Transthyretin Cardiac Amyloidosis: A Cardio-Orthopedic Disease

Interactions between pathological and functional amyloid: A match made in Heaven or Hell?

The amyloid state of proteins occurs in many different contexts in Nature and in modern society, ranging from the pathological kind (neurodegenerative diseases and amyloidosis) via man-made forms (food processing and - to a much smaller extent - protein biologics) to functional versions (bacterial biofilm, peptide hormones and signal transmission). These classes all come together in the human body which endogenously produces amyloidogenic protein able to form pathological human amyloid (PaHA), hosts a microbiome which continuously makes functional bacterial amyloid (FuBA) and ingests food which can contain amyloid. This can have grave consequences, given that PaHA can spread throughout the body in a "hand-me-down" fashion from cell to cell through small amyloid fragments, which can kick-start growth of new amyloid wherever they encounter monomeric amyloid precursors. Amyloid proteins can also self- and cross-seed across dissimilar peptide sequences. While it is very unlikely that ingested amyloid plays a role in this crosstalk, FuBA-PaHA interactions are increasingly implicated in vivo amyloid propagation. We are now in a position to understand the structural and bioinformatic basis for this cross-talk, thanks to the very recently obtained atomic-level structures of the two major FuBAs CsgA (E. coli) and FapC (Pseudomonas). While there are many reports of homology-driven heterotypic interactions between different PaHA, the human proteome does not harbor significant homology to CsgA and FapC. Yet we and others have uncovered significant cross-stimulation (and in some cases inhibition) of FuBA and PaHA both in vitro and in vivo, which we here rationalize based on structure and sequence. These interactions have important consequences for the transmission and development of neurodegenerative diseases, not least because FuBA and PaHA can come into contact via the gut-brain interface, recurrent infections with microbes and potentially even through invasive biofilm in the brain. Whether FuBA and PaHA first interact in the gut or the brain, they can both stimulate and block each other's aggregation as well as trigger inflammatory responses. The microbiome may also affect amyloidogenesis in other ways, e.g. through their own chaperones which recognize and block growth of both PaHA and FuBA as we show both experimentally and computationally. Heterotypic interactions between and within PaHA and FuBA both in vitro and in vivo are a vital part of the amyloid phenomenon and constitute a vibrant and exciting frontier for future research.

Transthyretin Cardiac Amyloidosis in a Very Elderly Patient With a History of Inferior Myocardial Infarction: A Case Report

Transthyretin cardiac amyloidosis (ATTR-CA) involves the buildup of transthyretin protein in the heart muscle in the form of amyloid fibrils, which can affect heart structure and function. Common ECG findings of ATTR-CA include low QRS voltage and a pseudo-myocardial infarction (MI) pattern, defined as pathological Q waves or QS complexes in two consecutive leads without a history of MI or echocardiographic evidence of akinetic areas. Here, we present a case of ATTR-CA in a very elderly patient, in whom pathological Q waves on ECG were true indicators of a prior inferior MI. A 96-year-old woman with a history of inferior MI presented to her primary care clinic with a one-week history of nocturnal dyspnea. She had undergone coronary stent placement in the distal right coronary artery five years earlier for inferior MI. An ECG revealed abnormal Q waves, ST elevation of 0.5 mm, and T wave inversion in limb leads III and aVF, with no significant findings suggestive of left ventricular (LV) hypertrophy. Over a two-year period, QRS voltage progressively decreased in all leads, while the ST-T changes remained unchanged. Transthoracic echocardiogram (TTE) showed LV concentric hypertrophy with an increased wall thickness of 14 mm, except in the infero-septal region. In basal and mid-short-axis views, infero-septal wall motion was severely reduced, with notable wall thinning in contrast to the global LV hypertrophy observed elsewhere - findings consistent with prior inferior MI. The patient was ultimately diagnosed with ATTR-CA based on technetium-99m-pyrophosphate scintigraphy and monoclonal protein detection tests. Clinicians should recognize that pathological Q waves in ATTR-CA do not always indicate a pseudo-MI pattern. When both ECG and TTE suggest an MI pattern, further evaluation for coronary artery disease is warranted as part of the ATTR-CA diagnostic workup. In patients with both ATTR-CA and prior MI, a comprehensive clinical approach addressing both conditions is essential for optimizing prognosis.

Prevalence of transthyretin amyloidosis in patients undergoing carpal tunnel surgery: a prospective cohort study and risk factor analysis

Transthyretin amyloidosis is a frequent cause of heart failure, resulting from an accumulation of abnormal proteins in the myocardium. Recent research has highlighted the importance of early diagnosis to enhance the effectiveness of specific treatments. Extra-cardiac symptoms may precede several years before cardiac complications, with carpal tunnel syndrome often considered a red flag. The aim of this prospective, observational cohort study was to determine the incidence rate of positive synovial biopsies for transthyretin amyloidosis in patients aged 60-80 years undergoing carpal tunnel decompression, and to identify risk factors. The diagnosis of transthyretin amyloidosis was confirmed through the analysis of synovial tissue biopsies using Congo Red and immunohistochemical staining. The study included 254 patients, with an 18.5% prevalence of transthyretin amyloidosis. Risk factors for positive test results were identified as male sex, trigger finger, hearing disorders and valve disease. A predictive analysis using logistic regression yielded a probability model for individuals belonging to the positive group.Level of evidence III.

Screening for cardiac amyloidosis in patients with tenosynovial red flags: A collaboration between family medicine and cardiology

BACKGROUND

Amyloid deposition in tenosynovial structures precedes cardiac involvement up to 20 years. Therefore, a cardiological screening in patients with a history of tenosynovial manifestations of cardiac amyloidosis (CA) could lead to an increased number of early diagnoses.

METHODS

Patients with tenosynovial manifestations of CA (carpal tunnel syndrome, atraumatic biceps tendon rupture, lumbar spinal stenosis) have been identified by general practitioners and evaluated in a Referral Center for CA. Patients with a high suspicion of CA underwent the CA diagnostic pathway.

RESULTS

Among 50 General Practitioners (GP) contacted, 10 (20%) agreed to participate in the study for a total of 5615 patients ≥60 years. One hundred forty-five patients met the inclusion criteria, 2 of them already had a diagnosis of CA, and 57 agreed to undergo a cardiological evaluation (electrocardiography, echocardiography, NTproBNP assay). The median age was 73 [67-80] years and 31 (54%) were women. Eight patients were suggested to start the CA diagnostic pathway, five of them underwent a complete diagnostic evaluation for CA, three refused to complete the diagnostic exams and no new diagnoses were made.

CONCLUSION

A screening program for CA in patients with tenosynovial manifestations identified by general practitioners is feasible, but may not yield a high rate of new diagnosis. In this study, we identified two patients who already had a diagnosis of CA, and among patients at high risk for CA, 37% refused to complete the diagnostic pathway. Increased awareness of CA among patients might increase participation and diagnostic yield in screening studies. Further validation of this protocol is needed to evaluate its diagnostic performance.

The Importance of Ultrasound-Guided Synovial Biopsy in the Workup of Seronegative Inflammatory Arthritis: A Case Report

We report a case of a 74-year-old male who presented with typical clinical features of rheumatoid arthritis (RA), as well as elevated markers of inflammation. However, the patient did not respond to multiple RA treatments, and an ultrasound-guided synovial biopsy (UGSB) of the right wrist was performed, which established the diagnosis of amyloidosis. A variety of inflammatory conditions sometimes get misdiagnosed as seronegative RA due to similarities in clinical presentation. This case report highlights the importance of a thorough workup in patients who appear to have seronegative RA. Given the wide availability of ultrasound-guided, minimally invasive synovial biopsies, these procedures should be employed more often to detect rare conditions that may mimic seronegative RA, such as amyloidosis.

Screening approaches to cardiac amyloidosis in different clinical settings: Current practice and future perspectives

Cardiac amyloidosis is a serious and progressive infiltrative disease caused by the deposition of amyloid fibrils in the heart. In the last years, a significant increase in the diagnosis rate has been observed owing to a greater awareness of its broad clinical presentation. Cardiac amyloidosis is frequently associated to specific clinical and instrumental features, so called "red flags", and it appears to occur more commonly in particular clinical settings such as multidistrict orthopedic conditions, aortic valve stenosis, heart failure with preserved or mildly reduced ejection fraction, arrhythmias, plasma cell disorders. Multimodality approach and new developed techniques such PET fluorine tracers or artificial intelligence may contribute to strike up extensive screening programs for an early recognition of the disease.