Clinical, electrocardiographic and echocardiographic findings in significant cardiac amyloidosis detected only at necropsy: comparison with cases diagnosed in life

Right Atrial Deformation Analysis in Cardiac Amyloidosis - Results from the Three-Dimensional Speckle-Tracking Echocardiographic MAGYAR-Path Study

BACKGROUND

Light-chain (AL) cardiac amyloidosis (CA) is characterized by fibril deposits, which are composed of monoclonal immunoglobulin light chains. The right ventricle is mostly involved in AL-CA and impairment of its function is a predictor of worse prognosis.

OBJECTIVES

To characterize the volumetric and functional properties of the right atrium (RA) in AL-CA by three-dimensional speckle-tracking echocardiography (3DSTE).

METHODS

A total of 16 patients (mean age: 64.5 ± 10.1 years, 11 males) with AL-CA were examined. Their results were compared to that of 15 age- and gender-matched healthy controls (mean age: 58.9 ± 6.9 years, 8 males). All cases have undergone complete two-dimensional Doppler and 3DSTE. A two-tailed p value of less than 0.05 was considered statistically significant.

RESULTS

Significant differences could be demonstrated in RA volumes respecting cardiac cycle. Total (19.2 ± 9.3% vs. 27.9 ± 10.7%, p = 0.02) and active atrial emptying fractions (12.1 ± 8.1 vs. 18.6 ± 9.8%, p = 0.05) were significantly decreased in AL-CA patients. Peak global (16.7 ± 10.3% vs. 31.2 ± 19.4%, p = 0.01) and mean segmental (24.3 ± 11.1% vs. 38.6 ± 17.6%, p =0.01) RA area strains, together with some circumferential, longitudinal and segmental area strain parameters, proved to be reduced in patients with AL-CA. Global longitudinal (4.0 ± 5.2% vs. 8.2 ± 5.5%, p = 0.02) and area (7.8 ± 8.1% vs. 15.9 ± 10.3%, p = 0.03) strains at atrial contraction and some circumferential and area strain parameters at atrial contraction were reduced in AL-CA patients.

CONCLUSION

Significantly increased RA volumes and deteriorated RA functions could be demonstrated in AL-CA.

Speckle Tracking and Transthyretin Amyloid Cardiomyopathy

Background

Amyloidosis is a disease caused by deposits of insoluble fibrils in extracellular spaces. The most common type of familial amyloidosis is mediated by mutation of transthyretin, especially Val30Met. Symptoms and ejection fraction decrease may occur in cardiac amyloidosis only in case of poor prognosis. Myocardial strain detected by two-dimensional speckle tracking echocardiography can indicate changes in myocardial function at early stages of the disease.

Objective

To determine the accuracy of left ventricular longitudinal strain by two-dimensional speckle tracking echocardiography in patients with familial amyloidosis caused by Val30Met transthyretin mutation.

Methods

Eighteen consecutive patients, carriers of transthyretin mutation, were evaluated by two-dimensional speckle tracking echocardiography, by which myocardial strain curves were obtained, following the American Society of Echocardiography recommendations.

Results

Patients were divided into three groups: 1- Val30Met with cardiac amyloidosis; 2-Val30Met with extracardiac amyloidosis; 3 - Val30Met without evidence of disease. As the three groups were compared by the Mann-Whitney test, we found a statistically significant difference between groups 1 and 2 in the mean longitudinal tension (p=0.01), mean basal longitudinal strain (p=0.014); in mean longitudinal tension and mean longitudinal strain between groups 1 and 3 (p=0.005); and in the ratio of longitudinal strain of apical septum segment to longitudinal strain of basal septum (p=0.041) between groups 2 and 3.

Conclusion

Left ventricular longitudinal strain detected by two-dimensional speckle tracking echocardiography is able to diagnose left ventricular dysfunction in early stages of familial amyloidosis caused by transthyretin Val30Met mutation.

Improving strategies for the diagnosis of cardiac amyloidosis

Amyloidosis refers to a group of rare but potentially fatal, protein misfolding diseases. The heart is frequently involved in the most common types, that is, immunoglobulin light chain and transthyretin amyloidosis and is the single most important predictor of patient outcomes. A major limitation in improving patient outcomes, in addition to developing novel therapeutics, is the late diagnosis of the disease. Once suspected, an organ for biopsy should be targeted and the amyloid type should be identified by mass spectrometry. An endomyocardial biopsy should be offered if cardiac involvement is in doubt. Echocardiography, MRI and nuclear imaging can provide valuable diagnostic and prognostic information and can secure the diagnosis if amyloid has been identified in an extracardiac tissue.