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

Electrocardiographic features and need for pacemaker in cardiac amyloidosis: Analysis of 58 cases

AIM

Amyloidosis is a disease in which amyloid fibrils can be deposited in different cardiac structures, and several electrocardiographic abnormalities can be produced by this phenomenon. The objective of this study was to describe the most common basal electrocardiographic alterations in patients diagnosed with cardiac amyloidosis (CA) and to determine if these abnormalities have an impact on the need of pacemaker.

METHODS

This retrospective study included patients who had an established diagnosis of CA [light-chain cardiac amyloidosis (LA-CA) or transthyretin cardiac amyloidosis (TTR-CA)] between January 2013 and March 2021. The baseline heart rate, the percentage of patients with a pseudo-infarct pattern, low-voltage pattern or cardiac conductions disturbances, and the impact of these factors on the need of pacemaker were analysed.

RESULTS

Fifty-eight patients with CA (20 with LA-CA and 38 with TTR-CA) were included, and the majority were male (69.0%). Twenty-one patients had atrial fibrillation (AF) at diagnosis. Thirty-five patients had a pseudo-infarct pattern, 35% had a low-voltage pattern, and 22% had criteria for ventricular hypertrophy. Two hirds had a conduction disorder: 18 patients with first degree atrioventricular block, 12 right bundle branch block, 3 left bundle branch block and 25 with a branch hemiblock. There were no differences between LA-CA and TTR-CA. Patients with TTR-CA had a greater need for pacemakers in the folow-up (39±40 meses). Bundle branch block was a predictor of the need for a permanent pacemaker (HR: 23.43; CI 95%: 4.09.134.09; P=.01).

CONCLUSIONS

Electrocardiographic abnormalities in patients diagnosed wich CA are heterogeneus. Most frecuent is the presence of conduction disorders, the pseudoinfarction pattern, followed by the low voltage pattern. Patients with any bundle branch block at the baseline electrocardiogram need more frecuent to require a pacemaker during follow-up, especially in TTR-CA.

Diagnosis of cardiac amyloid transthyretin (ATTR) amyloidosis by early (soft tissue) phase [99mTc]Tc-DPD whole body scan: comparison with late (bone) phase imaging

OBJECTIVES

Although expert consensus recommendations suggest 2-3 h as the time interval between bone-seeking radiotracers injection and acquisition, it has been reported that images obtained early after [^99mTc]Tc-HMDP administration are sufficient to diagnose cardiac amyloidosis. We evaluated the diagnostic performance of [^99mTc]Tc-DPD early phase whole body scan with respect to late phase imaging.

METHODS

We qualitatively and semiquantitatively reviewed [^99mTc]Tc-DPD imaging of 53 patients referred for suspect cardiac amyloidosis. Findings of early and late phase images were compared with SPECT results (considered the standard-of-reference) determining sensitivity and specificity for visual analysis of each phase imaging and for each semiquantitative index.

RESULTS

SPECT imaging was negative for cardiac accumulation in 25 patients and positive in 28. Visual analysis of early phase whole body scan had an extremely significant capability to predict SPECT results; nevertheless, complete agreement was not reached. Visual analysis of late phase imaging showed slightly better results. Semiquantitative analysis of early phase images, namely heart to mediastinum ratio, performed better than semiquantitative analysis of late phase images.

CONCLUSION

Visual analysis of [^99mTc]Tc-DPD early phase whole body scan is promising in diagnosing cardiac amyloidosis; further studies are needed to confirm our results in different clinical scenarios.

KEY POINTS

• Visual analysis of early phase planar imaging using [^99mTc]Tc-DPD is accurate to diagnose cardiac amyloidosis and may be satisfactory at least in frail patients with high cardiac burden of amyloid fibrils.

Diagnostic Tools for Cardiac Amyloidosis: A Pragmatic Comparison of Pathology, Imaging and Laboratories

Cardiac amyloidosis (CA) is a complex disease considered to be the most common underdiagnosed form of restrictive cardiomyopathy. Accumulation of misfolded proteins called amyloid fibrils in the extracellular space results in clinical deterioration and late diagnosis is associated with morbidity and mortality. Both types of this disease, light chain CA and transthyretin-related CA share many cardiac and extracardiac features that compromise multiple organs such as kidneys, musculoskeletal system, autonomic nervous system, and gastrointestinal tract. Early diagnosis and detection of CA are imperative. Clinicians should maintain a high degree of suspicion among patients with unexplained diastolic heart failure to implement different disease-altering therapies at the early stages of the disease. In this article, we provided a comprehensive review of multiple invasive and non-invasive cardiac imaging modalities with their respective degrees of sensitivities and specificity.

Transthyretin Gene Variants and Associated Phenotypes in Danish Patients with Amyloid Cardiomyopathy

Genotyping divides transthyretin cardiac amyloidosis (ATTR-CA) in hereditary (ATTRv) and wild type (ATTRwt) forms. This study investigated the prevalence and clinical presentation of ATTRv in a contemporary cohort of consecutive ATTR-CA patients diagnosed at a tertiary Danish amyloidosis center. Age at diagnosis, clinical- and echocardiographic data, and transthyretin (TTR) genotype were recorded. Relatives of ATTRv patients underwent clinical phenotyping and predictive gene testing. Genetic testing in 102 patients identified four TTR variant carriers: p.Pro63Ser, p.Ala65Ser (n = 2) and p.Val142Ile. The mean age of ATTRv index patients was significantly lower compared to ATTRwt patients: 70.2 ± 1.2 versus 80.0 ± 6.2, p-value: 0.005. Evaluation of ATTRv families identified seven TTR variant carriers with a median age of 65 years (range 48–76) and three were diagnosed with ATTR-CA by DPD-scintigraphy. Family members with ATTR-CA were all asymptomatic and had normal levels of cardiac biomarkers. In conclusion, the prevalence of ATTRv in a contemporary Danish ATTR-CA cohort is 4%. ATTRv index patients were significantly younger age at diagnosis than ATTRwt patients. Non-p.Leu131Met TTR variants have reduced penetrance at the age of 65 years in which approximately half of variant carriers have asymptomatic ATTR-CA with normal LV systolic function and cardiac biomarker analyses.

Usefulness of quantitative 99mTc-pyrophosphate SPECT/CT for predicting the prognosis of patients with wild-type transthyretin cardiac amyloidosis

PURPOSE

Wild-type transthyretin-related amyloidosis cardiomyopathy (ATTRwt-CM) is an increasingly recognized cause of heart failure especially in elderly patients. The purpose of the present study was to determine retrospectively whether the quantitative indices of ^99mTc-pyrophosphate (PYP) SPECT/CT help to predict the prognosis of ATTRwt-CM patients when compared with other clinical parameters.

MATERIALS AND METHODS

Sixty-eight patients with biopsy-proven ATTRwt-CM who underwent PYP SPECT/CT were enrolled. Baseline clinical characteristics, echocardiographic parameters, and qualitative and/or quantitative indices of planar and SPECT/CT imaging in PYP scintigraphy for each patient were included. For quantitative analysis of SPECT/CT, the accumulation ratio of PYP in the septum, posterior, anterior, lateral, and apex walls to the cavity pool was calculated as the septal wall-to-cavity ratio (Se/C), lateral wall-to-cavity ratio (La/C), anterior wall-to-cavity ratio (An/C), inferior wall-to-cavity ratio (In/C), and apical wall-to-cavity ratio (Ap/C), respectively. Endpoints for prognostic accuracy evaluation were cardiac death or hospitalization due to heart failure. Event-free survival rate was evaluated through Cox proportional hazards regression analysis, providing estimated hazard ratios (HRs) with 95% confidence intervals (CIs) and Kaplan-Meier curves.

RESULTS

High-sensitivity cardiac troponin T (hs-cTnT), La/C, age, interventricular septal thickness in diastole, and E/e' ratio in the septal wall were significantly associated with event-free survival (P < 0.05). For a multivariable Cox proportional hazards analysis, hs-cTnT (HR 1.153; 95% CI 1.034-1.286; P < 0.01), La/C (HR 2.091; 95% CI 1.012-4.322; P = 0.046), and age (HR 1.116; 95% CI 1.007-1.238; P = 0.037) were significant independent prognostic factors.

CONCLUSION

This study indicated that the quantitative indices of PYP SPECT/CT can help to predict the prognosis of ATTRwt-CM patients.

Impact of afterload and infiltration on coexisting aortic stenosis and transthyretin amyloidosis

OBJECTIVE

The coexistence of wild-type transthyretin cardiac amyloidosis (ATTR) is common in patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI). However, the impact of ATTR and AS on the resultant AS-ATTR is unclear and poses diagnostic and management challenges. We therefore used a multicohort approach to evaluate myocardial structure, function, stress and damage by assessing age-related, afterload-related and amyloid-related remodelling on the resultant AS-ATTR phenotype.

METHODS

We compared four samples (n=583): 359 patients with AS, 107 with ATTR (97% Perugini grade 2), 36 with AS-ATTR (92% Perugini grade 2) and 81 age-matched and ethnicity-matched controls. 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scintigraphy was used to diagnose amyloidosis (Perugini grade 1 was excluded). The primary end-point was NT-pro Brain Natriuretic Peptide (BNP) and secondary end-points related to myocardial structure, function and damage.

RESULTS

Compared with older age controls, the three disease cohorts had greater cardiac remodelling, worse function and elevated NT-proBNP/high-sensitivity Troponin-T (hsTnT). NT-proBNP was higher in AS-ATTR (2844 (1745, 4635) ng/dL) compared with AS (1294 (1077, 1554)ng/dL; p=0.002) and not significantly different to ATTR (3272 (2552, 4197) ng/dL; p=0.63). Diastology, hsTnT and prevalence of carpal tunnel syndrome were statistically similar between AS-ATTR and ATTR and higher than AS. The left ventricular mass indexed in AS-ATTR was lower than ATTR (139 (112, 167) vs 180 (167, 194) g; p=0.013) and non-significantly different to AS (120 (109, 130) g; p=0.179).

CONCLUSIONS

The AS-ATTR phenotype likely reflects an early stage of amyloid infiltration, but the combined insult resembles ATTR. Even after treatment of AS, ATTR-specific therapy is therefore likely to be beneficial.

Pitfalls of the Semi-Quantitative Analyzing 99mTc-Pyrophosphate Planar Images for Diagnosing Transthyretin Cardiac Amyloidosis: A Possible Solution

Background: Two different approaches, 1-h heart-to-contralateral (H/CL) ratio and 3-h visual grading scale relative to ribs (VGSr), have been established to interpret ^99mTc-PYP planar images for the detection of amyloid transthyretin cardiac amyloidosis (ATTR-CA). Since they are prone to pitfalls, this pilot study aimed to explore the diagnostic practicality of the 3-h visual grading scale relative to the upper segment of sternum (VGSs) approach for interpreting ^99mTc-PYP planar images. Methods: A total of 42 patients were enrolled in this retrospective study. SPECT/CT approach and planar approaches including H/CL ratio, VGSr, and VGSs were utilized to interpret the ^99mTc-PYP images obtained at both 1 and 3 h. The classification criteria of the latest expert consensus recommendations were considered as the gold standard. The concordance between the interpretation of each approach and the gold standard was investigated. Results: In addition to 1- and 3-h SPECT/CT approaches, the interpretation of planar images using the 3-h VGSs approach was also applicable, which turns identical to the gold standard (κ = 1.000; p < 0.001). Conclusions: For the interpretation of ^99mTc-PYP planar images, the 3-h VGSs approach should be the optimal method, particularly in the case without available or feasible tomography imaging. Only one imaging session (planar and SPECT/CT) at 3 h would be sufficient for the detection of ATTR-CA, and favorable for patient satisfaction.

Suspecting and diagnosing transthyretin amyloid cardiomyopathy (ATTR-CM) in India: An Indian expert consensus

Transthyretin cardiac amyloidosis (ATTR-CM) is a rare and under-recognized disorder characterized by the aggregation of transthyretin-derived insoluble amyloid fibrils in the myocardium. Heterogeneity of symptoms at presentation, makes its diagnosis often delayed. An expert panel gathered on a virtual platform across India to conduct a meeting for developing a guiding tool for ATTR-CM diagnosis. The panel recommended younger age (≥40 years) for suspecting ATTR-CM and thick-walled non-dilated hypokinetic ventricle was considered as one of the important red flags. Electrocardiogram (ECG) and echocardiography (ECHO) findings were recommended as primary tests to raise the suspicion while nuclear scintigraphy and hematological tests were recommended to confirm the diagnosis and rule out amyloid light-chain (AL) amyloidosis. Cardiac magnetic resonance (CMR) and biopsy were recommended in case of ambiguity in the presence of red flags. Considering the lack of expert guidelines in the Indian scenario, a standardized diagnostic algorithm was also proposed.

Cardiac Amyloidosis: A Review of Current Imaging Techniques

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

Global and Regional Variations in Transthyretin Cardiac Amyloidosis: A Comparison of Longitudinal Strain and 99mTechnetium Pyrophosphate Imaging

Background: There is limited data on the head-to-head comparison of ^99mTc-pyrophosphate (PYP) and echocardiographic strain imaging in the assessment of transthyretin (TTR) cardiac amyloidosis. Methods: At Mayo Clinic Arizona, patients that had undergone both a ^99mTc-PYP scan and transthoracic echocardiogram (TTE) within a 90-day period were retrospectively identified for chart review and strain imaging analysis. Patients were divided into two groups according to their ^99mTc-PYP results (PYP+ and PYP -) for the comparison. A standard 17-segment model was used for segmental, regional and global longitudinal strain comparison. A p-value of <0.05 was deemed as significant. Results: A total of 64 patients were included, the mean age was 75.1 ± 13.0 years and 57(89.1%) were male. Comparing the PYP+ to the PYP- group, the left ventricular global longitudinal strain was significantly worse (PYP+ vs. PYP-: -10.5 ± 2.6 vs. -13.1 ± 4.1, P = 0.003). PYP+ patients also had worse regional basal strain (-4.6 ± 2.6 vs. -8.8±4.0, p<0.001) and a trend of worse mid-ventricular strain (-9.6 ± 4.0 vs. -11.7± 4.4, P = 0.07), however, no statistical difference in apical region (-17.6 ± 4.73 vs. -19.0 ± 6.46, P = 0.35). This is consistent with an apical sparing pattern shown by the relative apical longitudinal strain index (1.3 ±0.5 vs. 1.0 ± 0.3, P = 0.008). Segment to segment analysis demonstrated significant difference in strain between PYP+ and PYP- segments in 4 segments: basal inferior (P = 0.006), basal anterolateral (P = 0.01), apical septal (P = 0.002) and apical inferior (P = 0.001). Left ventricular diastolic dysfunction was significantly different with 17 (77.3%) patients in group PYP+ versus 15 (36.6%) in PYP- participants (P = 0.002). Conclusion: Our study suggested that PYP uptake is related to overall worse LV segmental, regional and global longitudinal strain function, as well as diastolic function compared to patients without PYP uptake. This provides important data for clinicians to know the echocardiographic function features related to ^99mTc-PYP uptake and can serve as a hypothesis-generating study for future investigators.

Perfil Clínico, Laboratorial e de Métodos de Imagem na Amiloidose Sistêmica em um Centro de Referência Cardiológico Brasileiro

Fundamento

Amiloidose sistêmica é uma doença com manifestações clínicas diversas. O diagnóstico envolve suspeita clínica, aliada a métodos complementares.

Objetivo

Descrever o perfil clínico, laboratorial, eletrocardiográfico e de imagem no acometimento cardíaco da amiloidose sistêmica.

Métodos

Estudo de uma amostra de conveniência, analisando dados clínicos, laboratoriais, eletrocardiográficos, ecocardiográficos, medicina nuclear e ressonância magnética. Considerou-se significância estatística quando p < 0,05.

Resultados

Avaliaram-se 105 pacientes (com mediana de idade de 66 anos), sendo 62 homens, dos quais 83 indivíduos apresentavam amiloidose por transtirretina (ATTR) e 22 amiloidose por cadeia leve (AL). Na ATTR, 68,7% eram de caráter hereditário (ATTRh) e 31,3% do tipo selvagem (ATTRw). As mutações mais prevalentes foram Val142Ile (45,6%) e Val50Met (40,3%). O tempo de início dos sintomas ao diagnóstico foi 0,54 e 2,15 anos nas formas AL e ATTR (p < 0,001), respectivamente. O acometimento cardíaco foi observado em 77,9% dos ATTR e 90,9% dos AL. Observaram-se alterações de condução atrioventricular em 20% e intraventricular em 27,6% dos pacientes, sendo 33,7 % na ATTR e 4,5% das AL (p = 0,006). A forma ATTRw apresentou mais arritmias atriais que os ATTRh (61,5% x 22,8%; p = 0,001). Ao ecocardiograma a mediana da espessura do septo na ATTRw x ATTRh x AL foi de 15 mm x 12 mm x 11 mm (p = 0,193). Observou-se BNP elevado em 89,5% dos indivíduos (mediana 249 ng/mL, IQR 597,7) e elevação da troponina em 43,2%.

Conclusão

Foi possível caracterizar, em nosso meio, o acometimento cardíaco na amiloidose sistêmica, em seus diferentes subtipos, através da história clínica e dos métodos diagnósticos descritos.

[Diagnosis and treatment of cardiac amyloidosis : A position statement of the ESC working group on myocardial and pericardial diseases 2021]

Cardiac amyloidosis is still considered a rare disease, although recent data show that it is the cause of cardiac dysfunction more frequently than expected. The diagnosis of cardiac amyloidosis is based on the detection of extracellular deposits of misfolded proteins in the myocardium. This detection can be made invasively or noninvasively and is based on a tentative diagnosis that forms the foundation for further diagnostic measures. As different forms of amyloidosis may have different clinical presentations, suspicion of amyloidosis is often difficult. As not only the diagnostic possibilities have become broader but also new therapeutic possibilities have been tested in clinical studies, the working group on myocardial and pericardial diseases of the European Society of Cardiology (ESC) has set up a working group of experts to compile the current data on the clinical presentation, diagnostics and treatment of patients with cardiac amyloidosis, in order to subsequently develop diagnostic criteria and treatment options for patients with different forms of cardiac amyloidosis by consensus. The aim was to formulate a uniform Europe-wide acceptable concept for essential diagnostics and treatment for this group of patients. Only this will create the foundation for national and international registers and double-blind randomized treatment studies.

Plasmin activity promotes amyloid deposition in a transgenic model of human transthyretin amyloidosis

Cardiac ATTR amyloidosis, a serious but much under-diagnosed form of cardiomyopathy, is caused by deposition of amyloid fibrils derived from the plasma protein transthyretin (TTR), but its pathogenesis is poorly understood and informative in vivo models have proved elusive. Here we report the generation of a mouse model of cardiac ATTR amyloidosis with transgenic expression of human TTR^S52P. The model is characterised by substantial ATTR amyloid deposits in the heart and tongue. The amyloid fibrils contain both full-length human TTR protomers and the residue 49-127 cleavage fragment which are present in ATTR amyloidosis patients. Urokinase-type plasminogen activator (uPA) and plasmin are abundant within the cardiac and lingual amyloid deposits, which contain marked serine protease activity; knockout of α₂-antiplasmin, the physiological inhibitor of plasmin, enhances amyloid formation. Together, these findings indicate that cardiac ATTR amyloid deposition involves local uPA-mediated generation of plasmin and cleavage of TTR, consistent with the previously described mechano-enzymatic hypothesis for cardiac ATTR amyloid formation. This experimental model of ATTR cardiomyopathy has potential to allow further investigations of the factors that influence human ATTR amyloid deposition and the development of new treatments.

ATTR amyloidosis causes heart failure through the accumulation of misfolded transthyretin in cardiac muscle. Here the authors report a mouse model of ATTR amyloidosis and demonstrate the involvement of protease activity in ATTR amyloid deposition.

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.

Estimation of prevalence of transthyretin (ATTR) cardiac amyloidosis in an Australian subpopulation using bone scans with echocardiography and clinical correlation

BACKGROUND

Bone scans differentiate transthyretin (ATTR) cardiac amyloidosis from light chain amyloidosis and other causes of increased left ventricular (LV) wall thickness. We examined the prevalence and implications of cardiac uptake in the general population.

METHODS

Patients were included based on having undertaken a bone scan for non-cardiac indications using Technetium 99m hydroxymethylene diphosphonate (HMDP) or Technetium 99m methylene diphosphonate (MDP). Blinded image review was undertaken. Positive was defined as cardiac uptake ≥ rib AND heart/whole body ratio (H/WB) > 0.0388. Echocardiography and clinical records were reviewed.

RESULTS

6918 patients were included. 15/3472 HMDP scans were positive (14 males, 1 female): none in individuals aged < 65; 1.44% in males and 0.17% in females ≥ 65; 6.15% in males and 1.69% in females ≥ 85. Only 1/3446 MDP scans were positive. All HMDP positive patients had increased septal wall thickness on echocardiography. H/WB correlated positively with LV mass, and negatively with LV ejection fraction. No individual had an explanation other than ATTR for their positive scan.

CONCLUSION

In this Australian subpopulation, the prevalence of positive bone scans consistent with cardiac ATTR is 0% in individuals aged < 65. Prevalence increased with age, reaching 6.15% in men ≥ 85. The amount of HMDP uptake correlated with echocardiographic features of more advanced cardiac involvement. MDP does not appear useful in ATTR.

Energetic Basis for Exercise-Induced Pulmonary Congestion in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Transient pulmonary congestion during exercise is emerging as an important determinant of reduced exercise capacity in heart failure with preserved ejection fraction (HFpEF). We sought to determine whether an abnormal cardiac energetic state underpins this process.

METHODS

We recruited patients across the spectrum of diastolic dysfunction and HFpEF (controls, n=11; type 2 diabetes, n=9; HFpEF, n=14; and severe diastolic dysfunction attributable to cardiac amyloidosis, n=9). Cardiac energetics were measured using phosphorus spectroscopy to define the myocardial phosphocreatine to ATP ratio. Cardiac function was assessed by cardiovascular magnetic resonance cine imaging and echocardiography and lung water using magnetic resonance proton density mapping. Studies were performed at rest and during submaximal exercise using a magnetic resonance imaging ergometer.

RESULTS

Paralleling the stepwise decline in diastolic function across the groups (E/e' ratio; P<0.001) was an increase in NT-proBNP (N-terminal pro-brain natriuretic peptide; P<0.001) and a reduction in phosphocreatine/ATP ratio (control, 2.15 [2.09, 2.29]; type 2 diabetes, 1.71 [1.61, 1.91]; HFpEF, 1.66 [1.44, 1.89]; cardiac amyloidosis, 1.30 [1.16, 1.53]; P<0.001). During 20-W exercise, lower left ventricular diastolic filling rates (r=0.58; P<0.001), lower left ventricular diastolic reserve (r=0.55; P<0.001), left atrial dilatation (r=-0.52; P<0.001), lower right ventricular contractile reserve (right ventricular ejection fraction change, r=0.57; P<0.001), and right atrial dilation (r=-0.71; P<0.001) were all linked to lower phosphocreatine/ATP ratio. Along with these changes, pulmonary proton density mapping revealed transient pulmonary congestion in patients with HFpEF (+4.4% [0.5, 6.4]; P=0.002) and cardiac amyloidosis (+6.4% [3.3, 10.0]; P=0.004), which was not seen in healthy controls (-0.1% [-1.9, 2.1]; P=0.89) or type 2 diabetes without HFpEF (+0.8% [-1.7, 1.9]; P=0.82). The development of exercise-induced pulmonary congestion was associated with lower phosphocreatine/ATP ratio (r=-0.43; P=0.004).

CONCLUSIONS

A gradient of myocardial energetic deficit exists across the spectrum of HFpEF. Even at low workload, this energetic deficit is related to markedly abnormal exercise responses in all 4 cardiac chambers, which is associated with detectable pulmonary congestion. The findings support an energetic basis for transient pulmonary congestion in HFpEF.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Cardiovascular Involvement in Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) is a systemic disorder resulting from the extracellular deposition of amyloid fibrils of misfolded transthyretin protein in the heart. ATTR-CA is a life-threatening disease, which can be caused by progressive deposition of wild type transthyretin (wtATTR) or by aggregation of an inherited mutated variant of transthyretin (mATTR). mATTR Is a rare condition transmitted in an autosomal dominant manner with incomplete penetrance, causing heterogenous phenotypes which can range from predominant neuropathic involvement, predominant cardiomyopathy, or mixed. Diagnosis of ATTR-CA is complex and requires integration of different imaging tools (echocardiography, bone scintigraphy, magnetic resonance) with genetics, clinical signs, laboratory tests, and histology. In recent years, new therapeutic agents have shown good efficacy and impact on survival and quality of life in this subset of patients, nevertheless patients affected by ATTR-CA may still carry an unfavorable prognosis, thus highlighting the need for new therapies. This review aims to assess cardiovascular involvement, diagnosis, and management of patients affected by ATTR-CA.

Tafamidis treatment delays structural and functional changes of the left ventricle in patients with transthyretin amyloid cardiomyopathy

AIMS

Tafamidis improves outcomes in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). However, it is not yet known whether tafamidis affects cardiac amyloid deposition and structural changes in the myocardium. We aimed to determine disease-modifying effects on myocardial amyloid progression and to identify imaging parameters that could be applied for specific therapy monitoring.

METHODS AND RESULTS

ATTR-CM patients underwent serial cardiac magnetic resonance (CMR) imaging using T1 mapping techniques to derive extracellular volume (ECV). Patients receiving tafamidis 61 mg (n = 35) or 20 mg (n = 15) once daily showed stable measurements at follow-up (FU) {61 mg: 9.0 [interquartile range (IQR) 7.0-11.0] months, 20 mg: 11.0 (IQR 8.0-18.0) months} in left ventricular (LV) ejection fraction (LVEF; 61 mg: 47.6% vs. 47.5%, P = 0.935; 20 mg: 52.4% vs. 52.1%, P = 0.930), LV mass index (LVMI; 61 mg: 110.2 vs. 106.2 g/m2, P = 0.304; 20 mg: 114.5 vs. 115.4 g/m2, P = 0.900), and ECV (61 mg: 47.5% vs. 47.7%, P = 0.861; 20 mg: 56.7% vs. 57.5%, P = 0.759), whereas treatment-naïve ATTR-CM patients (n = 19) had clear signs of disease progression at the end of the observation period [12.0 (IQR 10.0-21.0) months; LVEF: 53.3% vs. 45.7%, P = 0.031; LVMI: 98.9 vs. 106.9 g/m2, P = 0.027; ECV: 49.3% vs. 54.6%, P = 0.023]. Between-group comparison at FU revealed positive effects in tafamidis 61 mg-treated compared to treatment-naïve patients (LVEF: P = 0.035, LVMI: P = 0.036, ECV: P = 0.030), while those treated with 20 mg showed no difference in the above LV measurements when compared with treatment-naïve (P = 0.120, P = 0.287, P = 0.158). However, both treatment groups showed clinically beneficial effects compared to the natural course [61 mg, 6-min walk distance (6-MWD): P = 0.005, N-terminal prohormone of brain natriuretic peptide (NT-proBNP): P = 0.002; 20 mg, 6-MWD: P = 0.023, NT-proBNP: P = 0.003].

CONCLUSION

Tafamidis delays myocardial amyloid progression in ATTR-CM patients, resulting in structural, functional, and clinical benefits compared to the natural course. Serial CMR including measurement of ECV may be appropriate for disease-specific therapy monitoring.

The utility of positron emission tomography in cardiac amyloidosis

Cardiac amyloidosis, characterized by progressive restrictive cardiomyopathy, presents unusual diagnostic challenges. Conventional cardiac scintigraphy has shown limited utility in the quantification of disease burden and serial follow-up of cardiac amyloidosis. The advent of specialized positron emission tomography with specific amyloid-binding radiotracers has the potential to change currently employed diagnostic algorithms for the imaging of cardiac amyloidosis. This review aims to discuss the diagnostic utility of amyloid-binding radiotracers, including Pittsburg compound B, florbetapir, florbetapan, and sodium fluoride. These tracers have promising potential for the early detection of the particular type of cardiac amyloidosis, pursuing relevant medical intervention, assessing amyloid burden, monitoring treatment response, and overall prognostication.

Diagnostic Work-Up of Cardiac Amyloidosis Using Cardiovascular Imaging: Current Standards and Practical Algorithms

Among non-ischemic cardiomyopathies, cardiac amyloidosis is one of the most common, being caused by extracellular depositions of amyloid fibrils in the myocardium. Two main forms of cardiac amyloidosis are known so far, including 1) light-chain (AL) amyloidosis caused by monoclonal production of light-chains, and 2) transthyretin (ATTR) amyloidosis, caused by dissociation of the transthyretin tetramer into monomers. Both AL and ATTR amyloidosis are progressive diseases with median survival from diagnosis of less than 6 months and 3 to 5 years, respectively, if untreated. In this regard, death occurs in most patients due to cardiac causes, mainly congestive heart failure, which can be prevented due to the presence of effective, life-saving treatment regimens. Therefore, early diagnosis of cardiac amyloidosis is crucial more than ever. However, diagnosis of cardiac amyloidosis may be challenging due to variable clinical manifestations and the perceived rarity of the disease. In this regard, clinical and laboratory reg flags are available, which may help clinicians to raise suspicion of cardiac amyloidosis. In addition, advances in cardiovascular imaging have already revealed a higher prevalence of cardiac amyloidosis in specific populations, so that the diagnosis especially of ATTR amyloidosis has experienced a >30-fold increase during the past ten years. The goal of our review article is to summarize these findings and provide a practical approach for clinicians on how to use cardiovascular imaging techniques, such as echocardiography, cardiac magnetic resonance, bone scintigraphy and, if required, organ biopsy within predefined diagnostic algorithms for the diagnostic work-up of patients with suspected cardiac amyloidosis. In addition, two clinical cases and practical tips are provided in this context.

Sex-related differences in the clinical characteristics of wild-type transthyretin amyloidosis cardiomyopathy

BACKGROUND

A significant male predominance has been reported in wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). Hence, female cases of ATTRwt-CM are overlooked, and sex-related differences in ATTRwt-CM remain unclear. This study aimed to examine sex-related differences in clinical characteristics and diagnostic approaches in ATTRwt-CM.

METHODS

We retrospectively analyzed 199 consecutive patients who were diagnosed with ATTRwt-CM and evaluated sex-related differences in clinical characteristics, imaging parameters, biomarkers, and diagnostic approaches.

RESULTS

Twenty-nine patients (15%) were female. These female patients were significantly older at diagnosis (77.1 ± 6.5 years vs. 82.9 ± 4.8 years; p<0.001) and had a more advanced New York Health Association functional class (2.2 ± 0.7 vs. 2.6 ± 0.8; p = 0.006) than their male counterparts. The median B-type natriuretic peptide levels were significantly higher (236 pg/mL vs. 394 pg/mL; p = 0.017) in female patients. Echocardiography revealed that the mean interventricular septum diameter was thinner (15.7 ± 2.6 mm vs. 14.1 ± 2.5 mm; p = 0.004) and left ventricular ejection fraction (LVEF) was preserved (51.2 ± 10.2% vs. 57.2 ± 9.1%; p = 0.003) in female patients. The mean heart-to-contralateral ratio obtained using ^99mTc-labeled pyrophosphate (^99mTc-PYP) was significantly lower (1.89 ± 0.33 vs. 1.63 ± 0.20; p < 0.001), moderate to severe aortic stenosis was more frequently observed (5% vs. 45%; p < 0.001), and the frequency of histological diagnosis was significantly lower (77% vs. 59%; p = 0.036) in female patients.

CONCLUSIONS

Female patients with ATTRwt-CM were predominantly octogenarians and less hypertrophic and had preserved LVEF and weaker cardiac uptake of the ^99mTc-PYP tracer compared with male patients. These characteristics contribute to the underdiagnosis of ATTRwt-CM in female patients.

99mTechnetium-labeled cardiac scintigraphy for suspected amyloidosis: a review of current and future directions

Cardiac amyloidosis (CA) is an underdiagnosed form of restrictive cardiomyopathy leading to a rapid progression into heart failure. Evaluation of CA requires a multimodality approach making use of echocardiography, cardiac magnetic imaging, and nuclear imaging. Technetium (Tc)-labeled cardiac scintigraphy has witnessed a resurgence in its application for the workup of CA. Advancements in disease-modifying therapies have fueled the rapid adoption of cardiac scintigraphy using bone tracers and the need for transformative novel studies. The goal of this review is to present diagnostic utility, currently recommended protocols, as well as a glimpse into the rapid evolution of Tc-labeled cardiac scintigraphy in the diagnosis of CA.

Characterization of hereditary transthyretin cardiac amyloidosis in Spain

INTRODUCTION AND OBJECTIVES

Hereditary transthyretin amyloidosis (hATTR) is a disease caused by mutations in the transthyretin gene that frequently shows cardiac involvement due to amyloid deposition in the myocardium. Our objective was to identify cardiac involvement in a Spanish cohort.

METHODS

Retrospective multicenter study of patients diagnosed with hATTR with cardiac involvement from Spanish centers. We collected demographic, clinical, and genetic data.

RESULTS

A total of 181 patients from 26 centers were included (65.2% men, with a median age at diagnosis of 62 years). The most frequent mutations were Val50Met (67.7%) and Val142Ile (12.4%). The main reason for consultation was extracardiac symptoms (69%), mainly neurological. The mean N-terminal pro-B-type natriuretic peptide level was 2145±3586 pg/mL. The most characteristic electrocardiogram findings were a pseudoinfarct pattern (25.9%) and atrioventricular block (25.3%). Mean ventricular thickness was 15.4±4.1mm. Longitudinal strain was reduced in basal segments by 29.4%. Late diffuse subendocardial enhancement was observed in 58.8%. Perugini grade 2 or 3 uptake was observed in 75% of scintigraphy scans. During follow-up, 24.9% of the patients were admitted for heart failure, 34.3% required a pacemaker, and 31.6% required a liver transplant. One third (32.5%) died during follow-up, mainly due to heart failure (28.8%). The presence of non-Val50Met mutations was associated with a worse prognosis.

CONCLUSIONS

HATTR cardiac amyloidosis in Spain shows heterogeneous genetic and clinical involvement. The prognosis is poor, mainly due to cardiac complications. Consequently early diagnosis and treatment are vital.

Advances in the treatment of transthyretin cardiac amyloidosis: Current and emerging therapies

Transthyretin cardiac amyloidosis (ATTR-CA) has been recognized as an underdiagnosed and undertreated cause of heart failure with often unrecognized multiorgan involvement. Guideline development and the establishment of nonbiopsy criteria for diagnosis of ATTR-CA have led to an increased rate of diagnosis and hence patients referred for therapies. ATTR is a protein misfolding disorder where the TTR tetramer disassociates into monomers which form insoluble amyloid depositions in organs, including the heart. ATTR-CA can be due to autosomal dominant transmitted gene mutation or due to misfolding of wild-type TTR. Prior to 2019, there were no FDA-approved pharmacological treatments for ATTR-CA. Understanding of ATTR-CA pathogenesis has enabled development of targeted strategies with novel disease-modifying therapies. Current and emerging therapies for ATTR-CA include (1) TTR gene silencing (siRNA, ASO, CRISPR/Cas9), (2) TTR tetramer stabilization, and (3) TTR amyloid fibril degradation. This review focuses on the pathophysiology of ATTR-CA, diagnostic criteria, and addresses current and emerging treatments for this diverse disorder.

Cardiovascular Diseases That Have Emerged From the Darkness

It is important for both the patient and physician communities to have timely access to information recognizing rapid progress in the diagnosis and treatment of familiar but relatively uncommon cardiovascular diseases. Patients with 3 cardiovascular diseases (ie, hypertrophic cardiomyopathy, pulmonary arterial hypertension, and transthyretin (TTR) cardiac amyloidosis (ATTR)]), once considered rare without effective management options and associated with malignant prognosis, have now benefited substantially from the development of a variety of innovative therapeutic strategies. In addition, in each case, enhanced diagnostic testing has expanded the patient population and allowed for more widespread administration of contemporary treatments. In hypertrophic cardiomyopathy, introduction of implantable defibrillators to prevent sudden death as well as high-benefit:low-risk septal reduction therapies to reverse heart failure have substantially reduced morbidity and disease-related mortality (to 0.5% per year). For pulmonary arterial hypertension, a disease once characterized by a particularly grim prognosis, prospective randomized drug trials with aggressive single (or combined) pharmacotherapy have measurably improved survival and quality of life for many patients. In cardiac amyloidosis, development of disease-specific drugs can for the first time reduce morbidity and mortality, prominently with breakthrough ATTR-protein-stabilizing tafamidis. In conclusion, in less common and visible cardiovascular diseases, it is crucial to recognize substantial progress and achievement, given that penetration of such information into clinical practice and the patient community can be inconsistent. Diseases such as hypertrophic cardiomyopathy, pulmonary arterial hypertension, and ATTR cardiac amyloidosis, once linked to a uniformly adverse prognosis, are now associated with the opportunity for patients to experience satisfactory quality of life and extended longevity.

Serial scanning with 99mTc-3, 3-diphosphono-1, 2-propanodicarboxylic acid (99mTc-DPD) for early detection of cardiac amyloid deposition and prediction of clinical worsening in subjects carrying a transthyretin gene mutation

BACKGROUND

To determine the capability of 99mTc-DPD scintigraphy to detect early cardiac involvement and predict clinical worsening in transthyretin (TTR) gene mutation patients.

METHODS

Eleven mutated subjects with normal interventricular septum (IVS) thickness, NT-proBNP level and no cardiac symptoms underwent three seriate 99mTc-DPD scans (visually and semiquantitatively analyzed), and was followed-up for 5-8-years.

RESULTS

Six patients showed no myocardial accumulation in all scans. Increased IVS thickness occurring in one patient 4 years after the last scan was the only abnormal finding in these patients; no cardiac symptoms developed during the follow-up. In three patients, cardiac radiotracer uptake was found at enrollment; other laboratory/instrumental abnormal findings occurred later and cardiac symptoms developed during the follow-up period. Two patients had a negative 99mTc-DPD scan at enrollment and showed cardiac uptake in the following scans. Increased mean left-ventricular (LV) wall thickness was found 3 years after positive scintigraphy; NT-proBNP increased later in one patient. These patients developed cardiac symptoms during the follow-up period.

CONCLUSIONS

99mTc-DPD scan detects cardiac involvement in subjects with TTR gene mutation earlier than ECG, echocardiography and biochemical markers, occurring some years before the fulfillment of current diagnostic criteria for cardiac amyloidosis. A positive 99mTc-DPD scan predicts cardiac symptoms onset.

Temporal Trends of Wild-Type Transthyretin Amyloid Cardiomyopathy in the Transthyretin Amyloidosis Outcomes Survey

BACKGROUND

Transthyretin amyloid cardiomyopathy results from the accumulation of wild-type (ATTRwt) or variant (ATTRv) transthyretin amyloid fibrils in the myocardium. THAOS (Transthyretin Amyloidosis Outcomes Survey) is a global, longitudinal, observational survey of patients with ATTRv and ATTRwt amyloidosis and asymptomatic patients with transthyretin mutations.

OBJECTIVES

This study explored temporal trends in ATTRwt amyloidosis diagnoses using data from THAOS.

METHODS

Using THAOS data from December 2007 to January 2020, the following comparisons were made according to year: ATTRwt amyloidosis diagnoses in the United States versus rest of the world, ATTRwt versus ATTRv amyloidosis with cardiac-associated mutations diagnoses, and ATTRwt amyloidosis diagnoses by tissue biopsy versus bone scintigraphy.

RESULTS

There were 1,069 patients with ATTRwt amyloidosis and 525 with ATTRv amyloidosis with cardiac mutations enrolled in THAOS. The median time from symptom onset to ATTRwt amyloidosis diagnosis did not change over the past 5 years (>60 months from 2015-2019). ATTRwt amyloidosis diagnoses increased from 2 in 2005 to >100 per year from 2016, with a more pronounced increase in the United States compared with the rest of the world. Diagnoses of ATTRwt amyloidosis by tissue biopsy increased yearly and peaked in 2014 before declining, whereas diagnoses by bone scintigraphy increased markedly since 2011. ATTRv amyloidosis with cardiac mutation diagnoses increased from 3 in 2005 to 37 in 2011, then plateaued. The proportion of patients with ATTRwt amyloidosis diagnosed with New York Heart Association functional class III/IV heart failure decreased from 2012 (46.4%) to 2019 (16.0%).

CONCLUSIONS

In the past decade, ATTRwt amyloidosis diagnoses increased worldwide. Despite the growing utilization of bone scintigraphy, patients are diagnosed several years after symptom onset. (Transthyretin Amyloidosis Outcomes Survey [THAOS]; NCT00628745).

Diagnostic and prognostic value of Technetium-99m pyrophosphate uptake quantitation for transthyretin cardiac amyloidosis

BACKGROUND

99mTc-pyrophosphate imaging has emerged as an important non-invasive method to diagnose transthyretin cardiac amyloidosis (ATTR-CM). Quantitation of 99mTc-pyrophosphate activity, on SPECT images, could be a marker of ATTR-CM disease burden. We assessed the diagnostic accuracy and clinical significance of 99mTc-pyrophosphate quantitation.

METHODS AND RESULTS

Patients who underwent 99mTc-pyrophosphate imaging for suspected ATTR-CM were included. Using SPECT images, radiotracer activity in the myocardium was calculated using cardiac pyrophosphate activity (CPA) and volume of involvement (VOI), with thresholds for abnormal activity derived from LVBP activity. Diagnostic accuracy was assessed using area under the receiver operating characteristic curve (AUC). In total, 124 patients were identified, mean age 73.9 ± 11.4, with ATTR-CM diagnosed in 43 (34.7%) patients. CPA had the highest diagnostic accuracy (AUC .996, 95% CI .987-1.00), and was significantly higher compared to the Perugini score (AUC .952, P = .016). In patients with ATTR-CM, CPA was associated with reduced left ventricular ejection fraction (adjusted odds ratio 1.28, P = .035) and heart failure hospitalizations (adjusted hazard ratio 1.29, P = .006).

CONCLUSION

Quantitative assessment of myocardial radiotracer activity with CPA or VOI have high diagnostic accuracy for ATTR-CM. Both measures are potential non-invasive markers to follow progression of disease or response to therapy.

Myocardial Work Does Not Have Additional Diagnostic Value in the Assessment of ATTR Cardiac Amyloidosis

Background: Reduced LV longitudinal strain (GLS) and increased relative apical sparing (RELAPS) and increased wall thickness have been proposed as features for transthyretin cardiac amyloidosis (ATTR-CA). Myocardial work (MW) has recently been shown as useful afterload independent disease marker, hence we aimed to investigate its use in differentiating ATTR-CA from heart failure with increased septal thickness but no cardiac amyloidosis (CA) (HFnCA). Methods: This study included patients with HF and increased septal thickness ≥ 14 mm. We included 59 patients with hereditary (ATTRv) and 27 wild type transthyretin amyloidosis (ATTRwt) described as ATTR-CA based on DPD scintigraphy. We also enrolled 30 non-amyloidosis heart failure patients with negative DPD scintigraphy, as a control group. Myocardial work (MW) was used to assess the index (GWI), constructive (GCW) and wasted (GWW) work. Relative wall thickness (RWT) and relative apical sparing (RELAPS) were tested as conventional measures. Results: The RWT and RELAPS were higher in ATTR-CA (p < 0.001) and predicted ATTR-CA (RWT; AUC = 0.84, p < 0.001) and RELAPS (AUC = 0.81, p < 0.001). MW; GWI (p = 0.04), GCW (p = 0.03), GWW (p = 0.001) were all lower in ATTR-CA compared with HFnCA but only GWW predicted ATTR-CA, (AUC = 0.75, p < 0.001). Binary logistic univariate regression analysis showed RWT (p = 0.003, β = 16.2) and RELAPS (p = 0.003, β = 2.3) to be associated with ATTR-CA but not MW. GWI and GCW correlated with NT-proBNP (p < 0.05) and Troponin (p < 0.01), but not RWT or RELAPS. Conclusion: Myocardial work had lower accuracy, compared to RWT or RELAPS, in identifying ATTR-CA but was better related to biomarkers. Thus, MW assessment is unlikely to have additional value in improving the diagnosis of heart failure due to ATTR-CA.

A descriptive study of transthyretin amyloidosis in a tertiary hospital without a referral unit

BACKGROUND AND OBJECTIVE

Transthyretin amyloidosis (ATTR) is a rare disease that is part of systemic amyloidosis and is life-threatening. It can affect all organs and systems, the most frequent being neurological and cardiac involvement. This study aims to detect possible ATTR cases and carry out a descriptive study of them.

MATERIAL AND METHODS

Descriptive single-centre study carried out in a tertiary hospital, which included patients with suspected ATTR between September 2016 and January 2020.

RESULTS

A total of 190 suspected ATTR patients were detected. The study includes 100 of these patients, as well as 10 relatives of patients in whom ATTR was detected in its genetic variant (ATTRv). In total, ATTRv was detected in 7 individuals (3 with a presymptomatic mutation of the disease), 16 patients with age-related ATTR and 31 individuals with unknown cardiac amyloidosis with the tests performed, which confirms the presence of this disease in non-endemic areas.

CONCLUSIONS

ATTR is a disease that must be taken into account in the differential diagnosis of patients with heart failure with preserved LVEF, especially if associated with neurological symptoms.

Aortic Valve Stenosis and Cardiac Amyloidosis: A Misleading Association

The association between aortic stenosis (AS) and cardiac amyloidosis (CA) is more frequent than expected. Albeit rare, CA, particularly the transthyretin (ATTR) form, is commonly found in elderly people. ATTR-CA is also the most prevalent form in patients with AS. These conditions share pathophysiological, clinical and imaging findings, making the diagnostic process very challenging. To date, a multiparametric evaluation is suggested in order to detect patients with both AS and CA and choose the best therapeutic option. Given the accuracy of modern non-invasive techniques (i.e., bone scintigraphy), early diagnosis of CA is possible. Flow-charts with the main CA findings which may help clinicians in the diagnostic process have been proposed. The prognostic impact of the combination of AS and CA is not fully known; however, new available specific treatments of ATTR-CA have changed the natural history of the disease and have some impact on the decision-making process for the management of AS. Hence the relevance of detecting these two conditions when simultaneously present. The specific features helping the detection of AS-CA association are discussed in this review, focusing on the shared pathophysiological characteristics and the common clinical and imaging hallmarks.

Pharmacotherapy review: Emerging treatment modalities in transthyretin cardiac amyloidosis

DISCLAIMER

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

This review aims to summarize the evidence and pharmacological characteristics of treatment options for transthyretin amyloid cardiomyopathy (ATTR-CM). Additionally, this review highlights the role of clinical pharmacists in helping to secure newly introduced therapies.

SUMMARY

ATTR-CM, a disease characterized by misfolded protein that is deposited in the myocardium and disrupts cardiac functioning, has historically been underdiagnosed due to the need for invasive biopsy and an illusion of rarity. Once diagnosed, limited treatment modalities for ATTR-CM have led providers to rely on nonpharmacological remedies or off-label use of medications with limited evidence of benefit. However, recent noninvasive diagnostic advancements and heightened disease state awareness have revealed increased prevalence of ATTR-CM. This has led to the introduction of several first-in-class pharmaceuticals with actions targeted at inhibiting the various phases of amyloidosis: TTR stabilizers include diflunisal and first-in-class, Food and Drug Administration (FDA)-approved tafamidis; TTR silencers include patisiran and inotersen; fibril disrupters include doxycycline with tauroursodeoxycholic acid; and alternative agents include green tea extract and curcumin.

CONCLUSION

ATTR-CM treatments have emerged and, despite current limited data, are continuing to evolve. Tafamidis, the only agent approved by FDA for ATTR-CM, shows promise to improve survival and quality of life in patients with ATTR-CM. Pharmacists can play a key role in assisting with agent selection for this disease state, as well as providing knowledge about current and future clinical trials evaluating the safety and efficacy of the available treatment modalities.

[Cardiac amyloidosis and aortic valve stenosis]

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

Quantitative SPECT/CT parameters of myocardial 99mTechnetium-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) uptake in suspected cardiac transthyretin amyloidosis

Background

^99mTc-labelled bisphosphonates are used for imaging assessment of patients with transthyretin cardiac amyloidosis (ATTR). Present study evaluates whether quantitative SPECT/CT measurement of absolute myocardial ^99mTc-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (Tc-DPD) uptake can diagnose patients with suspected ATTR.

Methods

Twenty-eight patients (25 male, age 80.03 ± 6.99 years) with suspected ATTR referred for Tc-DPD imaging had planar and SPECT/CT imaging of the chest. Three operators independently obtained Tc-DPD myocardial SUVmax and SUVmean above threshold (SMaT) (20, 40 and 60% of SUVmax), using a semi-automated threshold segmentation method. Results were compared to visual grading (0–3) of cardiac uptake.

Results

Twenty-two patients (78%) had cardiac uptake (2 grade 1, 15 grade 2, 5 grade 3). SUVmax and SMaT segmentation thresholds enabled separating grades 2/3 from 0/1 with excellent inter- and intra-reader correlation. Cut-off values 6.0, 2.5, 3 and 4 for SUVmax, SMaT_20,40,60, respectively, separated between grades 2/3 and 0 /1 with PPV and NPV of 100%. SMaT_20,40,60(cardiac)/SUVmean (liver) and SMaT_20,40,60(cardiac)/SUV_mean(liver/lung) separated grades 2 and 3.

Conclusion

Quantitative SPECT/CT parameters of cardiac Tc-DPD uptake are robust, enabling separation of patients with grades 2 and 3 cardiac uptake from grades 0 and 1. Larger patient cohorts will determine the incremental value of SPECT/CT quantification for ATTR management.

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

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

Cardiac amyloidosis screening using a relative apical sparing pattern in patients with left ventricular hypertrophy

Background

Cardiac amyloidosis (CA) mimics left ventricular hypertrophy (LVH). It is treatable, but its prognosis is poor. A simple screening tool for CA would be valuable. CA is more precisely diagnosed with echocardiographic deformation parameters (e.g., relative apical sparing pattern [RASP]) than with conventional parameters. We aimed to 1) investigate incremental benefits of echocardiographic deformation parameters over established parameters for CA screening; 2) determine the resultant risk score for CA screening; and 3) externally validate the score in LVH patients.

Methods

We retrospectively studied 295 consecutive non-ischemic LVH patients who underwent detailed diagnostic tests. CA was diagnosed with biopsy or ^99mTc-PYP scintigraphy. The base model comprised age (≥65 years [men], ≥70 years [women]), low voltage on the electrocardiogram, and posterior wall thickness ≥ 14 mm in reference to the literature. The incremental benefit of each binarized echocardiographic parameter over the base model was assessed using receiver operating characteristic curve analysis and comparisons of the area under the curve (AUC).

Results

Fifty-four (18%) patients had CA. RASP showed the most incremental benefit for CA screening over the base model. After conducting multiple logistic regression analysis for CA screening using four variables (RASP and base model components), a score was determined (range, 0–4 points). The score demonstrated adequate discrimination ability for CA (AUC = 0.86). This result was confirmed in another validation cohort (178 patients, AUC = 0.88).

Conclusions

We developed a score incorporating RASP for CA screening. This score is potentially useful in the risk stratification and management of LVH patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12947-021-00258-x.

Multimodality Imaging in Cardiac Amyloidosis

PURPOSE OF REVIEW

Cardiac amyloidosis is an increasingly recognized condition with a growing range of targeted therapies, but diagnosis requires a high index of suspicion and multimodality imaging expertise. Early diagnosis remains key to improving quality of life and survival. This article reviews the multimodality imaging approach to the diagnosis, differentiation, and prognosis of cardiac amyloidosis.

RECENT FINDINGS

Recent advances in multimodality cardiac imaging have allowed for earlier diagnosis of cardiac amyloidosis resulting in earlier initiation of life-saving therapy in cases of light chain amyloidosis and life-prolonging therapy in transthyretin amyloidosis. With these advances in multimodality imaging, it is important for cardiologists and cardiac imagers to be aware of the subtleties of early disease, the appropriate diagnostic approach as well as understanding the practicalities and pitfalls that are encountered with each modality.

Wild-Type Transthyretin Amyloidosis in Female Patients - Consideration of Sex Differences

Background: With recent advances in non-invasive diagnostic tools, some studies indicate that wild-type transthyretin amyloidosis (ATTRwt) may be more common in females than previously reported. However, the clinical characteristics of female ATTRwt patients have not been determined.

Methods and Results: Of the 78 consecutive patients with ATTRwt in our cohort, 14 (17.9 %) were female. Compared with male patients, female ATTRwt patients had smaller left ventricular (LV) wall thicknesses (ventricular septum thickness 12.9 vs. 14.2 mm [P=0.081]; posterior wall thickness 12.7 vs. 13.6 mm [P=0.035]) and a higher LV ejection fraction (EF; mean [±SD] 58.4±8.9% vs. 48.9±11.8%; P=0.006). However, the severity of heart failure (HF), as assessed by HF stage, New York Heart Association functional class and B-type natriuretic peptide concentrations, did not differ between female and male patients. Moreover, LV mass index and relative wall thickness were increased and the stroke volume index was reduced in both female and male patients. In organ biopsies, female patients had a higher sensitivity to transthyretin deposition from abdominal fat than male patients (positive abdominal fat biopsy 80.0 % vs. 26.5%; P=0.016).

Conclusions: This study suggests that a relatively large proportion of elderly females have ATTRwt. Female ATTRwt patients had HF symptoms even at the stage of mild LV hypertrophy and preserved EF. Abdominal fat biopsy may be useful to diagnose ATTRwt, especially in female patients with HF.

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

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

Prevalence of transthyretin amyloidosis in patients with heart failure and no left ventricular hypertrophy

AIMS

As evidenced by scintigraphy imaging, the prevalence of transthyretin (TTR) cardiac amyloidosis in heart failure patients with preserved ejection fraction (HFpEF) and left ventricular hypertrophy (LVH) ranges between 13% and 19%. The natural evolution of cardiac amyloidosis begins with the deposition of amyloid material in the myocardium, with LVH ensuing at later stages. With current imaging modalities, it is possible to detect TTR cardiac amyloidosis before the hypertrophic stage. The aim of this study was to determine the prevalence of TTR cardiac amyloidosis in HFpEF patients without LVH.

METHODS AND RESULTS

The study prospectively enrolled patients admitted for HF with LV ejection fraction (LVEF) ≥ 50% and LV wall thickness <12 mm. TTR cardiac amyloidosis was diagnosed according to accepted criteria, which include positive cardiac 99-Tc-DPD scintigraphy in the absence of monoclonal protein expansion in blood. Transthyretin gene sequencing was performed in positive patients. From July 2017 to January 2020, 329 patients with HFpEF and LV thickness <12 mm were identified. After exclusions, 58 patients completed the study with cardiac scintigraphy (79 years, 54% men; median LVEF 60% and LV wall thickness 10.5 mm). Three patients (5.2%) were positive for TTR cardiac amyloidosis; genetic analysis excluded the presence of hereditary TTR amyloidosis. Positive patients baseline characteristics (84 years, 67% men, LVEF 60%, and LV wall thickness 11 mm) were similar to patients without TTR, except for troponin levels (0.05 vs. 0.02 ng/mL, P = 0.03) and glomerular filtration rate (82 vs. 60 mL/min, P = 0.032), which were higher in TTR patients.

CONCLUSIONS

In a cohort of patients with HFpEF without LVH, the prevalence of TTR cardiac amyloidosis was 5%. Early diagnosis of cardiac involvement in TTR amyloidosis (before manifest LVH) would seem recommendable because newly approved specific treatments can prevent additional deposition of amyloid material.

Advances in Diagnosis and Treatment of Cardiac and Renal Amyloidosis

Diagnoses of amyloidosis are increasing annually, and advances in bone scintigraphy and cardiac MRI accompanied by development of nonbiopsy diagnostic criteria have specifically led to a huge increase in transthyretin amyloidosis cardiomyopathy (ATTR-CM) diagnoses worldwide. Tafamidis use is increasing, and there are several ongoing phase III clinical trials of novel agents that promise to transform the treatment landscape for patients with ATTR-CM. In systemic light chain (AL) amyloidosis, more effective chemotherapeutic agents continue to improve patient outcomes. Accelerating the removal of amyloid deposits to accompany these therapies remains the holy grail. However, in the meantime, early diagnosis is undoubtedly key in improving patient outcomes.

Early Diagnosis and Outcome in Patients With Wild-Type Transthyretin Cardiac Amyloidosis

Whether diagnostic timing in transthyretin (TTR) cardiac amyloidosis (CA) predisposes patients to worse outcomes is unresolved. We aimed to describe the long-term association of diagnostic timing (time from first onset of symptoms consistent with CA leading to medical contact to definitive diagnosis) with mortality in patients with wild-type TTR-CA (ATTRwt-CA). Overall, we reviewed the medical records of 160 patients seen at a tertiary care amyloidosis unit from January 1, 2016, to January 1, 2020 (median [interquartile range] follow-up, 21 [10 to 34] months), and compared them by survival. Median diagnostic timing was 4 (2 to 12) months and was longer in nonsurvivors (9 [3 to 15] vs 3 [1 to 7] months; P<.001). Patients diagnosed 6 or more months after symptom onset had higher mortality, with a median survival of 30 months (95% CI, 22 to 37 months). On Cox multivariable analysis, timing was independently associated with all-cause mortality (hazard ratio per month increase, 1.049 [95% CI, 1.017 to 1.083]) together with age at diagnosis, disease stage, New York Heart Association class, and coronary artery disease. In conclusion, diagnostic timing of ATTRwt-CA is associated with mortality. Timely diagnosis is warranted whenever "red flags" are present.