Musculoskeletal co-morbidities in patients with transthyretin amyloid cardiomyopathy: a systematic review

The prevalence of transthyretin-associated amyloidosis cardiomyopathy (ATTR-CM) has grown because of newer non-invasive diagnosis tools. Detecting the presence of extra-cardiac ATTR manifestations such as musculoskeletal pathologies considered 'red flags', when there is minimal or non-cardiac clinical involvement is primordial to carry out an early diagnosis. The aim of this systematic review is to examine the prevalence of musculoskeletal, ATTR-deposition-related co-morbidities in patients already diagnosed with ATTR-CM, specifically carpal tunnel syndrome, ruptured biceps tendon, spinal stenosis, and trigger finger. We performed a systematic review using PRISMA guidelines. Inclusion criteria were all studies in English and Spanish language and participants had to be patients diagnosed with ATTR-CM, by any diagnostic method, with the musculoskeletal co-morbidities subject of this review. The quality of the studies was based on the Risk of Bias Tool. This systematic review included 22 studies for final analysis. Carpal tunnel syndrome is reported in 21 studies, brachial biceps tendon rupture is reported in three, and spinal stenosis in eight studies. No articles that accomplished all the inclusion criteria for trigger finger were found. Regarding to the quality of the studies, all of them were categorized as being of high and moderate quality. The frequent association between ATTR-CM and carpal tunnel syndrome, ruptured biceps tendon, and lumbar spinal is confirmed, and the onset of these co-morbidities usually precedes the diagnosis of by years. This association defines them as red flags that should be search proactively due to the current treatment possibilities and the severity of the presentation of cardiac amyloidosis.

Strong positive light chain immunostaining in a patient with transthyretin amyloidosis

The two most common systemic amyloidosis types are immunoglobulin light chain (AL) and amyloid transthyretin (ATTR) amyloidosis, in which the precursor proteins responsible for amyloidosis are light chain and transthyretin, respectively. Identification of precursor proteins is paramount to determine the type of amyloidosis, given that both amyloidosis types lack specificity in clinical presentation. Congo red staining followed by immunohistochemistry or immunofluorescence using fibril protein-specific antibodies is crucial for the diagnosis of amyloidosis. Here we describe a patient who was initially diagnosed with AL amyloidosis due to strong positive kappa light chain staining results. However, the diagnosis was corrected to hereditary ATTR amyloidosis using mass spectrometry and gene sequencing, confirming the important role of mass spectrometry in identifying the amyloid precursor protein and ruling out false-positive result from immunohistochemistry.

LEFT ATRIAL FUNCTION AND VOLUME BY MAGNETIC RESONANCE IN PATIENTS WITH HEREDITARY AMYLOIDOSIS

Background

Left atrial (LA) enlargement is a reliable predictor of adverse cardiovascular events, and reduced atrial function is an independent risk factor for mortality in patients with amyloidosis. The objective of this study was to characterize the LA function in Mexican patients with a confirmed diagnosis of hereditary transthyretin amyloidosis (amyloid transthyretin [ATTR]).

Methods

All consecutive patients with diagnosis of hereditary ATTR who underwent a cardiac magnetic resonance study in the period from March 2016 to June 2017 were included in the study; the volumes and function of the left atrium were evaluated.

Results

Patients were divided into two groups, one with and one without cardiac amyloidosis. Statistically significant differences were observed between both groups in terms of indexed maximal LA volume, 26 mL versus 35.9mL, p = 0.03; indexed minimal LA volume, 10.7 mL versus 13.6mL, p = 0.03; and indexed LA pre-contraction volume, 17 mL versus 22.4mL, p = 0.03. No statistically significant differences were observed between both groups when comparing neither different ejection volumes nor the different ejection fractions.

Conclusions

Patients with hereditary ATTR with cardiac involvement have remodeling of the left atrium, with increased atrial volumes, without diminishing its function.