic options, there is an urgent need to avoid misdiagnoses. Methods and Results: Using CMR data from 502 patients (CA: n = 82), we trained convolutional neural networks (CNNs) to automatically diagnose patients with CA. We compared the diagnostic accuracy of different state-of-the-art deep learning techniques on common CMR imaging protocols in detecting imaging patterns associated with CA. As a result of a 10-fold cross-validated evaluation, the best-performing fine-tuned CNN achieved an average ROC AUC score of 0.96, resulting in a diagnostic accuracy of 94% sensitivity and 90% specificity. Conclusions: Applying AI to CMR to diagnose CA may set a remarkable milestone in an attempt to establish a fully computational diagnostic path for the diagnosis of CA, in order to support the complex diagnostic work-up requiring a profound knowledge of experts from different disciplines.

Performance of bone tracer for diagnosis and differentiation of transthyretin cardiac amyloidosis: a systematic review and meta-analysis

PURPOSE

Bone tracers have been validated for many years in detecting transthyretin cardiac amyloidosis (TTR-CA). However, several new studies suggest conflicting results. Our study aimed to systematically evaluate the accuracy of bone radiotracers for diagnosis and differentiation of TTR-CA via a systematic review and meta-analysis.

METHODS

We retrieved articles assessing the performance of bone tracer in diagnosing and differentiating TTR-CA from PubMed, the Cochrane Library, ScienceDirect, and DOAJ databases, dating up to 10 July 2020. The meta-analysis was conducted through Stata 16 software, and the risk of bias for the included studies was assessed by the QUADAS-2 tool. Moreover, we made a comprehensive review.

RESULTS

Fourteen articles were included in the systematic review, and 9 in the meta-analysis. The pooled sensitivity was 0.97 (95% confidence interval [95% CI] 0.85-0.99) with heterogeneity (I2=73.5, 95% CI 55.6-91.2), and the specificity was 0.92 (95% CI 0.82-0.96) with heterogeneity (I2=42.0, 95% CI 0.0-86.9). The pooled positive and negative likelihood ratios were 11.49 (95% CI 5.07-26.0) and 0.03 (95% CI 0.01-0.18), respectively. The diagnostic odds ratio was 341 (95% CI 53-2194), and the area under the receiver operating characteristic curve was 0.96 (95% CI 0.94-0.97).

CONCLUSION

The findings evidence that the bone radiotracer is a valuable noninvasive approach that provides high accuracy for diagnosing TTR-CA and plays a modest role in differentiating TTR-CA from immunoglobulin amyloid light-chain cardiac amyloidosis. 99mTc-HMDP may be more accurate than 99mTc-PYP, 99mTc-DPD, and 18F-NaF in the TTR-CA detecting process, and 18F-NaF is a promising bone tracer to diagnose and differentiate TTR-CA.

[Cardiac amyloidosis and aortic valve stenosis]

Aortic valve stenosis in old age has become a topic of interest for cardiology and cardiac surgery after the development of transvascular and transluminal minimally invasive techniques for aortic valve implantation. The observation of amyloid deposits in surgically excised valvular material led to the diagnostics of amyloidosis of the myocardium, which was discovered in up to 20% of the patients who underwent valve implantation. Clinical signs of cardiac amyloidosis, such as carpal tunnel syndrome and ruptured distal biceps tendon should be taken into account. In addition to the electrocardiogram (ECG), echocardiogram and magnetic resonance imaging, ^99mtechnetium bone scintigraphy plays a key diagnostic role. The simultaneous occurrence of severe aortic valve stenosis and amyloidosis explains the special hemodynamic situation of a low gradient with low blood flow in high-grade valve stenosis. The interventional or surgical valve implantation improves the prognosis for these patients, similarly to aortic valve stenosis alone, followed by a specific pharmaceutical treatment depending on the type of amyloidosis.

Clinical Importance of Left Atrial Infiltration in Cardiac Transthyretin Amyloidosis

Objectives

The aim of this study was to characterize left atrial (LA) pathology in explanted hearts with transthyretin amyloid cardiomyopathy (ATTR-CM); LA mechanics using echocardiographic speckle-tracking in a large cohort of patients with ATTR-CM; and to study the association with mortality.

Background

The clinical significance of LA involvement in ATTR-CM is of great clinical interest.

Methods

Congo red staining and immunohistochemistry was performed to assess the presence, type, and extent of amyloid and associated changes in 5 explanted ATTR-CM atria. Echo speckle tracking was used to assess LA reservoir, conduit, contractile function, and stiffness in 906 patients with ATTR-CM (551 wild-type (wt)-ATTR-CM; 93 T60A-ATTR-CM; 241 V122I-ATTR-CM; 21 other).

Results

There was extensive ATTR amyloid infiltration in the 5 atria, with loss of normal architecture, vessels remodeling, capillary disruption, and subendocardial fibrosis. Echo speckle tracking in 906 patients with ATTR-CM demonstrated increased atrial stiffness (median [25th-75th quartile] 1.83 [1.15-2.92]) that remained independently associated with prognosis after adjusting for known predictors (lnLA stiff: HR: 1.23; 95% CI: 1.03-1.49; P = 0.029). There was substantial impairment of the 3 phasic functional atrial components (reservoir 8.86% [5.94%-12.97%]; conduit 6.5% [4.53%-9.28%]; contraction function 4.0% [2.29%-6.56%]). Atrial contraction was absent in 22.1% of patients whose electrocardiograms showed sinus rhythm (SR) “atrial electromechanical dissociation” (AEMD). AEMD was associated with poorer prognosis compared with patients with SR and effective mechanical contraction (P = 0.0018). AEMD conferred a similar prognosis to patients in atrial fibrillation.

Conclusions

The phenotype of ATTR-CM includes significant infiltration of the atrial walls, with progressive loss of atrial function and increased stiffness, which is a strong independent predictor of mortality. AEMD emerged as a distinctive phenotype identifying patients in SR with poor prognosis.

Imaging Techniques as an Aid in the Early Detection of Cardiac Amyloidosis

The idea that performing a proper succession of imaging tests and techniques allows an accurate and early diagnosis of cardiac amyloidosis, avoiding the need to perform the myocardial biopsy, is becoming increasingly popular. Furthermore, being imaging techniques non-invasive, it is possible to perform the follow-up of the pathology through repeated image acquisitions. In the present review, the various innovative imaging methodologies are presented, and it is discussed how they have been applied for early diagnosis of cardiac amyloidosis (CA), also to distinguish the two most frequent subtypes in CA: immunoglobulin light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR); this allows to perform the therapy in a targeted and rapid manner.

Transthyretin cardiac amyloidosis: a review of the nuclear imaging findings with emphasis on the radiotracers mechanisms

Cardiac amyloidosis is a protein deposition disease characterized by the infiltration of the myocardium and coronary arteries resulting in a progressive thickening of both ventricles, interatrial septum and atrioventricular valves, eventually leading to organ failure. It is a disease hard to diagnose, due to the lack of diagnostic investigations. However, development of new and more accurate examinations is undergoing. Endomyocardial biopsy is the gold standard investigation for this disease, but it has its limitations (invasive and not widely available). Other investigations may be able to detect the presence of cardiac amyloidosis but cannot specify the type involved. To that end, nuclear medicine through bone scanning offers a simple, non-invasive solution to detect, differentiate and diagnose transthyretin cardiac amyloidosis (ATTR) from other types of cardiac amyloidosis. In order to demonstrate the importance of bone scanning we will present a few methods of image processing based on literature and a personalized method, followed by a few important examples of positive cases. The aim of this review was to present the current methods of ATTR detection with emphasis on nuclear medicine bone scanning and its important place in the decision algorithm of the cardiologist for a personalized approach to this pathology.

The Role of Imaging in Diagnosing Transthyretin Cardiac Amyloidosis

Cardiac amyloidosis is a rare underdiagnosed condition with increasing morbidity and mortality. Its diagnosis is challenging and requires high clinical suspicion. Several diagnostic tools aid in the diagnosis of cardiac amyloidosis such as electrocardiogram, echocardiography, and, most importantly, cardiac MRI. A wide range of clinical symptoms is associated with cardiac amyloidosis, with shortness of breath and peripheral edema being the most common presenting complaints. Here, we report a case of transthyretin cardiac amyloidosis and discuss the importance of imaging in establishing the diagnosis.

Emerging role of metabolomics in protein conformational disorders

Introduction: Metabolomics focuses on interactions among different metabolites associated with various cellular functions in cells, tissues, and organs. In recent years, metabolomics has emerged as a powerful tool to identify perturbed metabolites, pathways influenced by the environment, for protein conformational diseases (PCDs) and also offers wide clinical application.Area Covered: This review provides a brief overview of recent advances in metabolomics as applied to identify metabolic variations in PCDs, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, prion disease, and cardiac amyloidosis. The 'PubMed' and 'Google Scholar' database search methods have been used to screen the published reports with key search terms: metabolomics, biomarkers, and protein conformational disorders.Expert opinion: Metabolomics is the large-scale study of metabolites and is deemed to overwhelm other omics. It plays a crucial role in finding variations in diseases due to protein conformational changes. However, many PCDs are yet to be identified. Metabolomics is still an emerging field; there is a need for new high-resolution analytical techniques and more studies need to be carried out to generate new information.

Cardiac Amyloidosis: Multimodal Imaging of Disease Activity and Response to Treatment

Cardiac amyloidosis (CA) is a disease characterized by the deposition of misfolded protein deposits in the myocardial interstitium. Although advanced CA confers significant morbidity and mortality, the magnitude of deposition and ensuing clinical manifestations vary greatly. Thus, an improved understanding of disease pathogenesis at both cellular and functional levels would afford critical insights that may improve outcomes. This review will summarize contemporary therapies for the 2 major types of CA, transthyretin and light chain amyloidosis, and outline the capacity of imaging modalities to both diagnose CA, inform prognosis, and follow response to available therapies. We explore the current landscape of echocardiography, cardiac magnetic resonance, and bone scintigraphy in the assessment of functional and cellular parameters of dysfunction in CA throughout disease pathogenesis. Finally, we examine the impact of concurrent advances in both therapeutics and imaging on future research questions that improve our understanding of underlying disease mechanisms. Multimodal imaging in CA affords an indispensable tool to offer individualized treatment plans and improve outcomes in patients with CA.

Tenosynovial complications identify TTR cardiac amyloidosis among patients with hypertrophic cardiomyopathy phenotype

Recent evidence suggests that carpal tunnel syndrome (CTS) and brachial biceps tendon rupture (BBTR) represent red flags for ATTR cardiac amyloidosis (ATTR-CA). The prevalence of upper limb tenosynovial complications in conditions entering differential diagnosis with CA, such as HCM or Anderson-Fabry disease (AFD), and hence their predictive accuracy in this setting, still remains unresolved.

OBJECTIVE

To investigate the prevalence of CTS and BBTR in a consecutive cohort of ATTR-CA patients, compared with patients with HCM or AFD and with individuals without cardiac disease history.

PARTICIPANTS

Consecutive patients with a diagnosis of ATTR-CA, HCM and AFD were evaluated. A control group of consecutive patients was recruited among subjects hospitalized for noncardiac reasons and no cardiac disease history. The presence of BBTR, CTS or prior surgery related to these conditions was ascertained.

RESULTS

342 patients were prospectively enrolled, including 168 ATTR-CA (141 ATTRwt, 27 ATTRm), 81 with HCM/AFD (N = 72 and 9, respectively) and 93 controls. CTS was present in 75% ATTR-CA patients, compared with 13% and 10% of HCM/AFD and controls (P = 0.0001 for both comparisons). Bilateral CTS was present in 60% of ATTR-CA patients, while it was rare (2%) in the other groups. BBTR was present in 44% of ATTR-CA patients, 8% of controls and 1% in HCM/AFD.

CONCLUSIONS

CTS and BBTR are fivefold more prevalent in ATTR-CA patients compared with cardiac patients with other hypertrophic phenotypes. Positive predictive accuracy for ATTR-CA is highest when involvement is bilateral. Upper limb assessment of patients with HCM phenotypes is a simple and effective way to raise suspicion of ATTR-CA.

Cardiac Magnetic Resonance-Derived Extracellular Volume Mapping for the Quantification of Hepatic and Splenic Amyloid

BACKGROUND

Systemic amyloidosis is characterized by amyloid deposition that can involve virtually any organ. Splenic and hepatic amyloidosis occurs in certain types, in some patients but not others, and may influence prognosis and treatment. SAP (serum amyloid P component) scintigraphy is uniquely able to identify and quantify amyloid in the liver and spleen, thus informing clinical management, but it is only available in 2 centers globally. The aims of this study were to examine the potential for extracellular volume (ECV) mapping performed during routine cardiac magnetic resonance to: (1) detect amyloid in the liver and spleen and (2) estimate amyloid load in these sites using SAP scintigraphy as the reference standard.

METHODS

Five hundred thirty-three patients referred to the National Amyloidosis Centre, London, between 2015 and 2017 with suspected systemic amyloidosis who underwent SAP scintigraphy and cardiac magnetic resonance with T1 mapping were studied.

RESULTS

The diagnostic performance of ECV to detect splenic and hepatic amyloidosis was high for both organs (liver: area under the curve, -0.917 [95% CI, 0.880-0.954]; liver ECV cutoff, 0.395; sensitivity, 90.7%; specificity, 77.7%; P<0.001; spleen: area under the curve, -0.944 [95% CI, 0.925-0.964]; spleen ECV cutoff, 0.385; sensitivity, 93.6%; specificity, 87.5%; P<0.001). There was good correlation between liver and spleen ECV and amyloid load assessed by SAP scintigraphy (r=0.504, P<0.001; r=0.693, P<0.001, respectively). There was high interobserver agreement for both the liver and spleen (ECV liver intraclass correlation coefficient, 0.991 [95% CI, 0.984-0.995]; P<0.001; ECV spleen intraclass correlation coefficient, 0.995 [95% CI, 0.991-0.997]; P<0.001) with little bias across a wide range of ECV values.

CONCLUSIONS

Our study demonstrates that ECV measurements obtained during routine cardiac magnetic resonance scans in patients with suspected amyloidosis can identify and measure the magnitude of amyloid infiltration in the liver and spleen, providing important clues to amyloid type and offering a noninvasive measure of visceral amyloid burden that can help guide and track treatment.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Deep-learning-based cardiac amyloidosis classification from early acquired pet images

The objective of the present work was to evaluate the potential of deep learning tools for characterizing the presence of cardiac amyloidosis from early acquired PET images, i.e. 15 min after [18F]-Florbetaben tracer injection. 47 subjects were included in the study: 13 patients with transthyretin-related amyloidosis cardiac amyloidosis (ATTR-CA), 15 patients with immunoglobulin light-chain amyloidosis (AL-CA), and 19 control-patients (CTRL). [18F]-Florbetaben PET/CT images were acquired in list mode and data was sorted into a sinogram, covering a time interval of 5 min starting 15 min after the injection. The resulting sinogram was reconstructed using OSEM iterative algorithm. A deep convolutional neural network (CAclassNet) was designed and implemented, consisting of five 2D convolutional layers, three fully connected layers and a final classifier returning AL, ATTR and CTRL scores. A total of 1107 2D images (375 from AL-subtype patients, 312 from ATTR-subtype, and 420 from Controls) have been considered in the study and used to train, validate and test the proposed network. CAclassNet cross-validation resulted with train error mean ± sd of 2.001% ± 0.96%, validation error of 4.5% ± 2.26%, and net accuracy of 95.49% ± 2.26%. Network test error resulted in a mean ± sd values of 10.73% ± 0.76%. Sensitivity, specificity, and accuracy evaluated on the test dataset were respectively for AL-CA sub-type: 1, 0.912, 0.936; for ATTR-CA: 0.935, 0.897, 0.972; for control subjects: 0.809, 0.971, 0.909. In conclusion, the proposed CAclassNet model seems very promising as an aid for the clinician in the diagnosis of CA from cardiac [18F]-Florbetaben PET images acquired a few minutes after the injection.

The Importance of Multimodality Imaging in the Diagnosis and Management of Patients with Infiltrative Cardiomyopathies: An Update

Infiltrative cardiomyopathies (ICMs) comprise a broad spectrum of inherited and acquired conditions (mainly amyloidosis, sarcoidosis, and hemochromatosis), where the progressive buildup of abnormal substances within the myocardium results in left ventricular hypertrophy and manifests as restrictive physiology. Noninvasive multimodality imaging has gradually eliminated endomyocardial biopsy from the diagnostic workup of infiltrative cardiac deposition diseases. However, even with modern imaging techniques’ widespread availability, these pathologies persist in being largely under- or misdiagnosed. Considering the advent of novel, revolutionary pharmacotherapies for cardiac amyloidosis, the archetypal example of ICM, a standardized diagnostic approach is warranted. Therefore, this review aims to emphasize the importance of contemporary cardiac imaging in identifying specific ICM and improving outcomes via the prompt initiation of a targeted treatment.

Practical recommendations for the diagnosis and management of transthyretin cardiac amyloidosis

Cardiac amyloidosis (CA) is an infiltrative restrictive cardiomyopathy caused by accumulation in the heart interstitium of amyloid fibrils formed by misfolded proteins. Most common CA types are light chain amyloidosis (AL) caused by monoclonal immunoglobulin light chains and transthyretin amyloidosis (ATTR) caused by either mutated or wild-type transthyretin aggregates. Previously considered a rare disease, CA is increasingly recognized among patients who may be misdiagnosed as undifferentiated heart failure with preserved ejection fraction (HFPEF), paradoxical low-flow/low-gradient aortic stenosis, or otherwise unexplained left ventricular hypertrophy. Progress in diagnosis has been due to the refinement of cardiac echocardiographic techniques (speckle tracking imaging) and magnetic resonance (T1 mapping) and mostly due to the advent of bone scintigraphy that has enabled noninvasive diagnosis of ATTR, limiting the need for endomyocardial biopsy. Importantly, proper management of CA starts from early recognition of suspected cases among high prevalence populations, followed by advanced diagnostic evaluation to confirm diagnosis and typing, preferentially in experienced amyloidosis centers. Differentiating ATTR from other types of amyloidosis, especially AL, is critical. Emerging targeted ATTR therapies offer the potential to improve outcomes of these patients previously treated only palliatively.

Neurological complications of cardiomyopathies

There is a multifaceted relationship between the cardiomyopathies and a wide spectrum of neurological disorders. Severe acute neurological events, such as a status epilepticus and aneurysmal subarachnoid hemorrhage, may result in an acute cardiomyopathy the likes of Takotsubo cardiomyopathy. Conversely, the cardiomyopathies may result in a wide array of neurological disorders. Diagnosis of a cardiomyopathy may have already been established at the time of the index neurological event, or the neurological event may have prompted subsequent cardiac investigations, which ultimately lead to the diagnosis of a cardiomyopathy. The cardiomyopathies belong to one of the many phenotypes of complex genetic diseases or syndromes, which may also involve the central or peripheral nervous systems. A number of exogenous agents or risk factors such as diphtheria, alcohol, and several viruses may result in secondary cardiomyopathies accompanied by several neurological manifestations. A variety of neuromuscular disorders, such as myotonic dystrophy or amyloidosis, may demonstrate cardiac involvement during their clinical course. Furthermore, a number of genetic cardiomyopathies phenotypically incorporate during their clinical evolution, a gamut of neurological manifestations, usually neuromuscular in nature. Likewise, neurological complications may be the result of diagnostic procedures or medications for the cardiomyopathies and vice versa. Neurological manifestations of the cardiomyopathies are broad and include, among others, transient ischemic attacks, ischemic strokes, intracranial hemorrhages, syncope, muscle weakness and atrophy, myotonia, cramps, ataxia, seizures, intellectual developmental disorder, cognitive impairment, dementia, oculomotor palsies, deafness, retinal involvement, and headaches.

Cardiac Amyloidosis in Patients Undergoing TAVR: Why We Need to Think About It

Systemic amyloidosis encompasses a variety of diseases characterized by extracellular deposition of protein-derived fibrils in different tissues and organs. Immunoglobulin light-chain (AL) and transthyretin (ATTR) amyloid are the two types that more commonly affect the heart and in both subtypes cardiac involvement is the main determinant of prognosis. Recently, several studies have suggested that Cardiac Amyloidosis (CA) and Aortic Stenosis (AS) can coexist more frequently than previously suspected with prevalence ranging from 5,6% to 16% in different cohorts. The unexpected high prevalence of CA in AS and the availability of potentially effective treatment in CA should push us to carefully investigate elderly patients with aortic valve stenosis in order to identify those with coexistent amyloidosis. While the motivation to exclude amyloidosis was in the past their exclusion from active treatment of the valve disease, judged as futile because of their poor unavoidable prognosis, the improved therapeutic options available challenges this conservative approach. Aim of this review is to identify the triggers to investigate AS patients at risk of having concomitant ATTR-CA, to propose a diagnostic path to reach diagnosis and to discuss the changes in the therapeutic strategy caused by this discovery in the era of TAVR and active pharmacological treatments to slow down disease progression.

[Cardiac Amyloidosis: Experience in a National Reference Cardiovascular Institute]

Objectives

To determine the clinical, imaging and laboratory characteristics and one year after diagnosis survival of patients with cardiac amyloidosis in a national reference hospital.

Materials and methods

Case series study. We evaluated the clinical characteristics, complementary examinations and survival of patients with cardiac amyloidosis diagnosed, treated and followed up in the Clinical Cardiology service of the National Cardiovascular Institute - INCOR EsSalud in Lima, Peru.

Results

We found eight patients with diagnosis of cardiac amyloidosis. The median age was 64.5 years and 75% were male. The etiology of cases was unspecified cardiac amyloidosis (25%), transthyretin cardiac amyloidosis (37.5%), and light chain cardiac amyloidosis (37.5%). Symptomatic heart failure (NYHA II-III) was the most common initial presentation symptom (87.5%). The most frequent extracardiac manifestations were: sensory-motor neuropathy (62.5%), musculoskeletal (37.5%), nephropathy (25%), bilateral carpal tunnel syndrome (25%), monoclonal gammopathies (25%) and refractory pleural effusion (25 %). Survival at one year was 75% and the cause of the 2 deaths was sudden death.

Conclusions

In this study of cardiac amyloidosis at a specialized center, the most frequent clinical manifestations were heart failure and sensory-motor neuropathy. Mortality was 25% per year, and in all cases as sudden death.