Cardiac amyloidosis (CA) involves the abnormal deposition and accumulation of amyloid proteins in the heart muscle. A hallmark of disease progression is declining heart function, which can lead to structural irregularities, arrhythmias, and ultimately heart failure. Atrial fibrillation (AF) is the most common arrhythmia that presents in CA patients, and this arrhythmia is significant because it can moderately increase the risk of patients developing intracardiac thrombi, thereby putting them at risk for thromboembolic events. The management of this complication entails the use of anticoagulants like vitamin K antagonists and direct oral anticoagulants to reduce the risk of thrombus formation. This article seeks to review AF in CA and the use of anticoagulation therapy for the management and reduction of thromboembolic risk. The major conclusions of this review are centered around the need for safe administration of anticoagulant therapy to CA patients, regardless of their CHA2DS2-VASc risk score. This review highlights the importance of taking a multidisciplinary or collaborative approach to CA treatment to ensure that all aspects of this multifaceted disease can be properly managed while minimizing adverse events like bleeding risk and drug-drug interactions.

Misfolding and aggregation of transthyretin (TTR) is associated with numerous ATTR amyloidosis. TTR aggregates extracted from ATTR patients consist of not only full-length TTR, but also N-terminally truncated TTR fragments that can be produced by proteolytic cleavage, suggesting the presence of multiple misfolding pathways. Here, we report mechanistic studies of an early stage of TTR aggregation to probe the oligomerization process for the full-length as well as N-terminally truncated TTR. Our kinetic analyses using size exclusion chromatography revealed that amyloidogenic monomers dissociated from wild-type (WT) as well as pathogenic variants (V30M and L55P) form misfolded dimers, which self-assemble into oligomers, precursors of fibril formation. Dimeric interfaces in the full-length misfolded oligomers were investigated by examining the effect of single-point mutations on the two β-strands (F and H). The single-point mutations on the two β-strands (E92P on strand F and T119W on strand H) inhibited the dimerization of misfolded monomers, while the TTR variants can still form native dimers through the same F and H strands. These results suggest that the two strands are involved in intermolecular associations for both native and misfolded dimers, but detailed intermolecular interactions are different in the two forms of dimers. In the presence of a proteolytic enzyme, TTR aggregation is greatly accelerated. The two mutations on the two β-strands, however, inhibited TTR aggregation even in the presence of a proteolytic enzyme, trypsin. These results suggest that the two β-strands (F and H) play a critical role in aggregation of the N-terminally truncated TTR as well.

OBJECTIVE: 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.
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.

In patients with cardiac amyloidosis, pericardial involvement is common, with up to half of patients presenting with pericardial effusions. The pathophysiological mechanisms of pericardial pathology in cardiac amyloidosis include chronic elevations in right-sided filling pressures, myocardial and pericardial inflammation due to cytotoxic effects of amyloid deposits, and renal involvement with subsequent uremia and hypoalbuminemia. The pericardial effusions are typically small; however, several cases of life-threatening cardiac tamponade with hemorrhagic effusions have been described as a presenting clinical scenario. Constrictive pericarditis can also occur due to amyloidosis and its identification presents a clinical challenge in patients with cardiac amyloidosis who concurrently manifest signs of restrictive cardiomyopathy. Multimodality imaging, including echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging, is useful in the evaluation and management of this patient population. The recognition of pericardial effusion is important in the risk stratification of patients with cardiac amyloidosis as its presence confers a poor prognosis. However, specific treatment aimed at the effusions themselves is seldom indicated. Cardiac tamponade and constrictive pericarditis may necessitate pericardiocentesis and pericardiectomy, respectively.

Amyloidosis is a disease characterized by the deposition of protein fibrils. Cardiac involvement is a significant factor in determining prognosis. This study aimed to examine the clinical profile, outcomes, and long-term mortality rates in patients with transthyretin (ATTR) and amyloid light-chain (AL) amyloidosis. The retrospective cohort study included 94 patients with amyloidosis (69 with AL and 25 with ATTR amyloidosis) diagnosed between 2010 and 2022. The study involved multimodality imaging (ECG, echocardiography and cardiac magnetic resonance (CMR) data and survival analyses. Patients with ATTR amyloidosis were older and had a higher proportion of males compared to those with AL amyloidosis. Cardiac involvement was more prevalent in the ATTR group, including atrial fibrillation (AF), while pleural and pericardial effusion were more frequent in the AL group. Biomarkers such as NT-proBNP and troponin T were significantly elevated in both groups and were associated with all-cause mortality only in univariate analyses. CMR data, especially typical late gadolinium enhancement (LGE) was not associated with increased mortality, while pleural effusion and left atrial dilatation on echocardiography were identified as powerful predictors of mortality. In conclusion, both AL and ATTR amyloidosis exhibited poor outcomes. Cardiac involvement, particularly dilated left atrium and pleural effusion on echocardiography were associated with an increased risk of mortality, while typical LGE on CMR was not.

BACKGROUND: ATTR (ATTRv) amyloidosis neuropathy is characterized by progressive sensorimotor and autonomic nerve degeneration secondary to amyloid deposition caused by a misfolded transthyretin protein (TTR). Small nerve fiber neuropathy is an early clinical manifestation of this disease resulting from the dysfunction of the Aδ and C small nerve fibers. Tafamidis, a selective TTR stabilizer, has proven its efficacy in the earlier stages of hATTR.
OBJECTIVE: To evaluate the clinical course and utility of cutaneous pathological biomarkers in patients with ATTR amyloidosis treated with tafamidis compared to control patients.
METHODS: Forty patients diagnosed with early stages of ATTRv amyloidosis (polyneuropathy disability [PND] scores 0-II) underwent small and large nerve fiber neurological evaluations, and annual skin biopsies for intraepidermal nerve fiber density (IENFD) and amyloid deposition index (ADI) estimation. Thirty patients were allocated to receive tafamidis, and 10 patients served as controls. Tafamidis pharmacokinetics analysis was performed in patients who received the treatment.
RESULTS: At baseline, 12% of patients in stage PND 0 and 28% in PND I displayed small nerve fiber denervation in the distal thigh, whereas 23% and 38%, respectively, in the distal leg. Similarly, 72% and 84% had amyloid deposition in the distal thigh and 56% and 69% in the distal leg. Following 1 year of treatment, the tafamidis group showed significant clinical improvement compared to the control group, revealed by the following mean differences (1) -9.3 versus -4 points (p = <.00) in the patient\'s neuropathy total symptom score 6 (NTSS-6) questionnaire, (2) -2.5 versus +2.8 points (p = <.00) in the Utah Early Neuropathy Score (UENS), and (3) +1.2°C versus -0.6 (p = .01) in cold detection thresholds. Among the patients who received tafamidis, 65% had stable or increased IENFD in their distal thigh and 27% in the distal leg. In contrast, all patients in the control group underwent denervation. The ADI either decreased or remained constant in 31% of the biopsies in the distal thigh and in 24% of the biopsies in the distal leg of the tafamidis-treated patients, whereas it rose across all the biopsies in the control group. At the 4-year follow-up, the tafamidis group continued to display less denervation in the distal thigh (mean difference [MD] of -3.0 vs. -9.3 fibers/mm) and the distal leg (mean difference [MD] -4.9 vs. -8.6 fibers/mm). ADI in tafamidis-treated patients was also lower in the distal thigh (10 vs. 30 amyloid/mm2) and the distal leg (23 vs. 40 amyloid/mm2) compared to control patients. Plasma tafamidis concentrations were higher in patients with IENFD improvement and in patients with reduced amyloid deposition. Patients without amyloid deposition in the distal leg at baseline displayed delayed disease progression at 4 years.
CONCLUSIONS: Cutaneous IENFD and amyloid deposition assessments in the skin of the distal thigh and distal leg are valuable biomarkers for early diagnosis of ATTR amyloidosis and for measuring the progression of small nerve fiber neuropathy. Early treatment with tafamidis slows the clinical progression of the disease, skin denervation, and amyloid deposition in the skin. Higher plasma concentrations of tafamidis are associated with better disease outcomes, suggesting that increasing the drug dose could achieve better plasma concentrations and response rates. This study describes the longest small nerve fiber neuropathy therapeutic trial with tafamidis and is the first to report small fiber symptoms, function, and structural assessments as outcomes.

OBJECTIVE: To examine the efficacy and safety of patisiran, an RNA interference therapeutic, in patients from Taiwan with hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy.
METHODS: The APOLLO phase 3 trial included patients from Taiwan who received patisiran 0.3 mg/kg intravenously or placebo once every 3 weeks (q3w) for 18 months (18 M), followed by patisiran 0.3 mg/kg q3w in an ongoing global open-label extension (OLE) study. The primary endpoint was change from baseline in modified Neuropathy Impairment Score +7 (mNIS+7) at 18 M.
RESULTS: Eighteen Taiwanese patients were enrolled in APOLLO (patisiran, n = 8; placebo, n = 10; all A97S gene variant) and 14 continued in the global OLE. In this Taiwanese sub-population, beneficial treatment effects at 18 M were observed in mNIS+7 (least squares mean difference in change from baseline [patisiran-placebo], -26.5 points; 95% confidence interval: -45.5, -7.5). Patients who switched from placebo to patisiran demonstrated slowing of polyneuropathy progression at month 12 in the global OLE, while those who received patisiran in APOLLO maintained the beneficial treatment effects. Patisiran had an acceptable safety profile in the Taiwanese sub-population.
CONCLUSIONS: This analysis suggests that patisiran is well tolerated and may provide a substantial clinical benefit for Taiwanese patients with hATTR amyloidosis with polyneuropathy.
UNASSIGNED: The studies were registered on the ClinicalTrials.gov. The APOLLO study ClinicalTrials.gov identifier is NCT01960348 (https://clinicaltrials.gov/ct2/show/NCT01960348), with the registration date of October 10, 2013, and the first patient was enrolled on December 13, 2013. For the global OLE, the ClinicalTrials.gov identifier is NCT02510261 (https://clinicaltrials.gov/ct2/show/NCT02510261) with the registration date of July 29, 2015, and the first patient was enrolled on July 13, 2015.
METHODS: This study provides Class II evidence that treatment with patisiran is safe and efficacious in Taiwanese patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy.

BACKGROUND: Transthyretin amyloidosis (ATTR) is a progressive, heterogeneous rare disease manifesting as ATTR polyneuropathy (ATTR-PN), ATTR cardiomyopathy (ATTR-CM), or a mixed phenotype. Tafamidis meglumine (20 mg po qd) is approved in some markets to delay neurologic progression in ATTR-PN, while high-dose tafamidis (80/61 mg po qd) is approved worldwide to reduce cardiovascular mortality and cardiovascular-related hospitalization in ATTR-CM. The objective of this study was to assess the real-world benefit of high-dose tafamidis for delaying neurologic progression in patients with mixed-phenotype variant ATTR-CM (ATTRv-CM).
METHODS: This exploratory, retrospective, observational cohort study evaluated anonymized electronic medical records and included adult patients with mixed-phenotype ATTRv-CM treated with high-dose tafamidis for at least 6 months. Neurologic assessments included the Medical Research Council (MRC) Scale for Muscle Strength, Neuropathy Impairment Score (NIS) muscle weakness subscale, and Polyneuropathy Disability (PND) instrument. Modified body mass index (mBMI) was also assessed.
RESULTS: Patients (N = 10) started tafamidis treatment an average of 3.8 months after diagnosis, with an average treatment duration of 20.8 months. Seven of 10 patients demonstrated normal muscle strength on the MRC scale throughout the study, and 9 of 10 patients had no decline in muscle strength during the post-treatment period. The NIS muscle weakness subscale score was ≤ 60 for all patients in the study at all time points, suggesting normal function to mild impairment. Six of 10 patients had no change in walking capacity as measured by the PND instrument at pre- and post-assessments, while one-third of patients had a decrease in PND stage (signaling improvement) from pre- to post-assessment. mBMI remained relatively stable throughout the study.
CONCLUSIONS: This is the first real-world study to demonstrate the potential value of high-dose tafamidis for delaying neurologic disease progression in patients with mixed-phenotype ATTRv-CM. The findings underscore the importance of multidisciplinary assessment for patients with ATTR amyloidosis.
BACKGROUND: ClinicalTrials.gov: NCT05139680.

UNASSIGNED: Transthyretin (ATTR) cardiac amyloidosis is associated with an apical-sparing strain pattern on TTE. We hypothesize that strain indices derived from myocardial perfusion imaging (MPI) can identify this abnormality.
UNASSIGNED: A group with ATTR amyloidosis was compared to age-matched controls with LVH but without amyloidosis who underwent PET or SPECT MPI. Strain values were used to calculate the apical strain index (ASI), apex-to-base ratio (ABR), and ejection fraction to global strain ratio in multiple planes.
UNASSIGNED: A direct comparison using Welch\'s t-tests reveals 6 statistically significant metrics. After regression analysis, the circumferential ASI and ABR at rest remain significantly greater in the ATTR group compared to controls.
UNASSIGNED: MPI-derived strain from the circumferential plane at rest may distinguish cardiac amyloidosis from other forms of LVH. If these findings are confirmed with validation studies, routine MPI-derived strain analysis could identify patients with subclinical amyloidosis who may benefit from further testing.

BACKGROUND: Pericardial effusion is associated with amyloidosis, specifically amyloid light chain (AL) and transthyretin (ATTR) subtypes. However, the patients might present with different clinical symptoms.
OBJECTIVE: To determine the characteristics and associations of patients with pericardial effusion owing to either AL or ATTR amyloidosis.
METHODS: This study reviewed 26 studies from databases such as PubMed, MEDLINE, Web of Science, Google Scholar and CINAHL databases after protocol registration. The data were analyzed in IBM SPSS 21. Many statistical tests, such as Student t- and the Mann-Whitney U tests, were used. Multivariate logistic regression analysis was also performed. A p-value< 0.05 was considered significant.
RESULTS: A total of 531 patients with pericardial effusion secondary to amyloidosis were included. The mean age was 58.4±24.5 years. Most of the patients were male (72.9%). Common co-morbid conditions included hypertension (16.8%) and active smoking (12.9%). The most common time from symptom onset to the clinical presentation was less than 1 week (45%). ATTR amyloidosis was more common in older patients (p<0.05). Abdominal and chest discomfort were commonly associated with AL and ATTR amyloidosis, respectively (p<0.05). Patients with AL amyloidosis had a higher association with interventricular septal thickening and increased posterior wall thickness (p<0.05). First-degree atrioventricular block, left bundle branch block (LBBB), and atrial fibrillation (AF) were more associated with ATTR amyloidosis (p<0.05).
CONCLUSIONS: Pericardial effusion in patients with AL amyloidosis was associated with hypertrophic remodeling, while conduction abnormalities were associated with ATTR amyloidosis.