Noninvasive etiologic diagnosis of cardiac amyloidosis using 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy

Impact of tafamidis on myocardial strain in transthyretin amyloid cardiomyopathy

AIMS

The impact of tafamidis on myocardial strain in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) have been barely investigated. We aimed to determine tafamidis-induced changes using serial speckle tracking echocardiography and to identify imaging parameters for specific therapy monitoring.

METHODS AND RESULTS

ATTR-CM patients underwent serial TTE with two-dimensional (2 D) speckle tracking imaging. Patients receiving tafamidis free acid 61 mg (n = 62) or tafamidis meglumine 20 mg (n = 21) once daily (QD) showed stable measurements at follow-up (61 mg: 8.5 months, 20 mg: 7.0 months) in LV global longitudinal strain (GLS) (61 mg: -11.75% vs. -11.58%, p = 0.534; 20 mg: -10.61% vs. -10.12%, p = 0.309), right ventricular (RV) GLS (61 mg: -14.18% vs. -13.72%, p = 0.377; 20 mg: -14.53% vs. -13.99%, p = 0.452) and left atrial (LA) reservoir strain (LASr; 61 mg: 8.80% vs. 9.42%, p = 0.283; 20 mg: 8.23% vs. 8.67%, p = 0.589), whereas treatment-naïve ATTR-CM patients (n = 54) had clear signs of disease progression at the end of the observation period (10.5 months; LV-GLS: -11.71% vs. -10.59%, p = 0.001; RV-GLS: -14.36% vs. -12.99%, p = 0.038; LASr: 10.67% vs. 8.41%, p = 0.005). Between-group comparison at follow-up revealed beneficial effects of tafamidis free acid 61 mg on LASr (p = 0.003) and the LV (LV-GLS: p = 0.030, interventricular septum (IVS): p = 0.006), resulting in clinical benefits (six-minute walk distance (6-MWD): p = 0.006, NT-proBNP: p= <0.001), while patients treated with tafamidis meglumine 20 mg QD showed positive effects on LASr (p = 0.039), but no differences with respect to the LV (LV-GLS: p = 0.274, IVS: p = 0.068) and clinical status (6-MWD: p = 0.124, NT-proBNP: p = 0.053) compared to the natural course.

CONCLUSIONS

Treatment with tafamidis free acid 61 mg in ATTR-CM patients delays the deterioration of LA and LV longitudinal function, resulting in significant clinical benefits compared with natural history. Serial TTE with 2 D speckle tracking imaging may be appropriate for disease-specific therapy monitoring.

The short and long-term characteristics and outcomes of patients with grade 1 myocardial uptake on cardiac scintigraphy

AIMS

This study aimed to characterize the final diagnosis and prognosis of patients with grade 1 myocardial scintigraphy uptake, which is an unequivocal result for the diagnosis of transthyretin cardiac amyloidosis (ATTR-CA) requiring further invasive investigation with tissue biopsy.

METHODS AND RESULTS

We retrospectively compared the clinical and imaging parameters of patients suspected for ATTR-CA (based on clinical and echocardiographic parameters) with grade 1 vs. grades 2/3 technetium pyrophosphate uptake on cardiac scintigraphy. Prospectively, grade 1 patients underwent re-evaluation for ATTR-CA at long term. Of the 132 ATTR-CA suspected patients, 89 (67%) were diagnosed as grade 1 and 43 (33%) as grades 2/3 uptake. Grade 1 vs. grades 2/3 patients were younger and female predominant with lower biomarker levels and left ventricular mass. Based on available imaging and pathology findings, only 6 out of the 89 patients with grade 1 uptake (7%) were finally diagnosed with light-chain cardiac amyloidosis, whereas no patient was diagnosed with ATTR-CA. At 2 [interquartile range (IQR) 0.75, 3.25] years of follow-up, the survival of patients with grade 1 vs. grades 2/3 uptake was significantly better [hazard ratio 0.271 (95% confidence interval 0.130 to 0.563, P = 0.0005)]. Prospectively, 30 patients with grade 1 uptake were re-evaluated at a median follow-up of 3.2 (IQR 2.2, 3.9) years. Their New York Heart Association class, biomarker levels, and echocardiography findings remained stable. No patient (0/25) demonstrated grades 2/3 uptake at repeated long-term scintigraphy.

CONCLUSIONS

Patients with suspected ATTR-CA and a grade 1 scintigraphy uptake demonstrate a stable clinical, laboratory, imaging, and scintigraphy phenotype along with a benign survival profile at long-term follow-up. Larger studies should define the optimal evaluation strategy in this population.

Description of a different quantification method for amyloid burden (DPDload) and validation of SPECT/CT in cardiac amyloidosis

BACKGROUND

Bone tracers such as ^99mTc-DPD have shown high sensitivity and specificity in the non-invasive diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). This study aims to validate SPECT/CT and assess the usefulness of uptake quantification (DPDload) in the myocardial tissue as potential information on the amyloid burden.

METHODS

In a retrospective analysis of 46 patients with suspected CA, 23 cases with ATTR-CA had two quantification methods conducted to estimate amyloid burden (DPDload) through planar scintigraphic scans and a SPECT/CT.

RESULTS

SPECT/CT significantly provided an added value in the patient's diagnosis with CA (P<.05). The estimation of the amyloid burden substantiated that the most affected wall of the LV is the interventricular septum in most cases and the existence of a significant relationship between the Perugini score uptake and the DPDload.

CONCLUSIONS

We validate the need for SPECT/CT to complement planar imaging in diagnosing ATTR-CA. For its part, quantifying the amyloid load continues to be a complex area of research. It requires further studies with a larger number of patients to validate a standardized method of amyloid load quantification, both for diagnosis and treatment monitoring.

Ser77Tyr transthyretin amyloidosis in Israel: Initial manifestations and diagnostic features

OBJECTIVE

Amyloidosis due to the transthyretin Ser77Tyr mutation (ATTRS77Y) is a rare autosomal-dominant disorder, characterized by carpal-tunnel syndrome, poly- and autonomic-neuropathy, and cardiomyopathy. However, related symptoms and signs are often nonspecific and confirmatory tests are required. We describe the age and frequency of early symptoms and diagnostic features among individuals of Jewish Yemenite descent in Israel.

METHODS

Records of mutation carriers were retrospectively reviewed. ATTRS77Y diagnosis was defined by the presence of amyloid in tissue and/or amyloid-related cardiomyopathy.

RESULTS

We identified the Ser77Tyr mutation at the heterozygous state in 19 amyloidosis patients (mean age at diagnosis: 62 ± 5.7 years, range 49-70) and 30 amyloid-negative carriers. The probability for disease diagnosis increased from 4.4% at age 49 to 100% at 70 and occurred earlier in males. Initial symptoms preceded diagnosis by 5 ± 3.8 years (range 0-12) and were commonly sensory changes in the extremities. Erectile dysfunction predated these in 8/13 (62%) males. In two patients cardiac preceded neurological symptoms. Two patients declined symptoms. Electrophysiological studies near the time of diagnosis indicated a median neuropathy at the wrist in 18/19 (95%) and polyneuropathy in 13/19 (68%). Skin biopsy revealed epidermal denervation in 15/16 (94%) patients. Cardiomyopathy was identified in 16/19 (84%). Sensory complaints or epidermal denervations were present in 17/30 (57%) of amyloid-negative carriers and co-occurred in 10/30 (33%).

INTERPRETATION

ATTRS77Y symptoms commonly occur after age 50, but may begin earlier. Median neuropathy, skin denervation and cardiomyopathy are frequently identified. Symptoms may be absent in patients and common in amyloid-negative carriers.

[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.

Quantitative 99mTc-DPD-SPECT/CT assessment of cardiac amyloidosis

INTRODUCTION

Transthyretin (ATTR) amyloidosis is responsible for the majority of cardiac amyloidosis (CA) cases and can be reliably diagnosed with bone scintigraphy and the visual Perugini score. We aimed to implement a quantification method of cardiac amyloid deposits in patients with suspected cardiac amyloidosis and to compare performance to visual scoring.

METHODS AND MATERIALS

136 patients received 99mTc-DPD-bone scintigraphy including SPECT/CT of the thorax in case of suspicion of cardiac amyloidosis. Imaging phantom studies were performed to determine the scaling factor for standardized uptake value (SUV) quantification from SPECT/CT. Myocardial tracer uptake was quantified in a whole heart volume of interest.

RESULTS

Forty-five patients were diagnosed with CA. A strong relationship between cardiac SUVmax and Perugini score was found (Spearman r 0.75, p < 0.0001). Additionally, tracer uptake in bone decreased with increasing cardiac SUVmax and Perugini score (p < 0.0001). ROC analysis revealed good performance of the SUVmax for the detection of ATTR-CA with AUC of 0.96 ± 0.02 (p < 0.0001) with sensitivity 98.7% and specificity 87.2%.

CONCLUSION

We demonstrate an accessible and accurate quantitative SPECT approach in CA. Quantitative assessment of the cardiac tracer uptake may improve diagnostic accuracy and risk classification. This method may enable monitoring and assessment of therapy response in patients with ATTR amyloidosis.

SGLT2 inhibitor therapy for transthyretin amyloid cardiomyopathy: early tolerance and clinical response to dapagliflozin

AIMS

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve clinical outcomes in heart failure patients with reduced and preserved left ventricular ejection fraction (LVEF), but have not yet been investigated in transthyretin amyloid cardiomyopathy (ATTR-CM). This study aimed to evaluate tolerability, clinical outcomes, and changes in NT-proBNP levels and glomerular filtration rate (GFR) in ATTR-CM patients treated with dapagliflozin.

METHODS AND RESULTS

Patients with stable, tafamidis-treated ATTR-CM were retrospectively evaluated at the initiation of dapagliflozin and 3 months thereafter. Tafamidis-treated ATTR-CM patients without SGLT2i served as a reference cohort. Overall, SLGT2i therapy was initiated in 34 patients. Seventeen patients with stable disease on tafamidis, who were subsequently started on dapagliflozin, were included in the analysis. Patients selected for SGLT2i presented with signs of advanced disease, evidenced by higher Gillmore disease stage (stage ≥2: 53% vs. 27.5%; P = 0.041), baseline median NT-proBNP [median (IQR) 2668 pg/mL (1314-3451) vs. 1424 (810-2059); P = 0.038] and loop diuretic demand (76.5% vs. 45% of patients; P = 0.044), and lower LVEF (46.6 ± 12.9 vs. 53.7 ± 8.7%; P = 0.019) and GFR (51.8 ± 16.5 vs. 68.5 ± 18.6 mL/min; P = 0.037) compared with the reference cohort. At 3-month follow-up, a numerical decrease in NT-proBNP levels was observed in 13/17 (76.5%) patients in the dapagliflozin (-190 pg/mL, IQR: -1,028-71, P = 0.557) and 27/40 (67.5%) of patients in the control cohort (-115 pg/mL, IQR: -357-105, P = 0.551). Other disease parameters remained stable and no adverse events occurred.

CONCLUSIONS

In tafamidis-treated ATTR-CM patients, initiation of dapagliflozin was well tolerated. The efficacy of SGLT2i therapy in patients with ATTR-CM needs to be studied in randomized controlled trials.

99m Technetium-pyrophosphate bone scan: A potential biomarker for the burden of transthyretin amyloidosis in skeletal muscle: A preliminary study

INTRODUCTION/AIMS

Transthyretin amyloidosis (ATTR) proteins can infiltrate skeletal muscle and infrequently cause a myopathy. ^99m Technetium-pyrophosphate (^99m Tc-PYP) is a validated biomarker for cardiac involvement in variant and wild-type ATTR (ATTRv and ATTRwt, respectively). The aim of this study was to test the hypothesis that ^99m Tc-PYP is a biomarker for muscle burden of ATTR.

METHODS

Radioisotope uptake in the deltoid muscles of patients with ATTR was compared to uptake in control subjects without amyloidosis in a retrospective study. ^99m Tc-PYP scans were evaluated in 11 patients with ATTR (7 ATTRv, 4 ATTRwt) and 14 control subjects. Mean count (MC) values were measured in circular regions of interest (ROIs) 2.5-3.8 cm² in area. Tracer uptake was quantified in the heart, contralateral chest (CC), and deltoid muscles.

RESULTS

Tracer uptake was significantly higher over the deltoids and heart but not the CC, in patients with ATTR than in control subjects. MC values were 120.1 ± 43.7 (mean ± SD) in ATTR patients and 78.9 ± 20.4 in control subjects over the heart (p = 0.005), 73.3± 21.0 and 63.5 ± 14.4 over CC (p = 0.09), and 37.0 ± 11.7 and 26.0 ± 7.1 averaged over both deltoid muscles (p = 0.014).

DISCUSSION

^99m Tc-PYP is a potential biomarker for ATTR amyloid burden in skeletal muscle.

99mTc Bone-Avid Tracer Cardiac Scintigraphy: Role in Noninvasive Diagnosis of Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is an overlooked cause of heart failure, with substantial morbidity and mortality. The emergence of several novel therapies has fueled the interest in early and accurate diagnosis of ATTR-CA so that potentially life-saving pharmacologic therapy can be administered in a timely manner. The most promising imaging modality and biomarker is SPECT imaging with technetium 99m (99mTc)-radiolabeled bone-seeking tracers, which have high specificity in the diagnosis of ATTR-CA, potentially obviating biopsy. In this article, the authors provide a focused review on the use of 99mTc pyrophosphate (PYP), 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD), and hydroxymethylene diphosphonate (HMDP) for diagnosis of ATTR-CA, present a systematic approach to interpretation of the scans, and highlight several common pitfalls to illustrate important diagnostic principles for accurate interpretation of these images. The authors indicate when to use endomyocardial biopsy for the diagnosis of cardiac amyloidosis and conclude with a section on quantitation of 99mTc-PYP/DPD/HMDP imaging.

Does [99mTc]-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) soft tissue uptake allow the identification of patients with the diagnosis of cardiac transthyretin-related (ATTR) amyloidosis with higher risk for polyneuropathy?

BACKGROUND

With the introduction of several drugs for the therapy of transthyretin-related amyloidosis (ATTR) which slow down the disease, early detection of polyneuropathy (PNP) is becoming increasingly of interest. [99mTc]-3,3-Diphosphono-1,2-Propanodicarboxylic Acid (DPD) bone scintigraphy, which is used for the diagnosis of cardiac (c)ATTR, can possibly make an important contribution in the identification of patients at risk for PNP.

METHODS

Fifty patients with cATTR, who underwent both planar whole-body DPD scintigraphy and nerve conduction studies (NCS) were retrospectively evaluated. A subgroup of 22 patients also underwent quantitative SPECT/CT of the thorax from which Standardized Uptake Values (SUVpeak) in the subcutaneous fat tissue of the left axillar region were evaluated.

RESULTS

The Perugini score was significantly increased in patients with cATTR and additional diagnosis of PNP compared to patients without (2.51 ± 0.51 vs 2.13 ± 0.52; P = 0.03). Quantitative SPECT/CT revealed that DPD uptake in the subcutaneous fat of the left axillar region was significantly increased in cATTR patients with compared to patients without (1.36 ± 0.60 vs 0.74 ± 0.52; P = 0.04).

CONCLUSION

This study suggests that DPD bone scintigraphy is a useful tool for identification of patients with cATTR and a risk for PNP due to increased DPD soft tissue uptake.

Cardiac transplantation in transthyretin amyloid cardiomyopathy: Outcomes from three decades of tertiary center experience

Aims

Transthyretin cardiac amyloidosis (ATTR-CM) is a progressive and fatal cardiomyopathy. Treatment options in patients with advanced ATTR-CM are limited to cardiac transplantation (CT). Despite case series demonstrating comparable outcomes with CT between patients with ATTR-CM and non-amyloid cardiomyopathies, ATTR-CM is considered to be a contraindication to CT in some centers, partly due to a perceived risk of amyloid recurrence in the allograft. We report long-term outcomes of CT in ATTR-CM at two tertiary centers.

Materials and methods and Results

We retrospectively evaluated ATTR-CM patients across two tertiary centers who underwent transplantation between 1990 and 2020. Pre-transplantation characteristics were determined and outcomes were compared with a cohort of non-transplanted ATTR-CM patients. Fourteen (12 male, 2 female) patients with ATTR-CM underwent CT including 11 with wild-type ATTR-CM and 3 with variant ATTR-CM (ATTRv). Median age at CT was 62 years and median follow up post-CT was 66 months. One, three, and five-year survival was 100, 92, and 90%, respectively and the longest surviving patient was Censored > 19 years post CT. No patients had recurrence of amyloid in the cardiac allograft. Four patients died, including one with ATTRv-CM from complications of leptomeningeal amyloidosis. Survival among the cohort of patients who underwent CT was significantly prolonged compared to UK patients with ATTR-CM generally (p < 0.001) including those diagnosed under age 65 years (p = 0.008) or with early stage cardiomyopathy (p < 0.001).

Conclusion

CT is well-tolerated, restores functional capacity and improves prognosis in ATTR-CM. The risk of amyloid recurrence in the cardiac allograft appears to be low.

Microcalcification and 99mTc-Pyrophosphate Uptake without Increased Bone Metabolism in Cardiac Tissue from Patients with Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is characterized by high ^99mTc-labeled bone tracer uptake in the heart. However, the mechanism of bone tracer uptake into the heart remains controversial. Since bone tracer uptake into metastatic bone tumors is thought to be associated with increased bone metabolism, we examined ^99mTc-pyrophosphate (PYP) scintigraphy findings, endomyocardial biopsy (EMB) tissue findings, and the expression of bone metabolism-related genes in the EMB tissues in patients with ATTR-CA, amyloid light-chain cardiac amyloidosis (AL-CA), and noncardiac amyloidosis (non-CA) in this study. The uptake of ^99mTc-PYP in the heart was significantly higher in the ATTR-CA patients than in the AL-CA and non-CA patients. A higher percentage of ATTR-CA EMB tissue showed von Kossa-positive microparticles: ATTR-CA, 62%; AL-CA, 33%; and non-CA, 0%. Calcified microparticles were identified using transmission electron microscopy. However, none of the osteogenic marker genes, osteoclastic marker genes, or phosphate/pyrophosphate-related genes were upregulated in the EMB samples from ATTR-CA patients compared to those from AL-CA and non-CA patients. These results suggest that active calcification-promoting mechanisms are not involved in the microcalcification observed in the heart in ATTR-CA. The mechanisms explaining bone tracer uptake in the heart, which is stronger than that in the ribs, require further investigation.

Real-Life Evaluation of an Algorithm for the Diagnosis of Cardiac Amyloidosis

OBJECTIVE

To evaluate the real-life use of a modified Gillmore algorithm with a "one-stop-shop" approach, bone scintigraphy (BS), a monoclonal gammopathy test (GT), a salivary gland biopsy (SGB), and genetic testing performed at the same time for the diagnosis of cardiac amyloidosis at the French National Reference Centre for Cardiac Amyloidosis (Henri Mondor Hospital, Créteil, France).

METHODS

This retrospective cohort study included a total of 1222 patients with suspected amyloidosis who underwent BS and GT between June 2008 and May 2019.

RESULTS

Of 1222 patients, 349 had no cardiac uptake on BS and negative GT (BS-/GT-), 276 were BS-/GT positive (GT+), 420 patients were BS+/GT-, and 177 were BS+/GT+. Our one-stop-shop check-up enabled us to diagnose 892 (72.9%) patients; 330 (27.0%) patients required additional examinations, such as mass spectrometry and/or a cardiac biopsy. This subset notably included 112 patients with amyloid light chain amyloidosis. More than 64% of the patients with transthyretin amyloidosis or another type of amyloidosis were diagnosed during the one-stop shop visit. Sensitivity and specificity of BS for transthyretin amyloidosis diagnosis was 99% and 96%, respectively. For amyloid light chain diagnosis, sensitivity and specificity were 100% and 76%, respectively, for GT and 54% and 100%, respectively, for SGB. Of 910 transthyretin genetic tests, 205 (17%) detected mutations.

CONCLUSION

The results of our real-life cohort study confirmed the ability of a one-stop-shop approach with a modified Gillmore algorithm to diagnose cardiac amyloidosis and the interest of simultaneous testing for earlier diagnosis. The SGB has diagnostic value because it is easy, quick, and less invasive than a cardiac biopsy.

Peripheral nerve involvement in wild-type transthyretin amyloidosis

INTRODUCTION AND AIMRPOSE

Neurological involvement other than carpal tunnel syndrome (CTS) has rarely been observed in wild-type transthyretin amyloidosis (ATTRwt). The aim of our study was to investigate peripheral nerve involvement in ATTRwt.

METHODS

Patients diagnosed with ATTRwt (negative molecular testing, confirmed cardiac uptake at bone scintigraphy, Perugini score 2 or 3) were considered. Sixteen men (mean age 75 ± 6.2, range 65-86 years) were enrolled. Neurological examination (Neuropathy Impairment Score, NIS), questionnaires on autonomic function and quality of life (QoL), electrodiagnostic studies (EDX), nerve ultrasound, and Sudoscan (electrochemical skin conductance, ESC) were performed. The presence of peripheral neuropathy was defined according to the detection of any abnormal finding at lower limbs other than CTS at EDX studies, regardless of NIS scores.

RESULTS

Ten (62.5%) ATTRwt had abnormal NIS scores. At EDX, CTS was observed in 13/16 (81.2%), with 3/16 (18.8%) presenting also axonal peripheral neuropathy. Extensive workup ruled out common causes of neuropathy. Eight (50%) ATTRwt patients had orthostatic hypotension (OH). Abnormal ESC was observed in 9/14 (64%) ATTRwt patients.

DISCUSSION

Despite being uncommon, we observed peripheral nervous system involvement in ATTRwt (large and small fiber dysfunction). Being elderly, ATTRwt patients may have age-related conditions acting as confounding factors for the diagnosis of neuropathy that however can be detected with a careful examination and use of specific tests, including those for autonomic dysfunction.

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.

[Utility of the Method for Calculating the Heart to Contralateral Ratio for Cardiac Amyloidosis by Using Ray-summation Images in 99mTc-pyrophosphate Scintigraphy]

PURPOSE

The purpose of this study was to avoid the influence of background activity in the calculation of heart to contralateral ratio (H/CL) in ^99mTc-pyrophosphate (PYP) scintigraphy for diagnosis of cardiac amyloidosis. Therefore, we investigated the utility of the H/CL calculation method using ray-summation (ray-sum) images created by multi-planar reconstruction and summing slices of the heart range from single-photon emission computed tomography (SPECT) images.

METHODS

The subjects were 33 patients who underwent ^99mTc-PYP planar and SPECT/CT at 3 hours after injection. Ray-summation axial (ray-sum axial) and ray-summation coronal (ray-sum coronal) images were created and H/CL was calculated. We compared the differences in sensitivity, specificity, accuracy, and area under the curve (AUC) between the conventional method and our method, and calculated the cutoff values.

RESULTS

Comparison of the conventional method and our method showed no significant difference in sensitivity and AUC, while specificity was significantly improved to 97% (p=0.003) of ray-sum axial image and 90% (p=0.01) of ray-sum coronal image, and accuracy was significantly improved to 94% (p=0.02) of ray-sum axial image.

CONCLUSION

The H/CL calculation method using ray-sum images had higher diagnostic performance than the conventional method, with optimal cutoff of ray-sum axial images 3.07 and ray-sum coronal images 2.77.

Amyloidosis: What does pathology offer? The evolving field of tissue biopsy

Since the mid-nineteenth century pathology has followed the convoluted story of amyloidosis, recognized its morphology in tissues and made identification possible using specific staining. Since then, pathology studies have made a significant contribution and advanced knowledge of the disease, so providing valuable information on the pathophysiology of amyloid aggregation and opening the way to clinical studies and non-invasive diagnostic techniques. As amyloidosis is a heterogeneous disease with various organ and tissue deposition patterns, histology evaluation, far from offering a simple yes/no indication of amyloid presence, can provide a wide spectrum of qualitative and quantitative information related to and changing with the etiology of the disease, the comorbidities and the clinical characteristics of patients. With the exception of cardiac transthyretin related amyloidosis cases, which today can be diagnosed using non-biopsy algorithms when stringent clinical criteria are met, tissue biopsy is still an essential tool for a definitive diagnosis in doubtful cases and also to define etiology by typing amyloid fibrils. This review describes the histologic approach to amyloidosis today and the current role of tissue screening biopsy or targeted organ biopsy protocols in the light of present diagnostic algorithms and various clinical situations, with particular focus on endomyocardial and renal biopsies. Special attention is given to techniques for typing amyloid fibril proteins, necessary for the new therapies available today for cardiac transthyretin related amyloidosis and to avoid patients receiving inappropriate chemotherapy in presence of plasma cell dyscrasia unrelated to amyloidosis. As the disease is still burdened with high mortality, the role of tissue biopsy in early diagnosis to assure prompt treatment is also mentioned.

Incidental cardiac uptake of 99mTc-diphosphonates is predictive of poor outcome: data from 9616 bone scintigraphies

BACKGROUND

Bone scintigraphy (BS) is highly diagnostic for amyloid transthyretin (ATTR) cardiomyopathy. Prevalence and prognostic value of BS cardiac uptake is not well established. Our aim was to assess the prevalence of subclinical cardiac ATTR amyloidosis in patients undergoing [99mTc]MDP/DPD scintigraphy and to define their phenotype and prognosis.

METHODS AND RESULTS

BS scans performed for any clinical indications from 2009 to 2020 were reviewed. Patients were stratified according to Perugini visual score of cardiac uptake. Follow-up data were collected. Among 9616 BS scans, 0.7% (n = 67) showed cardiac uptake. In 47 (70%) patients, Perugini score was 1 and in 20 (30%) patients uptake was ≥ 2, suggesting cardiac ATTR amyloidosis. Forty subjects (61%) died during the follow-up (mean 47 ± 30 months). Compared with patients with Perugini score 1, those Perugini score ≥ 2 showed increased death rate (P = .018). Two (2/67) subjects were investigated for TTR gene mutations resulting negative.

CONCLUSIONS

In patients undergoing BS for different clinical indications, cardiac uptake suggesting cardiac ATTR amyloidosis is a rare, but still neglected finding, thus preventing possible diagnosis of ATTR cardiomyopathy. Importantly, cardiac uptake negatively affects the survival. Physicians should be aware of this rare, but crucial finding for timely diagnosis and treatment.

Redefining the epidemiology of cardiac amyloidosis. A systematic review and meta-analysis of screening studies

AIMS

An algorithm for non-invasive diagnosis of amyloid transthyretin cardiac amyloidosis (ATTR-CA) and novel disease-modifying therapies have prompted an active search for CA. We examined the prevalence of CA in different settings based on literature data.

METHODS AND RESULTS

We performed a systematic search for screening studies on CA, focusing on the prevalence, sex and age distribution in different clinical settings. The prevalence of CA in different settings was as follows: bone scintigraphy for non-cardiac reasons (n = 5 studies), 1% (95% confidence interval [CI] 0%-1%); heart failure with preserved ejection fraction (n = 6), 12% (95% CI 6%-20%); heart failure with reduced or mildly reduced ejection fraction (n = 2), 10% (95% CI 6%-15%); conduction disorders warranting pacemaker implantation (n = 1), 2% (95% CI 0%-4%); surgery for carpal tunnel syndrome (n = 3), 7% (95% CI 5%-10%); hypertrophic cardiomyopathy phenotype (n = 2), 7% (95% CI 5%-9%); severe aortic stenosis (n = 7), 8% (95% CI 5%-13%); autopsy series of 'unselected' elderly individuals (n = 4), 21% (95% CI 7%-39%). The average age of CA patients in the different settings ranged from 74 to 90 years, and the percentage of men from 50% to 100%. Many patients had ATTR-CA, but the average percentage of patients with amyloid light-chain (AL) CA was up to 18%.

CONCLUSIONS

Searching for CA in specific settings allows to identify a relatively high number of cases who may be eligible for treatment if the diagnosis is unequivocal. ATTR-CA accounts for many cases of CA across the different settings, but AL-CA is not infrequent. Median age at diagnosis falls in the eighth or ninth decades, and many patients diagnosed with CA are women.

Prevalence and Outcomes of Cardiac Amyloidosis in All-Comer Referrals for Bone Scintigraphy

The prevalence of cardiac amyloidosis (CA) in the general population and associated prognostic implications remain poorly understood. We aimed to identify CA prevalence and outcomes in bone scintigraphy referrals. Methods: Consecutive all-comers undergoing ^99mTc-3,3-diphosphono-1,2-propanodicarboxylic-acid (^99mTc-DPD) bone scintigraphy between 2010 and 2020 were included. Perugini grade 1 was defined as low-grade uptake and grade 2 or 3 as confirmed CA. All-cause mortality, cardiovascular death, and heart failure hospitalization (HHF) served as endpoints. Results: In total, 17,387 scans from 11,527 subjects (age, 61 ± 16 y; 63.0% women, 73.6% cancer) were analyzed. Prevalence of ^99mTc-DPD positivity was 3.3% (n = 376/11,527; grade 1: 1.8%, grade 2 or 3: 1.5%), and was higher among cardiac than noncardiac referrals (18.2% vs. 1.7%). In individuals with more than 1 scan, progression from grade 1 to grade 2 or 3 was observed. Among patients with biopsy-proven CA, the portion of light-chain (AL)-CA was significantly higher in grade 1 than grade 2 or 3 (73.3% vs. 15.4%). After a median of 6 y, clinical event rates were: 29.4% mortality, 2.6% cardiovascular death, and 1.5% HHF, all independently predicted by positive ^99mTc-DPD. Overall, adverse outcomes were driven by confirmed CA (vs. grade 0, mortality: adjusted hazard ratio [AHR] 1.46 [95% CI 1.12-1.90]; cardiovascular death: AHR 2.34 [95% CI 1.49-3.68]; HHF: AHR 2.25 [95% CI 1.51-3.37]). One-year mortality was substantially higher in cancer than noncancer patients. Among noncancer patients, also grade 1 had worse outcomes than grade 0 (HHF/death: AHR 1.45 [95% CI 1.01-2.09]), presumably because of longer observation and higher prognostic impact of early infiltration. Conclusion: Positive ^99mTc-DPD was identified in a substantial number of consecutive ^99mTc-DPD referrals and associated with adverse outcomes.

Extracellular Volume Fraction by Computed Tomography Predicts Long-Term Prognosis Among Patients With Cardiac Amyloidosis

BACKGROUND

Light chain (AL) and transthyretin (ATTR) amyloid fibrils are deposited in the extracellular space of the myocardium, resulting in heart failure and premature mortality. Extracellular expansion can be quantified by computed tomography, offering a rapid, cheaper, and more practical alternative to cardiac magnetic resonance, especially among patients with cardiac devices or on renal dialysis.

OBJECTIVES

This study sought to investigate the association of extracellular volume fraction by computed tomography (ECV_CT), myocardial remodeling, and mortality in patients with systemic amyloidosis.

METHODS

Patients with confirmed systemic amyloidosis and varying degrees of cardiac involvement underwent electrocardiography-gated cardiac computed tomography. Whole heart and septal ECV_CT was analyzed. All patients also underwent clinical assessment, electrocardiography, echocardiography, serum amyloid protein component, and/or technetium-99m (^99mTc) 3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy. ECV_CT was compared across different extents of cardiac infiltration (ATTR Perugini grade/AL Mayo stage) and evaluated for its association with myocardial remodeling and all-cause mortality.

RESULTS

A total of 72 patients were studied (AL: n = 35, ATTR: n = 37; median age: 67 [IQR: 59-76] years, 70.8% male). Mean septal ECV_CT was 42.7% ± 13.1% and 55.8% ± 10.9% in AL and ATTR amyloidosis, respectively, and correlated with indexed left ventricular mass (r = 0.426; P < 0.001), left ventricular ejection fraction (r = 0.460; P < 0.001), N-terminal pro-B-type natriuretic peptide (r = 0.563; P < 0.001), and high-sensitivity troponin T (r = 0.546; P < 0.001). ECV_CT increased with cardiac amyloid involvement in both AL and ATTR amyloid. Over a mean follow-up of 5.3 ± 2.4 years, 40 deaths occurred (AL: n = 14 [35.0%]; ATTR: n = 26 [65.0%]). Septal ECV_CT was independently associated with all-cause mortality in ATTR (not AL) amyloid after adjustment for age and septal wall thickness (HR: 1.046; 95% CI: 1.003-1.090; P = 0.037).

CONCLUSIONS

Cardiac amyloid burden quantified by ECV_CT is associated with adverse cardiac remodeling as well as all-cause mortality among ATTR amyloid patients. ECV_CT may address the need for better identification and risk stratification of amyloid patients, using a widely accessible imaging modality.

New quantitative indices of cardiac amyloidosis with 99mTc-pyrophosphate scintigraphy

PURPOSE

Amyloid light chain (AL) and transthyretin (ATTR) are the major subtypes of cardiac amyloidosis (CA). ^99mTc-pyrophosphate (PYP) scintigraphy is used to differentiate ATTR from other CA subtypes. We adapted the standardized uptake value (SUV) for ^99mTc-PYP and proposed two quantitative indices, amyloid deposition volume (AmyDV) and total amyloid uptake (TAU). This study aimed to evaluate the utility of these quantitative indices in differentiating ATTR from non-ATTRs.

MATERIALS AND METHODS

Before the SUV measurement, the Becquerel calibration factor (BCF) of ^99mTc was obtained by a phantom experiment. Thirty-two patients who had undergone hybrid SPECT/CT imaging 3 h after injection of ^99mTc-PYP (370 MBq) were studied. CT attenuation correction for image reconstruction was applied in all. We calculated SUV, AmyDV, and TAU using a quantitative analysis software program for bone SPECT (GI-BONE) and analyzed AmyDV using two methods: threshold method (set 40%); and constant value method (average SUV_max of ribs). We assessed the diagnostic ability of heart-to-contralateral lung (H/CL) ratio, SUV, AmyDV, and TAU to differentiate ATTR from non-ATTR using receiver operating characteristic (ROC) analysis.

RESULTS

Statistically significant differences in all quantitative indices were observed between ATTR and non-ATTR. The area under the curve of each quantitative index for discriminating between ATTR and non-ATTR were as follows: H/CL, 0.997; SUV_max, 0.953; SUV_mean (M1), 0.964; SUV_mean (M2), 0.969; AmyDV (M1), 0.875; AmyDV (M2), 0.974; and TAU, 0.974. The AmyDV (M2) had higher diagnostic ability than AmyDV (M1). Thus, TAU was calculated as AmyDV (M2) × SUV_mean (M2). In the ROC curve, SUV, AmyDV, and TAU had almost the same diagnostic ability as H/CL in distinguishing ATTR from non-ATTRs.

CONCLUSIONS

We propose two novel 3D-based quantitative parameters (AmyDV and TAU) that have almost equal ability to discriminate ATTR from non-ATTR.

Impact of Earlier Diagnosis in Cardiac ATTR Amyloidosis Over the Course of 20 Years

BACKGROUND

Diagnostic and therapeutic advances have led to much greater awareness of transthyretin cardiac amyloidosis (ATTR-CA). We aimed to characterize changes in the clinical phenotype of patients diagnosed with ATTR-CA over the past 20 years.

METHODS

This is a retrospective observational cohort study of all patients referred to the National Amyloidosis Centre (2002-2021) in whom ATTR-CA was a differential diagnosis.

RESULTS

We identified 2995 patients referred with suspected ATTR-CA, of whom 1967 had a diagnosis of ATTR-CA confirmed. Analysis by 5-year periods revealed an incremental increase in referrals, with higher proportions of patients having been referred after bone scintigraphy and cardiac magnetic resonance imaging (2% versus 34% versus 51% versus 55%, chi-square P<0.001). This was accompanied by a greater number of ATTR-CA diagnoses, predominantly of the wild-type nonhereditary form, which is now the most commonly diagnosed form of ATTR-CA (0% versus 54% versus 67% versus 66%, chi-square P<0.001). Over time, the median duration of associated symptoms before diagnosis fell from 36 months between 2002 and 2006 to 12 months between 2017 and 2021 (Mann-Whitney P<0.001), and a greater proportion of patients had early-stage disease at diagnosis across the 5-year periods (National Amyloidosis Centre stage 1: 34% versus 42% versus 44% versus 53%, chi-square P<0.001). This was associated with more favorable echocardiographic parameters of structure and function, including lesser interventricular septal thickness (18.0±3.8 mm versus 17.2±2.6 mm versus 16.9±2.3 mm versus 16.6±2.4 mm, P=0.01) and higher left ventricular ejection fraction (46.0%±8.9% versus 46.8%±11.0% versus 47.8%±11.0% versus 49.5%±11.1%, P<0.001). Mortality decreased progressively during the study period (2007-2011 versus 2012-2016: hazard ratio, 1.57 [95% CI, 1.31-1.89], P<0.001; and 2012-2016 versus 2017-2021: hazard ratio, 1.89 [95% CI, 1.55-2.30], P<0.001). The proportion of patients enrolled into clinical trials and prescribed disease-modifying therapy increased over the 20-year period, but even when censoring at the trial or medication start date, year of diagnosis remained a significant predictor of mortality (2012-2016 versus 2017-2021: hazard ratio, 1.05 [95% CI, 1.03-1.07], P<0.001).

CONCLUSIONS

There has been a substantial increase in ATTR-CA diagnoses, with more patients being referred after local advanced cardiac imaging. Patients are now more often diagnosed at an earlier stage of the disease, with substantially lower mortality. These changes may have important implications for initiation and outcome of therapy and urgently need to be factored into clinical trial design.

Diagnostic Accuracy of Bone Scintigraphy for the Histopathological Diagnosis of Cardiac Transthyretin Amyloidosis-A Retrospective Austrian Multicenter Study

We aimed to ascertain the real-world diagnostic accuracy of bone scintigraphy in combination with free light chain (FLC) assessment for transthyretin (ATTR) cardiac amyloidosis (CA) using the histopathological diagnosis derived from endomyocardial biopsy (EMB) as a reference standard. We retrospectively analyzed 102 patients (22% women) with suspected CA from seven Austrian amyloidosis referral centers. The inclusion criteria comprised the available results of bone scintigraphy, FLC assessment, and EMB with histopathological analysis. ATTR and AL were diagnosed in 60 and 21 patients (59%, 21%), respectively, and concomitant AL and ATTR was identified in one patient. The specificity and positive predictive value (PPV) of Perugini score ≥ 2 for ATTR CA were 95% and 96%. AL was diagnosed in three out of 31 patients (10%) who had evidence of monoclonal proteins and a Perugini score ≥ 2. When excluding all patients with detectable monoclonal proteins (n = 62) from analyses, the PPV of Perugini score ≥ 2 for ATTR CA was 100% and the NPV of Perugini score < 2 for ATTR CA was 79%. Conclusively, ATTR CA can be diagnosed non-invasively in the case of a Perugini score ≥ 2 and an unremarkable FLC assessment. However, tissue biopsy is mandatory in suspected CA in any other constellation of non-invasive diagnostic work-up.

Evolving trends in epidemiology and natural history of cardiac amyloidosis: 30-year experience from a tertiary referral center for cardiomyopathies

Objective

Natural history of cardiac amyloidosis (CA) is poorly understood. We aimed to examine the changing mortality of different types of CA over a 30-year period.

Patients and methods

Consecutive patients included in the "Trieste CA Registry" from January 1, 1990 through December 31, 2021 were divided into a historical cohort (diagnosed before 2016) and a contemporary cohort (diagnosed after 2016). Light chain (AL), transthyretin (ATTR) and other forms of CA were defined according to international recommendations. The primary and secondary outcome measures were all-cause mortality and cardiac death, respectively.

Results

We enrolled 182 patients: 47.3% AL-CA, 44.5% ATTR-CA, 8.2% other etiologies. The number of patients diagnosed with AL and ATTR-CA progressively increased over time, mostly ATTR-CA patients (from 21% before 2016 to 67% after 2016) diagnosed non-invasively. The more consistent increase in event-rate was observed in the long-term (after 50 months) in ATTR-CA compared to the early increase in mortality in AL-CA. In the contemporary cohort, during a median follow up of 16 [4-30] months, ATTR-CA was associated with improved overall and cardiac survival compared to AL-CA. At multivariable analysis, ATTR-CA (HR 0.42, p = 0.03), eGFR (HR 0.98, p = 0.033) and ACE-inhibitor therapy (HR 0.24, p < 0.001) predicted overall survival in the contemporary cohort.

Conclusion

Incidence and prevalence rates of ATTR-CA and, to a less extent, of AL-CA have been increasing over time, with significant improvements in 2-year survival of ATTR-CA patients from the contemporary cohort. Reaching an early diagnosis and starting disease-modifying treatments will improve long-term survival in CA.

Reliability and feasibility of visual grading systems and quantitative indexes on [99mTc]Tc-DPD imaging for cardiac amyloidosis

We aimed to evaluate the reliability and feasibility of visual grading systems and various quantitative indexes of [^99mTc]Tc-DPD imaging for cardiac amyloidosis (CA). Patients who underwent [^99mTc]Tc-DPD imaging with suspicion of CA were enrolled. On the planar image, myocardial uptake was visually graded using Perugini's and Dorbala's methods (PS and DS). As [^99mTc]Tc-DPD indexes, heart-to-whole body ratio (H/WB) and heart-to-contralateral lung ratio (H/CL) were measured on planar image. SUVmax, SUVmean, total myocardial uptake (TMU), and C-index were measured on SPECT/CT. Inter-observer agreement of the indexes and their association with visual grading and clinical factors were evaluated. A total of 152 [^99mTc]Tc-DPD images, of which 18 were positive, were analyzed. Inter-observer agreement was high for both DS (κ = 0.95) and PS (κ = 0.96). However, DS showed a higher correlation with quantitative indexes than PS. Inter-observer agreement was also high for SPECT/CT indexes, particularly SUVmax. SUVmax was significantly different between different DS groups (P = 0.014-0.036), and showed excellent correlations with H/WB and H/CL (r = 0.898 and 0.910). SUVmax also showed significant differences between normal, AL, and ATTR pathology (P = 0.022-0.037), and a significant correlation with extracellular volume on cardiac MRI (r = 0.772, P < 0.001). DS is a visual grading system for CA that is more significantly matched with quantitative indexes than PS. SUVmax is a reliable quantitative index on SPECT/CT, with a high inter-observer agreement, correlations with the visual grade, and potential association with cardiac MRI findings.

Identification of wild-type transthyretin cardiac amyloidosis in patients with carpal tunnel syndrome surgery (CACTuS)

AIMS

Wild-type transthyretin cardiac amyloidosis (ATTRwt) is an infiltrative cardiomyopathy with a poor prognosis. The condition is associated with carpal tunnel syndrome (CTS), which often precedes the ATTRwt diagnosis by several years. The aim of the study was (i) to screen patients with a recent history of CTS for ATTRwt using red flags, (ii) to determine whether patients with screened ATTRwt had less advanced disease compared with patients with clinical ATTRwt, and (iii) to assess the sensitivity and specificity of known red flags in ATTRwt.

METHODS AND RESULTS

Patients aged ≥60 years at the time of CTS surgery were invited for screening. Red flags were defined as elevated biomarker levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) or cardiac troponin, an electrocardiogram pattern associated with ATTRwt, left ventricular hypertrophy (LVH), and impaired longitudinal strain with apical sparring. All patients with a red flag were referred for a diagnostic scintigraphy. Patients with ATTRwt diagnosed by screening were compared with patients with clinical ATTRwt (n = 51) matched by age, gender, and CTS surgery. Among the 120 enrolled subjects (mean age 74.5 years, 90% male), the suspicion of ATTR was raised in 67 (55.8%), and 10 (8.3%) were diagnosed with ATTRwt. Patients identified with ATTRwt were predominantly asymptomatic and had mildly elevated NT-proBNP, mildly increased LVH, preserved left ventricular ejection fraction, and systolic longitudinal function, which differed significantly from clinical ATTRwt controls (P < 0.001).

CONCLUSIONS

The study found an ATTRwt prevalence of 8.3% in a population of age and gender-selected patients with a recent history of CTS. The identified patients with ATTRwt had less structural and functional cardiac involvement than clinical ATTRwt controls.

Multimodality imaging in cardiac amyloidosis: State-of-the-art review

Amyloidosis is a systemic disease, characterized by deposition of amyloid fibrils in various organs, including the heart. For the diagnosis of cardiac amyloidosis (CA) it is required a high level of clinical suspicion and in the presence of clinical, laboratorial, and electrocardiographic red flags, a comprehensive multimodality imaging evaluation is warranted, including echocardiography, magnetic resonance, scintigraphy, and computed tomography, that will confirm diagnosis and define the CA subtype, which is of the utmost importance to plan a treatment strategy. We will review the use of multimodality imaging in the evaluation of CA, including the latest applications, and a practical flow-chart will sum-up this evidence.

Quantitative technetium pyrophosphate and cardiovascular magnetic resonance in patients with suspected cardiac amyloidosis

BACKGROUND

Quantitation of myocardial 99m Tc-pyrophosphate activity may have high diagnostic accuracy, but its correlation with disease burden is unknown. We examined the relationship between 99m Tc-pyrophosphate quantitation and cardiac magnetic resonance (CMR) measures in patients with suspected transthyretin cardiac amyloidosis (ATTR-CM) or light chain cardiac amyloidosis (AL-CM).

METHODS

Consecutive patients who underwent 99mTc-pyrophosphate imaging and CMR were included. ATTR-CM and AL-CM were diagnosed using standard criteria. 99mTc-pyrophosphate images were assessed with standard parameters and quantified with cardiac pyrophosphate activity (CPA) and volume of involvement (VOI). We assessed the association between 99mTc-pyrophosphate image interpretation and CMR tissue characteristics.

RESULTS

Seventy patients were identified, mean age 70.4 ± 11.4 years, with ATTR-CM and AL-CM diagnosed in 22 (31%) and 11 (16%) patients, respectively. In patients with ATTR-CM, there were significant correlations between CPA (r2 = 0.509, P < 0.001) and VOI (r2 = 0.586, P < 0.001) with native myocardial T1 mapping values. Additionally, CPA (adjusted hazard ratio (aHR) 1.04, P = 0.016), VOI (aHR 1.12, P = 0.034), and average myocardial T1 (aHR 1.12, P = 0.025) were associated with incidence of heart failure hospitalization or death.

CONCLUSION

CPA and VOI were correlated with CMR measures of myocardial fibrosis in patients with ATTR-CM. 99mTc-pyrophosphate quantitation may have a role in ATTR-CM disease staging, guiding treatment, or following response to therapy.

Nuclear Molecular Imaging of Disease Burden and Response to Treatment for Cardiac Amyloidosis

Cardiac amyloidosis (CA) is a heterogeneous group of diseases in which extracellular insoluble amyloid proteins are deposited in specific organs and tissues locally or systemically, thereby interfering with physiological function. Transthyretin protein (TTR) and light chain (AL) amyloidosis are the most common types of cardiac amyloidosis. Radionuclide bone scintigraphy has recently become the most common non-invasive test for the diagnosis of TTR-CA but is of limited value for the diagnosis of AL-CA. PET has proved promising for the diagnosis of CA and its applications are expected to expand in the future. This review summarizes the current bone scintigraphy and amyloid-targeting Positron emission tomography (PET) imaging, the binding imaging properties of radiotracers, and the values of diagnosis, prognosis, and monitoring therapy response in CA.

Unveiling Cardiac Amyloidosis, its Characteristics, and Outcomes Among Patients With MR Undergoing Transcatheter Edge-to-Edge MV Repair

BACKGROUND

Mitral regurgitation (MR) and cardiac amyloidosis (CA) both primarily affect older patients. Data on coexistence and prognostic implications of MR and CA are currently lacking.

OBJECTIVES

This study sought to identify the prevalence, clinical characteristics, and outcomes of MR CA compared with lone MR.

METHODS

Consecutive patients undergoing transcatheter edge-to-edge repair (TEER) for MR at 2 sites were screened for concomitant CA using a multiparametric approach including core laboratory 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid bone scintigraphy and echocardiography and immunoglobulin light chain assessment. Transthyretin CA (ATTR) was diagnosed by 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (Perugini grade 1: early infiltration; grades 2/3: clinical CA) and the absence of monoclonal protein, and light chain (AL) CA via tissue biopsy. All-cause mortality and hospitalization for heart failure (HHF) served as the endpoints.

RESULTS

A total of 120 patients (age 76.9 ± 8.1 years, 55.8% male) were recruited. Clinical CA was diagnosed in 14 patients (11.7%; 12 ATTR, 1 AL, and 1 combined ATTR/AL) and early amyloid infiltration in 9 patients (7.5%). Independent predictors of MR CA were increased posterior wall thickness and the presence of a left anterior fascicular block on electrocardiography. Procedural success and periprocedural complications of TEER were similar in MR CA and lone MR (P for all = NS). After a median of 1.7 years, 25.8% had experienced death and/or HHF. MR CA had worse outcomes compared with lone MR (HR: 2.2; 95% CI: 1.0-4.7; P = 0.034), driven by a 2.5-fold higher risk for HHF (HR: 2.5; 95% CI: 1.1-5.9), but comparable mortality (HR: 1.6; 95% CI: 0.4-6.1).

CONCLUSIONS

Dual pathology of MR CA is common in elderly patients with MR undergoing TEER and has worse postinterventional outcomes compared with lone MR.

Tc-99m pyrophosphate scintigraphy for cardiac amyloidosis: concordance between planar and SPECT/CT imaging

The imaging protocol and the optimal cut-off points for quantitative assessment of technetium-99m pyrophosphate (Tc-99m PYP) cardiac amyloidosis scintigraphy remain controversial. The aim of this study was to evaluate the concordance between planar and SPECT images, and to investigate the contribution of SPECT/CT to diagnostic precision. All patients referred to our department for Tc-99m PYP cardiac imaging between April 2019 and April 2022 were included in the study. Heart-to-contralateral lung (H/CL) ratios were calculated from anterior planar images at both 1- and 3 h, and visual grading was done in SPECT/CT images at both time points. A total of 141 patients were included in the study (median age 59 years, 54% female). There was a strong positive correlation between H/CL ratios calculated at 1- and 3 h (Pearson's ρ = 0.842, p < 0.001). The highest level of concordance between planar and SPECT/CT images was achieved at a H/CL cut-off point of 1.5 for 1-h images, and 1.4 for 3-h images. SPECT/CT imaging contributed to diagnostic precision in both 1- and 3-h images by reducing the rate of equivocal results from 83% (n = 117) to 25% (n = 35), and from 77% (n = 108) to 27% (n = 38), respectively. Our findings have three implications: (1) planar imaging at both 1- and 3 h could be redundant, (2) a lower H/CL cut-off point for 3-h planar images could improve concordance between planar and SPECT imaging, and (3) SPECT/CT in both 1- and 3 h could improve the diagnostic precision by offering markedly reduced equivocal results.

Dyspnoe und Ödeme bei einem 79-jährigen Patienten

Hintergrund

Die Transthyretin-Amyloidose (ATTR-Amyloidose) führt zur Ablagerung von unlöslichen Fibrillen im Interstitium der betroffenen Organe. Eine kardiale Beteiligung kann sich durch Dyspnoe, Ödeme, Rhythmusstörungen bis hin zur manifesten Herzinsuffizienz und Tod äußern.

Fallbericht

Ein 79-jähriger Mann stellte sich mit Dyspnoe sowie Gewichtszunahme vor. In der Echokardiographie Hypertrophie bei restriktiver Kardiomyopathie. In der Knochenszintigraphie Tracer-Mehranreicherung, hochverdächtig auf eine ATTR-Amyloidose, welche mittels Biopsie bestätigt werden konnte.

Schlussfolgerungen

Die Diagnose einer kardialen ATTR-Amyloidose stellt für den Kliniker eine Herausforderung dar und setzt dessen erhöhte Aufmerksamkeit voraus. Die Diagnosestellung sollte strukturiert erfolgen unter Einbeziehung von Labor, bildgebenden Verfahren sowie Myokardbiopsie.

Multimodality Imaging in the Diagnosis and Assessment of Cardiac Amyloidosis

Amyloidosis is a rare disorder where abnormal protein aggregates are deposited in tissues forming amyloid fibrils, leading to progressive organ failure. Although any organ can be affected, cardiac involvement is the main cause of morbidity and mortality associated with amyloidosis as diagnosis is often delayed due to the indolent nature of the disease in some forms. An early diagnosis of disease and knowledge of the type/subtype of cardiac amyloidosis (CA) are essential for appropriate management and better outcome. Echocardiography is often the first line of investigation for patients suspected of CA and offers superior hemodynamic assessment. Although cardiovascular magnetic resonance (CMR) imaging is not diagnostic of CA, it provides vital clues to diagnosis and has a role in disease quantification and prognostication. Radiolabeled bone seeking tracers are the mainstay of diagnosis of CA and when combined with screening of monoclonal light chains, bone scintigraphy offers high sensitivity in diagnosing transthyretin type of CA. This review aims to describe the noninvasive imaging assessment and approach to diagnosis of patients with suspected CA. Imaging features of echocardiography, nuclear scintigraphy, and CMR are described with a brief mention on computed tomography.

Prevalence and diagnostic value of extra-left ventricle echocardiographic findings in transthyretin-related cardiac amyloidosis

BACKGROUND

Cardiac amyloidosis (CA) is cardiomyopathy with a hypertrophic phenotype characterised by diffuse deposition of anomalous fibrillar proteins in the extracellular matrix.

OBJECTIVES

To evaluate the prevalence and diagnostic value of extra left ventricle echocardiographic findings in patients with left ventricular (LV) hypertrophic phenotype and amyloid deposition.

METHODS

A group of 146 patients with LV thickness ≥15 mm were enrolled: 70 patients who received a definite diagnosis of sarcomeric hypertrophic cardiomyopathy (HCM group) and 76 patients with transthyretin cardiac amyloidosis (CA group). Echocardiographic analysis of crista terminalis (CriT), atrio-ventricular plane (AVP), mitro-aortic lamina (MAL), anterior ascending aortic wall, interatrial septum (IAS), Eustachian valve (EusV) and coumadin ridge (CouR) was performed in all patients, and these structures were compared among the two groups.

RESULTS

CA group showed significantly higher dimensions of CriT, IAS, CouR, AVP, MAL and IAS compared to the HCM group. The logistic analysis showed that LV EF, LV septal thickness, CriT presence, CriT area, MAL and IAS were all predictors of CA in univariate analyses. The stepwise multivariate analysis showed independent predictors of CA: CriT area, MAL and LVEF. According to areas under the receiver operating characteristic curves the best cut-off values to determine CA were identified (IAS > 9 mm, MAL > 7 mm, CriT > 9 mm²). Among these 3 independent predictors, IAS > 9 mm had the best specificity (96%) and positive predictive value (93%) in identifying CA.

CONCLUSIONS

evidence of extra left ventricle sites of amyloid deposition is a frequent finding in CA. In the context of hypertrophic phenocopies, an increased thickness of IAS, and/or CT and/or MAL should suggest a diagnosis of transthyretin CA.

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.

Cardiomyopathy correlates to nerve damage in p.A117S late-onset transthyretin amyloid polyneuropathy

Objective

Late‐onset hereditary transthyretin amyloidosis with polyneuropathy (ATTRv‐PN) is often associated with heart involvement. Recent advances in cardiac imaging allow the detection of cardiac amyloidosis. This study aimed to explore cardiomyopathy by cardiac imaging and its clinical correlates with polyneuropathy in late‐onset ATTRv‐PN.

Methods

Polyneuropathy was assessed by intraepidermal nerve fiber (IENF) density, nerve conduction study (NCS), autonomic function tests, quantitative sensory testing, and clinical questionnaires. Cardiomyopathy was evaluated by echocardiography, ^99mTc‐pyrophosphate (PYP) single‐photon emission computed tomography (SPECT) imaging, cardiac magnetic resonance imaging (CMR), and serum Pro‐B‐type natriuretic peptide. Healthy controls and patients with Brugada syndrome were enrolled for comparison of CMR.

Results

Fifty late‐onset ATTRv‐PN patients (38 men, 46 with p. A117S mutation), aged 63.7 ± 5.5 years, of polyneuropathy disability stage 1–4 were enrolled. All patients presented polyneuropathy in NCS, and 74.5% of patients had reduced IENF density in distal legs. All patients showed significant radiotracer uptake in the heart on ^99mTc‐PYP SPECT imaging, and 87.8% of patients had abnormally increased left ventricular (LV) septum thickness on echocardiography. CMR showed longer myocardial native T1, larger extracellular volume, greater LV mass index, and higher LV mass to end‐diastolic volume ratio in ATTRv‐PN patients than healthy controls and patients with Brugada syndrome. These CMR parameters were associated with skin denervation, absent sympathetic skin responses, elevated thermal thresholds, worsened NCS profiles, and functional deficits of polyneuropathy.

Interpretation

Late‐onset ATTRv‐PN coexisted with cardiomyopathy regardless of the clinical severity of polyneuropathy. The cardiac amyloid burden revealed by CMR was correlated with pathophysiology and clinical disability of nerve degeneration.

99mTc-Labeled Iron Oxide Nanoparticles as Dual-Modality Contrast Agent: A Preliminary Study from Synthesis to Magnetic Resonance and Gamma-Camera Imaging in Mice Models

The combination of two imaging modalities in a single agent has received increasing attention during the last few years, since its synergistic action guarantees both accurate and timely diagnosis. For this reason, dual-modality contrast agents (DMCAs), such as radiolabeled iron oxide (namely Fe₃O₄) nanoparticles, constitute a powerful tool in diagnostic applications. In this respect, here we focus on the synthesis of a potential single photon emission computed tomography/magnetic resonance imaging (SPECT/MRI) DMCA, which consists of Fe₃O₄ nanoparticles, surface functionalized with 2,3-dicarboxypropane-1,1-diphosphonic acid (DPD) and radiolabeled with ^99mTc, [^99mTc]Tc-DPD-Fe₃O₄. The in vitro stability results showed that this DMCA is highly stable after 24 h of incubation in phosphate buffer saline (~92.3% intact), while it is adequately stable after 24 h of incubation with human serum (~67.3% intact). Subsequently, [^99mTc]Tc-DPD-Fe₃O₄ DMCA was evaluated in vivo in mice models through standard biodistribution studies, MR imaging and gamma-camera imaging. All techniques provided consistent results, clearly evidencing noticeable liver uptake. Our work documents that [^99mTc]Tc-DPD-Fe₃O₄ has all the necessary characteristics to be a potential DMCA.

Tc-99m HMDP bone scintigraphy for cardiac amyloidosis diagnosis: A false positive case

A 68-year-old man with heart failure (left ventricular ejection fraction = 30%) and normal coronary angiography underwent bone scintigraphy for suspected transthyretin-related cardiac amyloidosis (CA).1 He received 532 MBq (14.3 mCi) Tc-99m hydroxy-methyl-diphosphonate (HMDP) and data were acquired 2 hours after injection. On anterior and posterior whole-body scans (Figure 1 A and B), diffuse cardiac, hepatic, and soft-tissue uptake of the radiotracer was seen, in association with low skeletal uptake. It was established that the patient had recently been hospitalized for heart failure exacerbation and had received an intravenous iron injection, which is a recommended treatment for heart failure.2 In consultation with our hospital's cardiology team, it was decided to repeat the bone scan at a time when the patient had received no recent iron infusion. Two months after the first bone scan, the patient received 556 MBq (15 mCi) of 99m-Tc HMDP, and no cardiac, hepatic, or soft-tissue uptake was detected (Figure 1C and D).

Systemic embolism in amyloid transthyretin cardiomyopathy

AIMS

Although systemic embolism is a potential complication in transthyretin amyloid cardiomyopathy (ATTR-CM), data about its incidence and prevalence are scarce. We studied the incidence, prevalence and factors associated with embolic events in ATTR-CM. Additionally, we evaluated embolic events according to the type of oral anticoagulation (OAC) and the performance of the CHA2 DS2 -VASc score in this setting.

METHODS AND RESULTS

Clinical characteristics, history of atrial fibrillation (AF) and embolic events were retrospectively collected from ATTR-CM patients evaluated at four international amyloid centres. Overall, 1191 ATTR-CM patients (87% men, median age 77.1 years [interquartile range-IQR 71.4-82], 83% ATTRwt) were studied. A total of 162 (13.6%) have had an embolic event before initial evaluation. Over a median follow-up of 19.9 months (IQR 9.9-35.5), 41 additional patients (3.44%) had an embolic event. Incidence rate (per 100 patient-years) was 0 among patients in sinus rhythm with OAC, 1.3 in sinus rhythm without OAC, 1.7 in AF with OAC, and 4.8 in AF without OAC. CHA2 DS2 -VASc did not predict embolic events in patients in sinus rhythm whereas in patients with AF without OAC, only those with a score ≥4 had embolic events. There was no difference in the incidence rate of embolism between patients with AF treated with vitamin K antagonists (VKAs) (n = 322) and those treated with direct oral anticoagulants (DOACs) (n = 239) (p = 0.66).

CONCLUSIONS

Embolic events were a frequent complication in ATTR-CM. OAC reduced the risk of systemic embolism. Embolic rates did not differ with VKAs and DOACs. The CHA2 DS2 -VASc score did not correlate well with clinical outcome in ATTR-CM and should not be used to assess thromboembolic risk in this population.

Transthyretin Cardiac Amyloidosis Scintigraphy Using Planar D-SPECT on Dedicated Cardiac CZT Camera

BACKGROUND

Bone scintigraphy is a main diagnostic tool in suspected ATTR patients. Almost all literature is based on conventional whole body gamma cameras, and there is very sparse data evaluating the use of dedicated cardiac CZT cameras. The aim of this study was to evaluate the utility of bone scintigraphy in suspected transthyretin cardiac amyloidosis (ATTR-CA) patients on a dedicated cardiac CZT camera.

METHODS

Seventy-three patients with suspected ATTR-CA underwent planar and SPECT Tc-99 m pyrophosphate scintigraphy using dedicated cardiac CZT camera between May and August 2019.

RESULTS

Planar D-SPECT image quality was mostly good. Six patients were identified as ATTR-CA positive. Inter-observer agreement based on both Perugini score and on planar D-SPECT H/CL ratio was excellent.

CONCLUSIONS

ATTR-CA scintigraphy using dedicated cardiac CZT camera was feasible, and yielded planar D-SPECT images with excellent inter-observer agreement.

RWT/SaVR-A Simple and Highly Accurate Measure Screening for Transthyretin Cardiac Amyloidosis

Background: Cardiac amyloidosis is an underdiagnosed condition and simple methods for accurate diagnosis are warranted. We aimed to validate a novel, dual-modality approach to identify transthyretin cardiac amyloidosis (ATTR-CA), employing echocardiographic relative wall thickness (RWT), and ECG S-wave from aVR (SaVR), and compare its accuracy with conventional echocardiographic approaches. Material and methods: We investigated 102 patients with ATTR-CA and 65 patients with left ventricular hypertrophy (LVH), all with septal thickness > 14 mm. We validated the accuracy of echocardiographic measures, including RWT, RWT/SaVR, posterior wall thickness (PWT), LV mass index (LVMI), left atrial volume index (LAVI), global longitudinal strain (GLS), and relative apical sparing (RELAPS) to identify ATTR-CA diagnosed using DPD-scintigraphy or abdominal fat biopsy. Results: PWT, RWT, RELAPS, troponin, and RWT/SaVR were significantly higher in ATTR-CA compared to LVH. RWT/SaVR > 0.7 was the most accurate parameter to identify ATTR-CA (sensitivity 97%, specificity 90% and accuracy 91%). RELAPS was found to have much less accuracy (sensitivity 74%, specificity 76% and accuracy 73%). Conclusion: We can confirm the very strong diagnostic accuracy of RWT/SaVR to identify ATTR-CA in patients with septal thickness > 14 mm. Given its high sensitivity and specificity, RWT/SaVR > 0.7 has the potential to implement as a non-invasive, simple, and widely available diagnostic tool when screening for ATTR-CA.