ASNC/AHA/ASE/EANM/HFSA/ISA/SCMR/SNMMI Expert Consensus Recommendations for Multimodality Imaging in Cardiac Amyloidosis: Part 2 of 2—Diagnostic Criteria and Appropriate Utilization

Protocol of the follow-up of patients with transthyretin amyloid cardiomyopathy by multimodality imaging (FAITH) study: a prospective observational study in patients with ATTR-CM undergoing treatment with tafamidis

INTRODUCTION

This prospective observational study of patients with transthyretin amyloid cardiomyopathy (ATTR-CM) undergoing treatment with tafamidis aims at identifying quantitative image markers and comparing imaging modalities regarding the follow-up and prognostication of these patients, with the goal of providing a multiparametric score to predict treatment response.

METHODS AND ANALYSIS

Patients with a board-approved decision to receive tafamidis will undergo, in addition to standard of care, baseline and follow-up cardiovascular magnetic resonance (CMR) scans at 9 and 18 months. In total, the study plans to recruit and scan 60 patients. A blinded read will take place in a CMR research core laboratory. The final statistical analysis will be based on developing a multiparametric score for the prediction of treatment response. The study will be managed through the Amyloidosis Center Charité Berlin, a clinical unit formed from the three clinical campus sites of the Charité in Berlin, using the Berlin Research Network for CMR.

ETHICS AND DISSEMINATION

The study was approved by the Charité-Universitätsmedizin Berlin ethics committee EA1/262/23. The results of the study will be disseminated through international peer-reviewed publications and congress presentations.

TRIAL REGISTRATION NUMBER

Approved WHO primary register: German Clinical Trials Register: https://www.drks.de/DRKS00033884. WHO International Clinical Registry Platform: https://trialsearch.who.int/?TrialID=DRKS00033884. Recruitment started on 1 July 2024.

Transthyretin Amyloid Cardiomyopathy: Current Diagnostic Approach and Risk Stratification with Multimodality Imaging

Amyloidosis is an infiltrative disease that may cause cardiomyopathy if the precursor protein that misfolds and forms the amyloid is transthyretic or plasma abnormal light chains. Transthyretin amyloid cardiomyopathy has to be diagnosed timely and accurately since there are specific treatment options to support the patients. Multimodality imaging including electrocardiography, echocardiography with strain imaging and cardiac magnetic resonance applying late gadolinium enhancement imaging, native T1 mapping and extracellular volume, raise a high suspicion of the disease and bone scintigraphy set the diagnosis even without the need of biopsy. However, the morbidity and mortality remain high and the need for risk stratification and assessment of the response to treatment are of paramount importance. Cardiac imaging biomarkers offer a thoughtful insight into the prognosis of these patients at diagnosis and after treatment. The current narrative review aims to enlighten the use of multimodality cardiac imaging in transthyretic amyloid cardiomyopathy throughout the disease pathogenesis and evolution from diagnosis to prognosis and response to treatment in a personalized manner.

Prevalence and characteristics of transthyretin amyloid cardiomyopathy in hypertrophic cardiomyopathy

AIMS

Recognition of transthyretin amyloid cardiomyopathy is increasing due to advances in cardiac imaging and diagnostic strategies, but questions remain regarding disease frequency and characteristics. We examined the prevalence and characteristics of transthyretin amyloid cardiomyopathy in older patients with hypertrophic cardiomyopathy of unascertained aetiology.

METHODS AND RESULTS

TTRACK was a multicentre, non-interventional, cross-sectional epidemiologic study funded by Pfizer and conducted in 20 hospitals and medical centres in 11 countries (NCT03842163). Eligible patients were aged ≥50 years, had hypertrophic cardiomyopathy (maximal end-diastolic left ventricular wall thickness ≥15 mm on echocardiogram) without an identified genetic or alternative origin at study enrolment, and underwent 99mTechnetium bone scintigraphy, with or without single photon emission computed tomography (SPECT). Cardiac-versus-bone uptake on scans was visually scored from 0 to 3 (Perugini scoring). Patients with grades 1-3 underwent monoclonal protein and laboratory testing and transthyretin (TTR) gene sequencing. Of 766 eligible patients, 691 (90.2%) had scintigraphy alone and 75 (9.8%) scintigraphy plus SPECT. Two hundred and eight patients (27.2%) had grade 2 or 3 cardiac uptake on scintigraphy; 144 (18.8%) had grade 2 or 3 cardiac uptake and no evidence of plasma cell dyscrasia and were diagnosed with transthyretin amyloid cardiomyopathy. Of patients with transthyretin amyloid cardiomyopathy, 11 (7.6%) had a pathogenic TTR gene variant and 34 (23.8%), 74 (51.7%), and 35 (24.5%) had New York Heart Association class I, II, and III/IV heart failure (HF) symptoms, respectively. Clinical and laboratory diagnostic characteristics were observed in ≥90% of patients with transthyretin amyloid cardiomyopathy. The characteristics most strongly associated with transthyretin amyloid cardiomyopathy on multivariable analysis were carpal tunnel syndrome (odds ratio [OR] 54.3; P < 0.0001) and male sex (OR 7.9; P < 0.0001).

CONCLUSIONS

In the TTRACK study, almost one in five patients ≥50 years of age with hypertrophic cardiomyopathy had transthyretin amyloid cardiomyopathy. Greater awareness of the frequency and characteristics of transthyretin amyloid cardiomyopathy in older patients with hypertrophic cardiomyopathy are needed to help improve early detection of this debilitating but treatable disease.

Impact of the Noninvasive Diagnostic Algorithm on Clinical Presentation and Prognosis in Cardiac Amyloidosis

Background

The introduction of a noninvasive diagnostic algorithm in 2016 led to increased awareness and recognition of cardiac amyloidosis (CA).

Objectives

The purpose of this study was to analyze the impact of the introduction of the noninvasive diagnostic algorithm on diagnosis and prognosis in a multicenter Italian CA cohort.

Methods

This was a retrospective analysis of 887 CA patients from 5 Italian Cardiomyopathies Referral Centers: 311 light-chain CA, 87 variant transthyretin (TTR)-related CA, 489 wild-type TTR-related CA. Clinical characteristics and outcomes (all-cause mortality and heart failure [HF] hospitalizations) were compared overall and for each CA subtype between patients diagnosed before versus after 2016. Outcomes were further compared by propensity score weighted Kaplan-Meier analysis and Cox regression analysis.

Results

CA diagnoses increased after 2016, in particular for wild-type TTR-related CA. Patients diagnosed after versus before 2016 were older, had less frequently a history of HF prior to diagnosis, and NYHA functional class III-IV at diagnosis. Over a median follow-up of 18 months, 172 (86%) patients diagnosed before 2016 died or had an HF hospitalization, versus 300 (44%) diagnosed after 2016. Propensity score weighted Kaplan-Meier analysis showed worse outcomes (P < 0.001) for patients diagnosed before 2016. At Cox regression analysis, CA diagnosis after 2016 was an independent protective factor for the composite outcome (HR: 0.69; P = 0.001), with interaction by CA subtype (significant in TTR-related CA and null in light-chain).

Conclusions

CA patients diagnosed after 2016 showed a less severe phenotype and a better prognosis. The impact of the noninvasive diagnostic algorithm on outcomes was particularly relevant in TTR-related CA.

Transforming Heart Failure Management: The Power of Strain Imaging, 3D Imaging, and Vortex Analysis in Echocardiography

Heart failure (HF) remains a critical global health challenge, necessitating advancements in diagnostic and therapeutic strategies. This review explores the evolution of imaging technologies and their impact on HF management, focusing on three-dimensional echocardiography (3DE), myocardial strain imaging, and vortex dynamics imaging. Three-dimensional echocardiography enhances traditional echocardiography by providing more accurate assessments of cardiac structures, while myocardial strain imaging offers the early detection of subclinical myocardial dysfunction, crucial in conditions such as chemotherapy-induced cardiotoxicity and ischemic heart disease. Vortex dynamics imaging, a novel technique, provides insights into intracardiac flow patterns, aiding in the evaluation of left ventricular function, valve diseases, and congenital heart anomalies. The integration of these advanced imaging modalities into clinical practice facilitates personalized treatment strategies, enabling the earlier diagnosis and more precise monitoring of disease progression. The ongoing refinement of these imaging techniques holds promise for improving patient outcomes and advancing the field of precision medicine in HF care.

Defining echocardiographic predictors of outcome in cardiac amyloidosis by subtype

BACKGROUND

Current echocardiographic risk factors for prognosis in cardiac amyloidosis (CA) do not distinguish between the two main subtypes: transthyretin cardiomyopathy (TTR) and immunoglobulin light chain cardiomyopathy (AL), each of which require distinct diagnostic and therapeutic approaches. Additionally, only traditional parameters have been studied with little data on advanced techniques. Accordingly, we sought to determine whether differences exist in 2D transthoracic echocardiography (2DE) predictors of survival between the CA subtypes using a comprehensive approach.

METHODS

220 patients (72±12 years) with confirmed CA (AL=89, TTR=131) who underwent 2DE at the time of CA diagnosis were enrolled. Left ventricular (LV) dimensions, indexed mass (LVMi), global longitudinal strain (LVGLS), apical-sparing ratio (LVASR), diastology, right ventricular (RV) size and function indices including tricuspid annular systolic excursion (TAPSE), RV free-wall (RVFWS) and global (RVGLS) strain, indexed left (LA) and right atrial volumes (LAVi and RAVi), LA strain (reservoir and booster) and RV systolic pressure (RVSP) were measured. A propensity-score weighted stepwise variable selection Cox proportional hazards model derived from NYHA class and renal impairment status at diagnosis was used to determine the associations between 2DE parameters and mortality specific to CA subtype over a median follow-up of 36-months.

RESULTS

After adjusting for age, atrial fibrillation and treatment, parameters associated with survival were RVFWS (p=0.003, HR 1.15, 95% CI[1.053,1.245]) and RVSP (p=0.03, HR 1.03, 95% CI[1.004,1.063]) in AL and LVASR (p=0.007, HR 6.68, 95% CI[1.75,25.492]) and RAVi (p=0.049, HR 1.03, 95% CI[1.000,1.052]) in TTR.

CONCLUSIONS

Echocardiographic prognosticators for survival are specific to cardiac amyloid subtype. These results potentially provide information critical for clinical decision-making and follow-up in these patients.

Scintigraphic and Echocardiographic Study of Patients with Pathogenic or Probably Pathogenic Variants of the TTR Gene without Overt Cardiac Involvement

BACKGROUND

Transthyretin amyloidosis (ATTR) is an infiltrative disease caused by abnormal protein deposition mainly in the heart and peripheral nervous system. When it affects the heart, the disease presents as restrictive cardiomyopathy; when it affects the peripheral and autonomic nervous system, it manifests as polyneuropathy, and is called familial amyloid polyneuropathy (FAP). There are two ATTR subtypes: wild-type ATTR, where there is no mutation, and mutant ATTR (ATTRm), which is characterized by a mutation in the gene encoding the transthyretin protein (TTR). In both subtypes, cardiac involvement is the major marker of poor prognosis.

OBJECTIVES

To assess the prevalence of subclinical cardiac involvement in a sample of patients with TTR gene mutation by using pyrophosphate scintigraphy and strain echocardiography; to compare scintigraphy and strain findings; to evaluate the association between neurological manifestations (FAP) and subclinical cardiac involvement; and to analyze whether there is an association between any specific mutation and cardiac involvement.

METHODS

This is a cross-sectional study with carriers of the TTR gene mutation, without cardiovascular symptoms or changes in electrocardiographic or conventional echocardiographic parameters. All patients underwent pyrophosphate scintigraphy and strain echocardiography. Subclinical cardiac involvement was defined as a Perugini score ≥ 2, heart-to-contralateral lung (H/CL) ratio ≥ 1.5 at 1 h, H/CL ≥1.3 at 3 h, or global longitudinal strain (GLS) ≤ -17%. Descriptive and analytical analyses were performed and Fisher's exact test and Mann-Whitney test were applied. A value of p < 0.05 was considered significant.

RESULTS

The 23 patients evaluated had a median age of 51 years (IQR 37-57 years), 15 (65.2%) were female, 12 (52.2%) were Pardo, nine (39.1%) had systemic arterial hypertension, and nine (39.1%) had a previous diagnosis of FAP. Of the nine patients with FAP, 8 (34.8%) were on tafamidis. The associated mutations were Val142IIe, Val50Met, and IIe127Val. The median GLS in the sample was -19% (-16% to -20%). Of the 23 patients, nine (39.1%; 95% CI = 29-49%) met criteria for cardiac involvement, six (26%) by the GLS-based criteria only. There was no association between having FAP and being an asymptomatic carrier, as assessed by strain echocardiography and pyrophosphate scintigraphy (p = 0.19). The prevalence of systemic arterial hypertension, diabetes mellitus, dyslipidemia, smoking, and reduced GLS did not differ between groups. Septal e' wave velocity was the only variable that significantly differed between individuals with and without reduced GLS, with an area under the ROC curve of 0.80 (95% CI = 0.61-0.98, p = 0.027). The best diagnostic accuracy was achieved with a septal e' velocity ≤ 8.5 cm/s. There was no association between mutation type and preclinical cardiac involvement, nor between tafamidis use and lower degree of cardiac involvement (37.5% versus 40.0%, p = 0.90).

CONCLUSION

Subclinical cardiac involvement was common in a sample of TTR mutation carriers without cardiac involvement. Reduced left ventricular GLS was the most frequent finding. There was no association between the presence of amyloid polyneuropathy and subclinical cardiac involvement. Type of mutation was not associated with early cardiac involvement. In this sample, the use of tafamidis 20 mg/day was not associated with a lower prevalence of subclinical cardiac involvement.

Clinical and Prognostic Implications of Right Ventricular Uptake on Bone Scintigraphy in Transthyretin Amyloid Cardiomyopathy

BACKGROUND

The extent of myocardial bone tracer uptake with technetium pyrophosphate, hydroxymethylene diphosphonate, and 3,3-diphosphono-1,2-propanodicarboxylate in transthyretin amyloid cardiomyopathy (ATTR-CM) might reflect cardiac amyloid burden and be associated with outcome.

METHODS

Consecutive patients with ATTR-CM who underwent diagnostic bone tracer scintigraphy with acquisition of whole-body planar and cardiac single-photon emission computed tomography (SPECT) images from the National Amyloidosis Centre and 4 Italian centers were included. Cardiac uptake was defined according to the Perugini classification: 0=absent cardiac uptake; 1=mild uptake less than bone; 2=moderate uptake equal to bone; and 3=high uptake greater than bone. Extent of right ventricular (RV) uptake was defined as focal (basal segment of the RV free wall only) or diffuse (extending beyond basal segment) on the basis of SPECT imaging. The primary outcome was all-cause mortality.

RESULTS

Among 1422 patients with ATTR-CM, RV uptake accompanying left ventricular uptake was identified by SPECT imaging in 100% of cases at diagnosis. Median follow-up in the whole cohort was 34 months (interquartile range, 21 to 50 months), and 494 patients died. By Kaplan-Meier analysis, diffuse RV uptake on SPECT imaging (n=936) was associated with higher all-cause mortality compared with focal (n=486) RV uptake (77.9% versus 22.1%; P<0.001), whereas Perugini grade was not associated with survival (P=0.27 in grade 2 versus grade 3). On multivariable analysis, after adjustment for age at diagnosis (hazard ratio [HR], 1.03 [95% CI, 1.02-1.04]; P<0.001), presence of the p.(V142I) TTR variant (HR, 1.42 [95% CI, 1.20-1.81]; P=0.004), National Amyloidosis Centre stage (each category, P<0.001), stroke volume index (HR, 0.99 [95% CI, 0.97-0.99]; P=0.043), E/e' (HR, 1.02 [95% CI, 1.007-1.03]; P=0.004), right atrial area index (HR, 1.05 [95% CI, 1.02-1.08]; P=0.001), and left ventricular global longitudinal strain (HR, 1.06 [95% CI, 1.03-1.09]; P<0.001), diffuse RV uptake on SPECT imaging (HR, 1.60 [95% CI, 1.26-2.04]; P<0.001) remained an independent predictor of all-cause mortality. The prognostic value of diffuse RV uptake was maintained across each National Amyloidosis Centre stage and in both wild-type and hereditary ATTR-CM (P<0.001 and P=0.02, respectively).

CONCLUSIONS

Diffuse RV uptake of bone tracer on SPECT imaging is associated with poor outcomes in patients with ATTR-CM and is an independent prognostic marker at diagnosis.

Comorbidity of patients with noncommunicable diseases in general practice. Eurasian guidelines

Создание руководства поддержано Советом по терапевтическим наукам отделения клинической медицины Российской академии наук.

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.

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.

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.

Uneven burden of cardiac amyloidosis in people of African descent - global imbalance in resources and access

Transthyretin cardiac amyloidosis (TTR-CA) is now increasingly becoming recognized as an important cause of heart failure, and some studies have shown that as much as a third of diastolic heart failure could be attributed to TTR-CA. Black populations are particularly at risk for TTR-CA as the most common form of the disease (hereditary TTR-CA) has a genetic basis and the gene responsible is most prevalent among people with West African ancestry. This perspective piece explores the challenges that individuals of African and Caribbean populations face when confronted with the burden of TTR-CA. Key issues include the absence of rigorous disease registries, deficits in human resources, a lack of infrastructure for testing and treatment, poor awareness and health literacy, financial limitations including an inadequate public health budget, and the absence of social safety nets. To address these challenges, proactive strategies are needed to build infrastructure and local capacity which will provide the framework for an effective response. Interventions should include healthcare financing mechanisms to protect and care for vulnerable and at-risk populations with a long-term strategy of increasing the financial remuneration for health workers in developing countries to prevent the brain drain. Additionally, pharmaceutical companies need to play an active role in promoting inclusive access and global health equity in the access to the new treatments for TTR-CA which predominantly affects Black populations. Collaborative ventures with international centers of excellence can help improve access in these communities, leveraging their expertise and resources.

Imaging of metabolic and overload disorders in tissues and organs

Metabolic and overload disorders are a heterogeneous group of relatively uncommon but important diseases. While imaging plays a key role in the early detection and accurate diagnosis in specific organs with a pivotal role in several metabolic pathways, most of these diseases affect different tissues as part of a systemic syndromes. Moreover, since the symptoms are often vague and phenotypes similar, imaging alterations can present as incidental findings, which must be recognized and interpreted in the light of further biochemical and histological investigations. Among imaging modalities, MRI allows, thanks to its multiparametric properties, to obtain numerous information on tissue composition, but many metabolic and accumulation alterations require a multimodal evaluation, possibly using advanced imaging techniques and sequences, not only for the detection but also for accurate characterization and quantification. The purpose of this review is to describe the different alterations resulting from metabolic and overload pathologies in organs and tissues throughout the body, with particular reference to imaging findings.

Prevalence of transthyretin amyloidosis among heart failure patients with preserved ejection fraction in Japan

AIMS

Heart failure with preserved ejection fraction (HFpEF), which is caused by wide various conditions, has become a major public health problem. Transthyretin amyloid cardiomyopathy (ATTR-CM), which is thought to be an underdiagnosed disease, can cause HFpEF. Non-invasive diagnosis using 99mTechnetium (Tc)-pyrophosphate (PYP) scintigraphy enables accurate diagnosis of ATTR-CM. The aim of this study was to clarify the prevalence and characteristics of ATTR-CM among Japanese patients with HFpEF.

METHODS AND RESULTS

This study was a multicentre, prospective, observational study conducted in Japan. We enrolled 373 patients with HFpEF [left ventricular (LV) ejection fraction ≥50%] aged ≥65 years who were admitted to the department of cardiology from September 2018 to January 2022. A 99mTc-PYP scintigraphy scan was performed during admission in all eligible patients. Cardiac 99mTc-PYP retention was graded according to a previously reported visual scale ranging from 0 to 3 points. The scan was considered positive when it revealed moderate-to-severe 99mTc-PYP uptake (Grade 2-3) in both ventricles. Patients were divided into ATTR-CM and non-ATTR-CM patients according to positive (Grade 2-3) or negative (Grade 0-1) 99mTc-PYP scintigraphy, respectively. Medical history, blood tests, electrocardiogram, echocardiography, and magnetic resonance imaging in the two groups of patients were compared. Among the 373 patients with HFpEF, 53 patients (14.2%; 95% confidence interval: 10.7-17.7) showed positive uptake on 99mTc-PYP scintigraphy. An endomyocardial biopsy was performed in 32 patients and confirmed amyloidosis in all cases. There were no significant differences between the two groups in age, severity of heart failure as assessed by the New York Heart Association (NYHA) functional classification, renal function values, left ventricular ejection fraction, and tricuspid regurgitant pressure gradient (ATTR-CM, n = 53 vs. non-ATTR-CM, n = 320). Patients in the ATTR-CM group had a higher N-terminal pro-brain natriuretic peptide level [2314 (1081-3398) vs. 900 (415-1828), P < 0.001], higher sensitive troponin T level (0.074 ± 0.049 vs. 0.035 ± 0.038, P < 0.001), and higher mean LV maximal wall thickness [12.5 (11-14) vs. 10.5 (9.5-11.5), P < 0.001].

CONCLUSIONS

ATTR-CM is an underdiagnosed disease with a significant prevalence in Japanese patients with HFpEF. This study showed that results of examinations for ATTR-CM patients appear to be worse than those for non-ATTR-CM patients, but clinical severities of heart failure as assessed by the NYHA functional classification are similar in ATTR-CM and non-ATTR-CM patients, and the clinical overlap between ATTR-CM and non-ATTR-CM is high.

Utility of nuclear cardiovascular imaging in the cardiac intensive care unit

The contemporary Cardiac Intensive Care Unit (CICU) has evolved into a complex unit that admits a heterogeneous mix of patients with a wide range of acute cardiovascular diseases often complicated by multi-organ failure. Although electrocardiography (ECG) and echocardiography are well-established as first-line diagnostic modalities for assessing patients in the CICU, nuclear cardiology imaging has emerged as a useful adjunctive diagnostic modality. The versatility, safety and accuracy of nuclear imaging (e.g., perfusion, metabolism, inflammation) for the assessment of patient with coronary artery disease, ventricular arrhythmias, infiltrative cardiomyopathies, infective endocarditis and inflammatory aortopathies has been proven useful and now often incorporated into the best practices for the management of critically ill cardiac patients. Thus, clinicians must familiarize themselves with the value and current and future applications of nuclear imaging in the management of the cardiac patient in the CICU.

Cardiac Amyloidosis

Amyloidosis is a pathologic and clinical condition resulting from the accumulation of insoluble aggregates of misfolded proteins in tissues. Extracellular deposition of amyloid fibrils in the myocardium leads to cardiac amyloidosis, which is often overlooked as a cause of diastolic heart failure. Although cardiac amyloidosis was previously believed to have a poor prognosis, recent advances in diagnosis and treatment have emphasized the importance of early recognition and changed management of this condition. This article provides an overview of cardiac amyloidosis and summarizes current screening, diagnosis, evaluation, and treatment options.

The major factor of left ventricular systolic dysfunction in patients with cardiac amyloidosis: Amyloid overload or microcirculation impairment?

Purpose

Amyloid overload and microcirculation impairment are both detrimental to left ventricular (LV) systolic function, while it is not clear which factor dominates LV functional remodeling in patients with cardiac amyloidosis (CA). The purpose of this study was to investigate the major factor of LV systolic dysfunction using cardiac magnetic resonance imaging.

Materials and methods

Forty CA patients and 20 healthy controls were included in this study. The CA group was divided into two subgroups by the left ventricular ejection fraction (LVEF): patients with reduced LVEF (LVEF < 50%, rLVEF), and patients with preserved LVEF (LVEF ≥ 50%, pLVEF). The scanning sequences included cine, native and post-contrast T1 mapping, rest first-pass perfusion and late gadolinium enhancement. Perfusion and mapping parameters were compared among the three groups. Correlation analysis was performed to evaluate the relationship between LVEF and mapping parameters, as well as the relationship between LVEF and perfusion parameters.

Results

Remarkably higher native T1 value was observed in the rLVEF patients than the pLVEF patients (1442.2 ± 85.8 ms vs. 1407.0 ± 93.9 ms, adjusted p = 0.001). The pLVEF patients showed significantly lower slope dividing baseline signal intensity (slope%BL; rLVEF vs. pLVEF, 55.1 ± 31.0 vs. 46.2 ± 22.3, adjusted p = 0.001) and a lower maximal signal intensity subtracting baseline signal intensity (MaxSI-BL; rLVEF vs. pLVEF, 43.5 ± 23.9 vs. 37.0 ± 18.6, adjusted p = 0.003) compared to the rLVEF patients. CA patients required more time to reach the maximal signal intensity than the controls did (all adjusted p < 0.01). There was no significant correlation between LVEF and first-pass perfusion parameters, while significant negative correlation was observed between LVEF and native T1 (r = -0.434, p = 0.005) in CA patients.

Conclusion

Amyloid overload in the myocardial interstitium may be the major factor of LV systolic dysfunction in CA patients, other than microcirculation impairment.

Light Chain Testing Abnormalities Among Patients With Transthyretin Amyloid Cardiomyopathy Referred for Technetium-99m Pyrophosphate Imaging

Clinical algorithms stipulate that transthyretin amyloid cardiomyopathy (ATTR-CM) can be diagnosed noninvasively by technetium-99m pyrophosphate (PYP) imaging when light chain (AL) amyloidosis has been excluded. We sought to define the distribution of light chain abnormalities and final diagnosis of ATTR-CM among patients referred for PYP imaging. We conducted a retrospective cohort study of 378 sequential patients with suspected ATTR-CM, referred for PYP imaging from October 2014 to January 2019. PYP scans were adjudicated as per guidelines. We found that 97 patients (26%) had abnormal plasma cell dyscrasia (PCD) markers, including serum free light chain (FLC) and/or urine/serum immunofixation electrophoresis (IFE). After exclusions for incomplete data or known AL amyloidosis, the final study population with abnormal PCD testing was n = 82. Final adjudication of amyloidosis was determined by multidisciplinary clinical assessment and/or tissue biopsy. The median age of cohort was 75 (68 to 81) years, 88% were men, and 33% were Black. Of the 82 patients, 62 had positive PYP scans (76%) and 20 had negative PYP scans (24%). A total of 64 patients had adjudicated ATTR-CM, confirmed by tissue biopsy in 41 (64%). Of those with confirmed ATTR-CM, 44 (69%) had abnormal FLC ratio between 1.65 and 3.1 and normal IFE. In conclusion, among patients referred for technetium-99m-PYP imaging for suspected ATTR-CM, 26% exhibited abnormalities of PCD markers. An FLC ratio 1.65 to 3.1, with normal IFE was noted in 69% of those with ATTR-CM, suggesting that ATTR-CM can be diagnosed noninvasively without cardiac biopsy in patients with positive PYP scan and similar plasma cell testing results.

A study protocol for an observational cohort investigating cardiac transthyretin amyloidosis flow reserve before and after Tafamidis treatment: The AMYTRE study

Introduction

Anginal symptoms and signs of ischemia have been reported in some patients with cardiac transthyretin amyloidosis (ATTR) without obstructive epicardial coronary artery disease (CAD). Few studies found that coronary microvascular dysfunction was highly prevalent in subjects with cardiac amyloidosis, even in the absence of epicardial CAD. The purpose of this study is to confirm the coronary microvascular dysfunction, and to go further with evaluation of the effect of Tafamidis on microvascular dysfunction after 24 months of treatment.

Methods and analysis

This study is a multicentric, prospective, observational cohort study. Adult patients with confirmed ATTR cardiomyopathy seen in the nuclear medicine departments of three large referral centers and treated with Tafamidis will be included. At baseline, patients will have a clinical and echocardiography evaluation. They will undergo a dynamic rest/stress cardiac scintigraphy with flow and reserve measurements before and 24 months after Tafamidis introduction. The primary outcome of this study will be the variation of stress and rest myocardial blood flow and flow reserve between baseline and 24 months after treatment. The effect of Tafamidis will be assessed by an intention to treat analysis.

Ethics and dissemination

The study has received the following approvals: Orleans Hospital Research Committee (CHRO-2021-05) and Sud-Mediterranée IV Regional Ethics Committee (21 06 02). Results will be made available to physicians, the funders, and other researchers.

Clinical trial registration

[https://clinicaltrials.gov/ct2/show/NCT05103943], identifier [NCT05103943].

Multi-Imaging Characterization of Cardiac Phenotype in Different Types of Amyloidosis

BACKGROUND

Bone scintigraphy is extremely valuable when assessing patients with suspected cardiac amyloidosis (CA), but the clinical significance and associated phenotype of different degrees of cardiac uptake across different types is yet to be defined.

OBJECTIVES

This study sought to define the phenotypes of patients with varying degrees of cardiac uptake on bone scintigraphy, across multiple types of systemic amyloidosis, using extensive characterization comprising biomarkers as well as echocardiographic and cardiac magnetic resonance (CMR) imaging.

METHODS

A total of 296 patients (117 with immunoglobulin light-chain amyloidosis [AL], 165 with transthyretin (TTR) amyloidosis [ATTR], 7 with apolipoprotein AI amyloidosis [AApoAI], and 7 with apolipoprotein AIV amyloidosis [AApoAIV]) underwent deep characterization of their cardiac phenotype.

RESULTS

AL patients with grade 0 myocardial radiotracer uptake spanned the spectrum of CMR findings from no CA to characteristic CA, whereas AL patients with grades 1 to 3 always produced characteristic CMR features. In ATTR, the CA burden strongly correlated with myocardial tracer uptake, except in Ser77Tyr. AApoAI presented with grade 0 or 1 and disproportionate right-sided involvement. AApoAIV always presented with grade 0 and characteristic CA. AL grade 1 patients (n = 48; 100%) had characteristic CA, whereas only ATTR grade 1 patients with Ser77Tyr had characteristic CA on CMR (n = 5; 11.4%). After exclusion of Ser77Tyr, AApoAI, and AApoAIV, CMR showing characteristic CA or an extracellular volume of >0.40 in patients with grade 0 to 1 cardiac uptake had a sensitivity and specificity of 100% for AL.

CONCLUSIONS

There is a wide variation in cardiac phenotype between different amyloidosis types across different degrees of cardiac uptake. The combination of CMR and bone scintigraphy can help to define the diagnostic differentials and the clinical phenotype in each individual patient.

Transthyretin cardiac amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is an increasingly recognized cause of heart failure (HF) and mortality worldwide. Advances in non-invasive diagnosis, coupled with the development of effective treatments, have shifted ATTR-CA from a rare and untreatable disease to a relatively prevalent condition that clinicians should consider on a daily basis. Amyloid fibril formation results from age-related failure of homoeostatic mechanisms in wild-type ATTR (ATTRwt) amyloidosis (non-hereditary form) or destabilizing mutations in variant ATTR (ATTRv) amyloidosis (hereditary form). Longitudinal large-scale studies in the United States suggest an incidence of cardiac amyloidosis in the contemporary era of 17 per 100 000, which has increased from a previous estimate of 0.5 per 100 000, which was almost certainly due to misdiagnosis and underestimated. The presence and degree of cardiac involvement is the leading cause of mortality both in ATTRwt and ATTRv amyloidosis, and can be identified in up to 15% of patients hospitalized for HF with preserved ejection fraction. Associated features, such as carpal tunnel syndrome, can preceed by several years the development of symptomatic HF and may serve as early disease markers. Echocardiography and cardiac magnetic resonance raise suspicion of disease and might offer markers of treatment response at a myocardial level, such as extracellular volume quantification. Radionuclide scintigraphy with 'bone' tracers coupled with biochemical tests may differentiate ATTR from light chain amyloidosis. Therapies able to slow or halt ATTR-CA progression and increase survival are now available. In this evolving scenario, early disease recognition is paramount to derive the greatest benefit from treatment.

Critical Comparison of Documents From Scientific Societies on Cardiac Amyloidosis: JACC State-of-the-Art Review

Over the last year, 5 national or international scientific societies have issued documents regarding cardiac amyloidosis (CA) to highlight the emerging clinical science, raise awareness, and facilitate diagnosis and management of CA. These documents provide useful guidance for clinicians managing patients with CA, and all include: 1) an algorithm to establish a diagnosis; 2) an emphasis on noninvasive diagnosis with the combined use of bone scintigraphy and the exclusion of a monoclonal protein; and 3) indications for novel disease-modifying therapies for symptomatic CA, either with or without peripheral neuropathy. Nonetheless, the documents diverge on specific details of diagnosis, risk stratification, and treatment. Highlighting the similarities and differences of the documents by the 5 scientific societies with respect to diagnosis, risk stratification, and treatment offers useful insight into the knowledge gaps and unmet needs in the management of CA. An analysis of these documents, therefore, highlights "gray zones" requiring further investigation.

Inter-observer reproducibility and intra-observer repeatability in 99mTc-pyrophosphate scan interpretation for diagnosis of transthyretin cardiac amyloidosis

AIM

The purpose of this study was to determine the inter- and intra-observer variability in 99mtechnetium-pyrophosphate (99mTc-PYP) scan interpretation for diagnosis of transthyretin cardiac amyloidosis (ATTR).

METHODS AND RESULTS

Our study cohort comprised 100 consecutive subjects referred for 99mTc-PYP imaging based on clinical suspicion of ATTR cardiac amyloidosis. Myocardial 99mTc-PYP uptake was assessed by both visual (comparison of myocardial to rib uptake) and semi-quantitative (heart-to-contralateral lung uptake ratio, H:CL) methods. Twenty scans were analyzed twice, at least 48 hours apart, by each of two independent observers. Patients with visual scores of ≥ 2 on planar imaging as well as myocardial uptake on SPECT/CT were classified as ATTR positive. Diagnosis of ATTR by visual 99mTc-PYP grade was perfectly reproducible [concordance: positive and negative scans 100% (53/53 and 47/47, respectively). Both inter- and intra-observer correlations for H:CL ratio (r2 = 0.90, 0.99 (Observer 1) and 0.98 (Observer 2), respectively) and repeatability values on Bland-Altman plots were excellent. The coefficient of variation (%) for Observers 1 and 2 was 3.21 (2.14 to 4.29) and 7.49 (4.95 to 10.09), respectively. In addition, there was 100% concordance in positive and negative scan interpretation by visual grading between novice CV imagers (< 3 years' experience) and an experienced CV imager (10 years' experience).

CONCLUSIONS

This study showed excellent inter-observer reproducibility and intra-observer repeatability of 99mTc-PYP visual scan interpretation and H:CL ratio for diagnosis of cardiac ATTR amyloidosis. Cardiac ATTR amyloidosis can be diagnosed reliably using 99mTc-PYP SPECT/CT by novice and experienced CV imagers.

Nuclear Cardiology in Women and Underrepresented Minority Populations

PURPOSE OF REVIEW

To outline sex-specific features of coronary artery disease (CAD) that should be considered in the assessment of women, including those from ethnic minority populations with suspected stable ischemic heart disease (IHD). Second, to determine the latest nuclear imaging tools available to assess microvascular CAD.

RECENT FINDINGS

Latest studies indicate that women are more likely to have ischemia with no obstructive coronary arteries (INOCA) and paradoxically have worse outcomes. Therefore, the evaluation of women with suspected IHD should include assessing microvascular and epicardial coronary circulation. The prevalence of CAD is increasing in younger women due to the increased cardiovascular disease (CVD) risk burden. CAD is often underrecognized in these patients. There is increasing recognition that INOCA is not benign and should be accurately diagnosed and managed. Nuclear imaging assesses the full spectrum of CAD from microvascular CAD to multivessel obstructive epicardial CAD. Further research on myocardial blood flow (MBF) assessment with PET MPI is needed.

Enhanced quantitative method for the diagnosis of grade 1 cardiac amyloidosis in 99mTc-DPD scintigraphy

The lack of a standardized cut-off value in the quantitative method and an inter-observer disagreement in the evaluation of the semiquantitative score in 99mTc-DPD scintigraphy leaves several patients with cardiac amyloidosis (CA) undiagnosed (grade 1 and H/CL: 1-1.49). This study aims to increase diagnostic productivity of 99mTc-DPD scintigraphy in CA. This is a retrospective study of 170 patients with suspicion of CA. A total of 81 (47.6%) were classified as transthyretin CA (TTR-CA) and 9 (5.3%) as light-chain CA (LC-CA) applying the visual score. An enhanced quantitative method and cut-off point were attempted to reclassify inconclusive patients and reduce inter-observer variability. Applying the proposed quantitative method, of the 19 patients with grade 1 uptake, 2 became grade 0 (none-CA), 2 were reclassified as grade 3 (TTR-CA), and 2 were regrouped as grade 2 (1 TTR-CA and 1 LC-CA). Adjusting the quantitative method's cut-off value to 1.3, four patients previously inconclusive were reclassified as TTR-CA, the diagnosis was confirmed in 3 and rejected in 1. When a 1.3 threshold is compared to 1.5, the sensitivity increases to 94% without reducing its specificity. The quantitative method improves the visual interpretation, reclassifying doubtful cases. The optimization of the cut-off value from 1.5 to 1.3 reclassifies a higher percentage of patients as TTR-CA with a higher sensitivity without reducing its specificity.

Multimodality imaging in patients with heart failure and preserved ejection fraction: an expert consensus document of the European Association of Cardiovascular Imaging

Nearly half of all patients with heart failure (HF) have a normal left ventricular (LV) ejection fraction (EF) and the condition is termed heart failure with preserved ejection fraction (HFpEF). It is assumed that in these patients HF is due primarily to LV diastolic dysfunction. The prognosis in HFpEF is almost as severe as in HF with reduced EF (HFrEF). In contrast to HFrEF where drugs and devices are proven to reduce mortality, in HFpEF there has been limited therapy available with documented effects on prognosis. This may reflect that HFpEF encompasses a wide range of different pathological processes, which multimodality imaging is well placed to differentiate. Progress in developing therapies for HFpEF has been hampered by a lack of uniform diagnostic criteria. The present expert consensus document from the European Association of Cardiovascular Imaging (EACVI) provides recommendations regarding how to determine elevated LV filling pressure in the setting of suspected HFpEF and how to use multimodality imaging to determine specific aetiologies in patients with HFpEF.

Opportunities for Earlier Diagnosis and Treatment of Cardiac Amyloidosis

Despite the rapid expansion of noninvasive (nonbiopsy) diagnosis, contemporary patients with cardiac amyloidosis too often present with advanced features of disease, such as diminished quality of life, elevated natriuretic peptides, and advanced heart failure. Therapeutics for transthyretin cardiomyopathy (ATTR-CM) are most effective when administered before significant symptoms of cardiac dysfunction manifest, making early identification of affected individuals of paramount importance. Community engagement and ensuring that a broad range of clinicians have working knowledge of how to screen for ATTR-CM in everyday practice will be an important step in moving disease identification further upstream. However, reliance on the appropriate and timely diagnosis by individual clinicians may continue to underperform. This review highlights how targeted screening of special populations may facilitate earlier diagnosis. Systems of care that operationalize screening of high-risk subpopulations and prospective validation of novel approaches to ATTR-CM identification are needed.

Cardiac magnetic resonance in the assessment of hypertrophic cardiomyopathy phenotypes and stages - pictorial review

The aim of this paper is to present recent advances in hypertrophic cardiomyopathy (HCM) diagnosis and treatment based on a literature review. Special emphasis has been placed on the role of cardiac magnetic resonance imaging (CMR) for the assessment of morphological and functional consequences of different stages of HCM including prognostication. The text is illustrated with the images and data of the HCM patients diagnosed with CMR study in our hospital. CMR is an important tool, particularly relevant in novel risk factors and LV dysfunction groups. The HCM group with overt left ventricular dysfunction is underrecognized, often labelled by clinicians as dilated cardiomyopathy. Advanced diagnostic and management strategies effectively influence the natural history of HCM.

Global Left Ventricular Myocardial Work Efficiency in Heart Failure Patients with Cardiac Amyloidosis: Pathophysiological Implications and Role in Differential Diagnosis

Introduction

Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy and a common cause of heart failure with preserved and mid-range ejection fraction (HFpEF and HFmrEF). Left ventricular (LV) systolic assessment is pivotal in differential diagnostic and prognostic stratification in CA. However, nondeformation and deformation-based parameters classically implied had many limitations. Myocardial work (MW) has been recently introduced for the evaluation of myocardial performance, in a load-independent fashion, in patients with cardiomyopathies.

Aims

This study aimed to evaluate MW parameters in LV performance assessment in CA and their possible role in differential diagnosis between AL and ATTR forms, compared with other echocardiographic parameters, also exploring the possible association between MW parameters and blood biomarkers.

Materials and Methods

The study population consisted of 25 patients with CA (10 with AL amyloidosis and 15 with wild-type ATTR [ATTRwt] form) and HFpEF or HFmrHF, enrolled between March 2018 and December 2019, undergoing a comprehensive clinical, biochemical, and imaging evaluation. Ten healthy individuals were studied as controls. ATTR patients had a noninvasive diagnosis of wtATTR-CA (positive ^99mTc-hydroxy methylene-diphosphonate scintigraphy with a negative hematological screening), while AL patients underwent endomyocardial biopsy. All patients underwent standard transthoracic echocardiography. MW and related indices were estimated using a vendor-specific module.

Results

Compared to the ATTRwt group, patients in the AL group showed a more pronounced myocardial performance impairment assessed by Global Word Efficiency (GWE: 83.5% ± 6.3% vs. 88.2% ± 3.6%; P = 0.026). In multiple linear regression analysis, cardiac troponin I (Β = -0.55; P < 0.0001), global longitudinal strain (Β =0.35; P < 0.008), and regional relative strain ratio (Β = -0.30; P < 0.016) were significant predictors of GWE reduction in CA patients. At receiver operating characteristics curve analysis, among all other deformation-based and nondeformation-based echocardiographic parameters, GWE showed the highest area under the curve (AUC) (AUC 0.74; 95% CI: 0.55-0.96; P < 0.04). The optimal cutoff was determined by sensitivity/specificity analysis: a GWE < 86.5% identified patients with AL amyloidosis with a sensitivity and specificity, respectively, of 80.0% and 66.7%.

Conclusions

The results of our pivotal study seem to highlight the importance of new deformation parameters to study myocardial performance in patients with CA, and to differentiate between AL CA and ATTR CA.

An optimized imaging protocol for [99mTc]Tc-DPD scintigraphy and SPECT/CT quantification in cardiac transthyretin (ATTR) amyloidosis

BACKGROUND

In [99mTc]Tc-DPD scintigraphy for myocardial ATTR amyloidosis, planar images 3 hour p.i. and SPECT/CT acquisition in L-mode are recommended. This study investigated if earlier planar images (1 hour p.i.) are beneficial and if SPECT/CT acquisition should be preferred in H-mode (180° detector angle) or L-mode (90°).

METHODS

In SPECT/CT phantom measurements (NaI cameras, N = 2; CZT, N = 1), peak contrast recovery (CRpeak) was derived from sphere inserts or myocardial insert (cardiac phantom; signal-to-background ratio [SBR], 10:1 or 5:1). In 25 positive and 38 negative patients (reference: endomyocardial biopsy or clinical diagnosis), Perugini scores and heart-to-contralateral (H/CL) count ratios were derived from planar images 1 hour and 3 hour p.i.

RESULTS

In phantom measurements, accuracy of myocardial CRpeak at SBR 10:1 (H-mode, 0.95-0.99) and reproducibility at 5:1 (H-mode, 1.02-1.14) was comparable for H-mode and L-mode. However, L-mode showed higher variability of background counts and sphere CRpeak throughout the field of view than H-mode. In patients, sensitivity/specificity were ≥ 95% for H/CL ratios at both time points and visual scoring 3 hour. At 1 hour, visual scores showed specificity of 89% and reduced reader's confidence.

CONCLUSIONS

Early DPD images provided no additional value for visual scoring or H/CL ratios. In SPECT/CT, H-mode is preferred over L-mode, especially if quantification is applied apart from the myocardium.

Cardiovascular outcomes after cardiac resynchronization therapy in cardiac amyloidosis

Aims

Cardiac resynchronization therapy (CRT) is highly effective in dilated cardiomyopathy (DCM) patients with impaired left ventricular ejection fraction (LVEF) and left bundle block branch. In cardiac amyloidosis (CA) patients, left ventricular dysfunction and conduction defects are common, but the potential of CRT to improve cardiac remodelling and survival in this particular setting remains undefined. We investigated cardiovascular outcomes in CA patients after CRT implantation in terms of CRT echocardiographic response and major cardiovascular events (MACEs).

Methods and results

Our retrospective study included 47 CA patients implanted with CRT devices from January 2012 to February 2020, in nine French university hospitals (77 ± 6 years old, baseline LVEF 30 ± 8%) compared with propensity‐matched (1:1 for age, LVEF at implantation, and CRT indication) DCM patients with a CRT device. CA patients had lower rates of CRT response (absolute delta LVEF ≥ 10%) compared with DCM patients (36% vs. 70%, P = 0.002). After multivariate Cox analysis, CA was independently associated with MACE (hospitalization for heart failure/cardiovascular death) [hazard ratio (HR) 3.73, 95% confidence interval (CI) 1.85–7.54, P < 0.001], along with the absence of CRT response (HR 3.01, 95% CI 1.56–5.79, P = 0.001). The presence of echocardiographic CRT response (absolute delta LVEF ≥ 10%) was the only predictive factor of MACE‐free survival in CA patients (HR 0.36, 95% CI 0.15–0.86, P = 0.002).

Conclusion

Compared with a matched cohort of DCM patients, CA patients had a lower rate of CRT response and consequently a worse cardiovascular prognosis after CRT implantation. However, CRT could be beneficial even in CA patients given that CRT response was associated with better cardiac outcomes in this population.

Artificial Intelligence-Enhanced Electrocardiogram for the Early Detection of Cardiac Amyloidosis

OBJECTIVE

To develop an artificial intelligence (AI)-based tool to detect cardiac amyloidosis (CA) from a standard 12-lead electrocardiogram (ECG).

METHODS

We collected 12-lead ECG data from 2541 patients with light chain or transthyretin CA seen at Mayo Clinic between 2000 and 2019. Cases were nearest neighbor matched for age and sex, with 2454 controls. A subset of 2997 (60%) cases and controls were used to train a deep neural network to predict the presence of CA with an internal validation set (n=999; 20%) and a randomly selected holdout testing set (n=999; 20%). We performed experiments using single-lead and 6-lead ECG subsets.

RESULTS

The area under the receiver operating characteristic curve (AUC) was 0.91 (CI, 0.90 to 0.93), with a positive predictive value for detecting either type of CA of 0.86. By use of a cutoff probability of 0.485 determined by the Youden index, 426 (84%) of the holdout patients with CA were detected by the model. Of the patients with CA and prediagnosis electrocardiographic studies, the AI model successfully predicted the presence of CA more than 6 months before the clinical diagnosis in 59%. The best single-lead model was V5 with an AUC of 0.86 and a precision of 0.78, with other single leads performing similarly. The 6-lead (bipolar leads) model had an AUC of 0.90 and a precision of 0.85.

CONCLUSION

An AI-driven ECG model effectively detects CA and may promote early diagnosis of this life-threatening disease.

The Cooperative Relationship Between ASNC and JSNC

The Japanese Society of Nuclear Cardiology (JSNC) and the American Society of Nuclear Cardiology (ASNC) has a cooperative relationship through a memorandum of understanding (MOU), based on which we hold a joint symposium in the JSNC annual meeting in early summer. In addition to the joint symposium this year, a joint webinar was held in early June. The theme of the joint symposium and webinar was cardiac amyloidosis. We consider the success of this collaborative work to be the fruit of the close friendship between JSNC and ASNC. The cooperative relationship between JSNC and ASNC will continue to grow.

99mTc-DPD scintigraphy in immunoglobulin light chain (AL) cardiac amyloidosis

Aims

Technetium-99m-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (^99mTc-DPD scintigraphy) is recognized as highly accurate for the non-invasive diagnosis of transthyretin (ATTR) cardiac amyloidosis (CA). A proportion of patients with immunoglobulin light chain (AL) CA have also been reported to show cardiac ^99mTc-DPD uptake. Herein, we assessed the frequency and degree of cardiac ^99mTc-DPD uptake and its clinical significance among patients with AL CA.

Methods and results

Between 2010 and 2017, 292 consecutive patients with AL CA underwent ^99mTc-DPD scintigraphy and were included in this study: 114 (39%) had cardiac ^99mTc-DPD uptake: grade 1 in 75%, grade 2 in 17%, and grade 3 in 8% of cases. Patients with cardiac ^99mTc-DPD uptake had poorer cardiac systolic function and higher N-terminal pro-brain natriuretic peptide. No differences were noted in cardiac magnetic resonance parameters between patients with and without cardiac ^99mTc-DPD uptake (N = 19 and 42, respectively). Patients with cardiac ^99mTc-DPD uptake showed a trend to worse survival than those with no uptake (log-rank P = 0.056). Among 22 patients who underwent serial ^99mTc-DPD scintigraphy, 5 (23%) showed reduction in the grade of cardiac uptake.

Conclusions

In this large cohort of patients with AL CA, ^99mTc-DPD scintigraphy ∼40% of cases showed cardiac uptake, including grade 2–3 in 10% of all patients (25% of those with cardiac ^99mTc-DPD uptake). Cardiac ^99mTc-DPD uptake was associated with poorer cardiac function and outcomes. These data highlight the critical importance of ruling out AL amyloidosis in all patients with cardiac ^99mTc-DPD uptake to ensure such patients are not assumed to have ATTR CA.

State of the art of 18F-FDG PET/CT application in inflammation and infection: a guide for image acquisition and interpretation

AIM

The diagnosis, severity and extent of a sterile inflammation or a septic infection could be challenging since there is not one single test able to achieve an accurate diagnosis. The clinical use of 18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) imaging in the assessment of inflammation and infection is increasing worldwide. The purpose of this paper is to achieve an Italian consensus document on [18F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases, such as osteomyelitis (OM), prosthetic joint infections (PJI), infective endocarditis (IE), prosthetic valve endocarditis (PVE), cardiac implantable electronic device infections (CIEDI), systemic and cardiac sarcoidosis (SS/CS), diabetic foot (DF), fungal infections (FI), tuberculosis (TBC), fever and inflammation of unknown origin (FUO/IUO), pediatric infections (PI), inflammatory bowel diseases (IBD), spine infections (SI), vascular graft infections (VGI), large vessel vasculitis (LVV), retroperitoneal fibrosis (RF) and COVID-19 infections.

METHODS

In September 2020, the inflammatory and infectious diseases focus group (IIFG) of the Italian Association of Nuclear Medicine (AIMN) proposed to realize a procedural paper about the clinical applications of [18F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases. The project was carried out thanks to the collaboration of 13 Italian nuclear medicine centers, with a consolidate experience in this field. With the endorsement of AIMN, IIFG contacted each center, and the pediatric diseases focus group (PDFC). IIFG provided for each team involved, a draft with essential information regarding the execution of [18F]FDG PET/CT or PET/MRI scan (i.e., indications, patient preparation, standard or specific acquisition modalities, interpretation criteria, reporting methods, pitfalls and artifacts), by limiting the literature research to the last 20 years. Moreover, some clinical cases were required from each center, to underline the teaching points. Time for the collection of each report was from October to December 2020.

RESULTS

Overall, we summarized 291 scientific papers and guidelines published between 1998 and 2021. Papers were divided in several sub-topics and summarized in the following paragraphs: clinical indications, image interpretation criteria, future perspectivess and new trends (for each single disease), while patient preparation, image acquisition, possible pitfalls and reporting modalities were described afterwards. Moreover, a specific section was dedicated to pediatric and PET/MRI indications. A collection of images was described for each indication.

CONCLUSIONS

Currently, [18F]FDG PET/CT in oncology is globally accepted and standardized in main diagnostic algorithms for neoplasms. In recent years, the ever-closer collaboration among different European associations has tried to overcome the absence of a standardization also in the field of inflammation and infections. The collaboration of several nuclear medicine centers with a long experience in this field, as well as among different AIMN focus groups represents a further attempt in this direction. We hope that this document will be the basis for a "common nuclear physicians' language" throughout all the country.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40336-021-00445-w.

Wild-type TTR amyloidosis among patients with unexplained heart failure and systolic LV dysfunction

AIM

Transthyretin cardiac amyloidosis (ATTR-CA) is an increasingly recognized cause of heart failure (HF) with preserved left ventricular ejection fraction (LVEF), typically presenting as restrictive cardiomyopathy. The potential co-existence of ATTR-CA with systolic heart failure has not been studied. The aim of this study is to describe the prevalence of ATTR-CA and its clinical characteristics in HF patients with reduced LVEF.

METHODS

Patients with an unexplained cause of LV systolic dysfunction were screened for ATTR-CA by a 99mTc-PYP planar scintigraphy. Patients in whom presence of ≥ 2 uptake was confirmed by SPECT imaging were included. Their clinical, laboratory and echocardiographic data were collected.

RESULTS

Out of 75 patients (mean age 65±12 years, LVEF 35.8±7.9%) included in this study, 7 (9.3%) patients (mean age 75±6 years, LVEF 32.0±8.3%) had ATTR-CA. Patients with ATTR-CA were more symptomatic at diagnosis (NYHA FC 3-4 (86% vs 35% (p = 0.03)) and had a more severe clinical course evident by recurrent hospitalizations for HF, and a need for intravenous diuretic treatment (p = 0.04 and p<0.01, respectively) at follow-up, compared with patients with no ATTR-CA. Patients with ATTR-CA had similar LVEF but a clear trend for larger LV mass index (157.1±60.6 g/m2 vs. 121.0±39.5 g/m2, p = 0.07) and a larger proportions of ATTR-CA patients had IVS thickness >13 mm (57.1% vs 13.1%, p = 0.02) as compared to HF patients with no ATTR-CA.

CONCLUSION

In our study, a meaningful percentage of patients with unexplained LV dysfunction had a co-existing ATTR-CA indicating that the clinical heterogeneity of ATTR-CA is much broader than previously thought.

Clinicopathological features of clinically undiagnosed sporadic transthyretin cardiac amyloidosis: a forensic autopsy-based series

OBJECTIVE

To investigate the clinicopathological features of sporadic amyloid transthyretin (ATTR) amyloidosis.

METHODS

We evaluated 1698 serial Japanese forensic autopsy patients. The extent and amount of ATTR deposition in the 16 cardiac regions, including the conduction system, were semiquantitatively evaluated. Ward's hierarchical cluster analysis was applied to classify the cases into subgroups. Also, the relationship between ATTR and amyloid atrial natriuretic factor (AANF) was evaluated.

RESULTS

Forty-four cardiac ATTR amyloidosis patients (mean age 85.4 ± 5.7 years; 22 men) without history of hereditary polyneuropathy were identified (2.6% of all patients, 8.8% of those aged ≥80 years). All the 44 patients were not in the bedridden state and died-out-of-hospital scenarios. Of these, 10 (23%) were sudden death. Cluster analysis classified the patients into three groups (mild, atria-predominant and the severe deposition group). Amyloid deposition had already started simultaneously from each atrium and ventricle; however, the atrial septum and basilar ventricular septum were the sites that revealed the most frequent deposition. Also, a possible association between ATTR and AANF deposits was identified.

CONCLUSIONS

Sporadic ATTR amyloidosis patients might already be susceptible to a risk for sudden death even from an early-phase. Also, ATTR amyloid deposition in such cases might progress with a certain degree of regularity.

Nuclear Imaging for the Diagnosis of Cardiac Amyloidosis in 2021

Cardiac amyloidosis is caused by the deposition of misfolded protein fibrils into the extracellular space of the heart. The diagnosis of cardiac amyloidosis remains challenging because of the heterogeneous manifestations of the disease. There are many different types of amyloidosis with light-chain (AL) amyloidosis and transthyretin (ATTR) amyloidosis being the most common types of cardiac amyloidosis. Endomyocardial biopsy is considered the gold standard for diagnosing cardiac amyloidosis and differentiating amyloid subtypes, but its use is limited because of the invasive nature of the procedure, with risks for complications and the need for specialized training and centers to perform the procedure. Radionuclide cardiac imaging has recently become the most commonly performed test for the diagnosis of ATTR amyloidosis but is of limited value for the diagnosis of AL amyloidosis. Positron emission tomography has been increasingly used for the diagnosis of cardiac amyloidosis and its applications are expected to expand in the future. Imaging protocols are under refinement to achieve better quantification of the disease burden and prediction of prognosis.

Nuclear cardiology: state of the art

Radionuclide imaging remains an essential component of modern cardiology. There is overlap with the information from other imaging techniques, but no technique is static and new developments have expanded its role. This review focuses on ischaemic heart disease, heart failure, infection and inflammation. Radiopharmaceutical development includes the wider availability of positron emission tomography (PET) tracers such as rubidium-82, which allows myocardial perfusion to be quantified in absolute terms. Compared with alternative techniques, myocardial perfusion scintigraphy PET and single photon emission computed tomography (SPECT) have the advantages of being widely applicable using exercise or pharmacological stress, full coverage of the myocardium and a measure of ischaemic burden, which helps to triage patients between medical therapy and revascularisation. Disadvantages include the availability of expertise in some cardiac centres and the lack of simple SPECT quantification, meaning that global abnormalities can be underestimated. In patients with heart failure, despite the findings of the STICH (Surgical Treatment for Ischemic Heart Failure) trial, there are still data to support the assessment of myocardial hibernation in predicting when abolition of ischaemia might lead to improvement in ventricular function. Imaging of sympathetic innervation is well validated, but simpler markers of prognosis mean that it has not been widely adopted. There are insufficient data to support its use in predicting the need for implanted devices, but non-randomised studies are promising. Other areas where radionuclide imaging is uniquely valuable are detection and monitoring of endocarditis, device infection, myocardial inflammation in sarcoidosis, myocarditis and so on, and reliable detection of deposition in suspected transthyretin-related amyloidosis.

Expert consensus on the monitoring of transthyretin amyloid cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a life-threatening condition with a heterogeneous clinical presentation. The recent availability of treatment for ATTR-CM has stimulated increased awareness of the disease and patient identification. Stratification of patients with ATTR-CM is critical for optimal management and treatment; however, monitoring disease progression is challenging and currently lacks best-practice guidance. In this report, experts with experience in treating amyloidosis and ATTR-CM developed consensus recommendations for monitoring the course of patients with ATTR-CM and proposed meaningful thresholds and frequency for specific parameters. A set of 11 measurable features across three separate domains were evaluated: (i) clinical and functional endpoints, (ii) biomarkers and laboratory markers, and (iii) imaging and electrocardiographic parameters. Experts recommended that one marker from each of the three domains provides the minimum requirements for assessing disease progression. Assessment of cardiac disease status should be part of a multiparametric evaluation in which progression, stability or improvement of other involved systems in transthyretin amyloidosis should also be considered. Additional data from placebo arms of clinical trials and future studies assessing ATTR-CM will help to elucidate, refine and define these and other measurements.