Differences in the characteristics and contemporary cardiac outcomes of patients with light-chain versus transthyretin cardiac amyloidosis

Cardiac amyloidosis is not a single disease: a multiparametric comparison between the light chain and transthyretin forms

AIMS

Systemic amyloidosis represents a heterogeneous group of diseases resulting from amyloid fibre deposition. The purpose of this study is to establish a differential diagnosis algorithm targeted towards the two most frequent subtypes of CA.

METHODS AND RESULTS

We prospectively included all consecutive patients with ATTR and AL evaluated between 2018 and 2022 in two centres in a score derivation cohort and a different validation sample. All patients had a complete clinical, biomarker, electrocardiographic, and imaging evaluation. Confirmation of the final diagnosis with amyloid typing was performed according to the current international recommendations. The study population included 81 patients divided into two groups: ATTR (group 1, n = 32: 28 variant and 4 wild type) and AL (group 2, n = 49). ATTR patients were younger (50.7 ± 13.9 vs. 60.2 ± 7.3 years, P = 0.0001), and significantly different in terms of NT-proBNP [ATTR: 1472.5 ng/L (97-4218.5) vs. AL 8024 ng/L (3058-14 069) P = 0.001], hs-cTn I [ATTR: 10 ng/L (4-20) vs. AL 78 ng/L (32-240), P = 0.0002], GFR [ATTR 95.4 mL/min (73.8-105.3) vs. AL: 68.4 mL/min (47.8-87.4) P = 0.003]. At similar left ventricular (LV) wall thickness and ejection fraction, the ATTR group had less frequently pericardial effusion (ATTR: 15% vs. AL: 33% P = 0.0027), better LV global longitudinal strain (ATTR: -13.1% ± 3.5 vs. AL: -9.1% ± 4.3 P = 0.04), RV strain (ATTR: -21.9% ± 6.2 vs. AL: -16.8% ± 6 P = 0.03) and better reservoir function of the LA strain (ATTR: 22% ± 12 vs. AL: 13.6% ± 7.8 P = 0.02). Cut-off points were calculated based on the Youden method. We attributed to 2 points for parameters having an AUC > 0.75 (NT-proBNP AUC 0.799; hs-cTnI AUC 0.87) and 1 point for GFR (AUC 0.749) and TTE parameters (GLS AUC 0.666; RV FWS AUC 0.649, LASr AUC 0.643). A score of equal or more than 4 points has been able to differentiate between AL and ATTR (sensitivity 80%, specificity 62%, AUC = 0.798). The differential diagnosis score system was applied to the validation cohort of 52 CA patients showing a sensitivity of 81% with specificity of 77%.

CONCLUSIONS

CA is a complex entity and requires extensive testing for a positive diagnosis. This study highlights a series of non-invasive checkpoints, which can be useful in guiding the decision-making process towards a more accurate and rapid differential diagnosis.

Tolerability and effectiveness of beta-blockers in patients with cardiac amyloidosis: A systematic review and meta-analysis

OBJECTIVE

This systematic review aimed to assess the tolerability of patients with cardiac amyloidosis (CA) to beta-blockers (BBs) and evaluate its association with adverse outcomes.

METHODS

We performed a comprehensive search from January 1, 2000 to October 20, 2023. Studies examining BB use and tolerance or the relationship between BB use and outcomes in patients with CA were included. Pooled adjusted hazard ratios (aHRs) for all-cause mortality were calculated using random- and fixed-effects models.

RESULTS

Eight observational studies involving 4002 patients with CA (87.5% with transthyretin CA [ATTR-CA] and 12.5% with immunoglobulin light chain CA [AL-CA]) were assessed. BBs were used by 52.5% of the patients. However, 26.3% of the patients discontinued BBs because of hypotension, bradycardia, or fatigue. Regarding the association between BB use and all-cause death, four studies were identified that included 2874 patients with ATTR-CA and 16 patients with AL-CA. The meta-analysis revealed no apparent relationship between BB use and all-cause mortality (pooled aHR = 0.78, 95% confidence interval (CI) = 0.40-1.51). Two studies on patients with ATTR-CA found no impact of BB use on all-cause mortality in the subgroup with left ventricular ejection fraction (LVEF) > 40%, but conflicting results exist for those with LVEF ≤40% (pooled aHR = 0.78, 95% CI = 0.40-1.54).

CONCLUSION

The limited number of observational studies that predominantly enrolled patients with ATTR-CA showed that BBs were used in almost half of the patients with CA, with varying tolerability. However, no significant association was observed between BB use and all-cause mortality.

Deep Learning to Classify AL versus ATTR Cardiac Amyloidosis MR Images

The aim of this work was to compare the classification of cardiac MR-images of AL versus ATTR amyloidosis by neural networks and by experienced human readers. Cine-MR images and late gadolinium enhancement (LGE) images of 120 patients were studied (70 AL and 50 TTR). A VGG16 convolutional neural network (CNN) was trained with a 5-fold cross validation process, taking care to strictly distribute images of a given patient in either the training group or the test group. The analysis was performed at the patient level by averaging the predictions obtained for each image. The classification accuracy obtained between AL and ATTR amyloidosis was 0.750 for cine-CNN, 0.611 for Gado-CNN and between 0.617 and 0.675 for human readers. The corresponding AUC of the ROC curve was 0.839 for cine-CNN, 0.679 for gado-CNN (p < 0.004 vs. cine) and 0.714 for the best human reader (p < 0.007 vs. cine). Logistic regression with cine-CNN and gado-CNN, as well as analysis focused on the specific orientation plane, did not change the overall results. We conclude that cine-CNN leads to significantly better discrimination between AL and ATTR amyloidosis as compared to gado-CNN or human readers, but with lower performance than reported in studies where visual diagnosis is easy, and is currently suboptimal for clinical practice.

Clinical profile of patients with cardiac amyloidosis in India

Limited data exists on patients with cardiac amyloidosis (CA) in India, due to underdiagnosis and late presentation. We present single centre data from 13 patients over a 4 year period with a median age of 65 years. A majority presented with symptomatic heart failure (69%) and eight patients had confirmed AL amyloidosis. At the end of the follow up period, 46% patients died, with 30% of the overall cohort dead within six months. Among the survivors, 71% continue to have NYHA grade III/IV symptoms. A suggested algorithm for earlier diagnosis in resource constrained settings is also presented.

Prevalence and Clinical Outcomes of Transthyretin Amyloidosis: A Systematic Review and Meta-analysis

BACKGROUND

Systematic evidence on the prevalence and clinical outcome of transthyretin amyloidosis (ATTR) is missing. We explored: a) the prevalence of cardiac amyloidosis in various patient subgroups, b) survival estimates for ATTR subtypes and c) the effects of novel therapeutics on the natural course of disease.

METHODS

A systematic review of literature published in Medline before 31/12/2021 was performed for the prevalence of cardiac amyloidosis & all-cause mortality of ATTR patients. Extracted data included sample size, age, sex, and all-cause mortality at 1, 2 and 5-years. Subgroup analyses were performed for ATTR subtype i.e., wild type ATTR (wtATTR) vs. hereditary ATTR (htATTR), htATTR genotypes and treatment subgroups.

RESULTS

We identified a total of 62 studies (n=277,882 individuals) reporting the prevalence of cardiac amyloidosis, which was high among patients with a hypertrophic cardiomyopathy phenotype, HFpEF, and elderly with aortic stenosis. Data on ATTR mortality were extracted from 95 studies (n=18,238 ATTR patients). Patients with wtATTR were older (p=7x10^-10 ) and more frequently male (p=5x10^-20 ) vs. htATTR. The 2-year survival of ATTR was 73.3% (95%CI 71.6-76.2); for non-subtyped ATTR 70.4% (95%CI 66.9-73.9), for wtATTR (76.0%, 95%CI: 73.0-78.9) and for htATTR (77.2%, 95%CI: 74.0-80.4); in meta-regression analysis wtATTR was associated with higher survival after adjusting for confounders. There was an interaction between survival and htATTR genotypes (p=10^-15 , Val30Met having the lowest and Val122Ile/Thr60Ala the highest mortality). ATTR 2-year survival was higher on tafamidis/patisiran compared to natural disease course (79.9%, 95%CI: 74.4-85.3 vs. 72.4%, 95%CI 69.8-74.9, p<0.05).

CONCLUSIONS

We report the prevalence of ATTR in various population subgroups and provide survival estimates for the natural course of disease and the effects of novel therapeutics. Important gaps in worldwide epidemiology research in ATTR were identified. This article is protected by copyright. All rights reserved.

Advanced Imaging in Cardiac Amyloidosis

This review serves as a synopsis of multimodality imaging in cardiac amyloidosis (CA), which is a disease characterized by deposition of misfolded protein fragments in the heart. It emphasizes and summarizes the diagnostic possibilities and their prognostic values. In general, echocardiography is the first diagnostic tool in patients with an identified systemic disease or unclear left ventricular hypertrophy. Several echocardiographic parameters will raise suspicion and lead to further testing. Cardiac magnetic resonance and scintigraphy with bone avid radiotracers are crucial for diagnosis of CA and even enable a distinction between different subtypes. The subject is illuminated with established guidelines and innovative recent publications to further improve early diagnosis of cardiac amyloidosis in light of current treatment options.

Deep Learning Supplants Visual Analysis by Experienced Operators for the Diagnosis of Cardiac Amyloidosis by Cine-CMR

Background: Diagnosing cardiac amyloidosis (CA) from cine-CMR (cardiac magnetic resonance) alone is not reliable. In this study, we tested if a convolutional neural network (CNN) could outperform the visual diagnosis of experienced operators. Method: 119 patients with cardiac amyloidosis and 122 patients with left ventricular hypertrophy (LVH) of other origins were retrospectively selected. Diastolic and systolic cine-CMR images were preprocessed and labeled. A dual-input visual geometry group (VGG ) model was used for binary image classification. All images belonging to the same patient were distributed in the same set. Accuracy and area under the curve (AUC) were calculated per frame and per patient from a 40% held-out test set. Results were compared to a visual analysis assessed by three experienced operators. Results: frame-based comparisons between humans and a CNN provided an accuracy of 0.605 vs. 0.746 (p < 0.0008) and an AUC of 0.630 vs. 0.824 (p < 0.0001). Patient-based comparisons provided an accuracy of 0.660 vs. 0.825 (p < 0.008) and an AUC of 0.727 vs. 0.895 (p < 0.002). Conclusion: based on cine-CMR images alone, a CNN is able to discriminate cardiac amyloidosis from LVH of other origins better than experienced human operators (15 to 20 points more in absolute value for accuracy and AUC), demonstrating a unique capability to identify what the eyes cannot see through classical radiological analysis.