Left Atria in Transthyretin Amyloid Cardiomyopathy: Structural and Functional Involvement

Diagnoses of transthyretin amyloid cardiomyopathy (ATTR-CM) have increased with the advent of techniques for noninvasive imaging to detect characteristic structural and functional changes in the ventricles. However, there are few structural and functional assessments of the atria in ATTR-CM.

To address this gap, researchers in Italy and the United Kingdom used histology and echocardiographic speckle-tracking to assess the structural and functional changes in the left atria of patients with ATTR-CM and determine whether these changes had prognostic value.

The investigators conducted a retrospective cohort study of patients enrolled in an ATTR-CM registry. Patients had heart failure and amyloidosis features on echocardiography. The diagnosis was confirmed by bone scintigraphy, cardiac biopsy, or biopsy of a noncardiac tissue, and the absence of light chain amyloid. They had not received disease-modifying therapies. Of 906 patients in the study, 61% had amyloidosis with the wild-type TTR gene and 39% had a hereditary form.

Patients underwent strain analysis with speckle-tracking echocardiography. The researchers also analyzed postmortem histology from 5 patients.

The postmortem histologic analysis showed amyloid infiltration in the left atria. There was fibrosis in the subendocardium but not the myocardial interstitium. Amyloid deposits were found in nodules in the myocardial interstitium and within fibrous tissue in the subendocardium.

The researchers found histologic evidence of myocardial remodeling but not myocyte injury. Vascular remodeling and decreased capillary networks were also observed.

By speckle-tracking echocardiography, the researchers found that patients with ATTR-CM had increased left atrial stiffness. Left atrial stiffness was associated with poorer survival after adjustment for other prognostic variables (P = .029).

The researchers also found evidence of left atrial functional impairment. Left atrial reservoir, conduit, and contraction functions were reduced.

Of the 62% of patients who were in sinus rhythm, 22% did not exhibit atrial contraction. This atrial electromechanical dissociation (AEMD) was associated with more severe diastolic dysfunction compared with patients in sinus rhythm who did have mechanical contraction.

Patients with AEMD also had reduced median survival compared with patients who were in sinus rhythm with mechanical contraction (P = .0018). These results indicated that cardiac dysfunction in ATTR-CM was not due solely to ventricular infiltration, and atrial involvement affected disease severity.

According to the researchers, their findings may also have some practical implications. First, left atrial stiffness may be useful as a prognostic factor. Second, screening for AEMD may also be useful to identify patients who do not have atrial fibrillation but may be prone to blood clots.

Source: Bandera F, Martone R, Chacko L, et al. Clinical importance of left atrial infiltration in cardiac transthyretin amyloidosis. JACC Cardiovasc Imaging. 2022;15:17-29.

Related Items

Subscribe to Amyloidosis News

Stay up to date with Amyloidosis News & updates by subscribing to receive the free AMN e‑Newsletter.

I'd like to receive: